Agilent 7890A Gas Chromatograph Advanced User Guide Agilent Technologies
Notices © Agilent Technologies, Inc. 2009 No part of this manual may be reproduced in any form or by any means (including electronic storage and retrieval or translation into a foreign language) without prior agreement and written consent from Agilent Technologies, Inc. as governed by United States and international copyright laws. Manual Part Number G3430-90015 Safety Notices CAUTION A CAUTION notice denotes a hazard.
Contents 1 Programming Run Time Programming 14 Using run time events 14 Programming run time events The run table 15 Adding events to the run table Editing events in the run table Deleting run time events 16 15 15 15 Clock Time Programming 17 Using clock time events 17 Programming clock time events Adding events to the clock table Editing clock time events 18 Deleting clock time events 18 17 17 User-Key Programming 19 To program a User Key 19 To play back (execute) the stored keystrokes To erase the st
Cryo Trap 40 Configure the cryo trap to the GC 40 Configure a heater to the cryo trap 40 Configure the coolant 40 Configure the user-configurable heater 41 Reboot the GC 41 Front Detector/Back Detector/Aux Detector/Aux Detector 2 To configure the makeup/reference gas 42 Lit offset 42 To configure the FPD heaters 42 Analog out 1/Analog out 2 Fast peaks 43 42 43 Valve Box 44 To assign a GC power source to a valve box heater 44 Thermal Aux 45 To assign a GC power source to an Aux thermal zone To configure
3 Options About Options 58 Calibration 59 Maintaining EPC calibration—inlets, detectors, PCM, and AUX To zero all pressure sensors in all modules 61 Column calibration 61 Communication 65 Configuring the IP address for the GC Keyboard and Display 4 65 66 Chromatographic Checkout About Chromatographic Checkout 68 To Prepare for Chromatographic Checkout To Check FID Performance 69 71 To Check TCD Performance 76 To Check NPD Performance 81 To Check uECD Performance 5 59 86 To Check FPD Perf
To start a sequence 114 To pause and resume a sequence To stop a sequence 115 To abort a sequence 115 6 115 Checking for Leaks Preparing the GC for Maintenance 118 Column and oven preparation 118 Inlet preparation 118 Detector preparation 118 Leak Check Tips 119 To Check for External Leaks To Check for GC Leaks 120 121 Leaks in Capillary Column (Microfluidic) Fittings 122 To Perform a SS Inlet Pressure Decay Test 123 To Correct Leaks in the Split Splitless Inlet 127 To Perform a Multimode Inle
Restrictors 162 Examples 163 1. Using an Aux epc channel to supply purge gas to a splitter 2.
Multiple injections with the MMI About the Packed Column Inlet Setting parameters 220 213 219 About the Cool On-Column Inlet 222 Setup modes of the COC inlet 223 Retention gaps 223 COC inlet temperature control 223 Setting COC inlet flows/pressures 224 Setting COC inlet parameters 225 About the PTV Inlet 226 PTV sampling heads 226 Heating the PTV inlet 227 Cooling the PTV inlet 228 PTV inlet split and pulsed split modes 228 PTV inlet splitless and pulsed splitless modes 232 PTV inlet solvent vent mode 23
Setting the oven parameters for constant temperature 282 Setting the oven parameters for ramped temperature 282 About the Oven Insert 284 About Columns 285 Selecting the correct packed glass column type 285 About the column modes 285 Select a column mode 286 Setting the column parameters for constant flow or constant pressure 287 Enter a flow or pressure program (optional) 287 Programming column pressure or flow 288 Backflushing a Column 289 Backflushing when connected to an MSD 289 Backflushing using a c
uECD gas flows 316 uECD linearity 316 uECD detector gas 316 uECD temperature 316 uECD analog output 317 Recommended starting conditions for new uECD methods uECD makeup gas notes 317 uECD temperature programming 318 Setting parameters for the uECD 318 About the NPD 319 New NPD features and changes 319 NPD software requirements 319 NPD flows and general information 319 NPD flow, temperature, and bead recommendations NPD required gas purity 322 Setting parameters for the NPD 323 Selecting an NPD bead type 324
Heating the valves 339 Valve temperature programming Configuring an Aux thermal zone Valve Control 341 The valve drivers 341 The internal valve drivers The external valve drivers Valve Types 339 340 341 342 343 Configuring a Valve 344 Controlling a Valve 345 From the keyboard 345 From the run or clock time tables 345 Simple valve: column selection 345 Gas sampling valve 346 Multiposition stream selection valve with sampling valve 12 347 7683B Sampler About the 7683B Sampler Hardware 350 Software 35
Cable Diagrams 363 Analog cable, general use 363 Remote start/stop cable 363 BCD cable 364 External event cable 365 14 GC Output Signals About Signals 368 Signal Types 369 Value 369 Analog Signals 371 Analog zero 371 Analog range 371 Analog data rates 372 Selecting fast peaks (analog output) 373 Digital Signals 374 Digital zero 374 Baseline level shifts 374 Agilent data systems 375 Zero Init Data Files 377 Column Compensation 378 Creating a column compensation profile 379 Making a run using analog out
Agilent 7890A Gas Chromatograph Advanced User Guide 1 Programming Run Time Programming 14 Using run time events 14 Programming run time events 15 The run table 15 Adding events to the run table 15 Editing events in the run table 15 Deleting run time events 16 Clock Time Programming 17 Using clock time events 17 Programming clock time events 17 Adding events to the clock table 17 Editing clock time events 18 Deleting clock time events 18 User-Key Programming 19 To play back (execute) the stored keystrokes 1
Run Time Programming Run time programming allows certain setpoints to change automatically during a run as a function of the chromatographic run time. Thus an event that is programmed to occur at 2 minutes will occur 2 minutes after every injection.
Programming run time events 1 Press [Run Table]. 2 Press [Mode/Type] to see the available run time events. 3 Scroll to the event to be programmed. Press [Enter]. 4 Enter values for the Time: and the other parameter. Press [Enter] after each entry. 5 Press [Mode/Type] to add another event. Press [Status] to terminate entries. The run table The programmed events are arranged in order of execution time in the Run Table. This is a brief example: RUN TABLE (1 of 3) Time: 0.
Deleting run time events 1 Press [Run Table]. 16 2 From within this table press [Delete] to delete events from the run time table. You will be asked to confirm the deletion. 3 Press [On/Yes] to delete the current timed event; press [Off/No] to cancel this operation. 4 To delete the entire table, press [Delete][Run Table].
Clock Time Programming Clock time programming allows certain setpoints to change automatically at a specified time during a 24- hour day. Thus, an event programmed to occur at 14:35 hours will occur at 2:35 in the afternoon. A running analysis or sequence has precedence over any clock table events occurring during this time. Such events are not executed.
5 Repeat this process until all entries are added. Editing clock time events 1 Press [Clock Table] to view all events programmed. 2 Scroll to the event you want to change. 3 To edit the time for an event, move the cursor to the line labelled Time: and type the desired time. 4 To edit a setpoint value, scroll to the setpoint item. Press [On/Yes] or [Off/No], or enter a numerical value for the setpoint. Deleting clock time events 1 Press [Clock Table].
User-Key Programming The two User Keys create macros (sets of frequently used keystrokes) and assign them to single keys. A macro is executed when the User Key is pressed. The stored keystrokes may be any keys except [Start], [Prog], [User Key 1], or [User Key 2]. This discussion assumes that you wish to program [User Key 1]. The process is the same for [User Key 2]. To program a User Key 1 Press [Prog]. Press [User Key 1]. 2 Press up to 31 keys, then press [User Key 1]. The keystrokes are stored.
Advanced User Guide
Agilent 7890A Gas Chromatograph Advanced User Guide 2 Configuration About Configuration 23 Assigning GC resources to a device 23 Setting configuration properties 24 General Topics 25 Unlock the GC Configuration 25 Ignore Ready = 25 Information displays 25 Unconfigured: 26 Oven 27 Front Inlet/Back Inlet 29 To configure the PTV or COC coolant 29 To configure the MMI coolant 31 Column # 33 To configure a single column 33 To configure multiple columns 35 Cryo Trap 40 Front Detector/Back Detector/Aux Detector/A
2 Configuration Time 51 Valve # 52 Front injector/Back injector 53 Sample tray (7683 ALS) 55 Instrument 56 22 Advanced User Guide
Configuration 2 About Configuration Configuration is a two- part process for most GC accessory devices that require power and/or communication resources from the GC. In the first part of the configuration process, a power and/or communication resource is assigned to the device. The second part of the configuration process allows setting of any configuration properties associated with the device.
2 Configuration Status Time Valve # 2 Dimensional GC Valve Front injector Back injector Sample tray Instrument In many cases you can move directly to the item of interest by pressing [Config][device]. 3 When the Configure Device Display opens, the cursor should be on the Unconfigured field. Press [Mode/Type] and follow the GC prompts to assign resources to the device. 4 After assigning resources, the GC prompts for you to power cycle the GC. Turn the GC power switch off and then on.
2 Configuration General Topics Unlock the GC Configuration Accessory devices including inlets, detectors, pressure controllers (AUX EPC and PCM), and temperature control loops (Thermal AUX) have electrical connections to a power source and/or the communication bus in the GC. These devices must be assigned GC resources before they can be used. Before assigning resources to a device, you must first unlock the GC configuration.
2 Configuration [ EPC3 ] = (DET-EPC) (FID) to an FID. EPC #3 is controlling detector gases [ EPC6 ] = (AUX_EPC) (PCM) EPC #6 is controlling a two- channel pressure control module. FINLET (OK) 68 watts 21.7 This heater is connected to the front inlet. Status = OK, meaning that it is ready for use. At the time that the GC was turned on, the heater was drawing 68 watts and the inlet temperature was 21.7 °C. [ F-DET ] = (SIGNAL) (FID) detector is type FID.
2 Configuration Oven See “Unconfigured:” on page 26 and “Ignore Ready =” on page 25. Maximum temperature Sets an upper limit to the oven temperature. Used to prevent accidental damage to columns. The range is 70 to 450 °C. Equilibration time The time after the oven approaches its setpoint before the oven is declared Ready. The range is 0 to 999.99 minutes. Used to ensure that the oven contents have stabilized before starting another run.
2 Configuration 6 Scroll to Slow oven cool down mode. Press [On/Yes] to run the oven fan at reduced speed during cool down, or [Off/No] to run it at normal speed. To configure the oven for cryogenic cooling All cryogenic setpoints are in the [Config][Oven] parameter list. Cryo [ON] enables cryogenic cooling, [OFF] disables it. Quick cryo cool This feature is separate from Cryo. Quick cryo cool makes the oven cool faster after a run than it would without assistance.
2 Configuration Front Inlet/Back Inlet See “Unconfigured:” on page 26 and “Ignore Ready =” on page 25. To configure the Gas type The GC needs to know what carrier gas is being used. 1 Press [Config][Front Inlet] or [Config][Back Inlet]. 2 Scroll to Gas type and press [Mode/Type]. 3 Scroll to the gas you will use. Press [Enter]. This completes carrier gas configuration. To configure the PTV or COC coolant Press [Config][Front Inlet] or [Config][Back Inlet].
2 Configuration Cryo timeout Use this setting to conserve cryogenic fluid. If selected, the instrument shuts down the inlet and cryogenic (subambient) cooling (if installed) when no run starts in the number of minutes specified. The setpoint range is 2 to 120 minutes (default 30 minutes). Turning cryo timeout off disables this feature. We recommend cryo timeout enabling to conserve coolant at the end of a sequence or if automation fails. A Post Sequence method could also be used.
Configuration 2 To configure the MMI coolant Press [Config][Front Inlet] or [Config][Back Inlet]. If the inlet has not been configured previously, a list of available coolants is displayed. Scroll to the desired coolant and press [Enter]. Cryo type/Cooling type [Mode/Type] displays a list of available coolants. Scroll to the desired coolant and press [Enter]. Normally, select the coolant type that matches the installed hardware.
2 Configuration Cryo fault This parameter is available with N2 cryo and CO2 cryo Cryo types. Shuts down the inlet temperature if it does not reach setpoint in 16 minutes of continuous cryo operation. Note that this is the time to reach the setpoint, not the time to stabilize and become ready at the setpoint. Shutdown behavior Both Cryo timeout and Cryo fault can cause cryo shutdown. If this happens, the inlet heater is turned off and the cryo valve closes. The GC beeps and displays a message.
2 Configuration Column # Length The length, in meters, of a capillary column. Enter 0 for a packed column or if the length is not known. Diameter The inside diameter, in millimeters, of a capillary column. Enter 0 for a packed column. Film thickness The thickness, in millimeters, of the stationary phase for capillary columns. Inlet Identifies the source of gas for the column. Outlet Identifies the device into which the column effluent flows.
2 Configuration Except for the simplest configurations, such as a column connected to a specific inlet and detector, we recommend that you begin by making a sketch of how the column will be connected. 1 Press [Config][Col 1] or [Config][Col 2], or press [Config][Aux Col #] and enter the number of the column to be configured. 2 Scroll to the Length line, type the column length, in meters, followed by [Enter]. 3 Scroll to Diameter, type the column inside diameter in microns, followed by [Enter].
2 Configuration You should check configurations for all columns to verify that they specify the correct pressure control device at each end. The GC uses this information to determine the flow path of the carrier gas. Only configure columns that are in current use in your GC’s carrier gas flow path. Unused columns configured with the same pressure control device as a column in the current flow path cause incorrect flow results.
2 Configuration Table 1 Choices for column configuration (continued) Inlet Outlet Unspecified PCM A, B, and C Thermal zone Aux PCM A, B, and C Front inlet Back inlet Other Inlets and outlets The pressure control devices at the inlet and outlet ends of a column, or series of columns in a flow path, control its gas flow. The pressure control device is physically attached to the column through a connection to a GC inlet, a valve, a splitter, a union, or other device.
2 Configuration A simple example An analytical column is attached at its inlet end to a spit/splitless inlet located at the front of the GC and the column outlet is attached to an FID located at the front detector position.
2 Configuration If other columns are currently defined, they may not use AUX 1, Front inlet, Front detector, or Back detector in their configuration. Complicated example The inlet feeds the analytical column which ends at a three- way splitter. The splitter has the column effluent and makeup gas coming in, and transfer lines (non- coated columns) to three different detectors. This is a case where a sketch is necessary. Split/splitless inlet Aux EPC µECD FPD 0.507 m x 0.10 mm x 0 µm MSD 0.
Configuration 2 The flows to the three detectors are based on the pressure drops through the capillaries and their resistance to flow. An Agilent flow calculator provided with the capillary flow splitter device is used to size the length and diameter of these capillary sections to obtain the desired split ratios. Your analytical method can set the flow or pressure for column # 2, the lowest numbered column in the split.
2 Configuration Cryo Trap This discussion assumes that the trap is mounted in position B, that you use liquid nitrogen coolant and control the trap with Thermal Aux 1. Configuration is in several parts: • Configure the trap to the GC • Configure a heater to the cryo trap. • Configure the coolant. • Configure the user- configurable heater. • Reboot the GC. Configure the cryo trap to the GC 1 Press [Config], then [Aux Temp #] and select Thermal Aux 1. Press [Enter]. 2 Press [Mode/Type].
2 Configuration If the value is not N2, press [Mode/Type], select N2 Cryo, press [Enter] and then [Clear]. This tells the GC what coolant will be used. Configure the user-configurable heater Many of the following steps tell you to reboot the GC. Ignore these requests by pressing [Clear]. Do not reboot until specifically told to do so in these instructions. 1 Press [Config] and select Aux 1. Press [Enter]. 2 Enter the following control values. Press [Enter], then [Clear] after each one.
2 Configuration Front Detector/Back Detector/Aux Detector/Aux Detector 2 See Ignore Ready = and “Unconfigured:” on page 26. To configure the makeup/reference gas The makeup gas line of your detector parameter list changes depending on your instrument configuration. If you have an inlet with the column not defined, the makeup flow is constant. If you are operating with column defined, you have a choice of two makeup gas modes. See “About Makeup Gas” on page 298 for details.
Configuration 2 Analog out 1/Analog out 2 Fast peaks The GC allows you to output analog data at two speeds. The faster speed—to be used only with the FID, FPD, and NPD—allows minimum peak widths of 0.004 minutes (8 Hz bandwidth), while the standard speed—which can be used with all detectors— allows minimum peak widths of 0.01 minutes (3.0 Hz bandwidth). To use fast peaks: 1 Press [Config][Analog out 1] or [Config][Analog out 2]. 2 Scroll to Fast peaks and press [On/Yes].
2 Configuration Valve Box See “Unconfigured:” on page 26 and “Ignore Ready =” on page 25. The valve box mounts on top of the column oven. It may contain up to four valves mounted on heated blocks. Each block can accommodate two valves. Valve positions on the blocks are numbered. We suggest that valves be installed in the blocks in numeric order. All heated valves in a valve box are controlled by the same temperature setpoint.
2 Configuration Thermal Aux See “Unconfigured:” on page 26 and “Ignore Ready =” on page 25. The auxiliary thermal controllers provide up to three channels of temperature control. These controllers are labeled Thermal Aux 1, Thermal Aux 2, and Thermal Aux 3. To assign a GC power source to an Aux thermal zone This procedure assigns a the heater power source from heater plug A1 or A2 to Thermal Aux 1, Thermal Aux 2, or Thermal Aux 3 temperature control zones.
2 Configuration To configure a nickel catalyst heater 1 Check that a power source for the Nickel Catalyst heater was assigned. See “To assign a GC power source to an Aux thermal zone” on page 45. 2 Press [Config][Aux Temp #] and scroll to Thermal Aux 1, Thermal Aux 2, or Thermal Aux 3 depending on where the Nickel Catalyst heater was assigned, and press [Enter]. 3 Scroll to Auxiliary type, press [Mode/Type], scroll to and select Nickel catalyst, and press [Enter].
2 Configuration PCM A/PCM B/PCM C See “Unconfigured:” on page 26 and “Ignore Ready =” on page 25. A pressure control module (PCM) provides two channels of gas control. Channel 1 is a simple forward- pressure regulator that maintains a constant pressure at its output. With a fixed downstream restrictor, it provides constant flow. Channel 2 is more versatile. With the normal flow direction (in at the threaded connector, out via the coiled tubing), it is similar to channel 1.
2 Configuration 4 Scroll to Aux Mode:, press [Mode/Type], select one of the following and press [Enter]: • Forward Pressure Control - Aux channel • Back Pressure Control- Aux channel For a definition of these terms see “Pressure Control Modules” on page 158. The pressure control mode for the main channel is set by pressing [Aux EPC #]. Select Mode: , press [Mode/Type], select the mode and press [Enter].
2 Configuration Pressure aux 1,2,3/Pressure aux 4,5,6/Pressure aux 7,8,9 See Ignore Ready = and “Unconfigured:” on page 26. An auxiliary pressure controller provides three channels of forward- pressure regulation. Three modules can be installed for a total of nine channels. The numbering of the channels depends on where the controller is installed. See “Auxiliary Pressure Controllers” on page 161 for details.
2 Configuration Status The [Status] key has two tables associated with it. You switch between them by pressing the key. The Ready/Not Ready status table This table lists parameters that are Not Ready or gives you a Ready for Injection display. If there are any faults, warnings, or method mismatches present, they are displayed here. The setpoint status table This table lists setpoints compiled from the active parameter lists on the instrument.
2 Configuration Time Press [Time] to open this function. The first line always displays the current date and time, and the last line always displays a stopwatch. The two middle lines vary: Between runs During a run Show last and next (calculated) run times. Show time elapsed and time remaining in the run. During Post Run time. Show last run time and remaining Post Run To set time and date 1 Press [Config][Time].
2 Configuration Valve # Up to 4 valves can be mounted in a temperature- controlled valve box and are normally wired to the valve box bracket V1 through V4 plugs, located inside the electrical compartment. Additional valves or other devices (4 through 8) can be wired using the plug labeled EVENT on the back of the GC. To configure a valve 1 Press [Config][Valve #] and enter the number (1 to 8) of the valve you are configuring. The current valve type is displayed.
2 Configuration Front injector/Back injector The GC supports two models of samplers. For the 7693A samplers, the GC recognizes which injector is plugged into which connector, INJ1 or INJ2. No configuration is needed. To move an injector from one inlet to another requires no settings: the GC detects the injector position. To configure the 7693A sampler system, see the 7693A Installation, Operation, and Maintenance manual.
2 Configuration To configure an injector (7683 ALS) This section applies to the 7683 ALS system. To configure the 7693A sampler system, see the 7693A Installation, Operation, and Maintenance manual. 1 Press [Config][Front Injector] or [Config][Back Injector]. 54 2 Scroll to Front/Back tower. 3 Press [Off/No] to change the present tower position from INJ1 to INJ2 or from INJ2 to INJ1.
Configuration 2 Sample tray (7683 ALS) This section applies to the 7683 ALS system. To configure the 7693A sampler system, see the 7693A Installation, Operation, and Maintenance manual. 1 Press [Config][Sample Tray]. 2 If the vial gripper is touching vials either too high or too low for reliable pickup, scroll to Grip offset and press [Mode/Type] to select: • Up to increase the gripper arm pickup height • Default • Down to decrease the gripper arm pickup height 3 Scroll to Bar Code Reader.
2 Configuration Instrument 1 Press [Config]. Scroll to Instrument and press [Enter]. 2 Scroll to Serial #. Enter a serial number and press [Enter]. This function can only be done by Agilent service personnel. 3 Scroll to Auto prep run. Press [On/Yes] to enable Auto prep run, [Off/No] to disable it. See “Pre Run and Prep Run” on page 171 for details. 4 Scroll to Zero Init Data Files. • Press [On/Yes] to enable it.
Agilent 7890A Gas Chromatograph Advanced User Guide 3 Options About Options 58 Calibration 59 Maintaining EPC calibration—inlets, detectors, PCM, and AUX 59 Auto zero septum purge 60 Auto flow zero 59 Zero conditions 60 Zero intervals 60 To zero a specific flow or pressure sensor 60 To zero all pressure sensors in all modules 61 Column calibration 61 Communication 65 Configuring the IP address for the GC 65 Keyboard and Display 66 Agilent Technologies 57
3 Options About Options The [Options] key is used for a group of functions that are usually set on installation and seldom changed afterward.
Options 3 Calibration Press [Calibration] to list the parameters that can be calibrated. These include: • Inlets • Detectors • ALS • Columns • Oven • Atmospheric pressure In general, you will only need to calibrate the EPC modules and capillary columns. ALS, oven, and atmospheric pressure calibration should only be performed be trained service personnel. The calibration displays are discussed in the Agilent 7890A Service Manual.
3 Options sensor output, and turns the gas back on. This takes about two seconds. The zero offset is used to correct future flow measurements. To activate this, select Calibration on the Options menu, then choose either Front inlet or Back inlet, press [Enter], and turn Auto flow zero on. Auto zero septum purge This is similar to Auto flow zero, but is for the septum purge flow. Zero conditions Flow sensors are zeroed with the carrier gas connected and flowing.
Options 3 Pressure sensors. Disconnect the gas supply line at the back of the GC. Turning it off is not adequate; the valve may leak. 4 Press [On/Yes] to zero or [Clear] to cancel. To zero all pressure sensors in all modules 1 Press [Service Mode], scroll to Diagnostics, and press [Enter]. 2 Scroll to Electronics and press [Enter]. 3 Scroll to Pneumatics and press [Enter]. 4 Scroll to Zero all pressure sensors and press [Info].
3 Options CAUTION When you measure the column flow rate, be sure to convert the measurement to normal temperature and pressure if your measurement device does not report data at NTP. If you enter uncorrected data, the calibration will be wrong. To estimate the actual column length or diameter from an elution time 1 Set oven ramp 1 to 0.00, then verify that the column is defined. 2 Perform a run using an unretained compound and record the elution time.
3 Options CAUTION When you measure the column flow rate, be sure to convert the measurement to normal temperature and pressure if your measurement device does not report data at NTP. If you enter uncorrected data, the calibration will be wrong. 4 Measure the actual flow rate through the column using a bubble meter. Record the value. Reinstall the column. 5 Press [Options], scroll to Calibration and press [Enter]. 6 From the calibration list, select the column and press [Enter].
3 Options CAUTION When you measure the column flow rate, be sure to convert the measurement to normal temperature and pressure if your measurement device does not report data at NTP. If you enter uncorrected data, the calibration will be wrong. 5 Measure the actual flow rate through the column using a bubble meter. Record the value. Reinstall the column. 6 Press [Options], scroll to Calibration and press [Enter]. 7 From the calibration list, select the column and press [Enter].
3 Options Communication Configuring the IP address for the GC For network (LAN) operation, the GC needs an IP address. It can get this from a DHCP server, or it can be entered directly from the keyboard. In either case, see your LAN administrator. To use a DHCP server 1 Press [Options]. Scroll to Communications and press [Enter]. 2 Scroll to Enable DHCP and press [On/Yes]. When prompted, turn the GC off and then on again. To set the LAN address at the keyboard 1 Press [Options].
3 Options Keyboard and Display Press [Options] and scroll to Keyboard and Display. Press [Mode/Type]. The following parameters are turned on and off by pressing the [On/Yes] or [Off/No] keys. Keyboard lock These keys and functions are operational when the keyboard lock is On: [Start], [Stop], and [Prep Run] [Load][Method] and [Load][Seq] [Seq]—to edit existing sequences [Seq Control]—to start or stop sequences. Hard configuration lock On prevents keyboard configuration changes; Off removes lock.
Agilent 7890A Gas Chromatograph Advanced User Guide 4 Chromatographic Checkout About Chromatographic Checkout 68 To Prepare for Chromatographic Checkout 69 To Check FID Performance 71 To Check TCD Performance 76 To Check NPD Performance 81 To Check uECD Performance 86 To Check FPD Performance (Sample 5188-5953) 91 To Verify FPD Performance (Sample 5188-5245) 98 Agilent Technologies 67
4 Chromatographic Checkout About Chromatographic Checkout The tests described in this section provide basic confirmation that the GC and detector can perform comparably to factory condition. However, as detectors and the other parts of the GC age, detector performance can change. The results presented here represent typical outputs for typical operating conditions and are not specifications. The tests assume the following: • Use of an automatic liquid sampler.
Chromatographic Checkout 4 To Prepare for Chromatographic Checkout Because of the differences in chromatographic performance associated with different consumables, Agilent strongly recommends using the parts listed here for all checkout tests. Agilent also recommends installing new consumable parts whenever the quality of the installed ones is not known. For example, installing a new liner and septum ensures that they will not contribute any contamination to the results.
4 Chromatographic Checkout Table 8 Recommended parts for checkout by inlet type (continued) Recommended part for checkout Part number 0.32-mm needle for 5-µL syringe 5182-0831 7693A ALS: Needle support insert, COC G4513-40529 7683B ALS: Needle support assembly for 0.25/0.32 mm injections G2913-60977 Insert, fused silica, 0.
4 Chromatographic Checkout To Check FID Performance 1 Gather the following: • Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm (19091J- 413) • FID performance evaluation (checkout) sample (5188- 5372) • Chromatographic- grade isooctane • 4- mL solvent and waste bottles or equivalent for autoinjector • 2- mL sample vials or equivalent for sample 2 Verify the following: • Capillary column jet installed. If not, select and install a capillary column jet.
4 Chromatographic Checkout Table 9 FID Checkout Conditions Column and sample Type HP-5, 30 m × 0.32 mm × 0.25 µm (19091J-413) Sample FID checkout 5188-5372 Column flow 6.5 mL/min Column mode Constant flow Split/splitless inlet Temperature 250 °C Mode Splitless Purge flow 40 mL/min Purge time 0.5 min Septum purge 3 mL/min Gas saver Off Multimode inlet Mode Splitless Inlet temperature 75 °C Initial time 0.1 min Rate 1 720 °C/min Final temp 1 250 °C Final time 1 5.
Chromatographic Checkout Table 9 4 FID Checkout Conditions (continued) Inlet temperature 75 °C Initial time 0.1 min Rate 1 720 °C/min Final temp 1 350 °C Final time 1 2 min Rate 2 100 °C/min Final temp 2 250 °C Final time 2 0 min Purge time 0.5 min Purge flow 40 mL/min Septum purge 3 mL/min Detector Temperature 300 °C H2 flow 30 mL/min Air flow 400 mL/min Makeup flow (N2) 25 mL/min Lit offset Typically 2 pA Oven Initial temp 75 °C Initial time 0.
4 Chromatographic Checkout Table 9 FID Checkout Conditions (continued) Solvent A wash volume 8 Solvent B pre washes 0 Solvent B post washes 0 Solvent B wash volume 0 Injection mode (7693A) Normal Airgap Volume (7693A) 0.20 Viscosity delay 0 Inject Dispense Speed (7693A) 6000 Plunger speed (7683) Fast, for all inlets except COC.
Chromatographic Checkout FID1 A, (C:\FID.
4 Chromatographic Checkout To Check TCD Performance 1 Gather the following: • Evaluation column, HP- 5 30 m × 0.32 mm × 0.
Chromatographic Checkout Table 10 4 TCD Checkout Conditions (continued) Mode Splitless Purge flow 60 mL/min Purge time 0.75 min Septum purge 3 mL/min Multimode inlet Mode Splitless Inlet temperature 40 °C Initial time 0.1 min Rate 1 720 °C/min Final temp 1 350 °C Final time 1 2 min Purge time 1.
4 Chromatographic Checkout Table 10 TCD Checkout Conditions (continued) Septum purge 3 mL/min Detector Temperature 300 °C Reference flow (He) 20 mL/min Makeup flow (He) 2 mL/min Baseline output < 30 display counts on Agilent ChemStation (< 750 µV) Oven Initial temp 40 °C Initial time 0 min Rate 1 20 °C/min Final temp 90 °C Final time 0 min Rate 2 15 °C/min Final temp 170 °C Final time 0 min ALS settings (if installed) 78 Sample washes 2 Sample pumps 6 Sample wash volume
4 Chromatographic Checkout Table 10 TCD Checkout Conditions (continued) Plunger speed (7683) Fast, for all inlets except COC. PreInjection dwell 0 PostInjection dwell 0 Manual injection Injection volume 1 µL Data system Data rate 5 5 Hz Display the signal output. A stable output at any value between 12.5 and 750 µV (inclusive) is acceptable. • If the baseline output is < 0.5 display units (< 12.5 µV), verify that the detector filament is on. If the offset is still < 0.5 display units (< 12.
4 Chromatographic Checkout 25 uV 70 C14 C15 C16 60 50 40 30 20 2 4 6 8 Time (min.
Chromatographic Checkout 4 To Check NPD Performance 1 Gather the following: • Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm (19091J- 413) • NPD performance evaluation (checkout) sample (18789- 60060) • 4- mL solvent and waste bottles or equivalent for autoinjector. • Chromatographic- grade isooctane • 2- mL sample vials or equivalent for sample. 2 Verify the following: • Capillary column jet installed. If not, select and install a capillary column jet. • Capillary column adapter installed.
4 Chromatographic Checkout Table 11 NPD Checkout Conditions (continued) Column flow 6.5 mL/min (helium) Split/splitless inlet Temperature 200 °C Mode Splitless Purge flow 60 mL/min Purge time 0.75 min Septum purge 3 mL/min Multimode inlet Mode Splitless Inlet temperature 60 °C Initial time 0.1 min Rate 1 720 °C/min Final temp 1 350 °C Final time 1 2 min Purge time 1.
Chromatographic Checkout Table 11 4 NPD Checkout Conditions (continued) Final time 2 0 min Purge time 0.
4 Chromatographic Checkout Table 11 NPD Checkout Conditions (continued) Inject Dispense Speed (7693A) 6000 Plunger speed (7683) Fast, for all inlets except COC. PreInjection dwell 0 PostInjection dwell 0 Manual injection Injection volume 1 µL Data system Data rate 5 Hz 6 If using a data system, prepare the data system to perform one run using the loaded checkout method. Make sure that the data system will output a chromatogram. 7 Start the run.
Chromatographic Checkout NPD1 B, (C:\NPD.
4 Chromatographic Checkout To Check uECD Performance 1 Gather the following: • Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm (19091J- 413) • uECD performance evaluation (checkout) sample (18713–60040, Japan: 5183- 0379) • 4- mL solvent and waste bottles or equivalent for autoinjector. • Chromatographic- grade isooctane • 2- mL sample vials or equivalent for sample. 2 Verify the following: • Clean fused silica indented mixing liner installed. If not, install it.
Chromatographic Checkout Table 12 4 uECD Checkout Conditions Column and sample Type HP-5, 30 m × 0.32 mm × 0.25 µm (19091J-413 Sample µECD checkout (18713-60040 or Japan: 5183-0379) Column mode Constant flow Column flow 6.5 mL/min (helium) Split/splitless inlet Temperature 200 °C Mode Splitless Purge flow 60 mL/min Purge time 0.75 min Septum purge 3 mL/min Multimode inlet Mode Splitless Inlet temperature 80 °C Initial time 0.
4 Chromatographic Checkout Table 12 uECD Checkout Conditions (continued) Inlet temperature 80 °C Initial time 0.1 min Rate 1 720 °C/min Final temp 1 350 °C Final time 1 2 min Rate 2 100 °C/min Final temp 2 250 °C Final time 2 0 min Purge time 0.
Chromatographic Checkout Table 12 4 uECD Checkout Conditions (continued) Solvent B post washes 0 Solvent B wash volume 0 Injection mode (7693A) Normal Airgap Volume (7693A) 0.20 Viscosity delay 0 Inject Dispense Speed (7693A) 6000 Plunger speed (7683) Fast, for all inlets except COC.
4 Chromatographic Checkout ECD1 B, (C:\ECD.
Chromatographic Checkout 4 To Check FPD Performance (Sample 5188-5953) To check FPD performance, first check the phosphorus performance, then the sulfur performance. Preparation 1 Gather the following: • Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm (19091J- 413) • FPD performance evaluation (checkout) sample (5188- 5953) • Phosphorus filter • Sulfur filter and filter spacer • 4- mL solvent and waste bottles or equivalent for autoinjector. • 2- mL sample vials or equivalent for sample.
4 Chromatographic Checkout Table 13 FPD Checkout Conditions (P) Column and sample Type HP-5, 30 m × 0.32 mm × 0.25 µm (19091J-413) Sample FPD checkout (5188-5953) Column mode Constant pressure Column pressure 25 psi Split/splitless inlet Temperature 200 °C Split/splitless Mode Splitless Purge flow 60 mL/min Purge time 0.75 min Septum purge 3 mL/min Multimode inlet Mode Splitless Inlet temperature 75 °C Initial time 0.
Chromatographic Checkout Table 13 4 FPD Checkout Conditions (continued)(P) Initial time 0.1 min Rate 1 720 °C/min Final temp 1 350 °C Final time 1 2 min Rate 2 100 °C/min Final temp 2 250 °C Final time 2 0 min Purge time 0.
4 Chromatographic Checkout Table 13 FPD Checkout Conditions (continued)(P) Sample pumps 6 Sample wash volume 8 Injection volume 1 µL Syringe size 10 µL Solvent A pre washes 2 Solvent A post washes 2 Solvent A wash volume 8 Solvent B pre washes 0 Solvent B post washes 0 Solvent B wash volume 0 Injection mode (7693A) Normal Airgap Volume (7693A) 0.20 Viscosity delay 0 Inject Dispense Speed (7693A) 6000 Plunger speed (7683) Fast, for all inlets except COC.
Chromatographic Checkout 4 If the baseline output is zero, verify the electrometer is on and the flame is lit. 9 If using a data system, prepare the data system to perform one run using the loaded checkout method. Make sure that the data system will output a chromatogram. 10 Start the run. If performing an injection using an autosampler, start the run using the data system or press [Start] on the GC.
4 Chromatographic Checkout Table 14 Evaluating checkout runs FPD P filter Typical range after 24 hours Limits at installation Noise 1.6 to 3.0 ≤4 Half-width (min) 0.05 to 0.07 — Output 34 to 80 ≤80 Sulfur performance 12 Install the sulfur filter and filter spacer. 13 Make the following method parameter changes. Table 15 Sulfur method parameters (S) Parameter Value ( mL/min) H2 flow 50 Air flow 60 14 Ignite the FPD flame if not lit. 15 Display the signal output and monitor.
Chromatographic Checkout 4 If performing a manual injection (with or without a data system): a Press [Prep Run] to prepare the inlet for splitless injection. b When the GC becomes ready, inject 1 µL of the checkout sample and press [Start] on the GC. 18 The following chromatogram shows typical results for a new detector with new consumable parts installed.
4 Chromatographic Checkout To Verify FPD Performance (Sample 5188-5245) To verify FPD performance, first check the phosphorus performance, then the sulfur performance. Preparation 1 Gather the following: • Evaluation column, DB5 15 m × 0.32 mm × 1.0 µm (123- 5513) • FPD performance evaluation (checkout) sample (5188- 5245) • Phosphorus filter • Sulfur filter and filter spacer • 4- mL solvent and waste bottles or equivalent for autoinjector. • 2- mL sample vials or equivalent for sample.
Chromatographic Checkout Table 17 4 FPD Phosphorus Checkout Conditions Column and sample Type DB-5MS, 15 m × 0.32 mm × 1.0 µm (123-5513) Sample FPD checkout (5188-5245) Column mode Constant flow Column flow 7.5 mL/min Split/splitless inlet Temperature 250 °C Mode Splitless Total purge flow 69.5 mL/min Purge flow 60 mL/min Purge time 0.75 min Septum purge 3 mL/min Multimode inlet Mode Splitless Inlet temperature 80 °C Initial time 0.
4 Chromatographic Checkout Table 17 FPD Phosphorus Checkout Conditions (continued) Inlet temperature 80 °C Initial time 0.1 min Rate 1 720 °C/min Final temp 1 350 °C Final time 1 2 min Rate 2 100 °C/min Final temp 2 250 °C Final time 2 0 min Purge time 0.75 min Purge flow 60 mL/min Septum purge 3 mL/min Detector Temperature 200 °C (On) Hydrogen flow 75.0 mL/min (On) Air (oxidizer) flow 100.0 mL/min (On) Mode Constant makeup flow Off Makeup flow 60.
Chromatographic Checkout Table 17 4 FPD Phosphorus Checkout Conditions (continued) Sample washes 2 Sample pumps 6 Sample wash volume 8 Injection volume 1 µL Syringe size 10 µL Solvent A pre washes 2 Solvent A post washes 2 Solvent A wash volume 8 Solvent B pre washes 0 Solvent B post washes 0 Solvent B wash volume 0 Injection mode (7693A) Normal Airgap Volume (7693A) 0.
4 Chromatographic Checkout If the baseline output is zero, verify the electrometer is on and the flame is lit. 9 If using a data system, prepare the data system to perform one run using the loaded checkout method. Make sure that the data system will output a chromatogram. 10 Start the run. If performing an injection using an autosampler, start the run using the data system or press [Start] on the GC.
4 Chromatographic Checkout Table 18 Evaluating checkout runs FPD P filter Typical range after 24 hours Limits at installation Noise 1.6 to 3.0 ≤4 Half-width (min) 0.05 to 0.07 — Output 34 to 80 ≤80 Sulfur performance 12 Install the sulfur filter. 13 Make the following method parameter changes. Table 19 Sulfur method parameters Parameter Value ( mL/min) H2 flow 50 Air flow 60 14 Ignite the FPD flame, if not lit. 15 Display the signal output and monitor.
4 Chromatographic Checkout If performing a manual injection (with or without a data system): a Press [Prep Run] to prepare the inlet for splitless injection. b When the GC becomes ready, inject 1 µL of the checkout sample and press [Start] on the GC. 18 The following chromatogram shows typical results for a new detector with new consumable parts installed.
Agilent 7890A Gas Chromatograph Advanced User Guide 5 Methods and Sequences Creating Methods 106 To program a method 107 To program the ALS 107 To program the ALS sampler tray 107 To program the 7683B ALS bar code reader 108 To save a method 109 To load a stored method 109 Method mismatch 109 Creating Sequences 111 About the priority sequence 111 To program a sequence 111 To program a priority sequence 112 To program an ALS subsequence 113 To program a valve subsequence 113 To program post sequence events
5 Methods and Sequences Creating Methods A method is the group of setpoints needed to run a single sample on the GC, such as oven temperature programs, pressure programs, inlet temperatures, sampler parameters, etc. A method is created by saving a group of setpoints as a numbered method using the [Store] key. At least 10 methods can be stored. Components for which setpoint parameters can be stored are shown in Table 21.
5 Methods and Sequences The GC also saves ALS setpoints. See the 7693A Installation, Operation, and Maintenance manual for details on its setpoints. Setpoint parameters are saved when the GC is turned off and loaded when you turn the instrument back on. However, if the hardware was changed while the instrument was turned off, it may not be possible to restore all setpoints in the method.
5 Methods and Sequences Configuration issues 1 To edit the sample tray configuration setpoints, press [Config][Sample Tray]. Normally, no tray configuration is required. If using a bar code reader and the tray gripper arm has difficulties retrieving a vial from the bar code reader, adjust the gripper offset (step 2). If the sample vial contacts the side of the turret hole when the tray delivers or retrieves the sample vial, then adjust the injector offset (step 3).
5 Methods and Sequences • Enable 3 of 9—encodes both letters and numbers, plus a few punctuation marks, and message length can be varied to suit both the amount of data to be encoded and the space available • Enable 2 of 5—restricted to numbers but does allow variable message length • Enable UPC code—restricted to numbers- only with fixed message length • Enable checksum—verifies that the checksum in the message matches the checksum calculated from the message characters, but does not include the checksum
5 Methods and Sequences Suppose your standalone GC is equipped with a single FID. You have created and saved methods that use this detector. Now you remove the FID and install a TCD in its place. When you try to load one of your stored methods, you observe an error message saying that the method and the hardware do not match. The problem is that the actual hardware is no longer the same as the hardware configuration saved in the method.
5 Methods and Sequences Creating Sequences A sequence specifies the samples to be run and the stored method to be used for each. The sequence is divided into a priority sequence (ALS only), subsequences (each of which uses a single method), and post- sequence events • Priority sequence—allows you to interrupt a running ALS or valve sequence to analyze urgent samples. (See “About the priority sequence” on page 111.
5 Methods and Sequences priority sequence, you must program it now. (Once the sequence starts, you cannot edit it without stopping it.) 3 Scroll to the Method # line of Subseq 1 and enter a method number. Use 0 for the currently active method, 1 to 9 for the stored methods, or [Off/No] to end the sequence. 4 Press [Mode/Type] to select a valve or injector type. (See “To program a valve subsequence” on page 113 or “To program an ALS subsequence” on page 113.
5 Methods and Sequences To program an ALS subsequence 1 See step 1 through step 3 of “To program a sequence” on page 111. 2 Press [Mode/Type] and select the injector type. 3 Enter injector sequence parameters (if using both injectors, there will be two sets of parameters): • Number of Injections/vial—the number of repeat runs from each vial. Enter 0 if no samples are to be injected. • Samples—the range (first–last) of sample vials to be analyzed.
5 Methods and Sequences To save a sequence 1 Press [Store][Seq]. 2 Enter an identifying number for the sequence. 3 Press [On/Yes] to store the sequence. Alternatively, press [Off/No] to cancel. A message is displayed if a sequence with the number you selected already exists. • Press [On/Yes] to replace the existing sequence or [Off/No] to cancel. Sequences can also be stored from within the stored sequence list ([Seq]) by scrolling to the appropriate sequence number and pressing the [Store] key.
5 Methods and Sequences Ready wait If a sequence is started but the instrument is not ready (due to oven temperature, equilibration times, etc.), the sequence will not start until all instrument setpoints are ready To pause and resume a sequence Press [Seq Control], scroll to Pause sequence, and press [Enter]. The sequence status changes to paused, and you are given the option to resume or stop the paused sequence. The sequence halts when the current sample run is complete.
5 116 Methods and Sequences Advanced User Guide
Agilent 7890A Gas Chromatograph Advanced User Guide 6 Checking for Leaks Preparing the GC for Maintenance 118 To Check for External Leaks 120 To Check for GC Leaks 121 Leaks in Capillary Column (Microfluidic) Fittings 122 To Perform a SS Inlet Pressure Decay Test 123 To Correct Leaks in the Split Splitless Inlet 127 To Perform a Multimode Inlet Pressure Decay Test 128 To Correct Leaks in the Multimode Inlet 132 To Perform a SS Inlet Pressure Decay Test 123 To Correct Leaks in the Packed Column Inlet 137 To
6 Checking for Leaks Preparing the GC for Maintenance Before most maintenance procedures, the GC must be made ready. The purpose of this preparation is to avoid damage to both the instrument (electronics, columns, etc.) and the user (shocks, burns). Column and oven preparation The main hazards here are temperature (burns) and column exposure to air. • Cool the oven by changing its setpoint to 35 °C. This allows the oven fan to assist cooling. • Leave the carrier gas flow On until the oven has cooled.
6 Checking for Leaks Leak Check Tips When checking for leaks, consider the system in two parts: external leak points and GC leak points. • External leak points include the gas cylinder (or gas purifier), regulator and its fittings, supply shutoff valves, and connections to the GC supply fittings. • GC leak points include inlets, detectors, column connections, valve connections, and connections between flow modules and inlets/detectors.
6 Checking for Leaks To Check for External Leaks Check for leaks at these connections: • Gas supply bulkhead fittings • Gas cylinder fitting • Regulator fittings • Traps • Shut- off valves • T- fittings Perform a pressure drop test. 1 Turn off the GC. 120 2 Set the regulator pressure to 415 kPa (60 psi). 3 Fully turn the regulator knob counterclockwise to shut the valve. 4 Wait 5 minutes. If there is a measurable drop in pressure, there is a leak in the external connections.
6 Checking for Leaks To Check for GC Leaks Check for leaks at these connections: • Inlet septum, septum head, liner, split vent trap, split vent trap line, and purge vent fittings • Column connections to inlets, detectors, valves, splitters, and unions • Fittings from the flow modules to the inlets, detectors, and valves • Column adapters • Agilent capillary flow fittings Advanced User Guide 121
6 Checking for Leaks Leaks in Capillary Column (Microfluidic) Fittings For capillary column fittings, a leak usually indicates that the fitting has been overtightened. Unless the fitting is obviously loose, do not tighten it further. Instead, remove the connection, trim the column end, and install it again. Also inspect the plate and connection for a broken column tip.
6 Checking for Leaks To Perform a SS Inlet Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting. After performing maintenance, first check for leaks in externally accessible areas. See “To Check for External Leaks”. If a leak is known to exist, check the externally accessible inlet fittings first, especially any connection that has seen recent maintenance, such as the septum nut, column adapter, column connection, and so forth.
6 Checking for Leaks • O- ring • ECD/TCD Detector plug (part no. 5060- 9055) 2 Load the inlet maintenance method and wait for the GC to become ready. 3 Remove the column, if installed. 4 Plug the column fitting with a column nut and a no- hole ferrule. 5 Remove the old septum and replace it with a new one. See To change the septum on the split/splitless inlet. 6 Inspect the O- ring and replace it if it is hard and brittle or cracked.
6 Checking for Leaks Back inlet purge vent Back inlet split vent Front inlet split vent Front inlet purge vent Front purge vent shown plugged 15 From the keypad, press [Service Mode]. Select Diagnostics > Front or Back Inlet > Pneumatics Control > Septum Purge control. 16 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds. 17 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No. 18 Quickly turn off the carrier gas supply at its source. 19 Monitor the pressure for 10 minutes.
6 Checking for Leaks If the pressure drops much faster than the acceptable rate, see “To Correct Leaks in the Split Splitless Inlet”. Retest. Note that liner size impacts pressure drop. An inlet with a smaller volume liner does not tolerate as large a leak rate as an inlet with a larger volume liner. 20 After the inlet passes the test, restore the GC to operating condition. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method.
6 Checking for Leaks To Correct Leaks in the Split Splitless Inlet If the inlet fails a pressure decay test, check the following: • Check the caps/plugs used in the test—make sure each is correctly installed and tight. • If you performed the leak test after performing maintenance, check for proper installation of the part(s) handled during the maintenance. • Check the tightness of the septum nut. See To change the septum on the split/Splitless inlet. • Check the septum. Replace if old or damaged.
6 Checking for Leaks To Perform a Multimode Inlet Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting. After performing maintenance, first check for leaks in externally accessible areas. See “To Check for External Leaks”. If a leak is known to exist, check the externally accessible inlet fittings first, especially any connection that has seen recent maintenance, such as the septum nut, column adapter, column connection, and so forth.
6 Checking for Leaks 2 Load the inlet maintenance method and wait for the GC to become ready. 3 Remove the column, if installed. 4 Plug the column fitting with a column nut and a no- hole ferrule. 5 Remove the old septum and replace it with a new one. See To change the septum on the multimode inlet. 6 Inspect the O- ring and replace it if it is hard and brittle or cracked. See To change the liner and O- ring on the Multimode inlet. 7 Set the inlet to Split Mode.
6 Checking for Leaks Back inlet purge vent Back inlet split vent Front inlet split vent Front inlet purge vent Front purge vent shown plugged 15 From the keypad, press [Service Mode]. Select Diagnostics > Front or Back Inlet > Pneumatics Control > Septum Purge control. 16 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds. 17 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No. 18 Quickly turn off the carrier gas supply at its source. 19 Monitor the pressure for 10 minutes.
6 Checking for Leaks If the pressure drops much faster than the acceptable rate, see “To Correct Leaks in the Multimode Inlet”. Retest. Note that liner size impacts pressure drop. An inlet with a smaller volume liner does not tolerate as large a leak rate as an inlet with a larger volume liner. 20 After the inlet passes the test, restore the GC to operating condition. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method.
6 Checking for Leaks To Correct Leaks in the Multimode Inlet If the inlet fails a pressure decay test, check the following: • Check the caps/plugs used in the test—make sure each is correctly installed and tight. • If you performed the leak test after performing maintenance, check for proper installation of the part(s) handled during the maintenance. • Check the tightness of the septum nut. See To change the septum on the Multimode inlet. • Check the septum. Replace if old or damaged.
6 Checking for Leaks To Perform a PP Inlet Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting. After performing maintenance, first check for leaks in externally accessible areas. See “To Check for External Leaks”. If a leak is known to exist, check the externally accessible inlet fittings first, especially any connection that has seen recent maintenance, such as the septum nut, column adapter, column connection, and so forth.
6 Checking for Leaks 4 Plug the column fitting. • If the capillary column adapter is installed, use a column nut and a no- hole ferrule • If a 1/8- inch packed column adapter is installed, use a 1/8- inch Swagelok cap (5180- 4121). • If a 1/4- inch packed column adapter is installed, use a 1/4- inch Swagelok cap (5180- 4120) 5 Remove the old septum and replace it with a new one. See To change the septum on the purged packed inlet.
6 Checking for Leaks Back inlet purge vent Back inlet split vent Front inlet split vent Front inlet purge vent Front purge vent shown plugged 14 From the keypad, press [Service Mode]. Select Diagnostics > Front or Back Inlet > Pneumatics Control > Septum Purge control. 15 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds. 16 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No. 17 Quickly turn off the carrier gas supply at its source. 18 Monitor the pressure for 10 minutes.
6 Checking for Leaks 19 After the inlet passes the test, restore the GC to operating condition. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method.
6 Checking for Leaks To Correct Leaks in the Packed Column Inlet If the inlet fails a pressure decay test, check the following: • Check the caps/plugs used in the test—make sure each is correctly installed and tight. • If you performed the leak test after performing maintenance, check for proper installation of the part(s) handled during the maintenance. • Check the tightness of the septum nut. See To change the septum on the purged packed inlet. • Check the septum. Replace if old or damaged.
6 Checking for Leaks To Perform a COC Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting. After performing maintenance, first check for leaks in externally accessible areas. See “To Check for External Leaks”. If a leak is known to exist, check the externally accessible inlet fittings first, especially any connection that has seen recent maintenance, such as the septum nut, column adapter, column connection, and so forth.
6 Checking for Leaks Back inlet split vent 6 Enter a pressure setpoint of 25 psi (172 kPa). Make sure that the pressure supplied to the GC is at least 10 psi (70 kPa) higher than the inlet pressure. 7 Wait 5 minutes for the pressure to equilibrate. If pressure cannot be achieved, there is either a large leak or the supply pressure is too low. 8 Set the Septum purge flow to 3.0 mL/min. 9 Cap the septum purge fitting with the ECD/TCD detector plug.
6 Checking for Leaks 11 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds. 12 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No. 13 Quickly turn off the carrier gas supply at its source. 14 Monitor the pressure for 10 minutes. Use the timer by pressing [Time] and [Enter]. A pressure drop of less than 1.0 psig (0.1 psi/min or less; 6.9 kPa or 0.69 kPa/min) is acceptable.
6 Checking for Leaks To Correct Leaks in the Cool On-Column Inlet If the inlet fails a pressure decay test, check the following: • Check the caps/plugs used in the test—make sure each is correctly installed and tight. • If you performed the leak test after performing maintenance, check for proper installation of the part(s) handled during the maintenance. • Check the tightness of the septum nut or cooling tower assembly. See To change a septum nut or cooling tower and septum on a COC inlet.
6 Checking for Leaks To Perform a PTV Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting. After performing maintenance, first check for leaks in externally accessible areas. See “To Check for External Leaks”. If a leak is known to exist, check the externally accessible inlet fittings first, especially any connection that has seen recent maintenance, such as the septum nut, column adapter, column connection, and so forth.
6 Checking for Leaks • ECD/TCD Detector plug (part no. 5060- 9055) 2 Load the inlet maintenance method and wait for the GC to become ready. 3 Remove the column, if installed. 4 Plug the column fitting with a column nut and a no- hole ferrule. 5 If using the septum head, and the quality of the septum (or Microseal) and GRAPHPACK- 3D ferrule on the glass liner are unknown, replace them now. See To change the septum on the PTV inlet and To change the liner on the PTV inlet.
6 Checking for Leaks Back inlet split vent Back inlet purge vent Front inlet split vent Front inlet purge vent Front purge vent shown plugged 14 From the keypad, press [Service Mode]. Select Diagnostics > Front or Back Inlet > Pneumatics Control > Septum Purge control. 15 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds. 16 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No. 17 Quickly turn off the carrier gas supply at its source. 18 Monitor the pressure for 10 minutes.
6 Checking for Leaks Note that liner size impacts pressure drop. An inlet with a smaller volume liner does not tolerate as large a leak rate as an inlet with a larger volume liner. 19 After the inlet passes the test, restore the GC to operating condition. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method.
6 Checking for Leaks To Correct Leaks in the PTV Inlet If the inlet fails a pressure decay test, check the following: • Check the caps/plugs used in the test—make sure each is correctly installed and tight. • If you performed the leak test after performing maintenance, check for proper installation of the part(s) handled during the maintenance. • If using a septum head, check the tightness of the septum nut. See To change the septum on the PTV inlet. • If using a septum head, check the septum.
6 Checking for Leaks To Perform a VI Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting. Initially test the VI with a sampling system installed. If the system fails the leak test, then isolate the VI from the sampler as described in “To Prepare the VI for a Closed System Leak Check” on page 150. After performing maintenance, first check for leaks in externally accessible areas. See “To Check for External Leaks”.
6 Checking for Leaks 3 Remove the column, if installed. 4 Plug the column fitting with a column nut and a no- hole ferrule. 5 Set the inlet to Split Mode. 6 Configure the column as 0 length. 7 Set the inlet temperature to 100 °C. 8 Set the Total flow to 60 mL/min. 9 Enter a pressure setpoint of 25 psi (172 kPa). Make sure that the pressure supplied to the GC is at least 10 psi (70 kPa) higher than the inlet pressure.
6 Checking for Leaks Front purge vent shown plugged 13 From the keypad, press [Service Mode]. Select Diagnostics > Front or Back Inlet > Pneumatics Control > Septum Purge control. 14 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds. 15 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No. 16 Quickly turn off the carrier gas supply at its source. 17 Monitor the pressure for 10–15 minutes. Use the timer by pressing [Time] and [Enter].
6 Checking for Leaks To Prepare the VI for a Closed System Leak Check To leak check the interface independently of the gas sampling device, you must disconnect the sampler from the interface to isolate the interface flow system from the sampler. WA R N I N G Be careful! The oven and/or inlet may be hot enough to cause burns. If either is hot, wear heat-resistant gloves to protect your hands.
Checking for Leaks 6 To Correct Leaks in the Volatiles Interface If the inlet fails a pressure decay test, check the following: • The caps and plugs used in the test—make sure each is correctly installed and tight. • If you performed the leak test after performing maintenance, check for proper installation of the part(s) handled during the maintenance. • The split vent and pressure sensing connections at the interface. • The sampler connection to the interface. • The sampler.
6 152 Checking for Leaks Advanced User Guide
Agilent 7890A Gas Chromatograph Advanced User Guide 7 Flow and Pressure Modules About Flow and Pressure Control 154 Maximum operating pressure 154 PIDs 155 Inlet Modules 156 Detector Modules 157 Pressure Control Modules 158 Auxiliary Pressure Controllers 161 Restrictors 162 1. Using an Aux epc channel to supply purge gas to a splitter 163 2.
7 Flow and Pressure Modules About Flow and Pressure Control The GC uses four types of electronic flow or pressure controllers; inlet modules, detector modules, pressure control modules (PCMs), and auxiliary pressure controllers (Aux EPCs). All of these modules mount in the slots at the top rear of the GC. The slots are identified by numbers, as shown here.
7 Flow and Pressure Modules PIDs The behavior of a pressure control module is governed by a set of three constants, called P (proportional), I (integral), and D (differential). Certain gases or special applications (such as QuickSwap, headspace vial pressurization, or splitter and backflush applications) require different PIDs than those provided at the factory.
7 Flow and Pressure Modules Inlet Modules These modules are used with specific inlets. They provide a controlled flow or pressure of carrier gas to the inlet and control the septum flow rate. Module locations depend on the type of module and the length of the tubing connecting it to the inlet. If you have a Front inlet, its flow module must go in Slot 1. If you have a Back inlet, its flow module must go in Slot 2.
7 Flow and Pressure Modules Detector Modules These are specific to the detector with which they are supplied, and differ according to the needs of that detector. For example, the FID module must supply controlled amounts of air, hydrogen, and makeup gas. The TCD module supplies the reference and makeup gases, but includes the reference switching valve that is essential to detector operation. Module locations depend on the type of module and the length of the tubing connecting it to the detector.
7 Flow and Pressure Modules Pressure Control Modules The PCM is a general purpose module with two independent control channels, designated 1 and 2. The general name of a PCM module is PCM #, where the # (actually, a letter) identifies the PCM (there can be up to 3 installed). The two channels are not identical. Channel 1 is a simple forward- pressure regulated channel that maintains constant flow through a fixed restrictor.
7 Flow and Pressure Modules For channel 1, gas input is via a threaded fitting. Gas output is via a coil of metal tubing with a Swagelok fitting on the end. For channel 2, the connections are the same as for channel 1 if channel 2 is to be used as a forward- pressure regulator. They are reversed—extra fittings/adapters will be needed—if it is to be used as a back- pressure regulator. PCMs can be installed in several locations: • In slot 1. The name is PCM A. • In slot 2. The name is PCM B. • In slot 5.
7 Flow and Pressure Modules • In slot 6. The name is always PCM C. PCM A or B PCM C Slot 3 Slot 4 PCM A PCM B Split vent trap and valve Back of GC Both channels of a PCM are controlled by the same parameter list. The first two lines refer to channel 1, the remaining lines refer to channel 2.
7 Flow and Pressure Modules Auxiliary Pressure Controllers The Auxiliary Pressure Controller (Aux epc) is also a general purpose device. It has three independent forward- pressure regulated channels. Channels are designated by numbers 1 through 9 (there can be up to 3 Aux epcs), depending on where the module is installed. If an auxiliary channel is specified as the Inlet during column configuration, that channel allows run time programming and three- ramp flow or pressure programming.
7 Flow and Pressure Modules Restrictors Both PCMs and auxiliary channels are controlled by pressure setpoints. To work properly, there must be adequate flow resistance downstream of the pressure sensor. Each channel provides a frit- type restrictor. Four frits are available. Table 24 Auxiliary channel frits Frit marking Flow resistance Flow characteristic Often used with Three blue rings High 3.33 ± 0.3 SCCM @ 15 PSIG FID Air, QuickSwap, Splitter, Deans Switch Two red rings Medium 30 ± 1.
7 Flow and Pressure Modules Examples 1. Using an Aux epc channel to supply purge gas to a splitter An Aux epc channel operates only in the forward- pressure mode; it provides a constant pressure at its outlet. It is used to provide gas to some other device, such as a splitter with a makeup gas input. Aux EPC Split/splitless inlet µECD 0.507 m x 0.10 mm x 0 µm FPD MSD 0.532 m x 0.18 mm x 0 µm 1.444 m x 0.18 mm x 0 µm 30 m x 0.25 mm x 0.
7 Flow and Pressure Modules Channel 1: Forward-pressure only This is identical to the carrier gas channel for the packed column inlet. Channel 2: Two-way channel If gas is supplied at the threaded connection and delivered by the tubing, this operates the same as channel 1. But the connections can be reversed—requiring some fittings—so that it will maintain the gas supplied to it at a fixed pressure. In this mode it behaves as a controlled leak.
Agilent 7890A Gas Chromatograph Advanced User Guide 8 Inlets Using Hydrogen 167 Inlet Overview 168 Carrier Gas Flow Rates 169 About Gas Saver 170 Pre Run and Prep Run 171 Auto Prep Run 172 About Heaters 173 About the Split/Splitless Inlet 175 Split/Splitless inlet split mode overview 176 Split/Splitless inlet splitless mode overview 177 The S/SL inlet pulsed split and splitless modes 178 Split/Splitless inlet split mode minimum operating pressures 179 Selecting the correct S/SL inlet liner 180 Vapor Volume
8 Inlets Cooling the PTV inlet 228 PTV inlet split and pulsed split modes 228 PTV inlet splitless and pulsed splitless modes 232 PTV inlet solvent vent mode 239 To develop a PTV method that uses large volume injection 247 Multiple injections with the PTV inlet 250 About the Volatiles Interface 255 About the VI split mode 257 About the VI splitless mode 261 About the VI direct mode 266 Preparing the Interface for Direct Sample Introduction 269 Setting parameters for the VI direct mode 272 166 Advanced Us
Inlets 8 Using Hydrogen WA R N I N G When using hydrogen (H2), as the carrier gas, be aware that hydrogen (H2) gas can flow into the oven and create an explosion hazard. Therefore, be sure that the supply is off until all connections are made, and ensure that the inlet and detector column fittings are either connected to a column or capped at all times when hydrogen (H2) gas is supplied to the instrument. WA R N I N G Hydrogen (H2) is flammable.
8 Inlets Inlet Overview Table 25 Comparing inlets Inlet Column Mode Sample concentration Split/splitless Capillary Split Pulsed split High High Splitless Pulsed splitless Low Low Split Pulsed split Splitless Pulsed splitless Solvent vent High High Low Low Low Multimode Capillary Comments Useful with large injections Useful with large injections Sample to column Very little Very little All All Very little Very little All All Multiple injections Most concentrate analytes and vent solvent A
Inlets 8 Carrier Gas Flow Rates The flow rates in Table 26 are recommended for all column temperatures. Table 26 Column type Column size and carrier flow rate Column size Carrier flow rate, mL/min Hydrogen Packed Capillary Advanced User Guide Helium Nitrogen 1/8-inch 30 20 1/4-inch 60 40 0.05 mm id 0.5 0.4 n/a 0.10 mm id 1.0 0.8 n/a 0.20 mm id 2.0 1.6 0.25 0.25 mm id 2.5 2.0 0.5 0.32 mm id 3.2 2.6 0.75 0.53 mm id 5.3 4.2 1.
8 Inlets About Gas Saver Gas saver reduces carrier flow from the split vent after the sample is on the column. It applies to the Split/Splitless and PTV inlets (all modes) and to the split and splitless modes of the Volatiles Interface. It is most useful in split applications. Column head pressure and flow rate are maintained, while purge and split vent flows decrease. Flows—except column flow—remain at the reduced level until you press [Prep Run].
8 Inlets Pre Run and Prep Run With some inlets and operating modes, certain instrument setpoints are different between runs than during an analysis. To restore the setpoints for injection, you must place the GC into the Pre Run state. You must use the Pre Run state when: • Using gas saver with any inlet. • Using splitless mode with any inlet. • Using a pressure pulse mode with any inlet. • Using the solvent vent mode of the PTV inlet. • Using the direct or splitless mode of the Volatiles Interface.
8 Inlets Non-Agilent samplers With most automatic injection systems, you do not need to use the [Prep Run] key. If your sampler or automation controller (for example, an integrator or workstation) does not support the [Prep Run] function, you must set the GC to Auto Prep Run. Auto Prep Run To set this parameter, usually for a non- Agilent integrator, workstation, or other controlling device: 1 Press [Config] to view a list of configurable parameters. 172 2 Scroll to Instrument and press [Enter].
8 Inlets About Heaters Inlets (and detectors, valve boxes, etc.) are heated. There are six heater connectors on the GC mainframe, located as shown here: Front of GC Near top right corner of front detector board 3 Near top right corner of back detector board 4 Left end of valve bracket 5 Right end of valve bracket 6 1 2 Near front inlet Near back inlet All heater connectors are square, 4- conductor receptacles mounted on brackets.
8 Inlets Table 27 Heater connectors by module (continued) Module Available heater connectors Aux heater 1 5 Aux heater 2 6 Front FPD uses heater connectors 3 and 5. Back FPD uses heater connectors 4 and 6. FPDs can be configured for one or two heater versions.
8 Inlets About the Split/Splitless Inlet This inlet is used for split, splitless, pulsed splitless, or pulsed split analyses. You can choose the operating mode from the inlet parameter list. The split mode is generally used for major component analyses, while the splitless mode is used for trace analyses. The pulsed splitless and pulsed split modes are used for the same type of analyses as split or splitless, but allow you to inject larger samples.
8 Inlets To determine the version that you have, press [Front Inlet] or [Back Inlet], scroll to the Pressure line, and press the [Info] key. The display will show the pressure range for the inlet—either 1 to 100 psi (for the standard version) or 1 to 150 psi (for the high- pressure version). Split/Splitless inlet split mode overview During a split injection, a liquid sample is introduced into a hot inlet where it vaporizes rapidly.
Inlets Carrier Supply 80 PSI Split 8 Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Split/Splitless inlet splitless mode overview In this mode, the split vent valve is closed during the injection and remains so while the sample is vaporized in the liner and transferred to the column. At a specified time after injection, the valve opens to sweep any vapors remaining in the liner out the split vent.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column The S/SL inlet pulsed split and splitless modes The pressure pulse modes increase inlet pressure just before the beginning of a run and return it to the normal value after a specified amount of time.
Inlets 8 You can do column pressure and flow programming when in the pressure pulse mode. However, the pressure pulse will take precedence over the column pressure or flow ramp. Pressure pulse Pressure or Flow Pressure or flow program 0 1 2 3 4 5 6 7 8 Split/Splitless inlet split mode minimum operating pressures The minimum recommended inlet total flow is 20 mL/minute. When the split/splitless inlet is operated in Split mode, there will be a minimum pressure at which the inlet can operate.
8 Inlets Table 28 Approximate minimum viable inlet pressures for split/splitless inlet in split mode, in psi (kPa) Split vent flow (mL/min) 50–100 100–200 200–400 400–600 Split liners - 5183-4647, 19251-60540 2.5 (17.2) 3.5 (24.1 4.5 (31) 6.0 (41.4) Splitless liners - 5062-3587, 5181-8818 4.0 (27.6) 5.5 (37.9) 8.0 (55.2) 11.0 (75.4) Split liners - 19251-60540, 5183-4647 3.0 (20.7) 4.0(27.6) — — Splitless liners - 5062-3587, 5181-8818 4.0 (27.6) 6.0 (41.
8 Inlets Splitless liner The liner volume must contain the solvent vapor. The liner should be deactivated to minimize sample breakdown during the purge delay. Solvent vapor volume can be reduced by using Pulsed Splitless mode. Use the “Vapor Volume Calculator“ to determine vapor volume requirements. Vapor volume < 300 µL Use 2 mm liner (250 µL volume), 5181- 8818 or similar. Vapor volume 225 – 300 µL reduce vapor volume.
8 Inlets Vapor Volume Calculator Agilent provides a Vapor Volume Calculator to help you determine if a liner is suitable for a method. To use the calculator install the Agilent Instrument utility provided with the GC. The calculator is also provided with the Agilent G4600AA Lab Advisor software.
8 Inlets If a column in the flow path is not defined 1 Press [Front Inlet] or [Back Inlet]. 2 Set the inlet temperature. 3 Set Total flow into the inlet. It must exceed your intended Septum Purge flow. Measure the split vent flow using a flow meter. 4 Subtract split vent flow and septum purge flow (see “Pre Run and Prep Run” on page 171) from Total flow to get column flow. 5 Calculate the split ratio (split vent flow/column flow). Adjust as needed.
8 Inlets Table 31 Splitless mode inlet parameters Parameter Allowed setpoint range Suggested starting value Gas saver time 0 to 999.
8 Inlets 6 Press [Prep Run] (see “Pre Run and Prep Run” on page 171) before manually injecting a sample (this is automatic for Agilent ALS). If a column in the flow path is not defined 1 Press [Front Inlet] or [Back Inlet]. 2 Scroll to Mode: and press [Mode/Type]. Select Splitless. 3 Set the inlet temperature. 4 Enter a Purge time. 5 Set your Total flow greater than the sum of column flow plus the septum purge flow—see “Pre Run and Prep Run” on page 171—to guarantee adequate column flow.
8 Inlets About the Multimode Inlet The Agilent Multimode (MMI) Inlet System has five operating modes: • The split mode is generally used for major component analyses. • The pulsed split mode is like the split mode, but with a pressure pulse applied to the inlet during sample introduction to speed the transfer of material to the column. • The splitless mode is used for trace analyses. • The pulsed splitless mode allows for a pressure pulse during sample introduction.
8 Inlets If using a Merlin Microseal™ septum, finger tighten the septum nut, until snug (not loose). The pressure capacity depends on the duckbill seal used. Heating the MMI Programming the MMI temperature is similar to programming the column oven. Access the inlet parameters by pressing [Front Inlet] or [Back Inlet]. Temperature can be programmed with an initial temperature and up to 10 ramps (rates and plateaus). See “MMI split and pulsed split modes” on page 191 for details.
8 Inlets inlet temperature program exceeds the Use cryo temperature. If the Use cryo temperature is less than the inlet setpoint, cryogen will cool the inlet to the initial setpoint and turn off. If using compressed air as the coolant when configuring the initial inlet setpoint, Use cryo temperature behaves differently when in Compressed air mode than it does when in N2 cryo or CO2 cryo mode.
8 Inlets Table 32 Approximate minimum viable inlet pressures for MMI in split mode, in psi (kPa) Split vent flow (mL/min) 50–100 100–200 200–400 400–600 Split liners - 5183-4647, 19251-60540 2.5 (17.2) 3.5 (24.1 4.5 (31) 6.0 (41.4) Splitless liners - 5062-3587, 5181-8818 4.0 (27.6) 5.5 (37.9) 8.0 (55.2) 11.0 (75.4) Split liners - 19251-60540, 5183-4647 3.0 (20.7) 4.0(27.6) — — Splitless liners - 5062-3587, 5181-8818 4.0 (27.6) 6.0 (41.
8 Inlets Splitless liner The liner volume must contain the solvent vapor. The liner should be deactivated to minimize sample breakdown during the purge delay. Solvent vapor volume can be reduced by using Pulsed Splitless mode. Use the “Vapor Volume Calculator“ to determine vapor volume requirements. Vapor volume < 300 µL Use 2 mm liner (250 µL volume), 5181- 8818 or similar. Vapor volume 225 – 300 µL reduce vapor volume.
8 Inlets Vapor Volume Calculator Agilent provides a Vapor Volume Calculator to help you determine if a liner is suitable for a method. To use the calculator install the Agilent Instrument utility provided with the GC. The calculator is also provided with the Agilent G4600AA Lab Advisor software. MMI split and pulsed split modes The two split modes—with or without a pressure pulse—divide the gas stream entering the inlet between the column flow and the split vent flow through the solenoid valve.
8 Inlets Cold split introduction For cold split sample introduction, use an initial inlet temperature below the normal boiling point of the solvent. If the liner volume is enough to hold all the vaporized solvent, start the first inlet temperature ramp at 0.1 minutes with a high heating rate (500 °C/min or higher). The final temperature should be high enough to volatilize the heaviest analytes from the liner and should be held for at least 5 minutes.
8 Inlets Split ratio The ratio of split flow to column flow. Column flow is set in the column parameter list. This line does not appear if a column in the flow path is not defined. Split flow Flow, in mL/min, from the split/purge vent. This line does not appear if a column in the flow path is not defined. Total flow These are the actual and setpoint values of the total flow into the inlet, which is the sum of the split flow, column flow, and septum purge flow.
8 Inlets If a column in the flow path is not defined 1 Press [Front Inlet]. 2 Set the inlet temperature (Initial temperature) and any desired ramps. 3 Set other parameters as described for a defined column. 4 Set Total flow into the inlet. Measure flows out of the split vent and septum purge vent using a flow meter. 5 Subtract the septum purge flow and split vent flow from Total flow to get column flow. 6 Calculate the split ratio (split vent flow/column flow).
Inlets Carrier Supply 80 PSI 8 Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap MMI Weldment FS = Flow Sensor PS = Pressure Sensor Advanced User Guide Column 195
8 Inlets Stage 2. Solvent purging After the sample has transferred to the column, the split vent valve opens to purge remaining solvent vapor from the inlet.
Inlets 8 Timelines This figure summarizes the flow, pressure, and temperature changes during a splitless mode analysis.
8 Inlets Cold splitless introduction For cold splitless introduction, use an initial inlet temperature below the normal boiling point of the solvent. For most solvents, starting the first inlet temperature ramp at 0.1 minutes provides good transfer and reproducibility. A program rate of 500 °C/min or higher is appropriate for thermally stable analytes. A final temperature of 350 °C, held for 5 minutes, has quantitatively transferred up to C44 alkane.
8 Inlets Table 35 Splitless mode inlet parameters Parameter Allowed setpoint range Suggested starting value Oven temperature No cryo, ambient+4 °C to 450 °C CO2 cryo, –40 °C to 450 °C N2 cryo, –80 °C to 450 °C 10 °C below solvent boiling point Oven initial time 0 to 999.9 minutes ≥ Inlet purge time Inlet purge time 0 to 200.0 minutes 2 x Liner volume Column flow Gas saver time 0 to 999.
8 Inlets Purge flow The flow, in mL/min, from the split vent, at Purge time. You will not be able to specify this value if operating with your column not defined. Total flow The Total flow line displays the actual flow to the inlet during a Pre- run (Pre- run light is on and not blinking) and during a run before purge time. You cannot enter a setpoint at these times. At all other times, Total flow will have both setpoint and actual values.
8 Inlets 8 Press [Prep Run] (see “Pre Run and Prep Run” on page 171) before manually injecting a sample. This is automatic if an Agilent sampler is used. MMI solvent vent mode This mode is typically used for large volume injections. For single injection use a 50 to 500 µL syringe and the ALS variable plunger speed to slowly inject the sample. The sample is injected into a cold inlet.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap MMI Weldment FS = Flow Sensor PS = Pressure Sensor Column Stage 2. Sample transfer When solvent venting ends, the split valve vent closes and the inlet heats to Final temperature 1. The sample transfers to the capillary column during Purge time. (Purge flow to split vent in a data system).
Inlets Carrier Supply 80 PSI 8 Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap MMI Weldment FS = Flow Sensor PS = Pressure Sensor Column Stage 3. Purge and cleanup The split valve opens again and the system returns to the Stage 1 configuration but with different setpoints. The MMI is flushed. Additional ramp rates are available to thermally clean the inlet or to reduce inlet temperature after sample transfer. This can extend the life of the liner.
8 Inlets A fundamental difficulty with solvent vent mode is the potential loss of volatile analytes with the solvent. Several solutions are possible for this situation: • The inlet liner can be packed with a more retentive material, such as Tenax. This greatly improves volatile analyte recovery but may impact recovery of higher boiling materials. • Some of the solvent can be left in the liner when sample transfer begins.
8 Inlets Table 36 The solvent vent process (continued) Step Parameter Value Inlet pressure Column pressure setpoint Analyte transfer ends, inlet is purged of residual vapor. Analysis begins. 5 At Saver time Flow at split vent Saver flow setpoint Inlet pressure Column pressure setpoint Analysis ends, carrier flow reduced to save gas (if Saver is on). Some important points • The flow through the column is governed by the pressure in the inlet.
8 Inlets Time Oven temperature Inlet temperature Inlet pressure Split vent flow Controlled by column flow or pressure setpoint or program Between runs Prep Run Start Run Vent pressure Saver or Purge flow Vent flow Initial time Vent end time Rate 1 Inlet is pressure controlled Initial time Final temperature 1 Final time 1 Purge time Rate 1 Other rates, temperatures, and times, if desired Controlled by column flow or pressure setpoint or program Purge flow Final temperature 1 Final time 1 Sa
8 Inlets control the inlet operation. This is discussed in more detail under “To develop a MMI method that uses large volume injection” on page 210. Setting parameters for solvent vent operation Mode: The current operating mode—solvent vent. Temperature Actual and setpoint initial inlet temperatures. Initial time The time, measured from Start Run, when the initial inlet temperature hold ends. Must be greater than Vent end time. Rate # Temperature program rate for inlet thermal ramps.
8 Inlets Table 37 Minimum attainable pressures Vent flow (mL/min) Actual vent pressure at “0“ psig setpoint Actual vent pressure at “0” kPa setpoint 1000 12.7 88 Vent flow The flow of carrier gas out the split vent during the vent period. Higher flows sweep the liner more quickly and reduce the time for solvent elimination. For most columns, 100 mL/min vent flow eliminates solvent at an acceptable rate but puts minimal material on the column.
8 Inlets If the column is not defined 1 Set up the parameters as described for the defined column case. 2 Set Total flow greater than the column flow plus the septum purge flow to guarantee adequate column flow. MMI Direct Mode MMI Direct Mode is a pneumatic configuration that allows on- column like behavior. In this mode, you still use a liner to trap involatile material but the sample can only enter the column. Direct mode works best with direct connect liners.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap MMI Weldment FS = Flow Sensor PS = Pressure Sensor Column To develop a MMI method that uses large volume injection This topic provides a recommended way to change from a splitless injection using a split/splitless inlet to a solvent vent mode injection using a Multimode inlet (MMI).
8 Inlets concentrating the analytes prior to injection. This requires an injector with variable speed injections, a "large" syringe, and knowledge of the sample and the solvent. When developing a solvent vent method, the goal for the injection is to determine the injection rates and temperatures needed to evaporate the solvent at the rate it enters the inlet. The development technique is to gradually scale up to an injection amount that produces a useful response.
8 Inlets • Start with the inlet temperature cold, near but slightly below the solvent boiling point. For example, if using methylene chloride (boiling point 39 °C), start with a temperature of 30–39 °C. • Use Splitless mode. • Ramp to the normal split/splitless inlet temperature 5 Note the response achieved. 6 Next, change the inlet mode to Solvent Vent. 7 Check the injector timings. a Install an empty sample vial in the injector turret or tray.
8 Inlets • The Vent Flow is too high. If the response of late eluters is too low: • The purge time is too short. • The final inlet temperature is too low. 10 If you need more injection volume and the 5 uL worked to give 5X response, change the syringe to a larger one, for example 50 uL. 11 Set up the data system to perform a 25 uL injection. 12 Configure the syringe. Make sure the plunger speeds on the injector are still set properly. 13 Recheck the injector timings. See step 12.
8 Inlets Setting parameters for the inlet in solvent vent mode Set or configure the following parameters in the data system's 7890A GC method editor. Syringe size — Verify the syringe size is configured correctly. The configured syringe size changes the available choices for injection volume. Injection volume — Select the injection volume, then enter a number of injections. The total injection volume will be displayed. Multiple Injection Delay — A pause time, in seconds, between injections.
Inlets Table 39 Inlet parameters Name Value Name Value Final temp 1 450 °C Vent flow 100 mL/min Final time 1 5 min Vent end time 0.2 min Rate 2 100 °C/min Purge time 2.0 min Final temp 2 250 °C Purge flow 50 mL/min Final time 2 0 min Table 40 8 Oven parameters Name Value Initial temp 40 °C Initial time 2.5 min Rate 1 25 °C/min Final temp 1 320 °C Final time 1 10.
8 Inlets C20 These results were compared with a splitless analysis of the same sample, which should produce 100% recovery of all analytes. The data showed that, under these conditions, compounds above C20 were completely recovered and that the recovery was independent of injection size. Compounds lower than C20 were partially vented with the solvent. Possible adjustments Depending on what you are trying to accomplish, you have a number of possible adjustments available.
Inlets 8 • Raise the inlet initial temperature to vaporize more solvent and allow more to be eliminated. This also increases the loss of volatile analytes since their vapor pressures also increase. To improve recovery of low boiling analytes • Reduce inlet temperature to lower the vapor pressure of the analytes and trap them more effectively. This also reduces solvent vapor pressure and more time will be needed to eliminate it. • Use a retentive packing in the liner.
8 Inlets C20 218 Advanced User Guide
8 Inlets About the Packed Column Inlet This inlet is also known as the purged packed inlet (PP). It is used with packed columns when high- efficiency separations are not required. It can also be used with wide- bore capillary columns, if flows greater than 10 mL/min are acceptable. If the columns are not defined (packed columns and undefined capillary columns), the inlet is usually flow- controlled.
8 Inlets The next figure shows the flow diagram for the packed column mode, with the column not defined the control is based on total carrier gas flow. Carrier Supply 80 PSI Septum Purge EPC Module Frit Frit Valve Valve PS FS PS Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Packed Column Setting parameters The inlet can operate in flow or pressure control mode. Flow is recommended for packed columns. Pressure is recommended for capillary columns.
8 Inlets Mode Press [Mode/Type] to see the choices. You may select an inlet mode of either Pressure control or Flow control. When the Inlet control mode is Pressure control, the column control mode can be set to Constant pressure, Ramped pressure, Constant flow, or Ramped flow. The column control mode is set from the Column parameters display. When the Inlet control mode is Flow control, only column flow can be set on the Column parameters display. Temperature The setpoint and actual temperature values.
8 Inlets About the Cool On-Column Inlet This inlet introduces liquid sample directly onto a capillary column. To do this, both the inlet and the oven must be cool at injection, either at or below the boiling point of the solvent. Because the sample does not vaporize immediately in the inlet, problems with sample discrimination and sample alteration are minimized. If done properly, cool- on column injection also provides accurate and precise results.
8 Inlets Setup modes of the COC inlet The COC inlet hardware must be set up for one of three usages, depending on the type of injection and column size. • 0.25 mm or 0.32 mm automated on- column. Use predrilled septa. • 0.53 mm automatic on- column or retention gap • 0.2 mm manual To select the correct hardware for a column and injection type, refer to Maintaining Your GC.
8 Inlets Track oven mode In the Track oven mode, the inlet temperature stays 3 °C higher than the oven temperature throughout the oven program. You cannot enter a temperature setpoint—it is set automatically. If you have CryoBlast, the inlet will track oven temperatures to –40°C; without CryoBlast, the lower limit is set by room temperature.
8 Inlets Setting COC inlet parameters Track oven mode 1 Press [Front Inlet] or [Back Inlet]. 2 Press [Mode/Type] and select Track oven. There is no setpoint for Track oven mode. Ramped temperature mode 1 Press [Front Inlet] or [Back Inlet]. Advanced User Guide 2 Press [Mode/Type] and select Ramped temp. 3 Enter a value for Temp. This is the starting temperature. 4 Enter an Init time. This is the length of time the inlet will stay at the starting temperature after a run has begun.
8 Inlets About the PTV Inlet The Agilent Programmed Temperature Vaporization (PTV) Inlet System has five operating modes: • The split mode is generally used for major component analyses. • The pulsed split mode is like the split mode, but with a pressure pulse applied to the inlet during sample introduction to speed the transfer of material to the column. • The splitless mode is used for trace analyses. • The pulsed splitless mode allows for a pressure pulse during sample introduction.
8 Inlets Septum head Septumless head The flow diagrams in the rest of this document show the septum head in place with a separate drawing for the septumless head. Heating the PTV inlet The control parameters for PTV temperature programming are the same as for the column oven, but are reached by pressing [Front Inlet]. Temperature can be programmed with an initial temperature and up to 3 rates and plateaus. Rates between 0.1 and 720 °C/min can be selected.
8 Inlets • Downward programming can be used to prepare the inlet for the next run. This can reduce cycle time for greater sample throughput. Cooling the PTV inlet If cryo is turned on, and if the inlet is cooled during a run, cryogen is used to achieve the setpoint. This may have a negative impact on the chromatographic performance of the oven and cause distorted peaks. The sample may be injected into either a cooled or heated inlet.
Inlets Carrier Supply 80 PSI Split 8 Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap PTV Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Cold split introduction For cold split sample introduction, use an initial inlet temperature below the normal boiling point of the solvent. If the liner volume is enough to hold all the vaporized solvent, start the first inlet temperature ramp at 0.1 minutes with a high heating rate (500 °C/min or higher).
8 Inlets A single temperature ramp is enough for the injection process. The remaining ramps may be used to clean the liner or to reduce the inlet temperature in preparation for the next injection. Hot split introduction For hot split introduction, set an initial temperature high enough to volatilize the analytes. No additional thermal parameters are required as the inlet will maintain the setpoint throughout the run.
8 Inlets Total flow These are the actual and setpoint values of the total flow into the inlet, which is the sum of the split flow, column flow, and septum purge flow. When you change the total flow, the split ratio and split flow change while the column flow and pressure remain the same. Septum Purge Gas saver Flow through the septum purge vent. On to reduce split vent flow at Saver time. Saver flow Reduced split vent flow, at least 15 mL/min. Saver time Time when flow is reduced to save gas.
8 Inlets 6 Calculate the split ratio (split vent flow/column flow). Adjust as needed PTV inlet splitless and pulsed splitless modes In these modes—with or without a pressure pulse—the split vent valve is closed during injection and vaporization of the sample and stays so while the sample transfers to the column. At a specified time after injection, the valve opens to sweep vapors left in the liner out the split vent. This avoids solvent tailing due to the large inlet volume and small column flow rate.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap PTV Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Stage 2. Solvent purging After the sample has transferred to the column, the split vent valve opens to purge remaining solvent vapor from the inlet.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap PTV Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Timelines This figure summarizes the flow, pressure, and temperature changes during a splitless mode analysis.
Inlets Split vent flow Purge flow Saver flow Inlet is pressure controlled Inlet pressure 8 Prep Run Start Run Purge Time Saver Time Stop Run Post Time Post pressure Column mode = Constant flow Inlet pressure Inlet temperature Prep Run Start Run Purge Time Stop Run Post Time Final temp 1 Initial temperature Prep Run Start Run Purge Time Cold splitless introduction For cold splitless introduction, use an initial inlet temperature below the normal boiling point of the solvent.
8 Inlets For most applications of cold splitless, a single temperature ramp is enough. The remaining ramps can be used to clean the liner or to decrease the inlet temperature to prepare for the next injection. Hot splitless introduction For hot splitless introduction, select an initial temperature high enough to volatilize the analytes. No additional temperature parameters are required as the inlet will maintain the setpoint throughout the run.
8 Inlets Table 43 Splitless mode inlet parameters (continued) Parameter Allowed setpoint range Suggested starting value Inlet purge time 0 to 999.9 minutes 2 x Liner volume Column flow Gas saver time 0 to 999.9 minutes After purge time Gas saver flow 15 to 1000 mL/min 15 mL/min greater than maximum column flow Inlet temperature No cryo, oven temp + 10 °C CO2 cryo, –50 °C to 450 °C N2 cryo, –60 °C to 450 °C 10 °C below solvent boiling point for 0.
8 Inlets Total flow The Total flow line displays the actual flow to the inlet during a Pre- run (Pre- run light is on and not blinking) and during a run before purge time. You cannot enter a setpoint at these times. At all other times, Total flow will have both setpoint and actual values.
8 Inlets PTV inlet solvent vent mode This mode is typically used for large volume injections. For single injection use a 50 or 100 µL syringe with variable plunger speed—slowly, 5 to 30 seconds. The sample is injected into a cold inlet. If conditions are properly chosen and the sample is suitable, analytes deposit in the inlet liner while the solvent evaporates and is swept out. Large or multiple injections can be used to concentrate sample in the inlet before transferring to the column for analysis.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap PTV Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Stage 2. Sample transfer When solvent venting ends, the split valve vent closes and the inlet heats to Final temperature 1. The sample transfers to the capillary column during Purge delay time.
Inlets Carrier Supply 80 PSI Split 8 Septum Purge EPC Module Frit Valve Frit Valve Valve PS FS PS Split Vent Trap PTV Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Stage 3. Purge and cleanup The split valve opens again and the system returns to the Stage 1 configuration but with different setpoints. The PTV inlet is flushed. Additional ramp rates are available to thermally clean the inlet or to reduce inlet temperature after sample transfer. This can extend the life of the liner.
8 Inlets A fundamental difficulty with solvent vent mode is the potential loss of volatile analytes with the solvent. Several solutions are possible for this situation: • The inlet liner can be packed with a more retentive material, such as Tenax. This greatly improves volatile analyte recovery but may impact recovery of higher boiling materials. • Some of the solvent can be left in the liner when sample transfer begins.
8 Inlets Table 44 The solvent vent process (continued) Step Parameter Value Inlet pressure Column pressure setpoint Analyte transfer ends, inlet is purged of residual vapor. Analysis begins. 5 At Saver time Flow at split vent Saver flow setpoint Inlet pressure Column pressure setpoint Analysis ends, carrier flow reduced to save gas (if Saver is on). Some important points • The flow through the column is governed by the pressure in the inlet.
8 Inlets Time Oven temperature Inlet temperature Inlet pressure Split vent flow Controlled by column flow or pressure setpoint or program Between runs Prep Run Start Run Vent pressure Saver or Purge flow Vent flow Initial time Vent end time Rate 1 Inlet is pressure controlled Initial time Final temperature 1 Final time 1 Purge time Rate 1 Other rates, temperatures, and times, if desired Controlled by column flow or pressure setpoint or program Purge flow Final temperature 1 Final time 1 Sa
8 Inlets control the inlet operation. This is discussed in more detail under “To develop a PTV method that uses large volume injection” on page 247. Setting parameters for solvent vent operation Mode: The current operating mode—solvent vent. Temperature Actual and setpoint initial inlet temperatures. Initial time The time, measured from Start Run, when the initial inlet temperature hold ends. Must be greater than Vent end time. Rate # Temperature program rate for inlet thermal ramps.
8 Inlets Table 45 Minimum attainable pressures Vent flow (mL/min) Actual vent pressure at “0“ psig setpoint Actual vent pressure at “0” kPa setpoint 1000 12.7 88 Vent flow The flow of carrier gas out the split vent during the vent period. Higher flows sweep the liner more quickly and reduce the time for solvent elimination. For most columns, 100 mL/min vent flow eliminates solvent at an acceptable rate but puts minimal material on the column.
8 Inlets If the column is not defined 1 Set up the parameters as described for the defined column case. 2 Set Total flow greater than the column flow plus the septum purge flow to guarantee adequate column flow. To develop a PTV method that uses large volume injection This topic provides a recommended way to change from a splitless injection using a split/splitless inlet to a solvent vent mode injection using a programmable temperature vaporization inlet (PTV).
8 Inlets Vent end time The vent end time setpoint must be greater than the time the needle spends in the inlet. If the vent time is too short, you will overload and contaminate the column and inlet. Adjust the vent time as you scale up the method. If using a PTV with an MSD, another tip for method development is to scan for solvent ions. Detecting the solvent ions can be useful in troubleshooting residual solvent bleed onto the column.
8 Inlets • Enter a Vent pressure of 0 psi (0 kPa) and Vent end time of 0.1 minutes. d Make an injection using the empty vial. Use a stopwatch or your GC's timer feature to time how long the needle is in the inlet. 8 Enter revised Solvent vent mode parameters. • Set the method's Vent end time to be about 0.05 min longer than the time the needle spends in the inlet. • Set the inlet temperature Initial time to be about 0.05 min longer than the Vent pressure time.
8 Inlets 16 If you need more response, repeat steps 10 through 15 to increase to larger volume. See the next section. Try performing 5 x 5 uL injections, then 5 x 50 uL injections. Multiple injections with the PTV inlet The preferred technique for concentrating analytes in the inlet liner is to use a single, large volume injection.
Inlets 8 An example These values were used for a sample with a broad range of boiling points. Table 46 Name Value Sample C10 to C44 hydrocarbons in hexane Mode Solvent vent MMI liner Glass wool packed Injection volume One 10.0 μL injection (25 μL syringe) Injection speed Fast Column 30 m x 320 μm x 0.25 μm -5, part number 19091J-413 Column flow 4 mL/min constant flow Table 47 Inlet parameters Name Value Name Initial temp 40 °C Rate 2 (off) Initial time 0.3 min Pressure 15.
8 Inlets Table 48 Oven parameters Name Value Rate 2 (off) Table 49 Detector parameters Name Value Detector FID Detector temp 400 °C Hydrogen flow 40 mL/min Air flow 450 mL/min Makeup (N2) 45 mL/min C20 These results were compared with a splitless analysis of the same sample, which should produce 100% recovery of all analytes.
8 Inlets compounds above C20 were completely recovered and that the recovery was independent of injection size. Compounds lower than C20 were partially vented with the solvent. Possible adjustments Depending on what you are trying to accomplish, you have a number of possible adjustments available. To eliminate more solvent • Increase the vent end time, inlet initial time, and purge time. This will not affect analytes that are quantitatively trapped but will eliminate more of the solvent peak.
8 Inlets After timing a trial set of 10 injections, the total time for the multiple injection set was measured to be approximately 1.3 minutes. The following timing changes were made: Table 50 Modifications Parameter Increased from To Inlet Init time 0.3 minutes 1.6 minutes Vent end time 0.2 minutes 1.5 minutes Purge time 2.0 minutes 3.0 minutes Oven Init time 2.5 minutes 3.0 minutes The result is shown in the next figure. Note the difference in the vertical scale (5000 versus 500).
8 Inlets About the Volatiles Interface The volatiles interface provides a simple, reliable way to introduce a gas sample into your GC from an external device such as a headspace, purge and trap, or air toxic sampler. Manual syringe injections cannot be made with this interface. The interface has a small volume and is highly inert, ensuring high sensitivity and resolution for applications requiring trace level detection. The figure shows the pneumatics in the split mode.
8 Inlets gas- phase sampler and from there is introduced into the interface. The second stream, called the pressure sensing line, passes through the frit block and is measured by a pressure sensor. This stream also provides a trickle flow to the interface. VI operating modes There are three modes of operation—split, splitless, and direct. The pneumatics differ for each operating mode and are discussed in detail in the rest of this document.
Inlets Table 52 8 Specifications of the volatiles interface (continued) Specification Value/Comment Recommended temperature: ≥ transfer line temperature of the external sampling device About the VI split mode When you introduce a sample in the split mode, a small amount of the sample enters the column while the major portion exits from the split vent. The ratio of split flow to column flow is controlled by the user.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Frit Valve Valve Valve PS FS PS Frit Gas Sampling Valve Headspace Purge and Trap Split Vent Trap FS = Flow Sensor PS = Pressure Sensor Column Setpoint dependencies Some setpoints are interdependent. If you change one setpoint, other setpoints may change to compensate. With a defined capillary column, setting column flow or linear velocity will set the inlet pressure.
8 Inlets Table 54 Setpoint dependencies (continued) When you change These setpoints change Column defined Column not defined Column flow* Pressure Split flow Total flow not available Split flow Split ratio Total flow not available Split ratio Split flow Total flow not available Total flow Split flow Split ratio No changes * This setpoint appears in [Col 1] or [Col 2]. Initial values Use the information in Table 55 to help you set up the operating conditions for your interface.
8 Inlets Split ratio The ratio of split flow to column flow. Column flow is set using [Col 1] or [Col 2]. This parameter is not available if your column is not defined. Split flow Flow, in mL/min, from the split vent. This parameter is not available if your column is not defined.
8 Inlets 6 Calculate the split ratio (split vent flow/column flow). Adjust as needed. 7 If desired, turn Gas saver on. Set Saver time after the sample has been introduced. 8 If Gas saver is on, be certain Auto prep run is On (see “Pre Run and Prep Run” on page 171) or press [Prep Run] before introducing the sample. About the VI splitless mode This mode is used to concentrate sample at the head of the GC column during desorb.
8 Inlets Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Frit Valve Valve Valve PS FS PS Frit Gas Sampling Valve Headspace Purge and Trap Split Vent Trap FS = Flow Sensor PS = Pressure Sensor Column During sampling Pressure upsets caused by switching valves and trap restrictions in the external sampling device can cause fluctuations in column flow rates. To compensate for this, the interface is flow controlled during sampling time.
Inlets 8 During this user- specified sampling period, the solenoid valve is closed. Flow to the interface is measured by a flow sensor and controlled by a proportional valve. Carrier Supply 80 PSI Split Septum Purge EPC Module Frit Frit Valve Valve Valve PS FS PS Frit Gas Sampling Valve Headspace Purge and Trap Split Vent Trap FS = Flow Sensor PS = Pressure Sensor Column After sampling end The solenoid valve opens. The system returns to the Before Prep Run state.
8 Inlets Table 56 Setpoint dependencies When you change These setpoints change Column defined Purging Column not defined You can change the Pressure and Total flow setpoints; other setpoints are not affected. Purge flow Total flow** Pressure Total flow** Column flow* Column flow* Pressure Total flow** Before and after sampling, not purging Pressure Column flow* Total flow** Column flow* Pressure Total flow** You can change the Pressure setpoint; other setpoints are not affected.
8 Inlets Table 57 Suggested starting values (continued) Parameter Allowed setpoint range Suggested starting value Interface purge time 0 to 999.9 minutes Gas saver time 0 to 999.9 minutes Must be after purge time Gas saver flow 15 to 100 mL/min 15 mL/min greater than maximum column flow Setting parameters for the VI splitless mode Mode: The current operating mode—splitless Temperature Actual and setpoint interface temperatures.
8 Inlets Total flow When your column is defined, Total flow displays the actual flow to the interface. You cannot enter a setpoint. If your column is not defined, Total flow will have both setpoint and actual values during purge time. All other times, the actual flow to the interface is displayed. Septum Purge mL/min. Gas saver Saver flow Flow through the septum purge vent, at least 15 On to reduce split vent flow at Saver time. Flow through the split vent after Saver time.
8 Inlets Carrier Supply 80 PSI Septum Purge EPC Module Frit Frit Valve Valve PS FS PS Frit Gas Sampling Valve Headspace Purge and Trap FS = Flow Sensor PS = Pressure Sensor Column During sampling Pressure upsets caused by switching valves in the external sampler can cause fluctuations in column flow rates. To compensate for this, the interface is flow controlled during sampling time. The sampling flow rate is calculated from the pressure setpoint that is active when sample introduction begins.
8 Inlets Carrier Supply 80 PSI Septum Purge EPC Module Frit Frit Valve Valve PS FS PS Frit Gas Sampling Valve Headspace Purge and Trap Column FS = Flow Sensor PS = Pressure Sensor After sampling end The interface is forward pressure controlled; pressure is sensed downstream from the proportional valve. The system returns to the idle state.
Inlets 8 Preparing the Interface for Direct Sample Introduction Before you can operate your interface in direct mode, you must: • Disconnect the split vent line • Configure the GC for a direct injection Disconnecting the split vent line WA R N I N G Be careful! The interface may be hot enough to cause burns. 1 Press [Front Inlet] or [Back Inlet]. Turn off the interface temperature and pressure and allow the interface to cool.
8 270 Inlets 5 Loosen the hex nut connecting the split vent line to the interface until you can remove the line. Put the line aside. You do not need to plug it. 6 Install a blanking nut into the split line port and finger- tighten the nut. Tighten the nut an additional 1/4- turn using two wrenches in opposition. 7 Place the interface in the heater block. Replace the clamping plate you removed earlier and tighten the screw until snug. Do not overtighten. If you removed the transfer line, replace it.
8 Inlets 8 Restore the GC to normal operating conditions. Perform a leak test on the interface fittings. Configuring for direct mode The GC cannot sense the presence of the split vent. When you disconnect or reconnect the vent, you must configure the GC so that the pneumatics work properly. 1 Press [Config][Back Inlet] or [Config][Front Inlet]. 2 Scroll to Mode and press [Mode/Type]. 3 Select Split vent removed. Press [Enter]. 4 Press [Back Inlet] or [Front Inlet].
8 Inlets Table 59 Suggested starting values Parameter Allowed setpoint range Suggested starting value Oven initial time 0 to 999.9 minutes ≥ interface sampling end Interface temperature Ambient + 10 °C to 400 °C ≥ transfer line temperature Interface sampling end 0 to 999.9 minutes 0.2 minutes longer than actual sampling time Setting parameters for the VI direct mode Temperature Actual and setpoint interface temperatures Sampling end The sample introduction interval, in minutes.
Inlets Advanced User Guide 4 Set Sampling end at 0.2 minutes longer than the sample introduction time. 5 Make certain Auto Prep Run is On (see “Pre Run and Prep Run” on page 171) or press [Prep Run] before introducing a sample.
8 274 Inlets Advanced User Guide
Agilent 7890A Gas Chromatograph Advanced User Guide 9 Columns and Oven About the Oven 276 Oven safety 276 Configuring the Oven 277 Cryogenic Operation 278 Cryogenic setpoints 278 About Oven Temperature Programming 280 Programming setpoints 280 Oven ramp rates 281 Setting the oven parameters for constant temperature 282 Setting the oven parameters for ramped temperature 282 About the Oven Insert 284 Selecting the correct packed glass column type 285 About the column modes 285 Select a column mode 286 Settin
9 Columns and Oven About the Oven Table 60 Oven capabilities Capability Range Temperature range –80 °C (liquid N2) or –40 °C (CO2) to the configured limit Maximum temperature 450 °C Temperature programming Up to six ramps Maximum run time 999.99 minutes Temperature ramp rates 0 to 120 °C/min, depending on instrument configuration Oven safety For safety, opening the oven door turns off power to the oven heater, fan, and cryogenic valve (if installed) but maintains the setpoints in memory.
Columns and Oven 9 Configuring the Oven Oven configuration sets maximum temperature, equilibration time the cool down mode, and the cryogenic setpoints, if cryo is installed. Maximum temperature Maximum allowable oven temperature setpoint. Some accessories, such as the valve box, valves and columns have specific temperature limits. When configuring Maximum temperature, these limits should be considered so that the accessories are not damaged.
9 Columns and Oven Cryogenic Operation The cryogenic valve lets you operate the oven below ambient temperature. Minimum attainable oven temperature depends on the type of valve installed. The GC senses the presence and type of cryogenic valve and disallows setpoints if no valve is installed. When cryogenic cooling is not needed or cryogenic coolant is not available, the cryogenic operation should be turned off.
9 Columns and Oven If the temperature goes below the minimum allowed temperature (–90 °C for liquid nitrogen,–70 °C for liquid CO2), the oven will shut down. External oven mode Isothermal internal mode and programmed external oven used to calculate column flow. Slow oven cool down mode during cool down.
9 Columns and Oven About Oven Temperature Programming You can program the oven temperature from an initial temperature to a final temperature using up to 20 ramps during a run. A single ramp temperature program raises the initial oven temperature to a specified final temperature at a specified rate and holds at the final temperature for a specified period of time. Final temperature 1 Final time 1 Rate 1 Rate 2 = 0 Initial time 1 Initial temperature The multiple- ramp temperature program is similar.
9 Columns and Oven Final temperature Temperature of the oven at the end of a heating or cooling rate. Final time Time in minutes that the oven will be held at the final temperature of a temperature- programmed rate. Total length of a run is determined by its oven temperature program. The maximum allowable time for a run is 999.99 minutes. If the program is still running at that time, the run terminates. Post run This function can be used with both isothermal and programmed methods.
9 Columns and Oven Table 61 Oven ramp rates 100/120 V oven ramp rate (°C/minute) 200/220/230/240 V oven ramp rate (°C/minute) Temperature range (°C) Without insert With optional Without insert insert With optional insert 50 to 70 75 120 120 120 70 to 115 45 95 95 120 115 to 175 40 65 65 110 175 to 300 30 45 45 80 300 to 450 20 35 35 65 Setting the oven parameters for constant temperature An isothermal run is one in which the oven is maintained at a constant temperature.
9 Columns and Oven Multiple ramps In a multiple- ramp program, Final time for one ramp is also Initial time for the next ramp. Thus, there is only one Initial time. 1 Set up the first oven ramp as described in “Single ramp”. Advanced User Guide 2 Enter the rate (Rate 2) at which you want the oven temperature to increase for the second oven ramp. 3 Enter the final temperature (Final temperature 2). 4 Enter the number of minutes (Final time 2) that you want the oven to hold the final temperature.
9 Columns and Oven About the Oven Insert The Oven Insert for Fast Chromatography reduces the oven volume so that the column and sample heat more quickly, yielding faster separation and faster chromatography. Furthermore, the smaller volume oven cools faster than a full- sized oven, reducing the overall analytical cycle time. Carrying strap WARNING! Metal parts may be hot enough to burn. The oven insert is used with any inlet, column, and detector mounted in the back position.
9 Columns and Oven About Columns In all GCs, a sample—which is a mixture of several components—is vaporized in an inlet, separated in a column, and examined in a detector. The column separates components in time because: • When a vaporized component is presented with a gas phase and a coating phase, it divides between the two phases according to its relative attraction to the two phases.
9 Columns and Oven • Ramped flow—Increases the mass flow rate in the column during the run according to a program you enter. A column flow profile can have up to three ramps, each consisting of a programmed increase followed by a hold period. The pressure modes The pressure modes are not available if the column is not defined or the inlet’s mode is set to Flow control. Pressures are gauge pressures—the difference between the absolute pressure and the local atmospheric pressure.
9 Columns and Oven Setting the column parameters for constant flow or constant pressure If the column is defined, you can enter any one of these quantities—the GC will calculate and display the other two. For example, you may have selected Constant pressure as the column mode. You decide to specify, as a starting condition, the column flow. The GC will compute the pressure necessary to achieve this flow (as well as the average linear velocity) and hold this pressure constant during the run.
9 Columns and Oven The oven program determines the length of the run. If a flow or pressure program ends before the analytical run does, the flow (or pressure) remains at the last final value. Programming column pressure or flow 1 Press [Col 1] or [Col 2], or press [Aux col #] and enter the column number. 288 2 Scroll to Initial pressure (or Initial flow). Type the desired value and press [Enter]. 3 Similarly, enter a value for Initial time. This completes the initial part of the program.
9 Columns and Oven Backflushing a Column Backflush is a means of discarding high- boilers from a column after the peaks of interest have eluted.
9 Columns and Oven Backflushing using a capillary flow technology device Because the following capillary flow technology (CFT) devices connect to a controlled carrier gas supply, they can be used to backflush a column: • G2855B Capillary Flow Technology Deans Switching System • G3180B Capillary Flow Technology Two- Way Splitter (with makeup gas) • G3183B Capillary Flow Technology Three- Way Splitter • G3185B QuickSwap Accessory A conceptual diagram for a simple setup is shown in the figure.
9 Columns and Oven If using an Agilent data system, a Backflush Wizard provides a straightforward interface for making these settings. 1 Verify that all columns are properly configured. 2 Since the backflush will run as a post- run program, set the method so that the oven program ends after the last peak of interest returns to baseline, or after reaching the last temperature of interest. 3 Press [Post Run] and enter the backflush duration as the Time.
9 Columns and Oven To backflush using a ramped pressure program In this case, the backflush occurs as part of the run, so the detectors continue to collect data. During the backflush, you may wish to turn off data collection in the data system. CAUTION To avoid damage to an MSD, Agilent strongly recommends setting up backflush as a post run event, not as part of a ramped column program.
9 Columns and Oven CAUTION To avoid damage to an MSD, Agilent strongly recommends setting up backflush as a post run event, not as part of a ramped column program. If you still choose to backflush as part of a run, be very careful that the flow into the MSD does not exceed the limits of the vacuum pump. 1 Verify that all columns are properly configured.
9 Columns and Oven • At the end of the backflush period (determined experimentally), switch the valve to Position 1 and turn data acquisition on. The system is now ready for the next run.
Columns and Oven 9 Nickel Catalyst Tube About the nickel catalyst tube The Nickel Catalyst Tube accessory, G2747A, is used for trace analysis of CO and CO2 with a flame ionization detector. The gas sample is separated on the column and passed over a heated catalyst in the presence of hydrogen, which converts the CO and CO2 peaks to CH4.
9 Columns and Oven Table 63 CAUTION Gas flows for a TCD/FID series installation Gas Flow rate, mL/min Carrier (helium) 30 TCD switching flow 25 FID hydrogen 45 (see Caution) FID air 500 Hydrogen flow is pressure-controlled, where an FID provides a known resistance. The nickel catalyst tube increases flow resistance, so that the calibration is no longer valid. You must measure hydrogen flow with a bubble or similar meter. The nickel catalyst can be damaged by exposure to air.
Agilent 7890A Gas Chromatograph Advanced User Guide 10 Detectors About Makeup Gas 298 About the FID 299 About the TCD 304 About the uECD 312 About the NPD 319 About the FPD 331 Agilent Technologies 297
10 Detectors About Makeup Gas Most detectors use a makeup gas to increase the flow rate through the detector body. This sweeps peaks out of the detector quickly, avoiding mixing of components and loss of resolution. This is particularly important with capillary columns because the column flow rates are so small. The makeup gas line of your detector parameter list changes depending on your instrument configuration. If you have an inlet with the column not defined, the makeup flow is constant.
10 Detectors About the FID The FID passes sample and carrier gas from the column through a hydrogen- air flame. The hydrogen- air flame alone creates few ions, but burning an organic compound increases the number of ions produced. A polarizing voltage attracts these ions to a collector located near the flame. The current produced is proportional to the amount of sample being burned. This current is sensed by an electrometer, converted to digital form, and sent to an output device.
10 Detectors Table 64 Properties of the FID Property Value/Comment Dynamic range 1 x 107 Sensitivity 10 to 100 picograms of an organic compound dependent on the molecular structure. Selectivity Responds to all organic compounds (C-H bonds) except those which do not burn or ionize in the hydrogen-air flame. There is little or no response for H2O, CO2, CO, N2, O2 CS2 or inert gases. Formaldehyde and heavily halogenated compounds give minimal response.
10 Detectors FID automatic reignition (Lit offset) Lit offset is the expected minimum difference between the FID output with the flame lit and the output with the flame off. The GC checks this value during runs and when loading a method. During a run, if the output falls below the Lit offset value, the FID will attempt to reignite three times. If after the third attempt the output does not increase by at least this value, the detector shuts down all functions except temperature and makeup gas flow.
10 Detectors Table 66 Recommended starting conditions (continued) Detector gases Flow range mL/min Suggested flow mL/min Column plus capillary makeup 10 to 60 30 Hydrogen 24 to 60 30 Air 200 to 600 400 Column plus capillary makeup 10 to 60 30 Hydrogen 24 to 60 30* Air 200 to 600 400 10 to 60 30 Standard installation With Nickel Catalyst Accessory: Standard installation With Nickel Catalyst Accessory: TCD to FID series installation Column plus capillary makeup TCD switching flow
Detectors 10 3 Set the detector temperature. The temperature must be greater than 150 °C for the flame to light. 4 Set the hydrogen flow rate, if desired, and press [Off/No]. 5 Change the air flow rate, if desired, and press [Off/No]. 6 If using a packed column, set the FID makeup gas to 0.0/Off. 7 If using a defined capillary column, set the makeup gas flow or combined column plus makeup gas flow. 8 Scroll to Flame and press [On/Yes].
10 Detectors About the TCD The TCD compares the thermal conductivities of two gas flows—pure carrier gas (the reference gas) and carrier gas plus sample components (the column effluent). This detector contains a filament that is heated electrically so that it is hotter than the detector body. The filament temperature is held constant while alternate streams of reference gas and column effluent pass over it.
Detectors Column effluent is forced away from the filament. TCD measures reference gas. Advanced User Guide 10 Column effluent is forced toward the filament. TCD measures peaks (if present).
10 Detectors TCD pneumatics This is the pneumatics design of the TCD. Makeup Reference Gas Vent Valve Frit EPC Module PS Frit Restrictor Reference switching valve Valve PS Restrictor Column PS = Pressure Sensor TCD carrier, reference, and makeup gas Reference and makeup gas must be the same as the carrier gas, and the gas type must be specified in both the inlet and detector parameter lists.
Detectors 10 4.0 3.0 Ratio of reference flow to column + makeup flow 2.0 1.0 0 10 20 30 40 50 60 Column + makeup flow, mL/min TCD gas pressures Choose a flow, find a pressure, set source pressure 10 psi (70 kPa) higher.
10 Detectors 20 16 Hydrogen 12 Makeup gas flow, mL/min Helium 8 Nitrogen 4 Pressure (psig) (kPa) 10 69 20 138 30 207 40 276 50 345 60 414 Selecting reference and makeup flows for the TCD Table 67 Recommended flow rates and temperatures Gas type Flow range Carrier gas (hydrogen, helium, nitrogen) Packed, 10 to 60 mL/min Capillary, 1 to 5 mL/min Reference (same gas type as carrier) 15 to 60 mL/min See the figures to select a value.
10 Detectors compounds may attack the filament. The immediate symptom is a permanent change in detector sensitivity due to a change in filament resistance. If possible, such compounds should be avoided. If this is not possible, the filament may have to be replaced frequently. Changing the TCD polarity during a run Negative polarity On inverts the peak so the integrator or ChemStation can measure it. Negative polarity can be a run table entry; see “Run Time Programming” on page 14.
10 Detectors 3 Verify that makeup gas type is the same as that plumbed to your instrument (next to Makeup line in the parameter list). Change the gas type, if necessary. 4 Set the reference gas flow rate. 5 If you are using packed columns, turn off the makeup gas (or proceed to step 6 and enter 2 to 3 mL/min, see “TCD carrier, reference, and makeup gas” on page 306) and proceed to step 7 6 If you are using capillary columns:, choose a flow mode and set the makeup gas flow or combined flow.
Detectors 10 2 m × 0.2 mm capillary column If column flow is 0.75 mL/min, the makeup must be at least 4.25 mL/min. Set it = 5. Reference flow will then be 3 × 5.75 = 17.25 mL/min. Total detector flow = 5.75 + 17.25 = 22.5 mL/min. 25 m × 0.32 mm capillary column If column flow = 10 mL/min, set makeup low to minimize sample dilution. Set it = 2 mL/min. Reference flow will then be 12 × 2 = 24 mL/min. Total detector flow = 12 + 24 = 36 mL/min.
10 Detectors About the uECD The micro- cell detector (uECD) contains a cell plated with 63Ni, a radioactive isotope. The 63Ni releases β particles that collide with carrier gas molecules to produce low- energy electrons—each β particle produces approximately 100 electrons. The free electrons produce a small current—called the reference or standing current—that is collected and measured in a pulsed circuit.
Detectors 10 ECD licenses Customers in the United states can purchase a uECD under either a General License or a Specific License. Customers outside the United States should contact their local Agilent sales office for information. Specific License Specific License uECDs require you to obtain a Materials License from the Nuclear Regulatory Commission (NRC) or the local state agency, permitting you to possess the amount and kind of radioisotope used in the detector.
10 Detectors isotope is ingested or inhaled. For this reason the cell must be handled with care: Radioactive leak tests must be performed at the required intervals, the inlet and outlet fittings must be capped when the detector is not in use, corrosive chemicals must not be introduced into the detector, and the effluent from the detector must be vented outside the laboratory environment.
Detectors WA R N I N G 10 You may not open the uECD cell unless authorized to do so by your local nuclear regulatory agency. Do not disturb the four socket-head bolts. These hold the cell halves together. Removing or disturbing them is a violation of the terms of the General License and could create a safety hazard. Safety precautions when handling uECDs • Never eat, drink, or smoke when handling uECDs. • Always wear safety glasses when working with or near open uECDs.
10 Detectors uECD gas flows Anode purge and makeup gas Restrictor Frit Vent PS 63Ni Valve Restrictor Capillary adapter EPC Module PS = Pressure Sensor Column uECD linearity The uECD response factor versus concentration curve is linear for four orders of magnitude or more (linear dynamic range = 104 or higher) for a broad range of compounds. You should still run a calibration curve on your samples to find the limits of the linear range for your materials.
Detectors 10 temperature of the last compound. If you operate at excessively high temperatures, your results will not necessarily improve and you may increase sample and column decomposition. uECD analog output If you intend to use the analog output from the uECD, you must set the output Range to 10. 1 Press [Analog Out 1] or [Analog Out 2]. 2 Scroll to Range. 3 Type 10 and press [Enter].
10 Detectors uECD temperature programming The uECD is flow sensitive. If you are using temperature programming, in which the column flow resistance changes with temperature, set up the instrument as follows: • Set the carrier gas in the Constant flow mode. Set detector makeup gas to Constant makeup. • If you choose to work in the constant pressure mode, the makeup gas should be set in the Column +makeup=constant mode.
Detectors 10 About the NPD New NPD features and changes The NPD firmware in this GC (A.01.08 or higher) is considerably different from that in earlier versions and from the 6890 firmware. Major changes are: • Equilibration time parameter has been removed. • Adjust Offset feature has been changed. • Auto Adjust on/off has been added. • Dry Mode has been added. • Blos/ceramic bead selector has been added. We strongly recommend that you allow the firmware to perform Auto Adjust and set the Bead Voltage.
10 Detectors The output current is proportional to the number of ions collected. It is sensed by an electrometer, converted to digital form, and sent to an output device.
10 Detectors Table 71 General operating values (continued) Gas or Setting Capillary makeup (helium, nitrogen) Recommendation Ceramic bead Nitrogen: 5 to 10 mL/min Helium: less than 5 mL/min Blos bead 1 to 20 mL/min Temperature Default is 250 °C; operating range is 150 °C to 400 °C. • <150 °C, the Adjust offset process will not start. • 325 to 335 °C is recommended. • Detector temperature should be greater than the highest oven temperature.
10 Detectors 150 Air 100 Flow, mL/min Helium 50 Nitrogen Pressure (psig) (kPa) 5 10 69 20 138 30 207 40 276 50 345 60 414 70 483 4 Hydrogen 3 Flow, mL/min 2 1 Pressure (psig) (kPa) 4 28 8 55 12 83 16 110 20 138 Temperature programming The NPD is flow sensitive. If you are using temperature programming, in which the column flow resistance changes with temperature, set up the instrument as follows: • Set the carrier gas in the Constant flow mode. Set detector makeup gas to Constant makeup.
Detectors 10 gases, including the detector hydrogen, air, and makeup gases. Do not use plastic (including Teflon) tubing, plastic- bodied traps, or O- ring seals. Setting parameters for the NPD Before operating the NPD, make sure that detector gases are connected, a column is installed, and the system is free of leaks. Set the oven temperature, inlet temperature, and column flow.
10 Detectors flow mode, choose Constant makeup. For a column in the constant pressure mode, choose Column +makeup=constant. c If your column is not defined, enter a makeup gas flow. Only constant flow is available. 13 Monitor the offset adjustment process. a If Auto Adjust is On, the adjust offset process starts automatically when the detector reaches setpoint.
Detectors 10 Changing from a ceramic bead to a Blos bead CAUTION The Blos bead is more delicate than the ceramic beads, and may be distorted during shipping. Before installing a Blos bead, verify that it is centered and adjust it if necessary. When you turn the NPD off, the GC remembers the bead voltage used and applies that voltage when the detector is turned back on. If you have changed from a ceramic bead to a Blos bead, this voltage will be too high and may damage the new bead.
10 Detectors 51.5 mm 1 43 mm 2 43 mm 1 3 Figure 1 2 3 Capillary optimized NPD jets For the adjustable NPD, select one of the following from Table 74. Table 74 Jets for adaptable fittings Figure 4 ID Jet type Part number Jet tip id Length 1 Capillary with extended jet (recommended) G1534-80590 0.29 mm (0.11 inch) 70.5 mm 2 Capillary 19244-80560 0.29 mm (0.011 inch) 61.5 mm 3 Capillary, high-temperature 19244-80620 0.47 mm (0.018 inch) 61.5 mm 4 Packed 18710-20119 0.46 mm (0.
10 Detectors Auto Adjust Bead Recommended On. When On, the automatic adjust offset process starts when the bead reaches the temperature setpoint after having been turned off or cooled below 150 °C. Auto adjust starts after Dry Bead hold time, if enabled. Auto Adjust Bead uses the adjust offset feature to protect the bead—especially new beads—by making sure that the desired offset is obtained with the lowest possible bead voltage.
10 Detectors Detector off When the detector is off, Adjust offset and Bead voltage are Off and initial Output is displayed. Detector on—detector temperature less than 150 °C. When you enter an Adjust offset value or press [On], detector gases turn on and the display blinks the Temp not ready message. Detector on—waiting for oven and/or detector to reach temperature setpoint and equilibrium. If the oven or detector is not at setpoint, the display continues to blink the Temp not ready message.
Detectors 10 • Keep the detector temperature high (320 to 335 °C). • Turn the hydrogen flow off during solvent peaks and between runs. Turning hydrogen off during a solvent peak When using the NPD, the baseline shifts after a solvent peak and can take some time to stabilize, especially with chlorinated solvents. To minimize this effect, turn off the hydrogen flow during the solvent peak and turn it back on after the solvent elutes.
10 Detectors • the detector is at the temperature setpoint • temperature is at least 150 °C • gas flows are on • Dry Bead time, if On, has elapsed Bead voltage is also useful for small adjustments between runs. If you observe a baseline drift, you can enter a small, one- time change to compensate for the drift. If you are not using the recommended Adjust offset process, note that large voltage jumps reduce bead life. Use increments no greater than 0.
Detectors 10 About the FPD The sample burns in a hydrogen- rich flame, where some species are reduced and excited. The gas flow moves the excited species to a cooler emission zone above the flame where they decay and emit light. A narrow bandpass filter selects light unique to one species, while a shield prevents intense carbon emission from reaching the photomultiplier tube (PMT). The light strikes a photosensitive surface in the PMT where a light photon knocks loose an electron.
10 Detectors FPD linearity Several mechanisms produce sulfur emission. The excited species is diatomic, so that emission intensity is approximately proportional to the square of the sulfur atom concentration. The excited species in the phosphorus mode is monatomic, leading to a linear relationship between emission intensity and atom concentration. FPD Lit Offset The default Lit Offset is 2.0 pA. Starting Up and Shutting Down the FPD The FPD creates a great deal of water vapor when the flame is on.
10 Detectors The phosphorus filter is yellow/green and transmits at 525 nanometers. Inlet liners for use with the FPD Compounds containing sulfur may adsorb on an inlet liner and degrade the GC’s performance. Use deactivated, clean liners or a cool on- column inlet, which injects directly onto the column. For best results with splitless injection, use liner 5181- 3316. FPD temperature considerations The minimum detector temperature to prevent water condensation is 120 °C.
10 Detectors Table 75 Recommended flows (continued) Sulfur mode flows, mL/min Phosphorus mode flows, mL/min Air 60 100 Carrier + makeup 60 60 Helium, either as carrier or makeup gas, may cool the detector gases below the ignition temperature. We recommend using nitrogen rather than helium. Lighting the FPD flame Before trying to light the flame, have the detector at operating temperature. Removing the condensate tubing may help, but be sure to replace it before making runs.
10 Detectors Manual ignition 1 Press [Front Det] or [Back Det]. 2 Scroll to Flame. Press [On/Yes]. The flame ignition sequence begins. Automatic ignition If the FPD output with the flame on falls below the flame- off output plus the Lit offset value, this is interpreted as a flame- out condition. The FPD runs the flame ignition sequence to relight the flame. If this fails, it runs the sequence again.
10 Detectors On ignition, the signal increases. Typical levels are 4 to 40 pA in sulfur mode, 10 to 70 pA in phosphorus mode. Verify that the flame is lit by holding a cold, shiny surface, such as a mirror or chrome- plated wrench, over the vent exit. Steady condensation indicates that the flame is lit.
Agilent 7890A Gas Chromatograph Advanced User Guide 11 Valves About Valves 338 The Valve Box 339 Heating the valves 339 Valve temperature programming 339 Configuring an Aux thermal zone 340 Valve Control 341 The valve drivers 341 The internal valve drivers 341 The external valve drivers 342 Valve Types 343 Configuring a Valve 344 Controlling a Valve 345 From the keyboard 345 From the run or clock time tables 345 Simple valve: column selection 345 Gas sampling valve 346 Multiposition stream selection valve
11 Valves About Valves Valves may be used to alter the usual inlet/column/detector flow path in the GC. Sampling valves can replace the inlet, switching valves can select columns, multiposition valves, used in conjunction with sampling valves, can perform the same functions for sample streams that an ALS performs for liquid samples.
Valves 11 The Valve Box The GC holds up to four valves in a heated valve box on top of the oven. The valve box is the preferred location for valves because it is a stable temperature zone, isolated from the column oven. Back of chromatograph Valve heater blocks Valve box, cover removed Figure 3 Diagram of valve locations on GC Valves may also be mounted inside the column oven. Heating the valves The valve box contains two heated blocks, each with two valve mounting locations (shaded in Figure 3).
11 Valves Configuring an Aux thermal zone To configure a thermal Aux zone (1 or 2), press [Config][Aux Temp #], then [1] or [2]. Press [Mode/Type], then select the type of device to be controlled. Press [Enter].
Valves 11 Valve Control Valves can be controlled manually from the keyboard or as part of a clock or run time program. Note that only sampling valves automatically reset at the end of a run. Other valve types remain at the new position until activated again. For other valve types, you must include any desired resets in the program. The valve drivers A valve driver is the software and circuitry in the GC that controls a valve or related function. There are eight drivers known as Valve 1 through Valve 8.
11 Valves Keyboard Connector V1 or Connector V2 Run table Internal valve drivers (1 through 4) Connector V3 or Connector V4 Clock table There is no direct relationship between the location of a valve in the valve box and the driver that controls it. This depends on how the solenoids are wired and the actuators are plumbed. Manual valves must be switch by hand, and are heated or unheated.
Valves 11 Valve Types There possible valve types are: Sampling A two- position (load and inject) valve. In load position, an external sample stream flows through an attached (gas sampling) or internal (liquid sampling) loop and out to waste. In inject position, the filled sampling loop is inserted into the carrier gas stream. When the valve switches from Load to Inject, it starts a run if one is not already in progress. See the example on page 346.
11 Valves Configuring a Valve 1 Press [Config]. Scroll to Valve #. 344 2 Enter the valve number and press [Enter]. The current valve type is displayed. 3 To change the valve type, press [Mode/Type], select the new valve type, and press [Enter].
11 Valves Controlling a Valve From the keyboard Valves (except multiposition valves) have two positions controlled by the [On] and [Off] keys. The keyboard commands for two- position valves are: [Valve #] [On] Rotates valve to one stop and [Valve #] [Off] stop Rotates valve to the other From the run or clock time tables The Valve On and Valve Off commands can be run time or clock time programmed.
11 Valves Use a run table entry to ensure that the valve is in the Off state between runs. Gas sampling valve If a valve is configured as a gas sampling valve, it starts a run automatically when it is switched to the Inject position. This can be done with a keyboard command or by a subsequence or clock table entry. You may have two gas sampling valves installed.
Valves 11 Load time Time in minutes that the valve remains in the Load position before becoming ready. Inject time Time in minutes that the valve remains in the Inject position before returning to the Load position. The sampling valve cycle is: 1 The sampling valve rotates to the Load position. Load time begins. Valve is not ready. 2 Load time ends. The valve becomes ready. 3 If everything else is ready, the GC becomes ready.
11 Valves Sampling valve Multiposition stream selection valve Sample streams in Selected stream out If the GC has one valve configured as a multiposition valve and another configured as a gas or liquid sampling valve, it assumes that they are to be used in series. This “double configuration” can be used to replace an automatic liquid sampler and sample tray in an analytical sequence. The multiposition valve becomes the sample tray; the sampling valve becomes the injector.
Agilent 7890A Gas Chromatograph Advanced User Guide 12 7683B Sampler About the 7683B Sampler 350 Setting Parameters for the ALS 351 Solvent Saver 352 Sample tray setpoints 353 Storing setpoints 353 Agilent Technologies 349
12 7683B Sampler About the 7683B Sampler The 7683B Automatic Liquid Sampler (ALS) is controlled by a sequence that specifies what samples are to be analyzed, where the sample vials are located in the sampler tray (if used), what methods are to be used for each sample, and possibly what to do after the last sample to clean out the column. See “Creating Sequences” on page 111 for more information on sequences.
7683B Sampler 12 Setting Parameters for the ALS Pressing either of the injector keys allows you to edit injector control setpoints, such as injection volumes, sample and solvent washes, etc. To edit the injector setpoints: 1 Press [Front Injector] or [Back Injector]. 2 Scroll to the desired setpoint. 3 Enter a setpoint value, or turn the setpoint On or Off. 4 Press [Mode/Type] to make selections for syringe size and syringe plunger speed. Injection volume Sample volume to be injected.
12 7683B Sampler Solvent B post washes (0-15) How many times the syringe is washed with solvent B after any solvent A washes. Solvent B pre washes (0-15) How many times the syringe is washed with solvent B after any solvent A prewashes and before the sample washes. Solvent B wash volume The percent of the syringe volume to be used for solvent B washes. Sample Draw Speed Speed of the syringe plunger when drawing in sample. Sample Disp Speed Speed of the syringe plunger when dispensing sample.
12 7683B Sampler Sample tray setpoints The sample tray delivers sample vials to the front and rear injectors according to the defined sequence parameters. There is a separate set of sequence parameters for each injector. The sample tray delivers vials to the front injector before the rear injector. Stored sequences and bar code configurations can be used to tell the sample tray where to deliver and retrieve sample vials. Enable bar code Turns the bar code reader on or off.
12 7683B Sampler 354 Advanced User Guide
Agilent 7890A Gas Chromatograph Advanced User Guide 13 Cables About Cables and Back Panel Connectors 356 Back panel connectors 356 Sampler connectors 356 The AUX connector 356 Signal connectors 357 REMOTE connector 357 EVENT connector 357 BCD input connector 357 RS-232 connector 357 LAN connector 357 Using the Remote Start/Stop cable 358 Cable Diagrams 363 Analog cable, general use 363 Remote start/stop cable 363 BCD cable 364 External event cable 365 Agilent Technologies 355
13 Cables About Cables and Back Panel Connectors Some parts of an analysis system are connected to the GC by cables. These cables and the back panel connectors to which they connect are described in this section. Back panel connectors These are the connectors on the back panel of the GC: SIG 1 SIG 2 SAMPLER 1 SAMPLER 2 TRAY REMOTE AUX EVENT BCD LAN RS-232 Sampler connectors If using an ALS, connect to the GC using the following connectors: SAMPLER 1 An injector, usually the front injector.
Cables 13 Signal connectors SIG1 and SIG2 are for the two analog output signals. REMOTE connector Provides a port to remotely start and stop other instruments. A maximum of 10 instruments can be synchronized using this connector. See “Using the Remote Start/Stop cable” on page 358 for more detail. EVENT connector This connector provides two passive contact closures and two 24- volt outputs for controlling external devices. The outputs are controlled by valve drivers 5 through 8.
13 Cables Using the Remote Start/Stop cable Remote start/stop is used to synchronize two or more instruments. For example, you might connect an integrator and the GC so that the [Start]/[Stop] buttons on either instrument control both of them. You can synchronize a maximum of ten instruments using Remote cables. Connecting Agilent products If connecting two Agilent products with Remote cables, the sending and receiving circuits will be compatible—just plug in both ends of the cable.
Cables 13 APG Remote - Suggested drive circuits A signal on the APG bus may be driven by another APG device or by one of the following circuits: • A relay, with one side connected to ground, when closed will set a logic- low state. • An NPN transistor, with the emitter connected to ground and the collector connected to the signal line will set a logic- low state if proper base current is supplied. • An open- collector logic gate will perform this same function.
13 Cables Start (Low True) Request to start run/timetable. Receiver is any module performing runtime- controlled activities. The 7890 GC requires a pulse duration of at least 500 micro- seconds to sense a start from an external device. Start Relay (Contact Closure) A 120 millisecond contact closure – used as an isolated output to start another device that is not compatible or connected with APG Remote pin 3.
Cables 13 Connecting Cables Connect a GC to an Agilent data system computer using LAN communications using a LAN cable. See Figure 4 below. LAN hub/switch Crossover LAN cable 5183-4648 LAN cable 8121-0940 GC LAN cable 8121-0940 Computer Computer GC Figure 4 Connecting the GC and computer with a hub/switch (shown at left) or a crossover cable (shown at right). Table 77 Typical IP addresses for an isolated LAN GC Computer IP address 10.1.1.101 10.1.1.100 Subnet mask 255.255.255.0 255.255.255.
13 Cables Table 78 Table 79 Cabling requirements (continued) 7890A GC connected to: Required Cable(s) Part number CTC automatic sampler Remote, 3395B/3396C Integrator Remote, 9 pin/15 pin Analog, 2 m, 6 pin 03396-61010 G1530-60570 Non-Agilent Integrator General purpose analog signal cable 2 m, 6 pin G1530-60560 Mass Selective Detector Remote, 2-m, 9-pin male/9-pin male G1530-60930 Non-Agilent data system General use remote, 9-pin male/spade lugs (various lengths) 35900-60670 (2 m), 35900
Cables 13 Cable Diagrams Analog cable, general use Connector 1 Connector 2 The pin assignments for the general use analog out cable are listed in Table 80.
13 Cables Table 81 Remote start/stop cable connections Connector 1, 9-pin male Connector 2, wire color Signal 1 Black Digital ground 2 White Prepare (low tone) 3 Red Start (low tone) 4 Green Start relay (closed during start) 5 Brown Start relay (closed during start) 6 Blue Open circuit 7 Orange Ready (high true input) 8 Yellow Stop (low tone) 9 Violet Open circuit BCD cable The BCD connector has eight passive inputs that sense total binary- coded decimal levels.
Cables 13 External event cable 6 3 7 4 1 8 5 2 Connector 1 Connector 2 Two passive relay contact closures and two 24- volt control outputs are provided. Devices connected to the passive contact closures must be connected to their own power sources. The pin assignments for this cable are listed in Table 83.
13 Cables 366 Advanced User Guide
Agilent 7890A Gas Chromatograph Advanced User Guide 14 GC Output Signals About Signals 368 Signal Types 369 Value 369 Analog Signals 371 Analog zero 371 Analog range 371 Analog data rates 372 Selecting fast peaks (analog output) 373 Digital Signals 374 Digital zero 374 Baseline level shifts 374 Agilent data systems 375 Column Compensation 378 Creating a column compensation profile 379 Making a run using analog output column compensation 379 Plotting a stored column compensation profile 380 Test Plot 381 A
14 GC Output Signals About Signals Signal is the GC output to a data handling device, analog or digital. It can be a detector output or the output from flow, temperature, or pressure sensors. Two signal output channels are provided. Signal output can be either analog or digital, depending on your data handling device. Analog output is available at either of two speeds, suitable to peaks with minimum widths of 0.004 minutes (fast data rate) or 0.01 minutes (normal rate).
GC Output Signals 14 Signal Types When assigning detector signals, use the [Mode/Type] key and choose from the Signal Type parameter list, or press a key or combination of keys. [Front], [Back], [–], and [Column Comp] will work, alone or in combination. For example, press [Back] for back detector or [Back][–][Front] for back detector minus front detector. The menu choices for signal subtraction (Front - Back and Back Front) only appear if the front and back detectors are of the same type.
14 GC Output Signals Table 84 370 Signal conversions (continued) Signal type 1 display unit is equivalent to: Pneumatic: Flow Pressure Diagnostic 1 mL/min 1 pressure unit (psi, bar, or kPa) Mixed, some unscaled Advanced User Guide
14 GC Output Signals Analog Signals If you use an analog recorder, you may need to adjust the signal to make it more usable. Zero and Range in the Signal parameter list do this. Analog zero Zero Subtracts value entered from baseline. Press [On/Yes] to set to current Value or [Off/No] to cancel. This is used to correct baseline elevation or offsets. A common application is to correct a baseline shift that occurs as the result of a valve operation.
14 GC Output Signals A: Range = 0 B: Range = 3 C: Range = 1 There are limits to usable range settings for some detectors. The table lists the valid range setpoints by detector. Table 85 Range limits Detector Usable range settings (2x) FID 0 to 13 NPD 0 to 13 FPD 0 to 13 TCD 0 to 6 υECD 0 to 6 Analog input 0 to 7 Range may be run time programmed. See “Run Time Programming” on page 14 for details.
GC Output Signals 14 Selecting fast peaks (analog output) 1 Press [Config][Analog 1] or [Config][Analog 2]. 2 Scroll to Fast peaks and press [On]. Agilent does not recommend using Fast peaks with a thermal conductivity detector. Since the gas streams switch at 5 Hz, the gain in peak width is offset by increased noise.
14 GC Output Signals Digital Signals The GC outputs digital signals only to an Agilent data system. The following discussions describe features that impact the data sent to data systems, not the analog data available to integrators. Digital zero Digital signal outputs respond to the Zero command by subtracting the signal level at the time of the command from all future values.
GC Output Signals 14 No correction Baseline level change Baseline shifting event occurs 3. Sig zero - val event occurs Run time correction 2. Baseline shifting event occurs 1. Store signal value event occurs Agilent data systems The GC can process data at various data rates, each corresponding to a minimum peak width. The table shows the effect of data rate selection.
14 GC Output Signals Table 86 EZChrom Elite/ChemStation data processing (continued) Data rate, Hz Minimum peak width, minutes Relative noise 1 0.2 0.22 0.5 0.4 0.16 0.2 1.0 0.10 0.1 2.0 0.07 Detector Column type Slow packed You cannot change the data rate during a run. You will see higher relative noise at the faster sampling rates. Doubling the data rate can double peak height while the relative noise increases by 40%.
GC Output Signals 14 Zero Init Data Files This feature applies to digital output only, and is mainly intended for non- Agilent data systems. It may help systems that have trouble with non- zero baseline output. When you turn it On, the GC immediately begins to subtract the current detector output value(s) from any future values. For example, if you turn it on when the output is 20 pA, the GC subtracts 20 pA from the digital output until you turn Zero Init Data Files Off.
14 GC Output Signals Column Compensation In temperature programmed analysis, bleed from the column increases as the oven temperature rises. This causes a rising baseline which makes peak detection and integration more difficult. Column compensation corrects for this baseline rise. A column compensation run is made with no sample injected. The GC collects an array of data points from all 4 detectors, whether installed, off, or working.
GC Output Signals 14 Creating a column compensation profile 1 Set up the instrument for a run. 2 Make a blank run to verify that the baseline is clean. This is particularly important for new conditions or if the GC has been idle for several hours. 3 Press [Column Comp]. 4 Select Col comp 1 or Col comp 2 (these are the two arrays). 5 Select Start compensation run and press [Enter].
14 GC Output Signals This changes the digital output. You cannot get both compensated and uncompensated digital data from the same detector at the same time. However, it does not affect the analog output. Plotting a stored column compensation profile 1 Press [Analog Out 1] or [Analog Out 2]. 380 2 Scroll to Type: and press [Mode/Type]. 3 Select the profile to be plotted. 4 Press [Start].
GC Output Signals 14 Test Plot Test plot is an internally generated “chromatogram” that can be assigned to a signal output channel. It consists of three baseline- resolved, repeating peaks. The area of the largest is approximately 1 Volt- sec, the middle one is 0.1 times the largest, and the smallest is 0.01 times the largest. Test plot can be used to verify the operation of external data processing devices without having to perform repeated chromatographic runs.
14 GC Output Signals 382 Advanced User Guide
Agilent 7890A Gas Chromatograph Advanced User Guide 15 Miscellaneous Topics Auxiliary Devices 384 About Auxiliary Pressure Control 384 About Aux Thermal Zone Control 385 About Auxiliary Device Contacts 385 About the 24V Auxiliary Device Power Supply 385 About Auxiliary Columns 385 About Auxiliary Detectors 386 To Use the Stopwatch 387 Service Mode 388 Service Reminders 388 Agilent Technologies 383
15 Miscellaneous Topics Auxiliary Devices About Auxiliary Pressure Control Pressure units There are two common ways of expressing gas pressures: psia Absolute pressure, measured relative to vacuum. psig Gauge pressure, measured relative to atmospheric pressure. This name is used because most pressure gauges have one side of the sensing element exposed to the atmosphere.
15 Miscellaneous Topics Setting parameters for auxiliary pressure control 1 Press [Aux EPC #] and scroll to the channel you wish to control. Press [Enter]. 2 Scroll to Initial pressure. Enter a value and press [Enter]. 3 If desired, enter a pressure program using the time and rate functions. 4 Press [On/Yes] to apply Initial pressure and start the program. About Aux Thermal Zone Control There can be up to 3 aux thermal controlled zones. These zones are 3- ramp programmable.
15 Miscellaneous Topics About Auxiliary Detectors The GC supports up to two auxiliary detectors in addition to the Front and Back detectors that mount on the top of the oven. Aux Det # 1 This can only be a TCD, and mounts in a carrier on the left side of the oven together with its flow module. Aux Det # 2 This can only be an analog input board (AIB). It is used to receive and process data from a non- Agilent detector or other source.
Miscellaneous Topics 15 To Use the Stopwatch In the stopwatch mode, both the time (to 0.1 second) and reciprocal time (to 0.01 min- 1) are displayed. The stopwatch is useful when measuring flows with a bubble flowmeter. 1 Press [Time] and scroll to the time = line. 2 Press [Enter] to start the stopwatch. 3 Press [Enter] again to stop. 4 Press [Clear] to set to zero. You can access other functions while the stopwatch is running. Press [Time] again to view the stopwatch display.
15 Miscellaneous Topics Service Mode The [Service Mode] key presents the Service Reminders and other functions. Service Reminders Internal counters This is a set of 12 counters that monitor the use of various items on the GC, such as syringes, septa, and columns. These counters only count runs and their definitions are fixed. You can set limits for each item; when a limit is reached, the Service Due light on the status board comes on. Examine the limits to identify the item that has reached its limit.
Miscellaneous Topics 15 Each counter has an ID that can be associated with a concept, such as front inlet gold seal, and can count the number of elapsed runs or seconds since the last reset, from which one can infer the gold- seal’s in- service time or count. A ChemStation can enable or disable individual counters in association with a method, so that only the counters for things used by the method advance. Other functions These are for use by trained Agilent personnel.
15 Miscellaneous Topics 390 Advanced User Guide
