QUICK START GUIDE HI 904 KARL FISCHER COULOMETRIC TITRATOR Revision 1.0 www.hannainst.
QUICK START GUIDE Dear customer, Congratulations on choosing a Hanna Instruments Product. This guide has been written for the HI 904 Karl Fischer Coulometric Titrator. Please read this Quick Start Guide carefully before using the instrument. This guide will provide you with the necessary information for the correct use of the instrument. The purpose of this guide is to present a quick overview of setting up and using the instrument.
QUICK START GUIDE Contents INTRODUCTION ..........................................................................................................5 SAFETY MEASURES.....................................................................................................6 TITRATOR CONNECTIONS .........................................................................................7 USER INTERFACE .........................................................................................................
QUICK START GUIDE 4
QUICK START GUIDE INTRODUCTION The HI 904 Karl Fischer Coulometric titrator is extremely flexible, capable of performing a wide variety of highly accurate and precise water content titration methods. The HI 904 finds a titration endpoint using a polarized electrode and an advanced detection algorithm. A constant flow of current is maintained between the two platinum pins of the titrator’s electrode.
QUICK START GUIDE SAFETY MEASURES The following safety measures must be followed: 1. Never connect or disconnect the pump assemblies with the titrator turned on. 2. Always check that the reagent and waste bottles, as well as the titration vessel are properly assembled. 3. Always wipe up spills and splashes immediately. 4.
QUICK START GUIDE TITRATOR CONNECTIONS Front View Rear View 7
QUICK START GUIDE USER INTERFACE Keypad The titrators have their own keypad with 29 keys grouped in four categories, as follows: Display The titrators have a 5.7” graphical backlit color display. The Standby Mode screen is shown below with short explanations. The user interface contains several screens. In each screen, many information fields are present at the same time. The information is displayed in an easy-to-read manner, using different size fonts.
QUICK START GUIDE HOW TO SELECT YOUR LANGUAGE from the main To change the language, press screen. Highlight the Language option and then press . Using the and keys select the language from the options listed in the Set Language screen and press . Restart the titrator in order to apply the new language setting. HOW TO USE THE CONTEXTUAL HELP .
QUICK START GUIDE BEFORE PERFORMING THE FIRST TITRATION Setup the Titrator • Make sure that all of the titrator assemblies are properly installed (see Instruction Manual, Setup section). • Make sure that the vessel system is properly sealed against atmospheric moisture (the fittings and tubes are correctly mounted). • The desiccant had been properly dried.
QUICK START GUIDE Fill Titration Vessel with Reagent The titration vessel must be filled with reagent up to the MIN marker (about 75 mL): • Lower the reagent tube below the liquid level inside the reagent bottle. • From the Idle screen, press . • Push and hold the FILL button located on the top of the air pump. • Wait until the vessel is filled up to the MIN marker with solvent. • Stop the air pump by pressing reagent in the vessel.
QUICK START GUIDE Liquid Samples: • Samples with low viscosity will be added using a syringe with needle (injection through the septum). • Weigh the syringe before and after injection in order to increase precision (back-weighing technique). Sample Volume Preparation Liquid samples with low viscosity can be added by volume. Samples should be added using a precision syringe and needle. Performing a Titration • From the main screen press for analyzing a sample.
QUICK START GUIDE Understanding the Displayed Information During a titration, the following screen is displayed: Viewing Graph During Titration Press to display the real time titration graph. The curve displayed is a plot of Electrode Potential vs. Titrated Water. A dashed horizontal line represents the user selected end point potential. Titration Termination The titration is terminated when the conditions of the Termination Criteria have been met.
QUICK START GUIDE • The Review Result screen will be displayed. • Use the and keys to display information related to the last titration performed. See titration report on page 15. Printing the titration report Connect a DOS / Windows compatible printer directly to the DB 25 connector (parallel port) located on the back of the titrator. Note: To connect the printer, please turn off the titrator and the printer. Printing out the report: • From the Review Report screen, press .
QUICK START GUIDE • Transferring a report file will automatically transfer the corresponding log file and titration graph BMP file (if applicable). • Press , to return to the General Options screen. • Press again, to return to the Idle screen. Titration report While scrolling with the and keys, the fields below can be seen on the titrator display or printed. The same information is available on the saved report file (KF_00003.rpt in this example, with all report fields selected).
QUICK START GUIDE Nr Titr 0 1 2 3 4 5 6 7 8 9 10 mV 385.7 385.7 385.8 385.7 385.4 385.5 385.8 385.3 385.3 386.0 386.8 Time 00:00:00 00:00:01 00:00:02 00:00:04 00:00:05 00:00:06 00:00:07 00:00:08 00:00:09 00:00:10 00:00:11 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 62.8 65.8 68.7 71.6 74.6 77.5 80.5 83.4 86.3 89.3 92.2 95.1 98.1 101.0 104.0 106.9 385.0 384.7 383.7 383.9 385.3 384.8 384.3 383.5 382.9 382.2 381.0 380.1 380.1 379.4 377.8 376.
INSTRUCTION MANUAL HI 904 KARL FISCHER COULOMETRIC TITRATOR Revision 1.00 www.hannainst.
Dear customer, Congratulations on choosing a Hanna Instruments product. Please read this instruction manual carefully before using the instrument. This manual will provide you with the necessary information for the correct use of the instrument. Hanna Instruments All rights are reserved. Reproduction in whole or in part is prohibited without the written consent of the copyright owner, Hanna Instruments Inc., 584 Park East Drive, Woonsocket, Rhode Island 02895, USA.
TABLE OF CONTENTS Chapter 1. INTRODUCTION Chapter 2. SETUP Chapter 3. USER INTERFACE Chapter 4. GENERAL OPTIONS Chapter 5. METHODS Chapter 6. TITRATION Chapter 7. AUXILIARY FUNCTIONS Chapter 8. MAINTENANCE, PERIPHERALS Chapter 9. OPTIMIZATION Appendix 1. TECHNICAL SPECIFICATIONS Appendix 2. RECOMMENDED REAGENTS Appendix 3.
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INTRODUCTION 1 INTRODUCTION The HI 904 is an automatic coulometric Karl Fischer titrator with high accuracy, great flexibility and repeatability. The titrator is designed to perform titrations for a variety of applications. The main attributes of this titrator are: Flexibility Support up to 100 titration methods (standard and user defined). High accuracy Precise pulsing coulometric generator. Precise mV measurement and current (µA) control.
INTRODUCTION 1-2
SETUP Chapter 2. Contents 2 SETUP ................................................................................................... 2 - 3 2.1 Unpacking ............................................................................................. 2 - 3 2.2 Safety Measures ..................................................................................... 2 - 4 2.3 Installation ........................................................................................... 2 - 5 2.3.
SETUP 2-2
SETUP 2 SETUP 2.1 Unpacking The titrator and the accessories are shipped in a single box containing: 1 2 3 4 5 6 7 8 9 10 11 12 13 ITEM QUANTITY Titrator ................................................................... 1 pc. Air Pump Assembly ................................................. 1 pc. Titration Vessel Assembly ......................................... 1 pc.
SETUP 14 15 16 17 18 19 Power Adapter ........................................................ USB Cable ............................................................... Instruction Manual Binder ......................................... USB Storage Device ................................................. HI 900 PC Application (Install Kit on USB Stick) ........ Quality Certificate .................................................... 1 1 1 1 1 1 pc. pc. pc. pc. pc. pc.
SETUP 2.3 Installation 2.3.
SETUP 2.3.2 Titrator Rear View 2.3.
SETUP 2.3.4 Titrator Assembly Note: Assembly operations must be completed before connecting the titrator to the power supply! 2.3.4.1 Connecting the Air Pump The diaphragm air pump system is designed to work with the specially designed bottle top assemblies. It allows the reagent in the titration vessel to be removed and/or replaced with minimal exposure of the interior of the vessel to ambient moisture from atmospheric humidity.
SETUP 2.3.4.2 Connecting the Reagent Adapter Holder The Reagent Adapter Holder is a convenient dock for the Reagent Exchange Adapter when it is not in use. The holder consists of a base that fastens to the titrator pump bay and a removable standard-taper glass tube. The glass tube holds the Reagent Exchange Adapter and will catch possible drips from the reagent/waste tubes. It is easily removable for cleaning purposes. Install the Reagent Adapter Holder with the following steps (see Figure 2.
SETUP 2.3.4.3 Titration Vessel The titration takes place in a sealed titration vessel. The titration vessel can also be referred to as a reaction vessel, titration cell or reaction cell. The primary design features of the HI 904 titration vessel include the following: • Durability, easy to use, clean and maintain. • All glass cells are manufactured with ground-glass joints for ultra-low water vapor permeability and high chemical resistivity to Karl Fischer reagents.
SETUP 2.3.4.3.1 Titration Vessel Components Warning: Always apply a thin layer of joint grease (supplied) to ground-glass joints before attaching. Improperly-greased joints may become permanently seized! To assemble the titration vessel, see Figure 4 and follow the steps below: Figure 4 Karl Fischer Detector Electrode The Karl Fischer detector electrode (F) consists of two parallel, platinum pins sealed into a 10mm diameter glass body.
SETUP Reagent Exchange Port The HI 904 titration vessel can be connected to the reagent and waste bottles using the Reagent Exchange port and the supplied adapter. The Reagent Exchange Adapter may remain connected to the titration vessel during operation if lower drift is not necessary. Otherwise, place the supplied glass stopper (G) in the Reagent Exchange Port. Sample Port The sample port consists of a silicone rubber septum (B) secured in place with an open-top GL18 cap (C).
SETUP 2.3.4.4 Electrical Connections • Connect the KF generator electrode to the 5-pin connector (C) using the supplied cable. • Connect the KF detector electrode to the BNC connector (D). • Connect the power adapter cable to the power input connector (B).
SETUP 2.3.5 Reagent, Waste Bottle Assembly The bottle top assemblies are equipped with desiccant cartridges containing molecular sieves, which ensures that the air passing through the reagent handling system has been dried. The molecular sieves have a limited capacity to absorb moisture and is typically exhausted after 3 to 5 weeks. Molecular sieves, indicating or otherwise, can be regenerated at 300°C.
SETUP 2.3.6 Reagent Exchange Adapter The Reagent Exchange Adapter is used to connect reagent and waste bottles to the titration vessel. The adapter consists of a set of o-rings and compression caps that form a seal around the reagent and waste tubes, and a ground-glass joint for connection to the titration vessel. The compression caps can be loosened when inserting tubes or adjusting the tube position and tightened to hold the tubes in place.
USER INTERFACE Chapter 3. Contents 3 USER INTERFACE .................................................................................. 3 - 3 3.1 Start Up ................................................................................................. 3 - 3 3.2 Description ............................................................................................ 3 - 4 3.2.1 Keypad .................................................................................................... 3 - 4 3.2.1.
USER INTERFACE 3-2
USER INTERFACE 3 USER INTERFACE 3.1 Start Up Once the instrument is assembled and installed, follow the steps below to start the titrator: • Connect the instrument to a power outlet with the supplied power adapter. • Turn on the titrator using the power switch located on the back of the instrument. • Wait until the titrator finishes the initialization process. • Press when prompted or wait a few seconds for titrator to start.
USER INTERFACE 3.2 Description This chapter describes the basic principles of navigation through the user interface, selecting fields and entering values from the keypad. 3.2.1 Keypad The titrator’s keypad is grouped into five categories, as follows: 3.2.1.1 Function Keys If one of these keys is pressed, the associated function is immediately performed.
USER INTERFACE 3.2.1.3 Arrow Keys These keys have the following functions: • Move the on-screen cursor. • Increase and decrease the stirrer speed and other settings. • In the alphanumeric screen, to select a character. • To navigate through menu options. 3.2.1.4 Numeric Keys Keys to Used for numeric entries. Toggles between positive and negative values. Decimal point. Initiates entry of exponent for scientific notation. 3.2.1.
USER INTERFACE 3.2.3 The Idle Screen After start up and initialization, the first screen displayed is the Idle Screen . Idle Screen fields: Method name: Displays the name of the selected method. Time and date: Displays the current date and time. Stirrer information: Actual / Set stirrer speed is displayed in RPM. When stirrer is off, the stirrer information is not displayed. Reagent: Displays the name of the current reagent.
USER INTERFACE 3.2.4 The Process Screen When the user presses while in Idle Screen, all titration related processes are started. The titrator displays the Process Screen. Process Screen fields: Method name: Displays the name of the selected method. Time and date: Displays the current date and time Process stage field: Displays the current process (Pre-titration, Drift Analysis, Standby, Sample Analysis). Process status: Displays the process status with a descriptive drawing.
USER INTERFACE 3.3 Menu navigation 3.3.1 Selecting an Option To select an option, simply press the option key below the virtual key. For example, to access the Method Options screen press the option key below it. 3.3.2 Selecting a Menu Item To select an item from the menu screen use the arrow keys and to move the cursor. When the menu is larger than the display, a scroll bar is active on the right side. The and be used to scroll through the pages. To activate the selected menu item, press 3.3.
USER INTERFACE 3.3.4 Saving Modifications The Saving Method screen allows the user to save the modifications. To exit from Saving Method screen without saving, press or highlight the Exit Without Saving . To save the Method option and then press modifications highlight the Save Method option and then press . Note: To access the contextual help menu, press displayed screen. Press or press at any time. Help is related to the again to return to the previous screen.
USER INTERFACE 3-10
GENERAL OPTIONS Chapter 4. Contents 4 GENERAL OPTIONS ............................................................................. 4 - 3 4.1 Date and Time Setting ....................................................................... 4 - 3 4.2 Display Settings .................................................................................. 4 - 4 4.3 Beeper ................................................................................................. 4 - 5 4.4 Stirrer ........................
GENERAL OPTIONS 4-2
GENERAL OPTIONS 4 GENERAL OPTIONS The General Options screen gives access to options that are not directly related to the from the main screen while in idle titration process. To access this screen, press mode. In Pre-titration, Drift Analysis, Standby or Titration process, the General Options can be accessed by pressing the <> key on a PS/2 keyboard. The available menus are described below: 4.1 Date and Time Setting This screen allows the user to set the date and time.
GENERAL OPTIONS 4.2 Display Settings This screen allows the user to customize the viewing features of the display. Option Keys: Increases the backlight saver time interval Decreases the backlight saver time interval The backlight intensity can be adjusted using the and keys. There are 8 levels of backlight intensity, ranging from 0 to 7. A color palette is displayed in the center of the screen, allowing an easy selection of the appropriate backlight intensity.
GENERAL OPTIONS 4.3 Beeper This screen allows the user to turn the Beeper On (Enable) or Off (Disable). The beeper will sound after a titration is completed, when an invalid key is pressed or when a critical error occurs during titration. 4.4 Stirrer This screen allows the user to select the internal magnetic stirrer, an external magnetic stirrer or a user-controlled stirrer uncontrolled by the titrator (custom). The external stirrer is automatically detected when it is connected.
GENERAL OPTIONS 4.5 Language Select an available language. 4.6 Reagent Exchange Reminder Coulometric Karl Fischer reagents have a limited titration capacity, meaning that there is a limited amount of water that a volume of reagent can react. For this reason, the HI 904 automatically tracks the total amount of water that has been reacted since the reagent was added to the titration vessel. By default, an “Exchange Reagent” reminder will appear after 1000 mg of water have been titrated.
GENERAL OPTIONS 4.7 Save Files to USB Storage Device This option allows the user to save files from titrator to a USB storage device. On the titrator, the available file types are: Standard Method Files - HIxxxxyy.MTD (e.g.: HI9001EN.MTD, HI9101EN.MTD) User Method Files - USERxxxx.MTD (e.g.: USER0001.MTD) Drift/Titration Report Files - DR_xxxxx.RPT, KF_xxxxx.RPT (e.g.: DR_00001.RPT, KF_00001.RPT) Insert the USB Storage Device into the USB port on the left side of the titrator.
GENERAL OPTIONS 4.8 Restore Files from USB Storage Device This screen allows the user to transfer files from the USB storage device to the titrator. Insert the USB Storage Device into the USB port on the left side of the titrator. The file types that can be transferred are: Standard Method Files - HIxxxxyy.MTD (e.g.: HI9001EN.MTD, HI9101EN.MTD) User Method Files - USERxxxx.MTD (e.g.: USER0001.MTD) Drift/Titration Report Files - DR_xxxxx.RPT, KF_xxxxx.RPT (e.g.: DR_00001.RPT, KF_00001.
GENERAL OPTIONS 4.9 USB Link with PC The USB Link feature is useful to transfer methods/reports directly to/from a PC. To use this feature, connect the USB cable to the labeled connector on rear of titrator and connect to a PC with HI 900 PC Application installed. The titrator automatically attempts to connect to the PC while on this screen. Inactive: Active: Ready: Transmit: Speed: 4.10 The titrator is not connected to the HI 900 PC Application. The titrator is connected to the HI 900 PC Application.
GENERAL OPTIONS Disconnect the KF electrode, then connect the HI 900940 calibration key to the electrode input (BNC connector). Depending on which parameters you want to check, follow the indications below: Checking the mV input accuracy: Set the multimeter to mV mode. If necessary, switch the calibration key to mV mode by pressing the red button. Connect the calibration key banana plugs to the multimeter mV input. Choose the current value using the and keys (from the pre-defined list).
GENERAL OPTIONS Configure the settings on the titrator Balance Configuration menu to match the settings for your particular balance (baud rate, data bits, parity, stop bit number, request command syntax). It may be necessary to change settings on your balance. Users should consult their balance instruction manual. Before leaving this screen, be sure the connection with the balance is working properly by pressing the 4.12 key.
GENERAL OPTIONS 4.13 Reset to Default Settings This option restores the manufacturer settings. Note: Please be careful!!! This will also delete all the user created methods, reports and restore all manufacturer settings such as titrator configuration, standard method parameters, etc. 4.14 Update Software This screen allows the user to update the titrator software from a USB storage device containing a software setup kit.
METHODS Chapter 5. Contents 5 METHODS .............................................................................................. 5 - 3 5.1 Selecting Methods ................................................................................ 5 - 3 5.2 Standard Methods ................................................................................. 5 - 4 5.2.1 Upgrading Standard Methods....................................................................... 5 - 4 5.2.2 Deleting Standard Methods .......
METHODS 5.5.10 Control Parameters ................................................................................... 5 - 16 5.5.10.1 Titration Speed .............................................................................................5 - 16 5.5.10.2 Standby Mode ..............................................................................................5 - 17 5.5.10.3 Standby Duration .......................................................................................... 5 - 17 5.5.10.
METHODS 5 METHODS All of the parameters required to complete an analysis are grouped into a method. The titrator is supplied with a pack of standard methods. Standard and user methods can be upgraded, stored or deleted by connecting the titrator to a PC using the HI 900 PC application or a USB storage device. 5.1 Selecting Methods To select a method, press the displayed. key (when available).
METHODS 5.2 Standard Methods The standard methods were developed for the most common types of analysis. Also, the standard methods can be used as a model to create new user methods. Only specific method parameters can be modified by the user (see Section 5.5, Method Options section). 5.2.
METHODS 5.2.3 Restoring the Standard Methods to the Manufacturer Settings You can restore the standard method to the manufacturer setting by highlighting a standard method and pressing . 5.3 User Methods These methods are defined by the user (usually by modifying a standard method). The user methods can be developed in accordance with the requirements of the user. All method parameters can be modified by the user. 5.3.
METHODS Note: Only a limited number of user methods can be generated. The titrator can hold 100 methods (standard and user). When it is reached, a warning message will be displayed. 5.3.2 Deleting User Methods To remove a user method, press want to delete and press (when available). Highlight the user method that you . A screen will appear in order to confirm the deletion. Press again to confirm, or press 5.4 to cancel the operation.
METHODS Save method: After making modifications, press 5.5 Method Options 5.5.1 Naming the User Method and select Save Method to keep the changes. This option allows you to enter a name for the new method (up to 24 characters). Use the arrow keys to navigate through the character table. Press character to the method name.
METHODS 5.5.2 Method Revision This option allows you to enter a string representing the current method revision. The revision string format should be “X.Y”, where X and Y are numerical digits. 5.5.3 Method Type Method type is a parameter listed in each method. In order to conduct a titration the user has to choose between KF Coulometric or Bromine Index.
METHODS 5.5.4 Pre-Analysis Stir Time To avoid erroneous results or unreachable endpoints when analyzing samples with limited solubility, the sample must be completely dissolved in the solvent prior to the start of a titration. The pre-analysis stir time can be set between 5 and 1000 seconds. After the sample is added to the reaction vessel the titrator will stir for the set period of time before any iodine is generated / bromine is consumed. 5.5.
METHODS 5.5.6 Stirbar Type Allows the user to edit the stirbar description. 5.5.7 Drift Entry Allows the user to choose the drift entry mode that is used during the titration process: Automatic - the drift rate will be calculated automatically after the Pre-titration of the solvent. User - the drift is set to a fixed value (entered by the user). The user enters the estimated drift value. The drift analysis stage will be skipped and the user must enter the drift value between 0.0 µg/min and 10.
METHODS 5.5.8 Reagent The user can enter a name for the reagent (up to 15 characters). Use the arrow keys to navigate through the character table; press reagent name.
METHODS 5.5.9 Sample Parameters This screen allows the user to access and configure the specific sample parameters. 5.5.9.1 Sample Determination This screen allows the user to select the sample determination mode. Normal sample determination is performed through direct titration of liquid samples that are soluble in solvent and have homogeneous distribution in water. External extraction is a method for the preparation of insoluble samples that require a water extraction.
METHODS 5.5.9.2 Sample Name This screen allows the user to enter a name for the sample (up to 14 characters). Use the to add the highlighted arrow keys to navigate through the character table. Press character to the sample name. 5.5.9.3 Sample Type (Normal Determination only) This option allows the user to select the type of the sample: mass or volume. This information is used to determine the appropriate sample size required by the titration prior to analysis.
METHODS 5.5.9.4 Sample Size This option allows the user to enter the sample size. For External/Dissolution, enter the size of the aliquot taken from the external vessel. Before the titration is started, the user is asked again to enter the sample size. The sample size (mass or volume) can be automatically acquired from the balance (when the balance feature is enabled - see Section 4.11, Setup Balance Interface) 5.5.9.5 Sample Density (Sample Type: Volume only) Enter the density of the sample in g/mL.
METHODS 5.5.9.6 only) External Solvent Size ( External Dissolution/Extraction determination mode Enter the mass of the solvent used for external dissolution or extraction of the sample. Weigh the solvent after determining the solvent water content but before adding sample to the solvent. 5.5.9.7 only) External Solvent Conc. (External Dissolution/Extraction determination modes Enter the concentration of water in the solvent. 5.5.9.
METHODS 5.5.10 Control Parameters The user can access and edit the parameters related to the titration. 5.5.10.1 Titration Speed Choose the desired titration speed for the method. Some samples or reagents may produce very abrupt endpoints, requiring slower titration speeds in order to avoid over-titration.
METHODS 5.5.10.2 Standby Mode When enabling this option, the titrator will automatically revert to Standby mode after a titration is completed. See also the Standby Duration option. 5.5.10.3 Standby Duration The user can enter the period of time which the cell is kept dry and ready for subsequent analysis after a titration has finished. The user can set the standby period up to 72 hours.
METHODS 5.5.10.4 Imposed Current The HI 904 uses a bivoltametric indicating electrode system. During a titration, the titrator monitors the voltage required to maintain a constant polarization current (imposed current). This option allows the user to select the electrode polarization current from the predefined list. Note: Higher polarization currents will speed the contamination of the electrode and potentially degrade samples. 5.5.10.
METHODS 5.5.10.6 Generator Current Mode This option allows the user to select the generator electrode current mode: Auto: The titrator will dynamically select the optimal current level (50-400 mA) depending on the dose size and the electrical resistance of the reagent. Fixed (400 mA): The titrator will always use 400-mA pulses. Note: If the generator is unable to produce enough current (depending on the Generator Current Mode), an error message will be displayed and the titration will be stopped. 5.5.10.
METHODS 5.5.11 Termination Parameters This screen allows the user to set the control parameters related to the end of the titration. 5.5.11.1 Maximum Duration Specify the maximum time a titration is allowed to run. Once this point is reached, the titration will be terminated even if the end point is not reached. The time can be set from 10 to 3600 seconds.
METHODS 5.5.11.2 Maximum Water Titrated The maximum water reacted during the titration must be set according to the analysis. If the titration end point is not reached, the titration will be terminated after the maximum titrated water has been reacted. The error message (“Limits Exceeded”) will appear on the display. Range is from 0.1 to 100.0 mg. 5.5.11.3 Termination Criterion This screen allows the user to set the titration termination criterion.
METHODS 5.5.11.4 End Point Stability Time This screen allows users to set the time period in which the electrode potential must remain stable. This setting is in accordance with the mV End Point termination criterion. 5.5.12 Result Unit The titrator provides the results based on the selected units. 5.6 Printing To print method parameters, press from the main screen, then .
METHODS 5.7 Bromine Index The HI 904 is capable of performing Bromine Index/Bromine Number determinations. Bromine Index/Number is a measure of the unsaturation of hydrocarbons, expressed as the amount of bromine required to react with 100 g of sample. Bromine Index is expressed as mg Br/100g; Bromine Number is expressed as g Br/100g.
METHODS 5-24
TITRATION Chapter 6. Contents 6 TITRATION ........................................................................................... 6 - 3 6.1 Idle ........................................................................................................ 6 - 3 6.2 Pre-titration.......................................................................................... 6 - 3 6.3 Drift Analysis ........................................................................................ 6 - 4 6.4 Standby ...
TITRATION 6-2
TITRATION 6 TITRATION 6.1 Idle The titrator first enters Idle mode when it is switched on. All of the HI 904’s software features and adjustable parameters can be accessed from the Idle state. This includes all of the user-adjustable method parameters, solvent handling system, file transfers, calibration checks, software upgrades, options for interface with PC and accessories as well as burette options. To access the titration menu (Process screen) press .
TITRATION During the pre-titration, the user cannot change the currently selected method or access the method parameters. Note: If the pre-titration lasts longer than 30 minutes the titrator switches to Idle mode. Errors may have occurred in your titration system (beaker is not properly sealed, wrong reagent, unconnected or bad electrode, etc.). Check the system and start pre-titration again. 6.
TITRATION 6.4 Standby After the drift rate has been determined, the HI 904 moves into Standby mode. In standby mode, the dryness of the titration vessel is maintained and the drift rate is continuously monitored and updated. From Standby mode, a sample analysis, or drift rate logging session can be launched as well as method selection, customization of method parameters, and general options (external keyboard only, by pressing <>).
TITRATION 6.5 Sample Analysis While in Standby mode, press . Note: If the drift value is zero a warning message appears to inform the user that the solvent may be overtitrated. The user can choose to continue the titration by pressing or to return to Standby in order to wait until the drift is stabilized at a higher value. mode by pressing Entering estimated concentration: The user has the option to enter the estimated concentration.
TITRATION Manual Entry Follow the steps below: 1. Attach a long needle (approximately 6 in. for best control) to a syringe that is large enough to hold at least one complete sample volume. For the volumetric addition of samples, use a precision-volume syringe. 2. Rinse the syringe and needle with sample 2-3 times by drawing in a small portion of sample, fully extending the plunger, shaking to coat the syringe interior, and expelling the sample into a waste collection container. 3.
TITRATION Automatic Mass Acquisition from Analytical Balance The sample size can be automatically acquired from the balance when connected to the titrator using the RS232 interface. Note: The user must make sure that the balance and the titrator are properly configured and the balance feature is enabled (see Section 4.11, Setup Balance Interface). Procedure 1. Place the syringe containing the sample on the balance. 2. Wait until the reading is stabilized and press . 3.
TITRATION The titrator returns to the previous screen and the sample size is automatically updated. Now the analysis can be started. Start Analysis Press to begin analysis. Suspend Titration While the titration is in progress, you can temporarily stop it by pressing will stop producing iodine. To continue the titration press . The generator .
TITRATION Viewing the Titration Curve During a titration, the titration curve can be displayed on the Titration Graph screen, by pressing . The titration report ID is also displayed inside the graph window. Press to stop the titration manually and return to Idle mode. Press to stop the titration and return to Standby mode. When the end point is reached the titration is finished and the following screen is displayed.
TITRATION Averaging Sample Analysis Results , the Sample Analysis History, Averaging and Statistical Data can be By pressing viewed. Use the Use and keys to scroll the results list. to choose the results that will be used for averaging. Note: When there are no results selected, dashes will appear in the Average Sample Concentration and the Standard Deviation fields.
TITRATION 6-12
AUXILIARY FUNCTIONS Chapter 7. Contents 7. AUXILIARY FUNCTIONS ....................................................................... 7 - 3 7.1 Air Pump ............................................................................................... 7 - 3 7.1.1 Filling the Vessel ......................................................................................... 7 - 3 7.1.2 Emptying the Vessel .................................................................................... 7 - 3 7.2 Stirrer..
AUXILIARY FUNCTIONS 7-2
AUXILIARY FUNCTIONS 7 AUXILIARY FUNCTIONS 7.1 Air Pump The air pump is used to add or remove the reagent in the titration vessel without exposure to atmospheric moisture. To start the air pump, press from the Idle screen. The air pump can be stopped by pressing 7.1.1 . Filling the Vessel To add reagent to the titration vessel: 1. Set up the reagent and waste bottle assemblies (see Section 2.3.5 Reagent, Waste Bottle Assembly). 2.
AUXILIARY FUNCTIONS 7.2 Stirrer Note: When custom stirrer is selected (see Section 4.4, Stirrer in General Options chapter), the commands related to the stirrer are not available. The stirrer can be turned on and off by pressing while in Idle mode. During the titration process the stirrer cannot be turned off. The stirring speed is set within the method parameters (see Section, 5.5.5 Stirring Speed). During the titration process, the stirring speed can be manually adjusted by using the keys.
AUXILIARY FUNCTIONS 7.3 Results To access the “Data Parameters” screen, press button. From the Data Parameters screen you can access the following options: 7.3.1 Review Last Titration Report The last titration report can be reviewed. The information seen in the report is based on the selections made in the Setup Titration Report screen. The following option keys are available: The titration graph can be reviewed by selecting . Print the titration report.
AUXILIARY FUNCTIONS 7.3.2 Review Available Reports Up to 100 reports can be saved on the titrator. To view one of the saved reports highlight a report and then press . All of the saved reports can be reviewed and printed. The report contains only the information selected in the Setup Titration Report screens during report generation. The following option keys are available: Review the titration graph. Print the titration report. Delete the selected report. 7.3.
AUXILIARY FUNCTIONS Company Name: Allows the company name to be recorded in each report. Operator Name: Allows the operator name to be recorded in each report. Electrode Name: Allows the electrode name to be recorded in each report. Fields 1, 2, 3: Allows any additional information to be recorded in each report. The fields must be selected from the Setup Titration Report screen (see Section 7.4.5, Setup Titration Report) in order to be displayed in the titration report. 7.3.
AUXILIARY FUNCTIONS 7.3.5 Setup Titration Report Customize a unique report to record the titration results. An asterisk means that it will be included in the titration report.
MAINTENANCE, PERIPHERALS Chapter 8. Contents 8 MAINTENANCE, PERIPHERALS ............................................................ 8 - 3 8.1 Generator Electrode Maintenance ....................................................... 8 - 3 8.2 Detector Electrode Maintenance .......................................................... 8 - 3 8.3 Reagent Adapter Holder Maintenance................................................. 8 - 4 8.4 Reagent Exchange Adapter Maintenance ...............................
MAINTENANCE, PERIPHERALS 8-2
MAINTENANCE, PERIPHERALS 8 MAINTENANCE, PERIPHERALS 8.1 Generator Electrode Maintenance Caution: Never heat generator electrodes over 50ºC when drying! This could cause permanent damage to the connector! Generator electrodes should be cleaned every 1-2 weeks, more frequently if working with “dirty” or “oily” samples. 1. Remove the desiccant cartridge from the top of the generator and disconnect the cable.
MAINTENANCE, PERIPHERALS If these signs are observed, the electrode pins may be dirty. Rinse the electrode with a solvent that is appropriate for the type of sample used – methanol is usually sufficient. Remove debris by gently wiping with a clean cloth or tissue. Allow the probe to dry completely before re-installing. If a more thorough cleaning is required, soak the electrode in HI 7061 Electrode Cleaning Solution for General Use, for several hours then rinse with water followed by methanol.
MAINTENANCE, PERIPHERALS 5. Wipe joint grease off of the ground-glass joints with a clean, dry cloth or tissue. 6. Dry the glass adapter in a drying oven, or thoroughly wipe dry. Allow that caps and o-rings to air dry. 7. Ensure that all pieces are thoroughly dry before re-assembly. 8.5 Peripherals Warning! Connection/disconnection of POWER CORD, PUMP ASSEMBLY, EXTERNAL PC DISPLAY, PRINTER, RS232 INTERFACE or EXPANSION DEVICE must be done only when titrator and external devices are turned off. 8.5.
MAINTENANCE, PERIPHERALS 8.5.2 Connecting an External PC Keyboard This connection allows you to use an external PS/2 PC Keyboard in addition to titrator’s keypad. Connect an external PC Keyboard (PS/2 connector).
MAINTENANCE, PERIPHERALS The correspondence between the Titrator’s Keypad and the United States 101-type external keyboar are: External PC Keyboard (United States 101) Titrator Keypad Function Key F-1 Function Key F-2 Function Key F-3 Function Key F-4 Function Key F-5 Option Key 1 (from left to right) Function Key F-6 Option Key 2 (from left to right) Function Key F-7 Option Key 3 (from left to right) Function Key F-8 Option Key 4 (from left to right) Function Key F-9 Option Key 5 (from left to r
MAINTENANCE, PERIPHERALS 8.5.3 Connecting a Printer A variety of parallel printers can be connected to the parallel port of the titrator using a standard DB-25 cable. Warning:The titrator and the external printer must both be OFF before they are connected. Connect the external printer to the standard 25–pin Socket. Turn on the titrator and then the printer.
MAINTENANCE, PERIPHERALS 8.5.4 Connecting to a Computer The titrator can be connected to a computer using a USB cable. HI 900 PC application needs to be installed on the PC. Connect the cable to the USB port on the rear panel of the titrator. Connect the cable to the USB port on the PC. Select the USB Link with PC screen on the titrator by following the path: General Options - USB Link with PC Launch the HI 900 PC application and then select the appropriate USB port on the PC.
MAINTENANCE, PERIPHERALS 8-10
METHODS OPTIMIZATION Chapter 9. Contents 9 OPTIMIZATION ..................................................................................... 9 - 3 9.1 Titrator Settings ................................................................................... 9 - 3 9.1.1 Control Parameters.................................................................................... 9 - 3 9.1.1.1 Endpoint Potential and Polarization Current ........................................................9 - 3 9.1.1.
METHODS OPTIMIZATION 9.2.5 Sample Preparation Techniques ................................................................... 9 - 9 9.2.5.1 Dilutions ..........................................................................................................9 - 9 9.2.5.2 External Dissolution ......................................................................................... 9 - 9 9.2.5.3 External Extractions .........................................................................................
METHODS OPTIMIZATION 9 OPTIMIZATION 9.1 Titration Settings This section provides the descriptions of critical titration parameters necessary for an analyst to modify a standard method or develop a titration method from scratch. HI 904 methods can be modified and customized based on the requirements of the sample, sample matrix and the Karl Fischer reagent formulation.
METHODS OPTIMIZATION The table that follows correlates endpoint potential ranges for each of the possible polarization current settings of the HI 904. The suggested endpoints below are applicable for reagents formulated with methanol. Endpoint potentials should be increased by 20 to 25% when titrating with reagent systems formulated for use with aldehydes or ketones or where methanol has been replaced with higher alcohols or substituted ethers like diethylene glycol monoethyl ether or 2-methoxyethanol.
METHODS OPTIMIZATION 9.1.2 Termination Parameters HI 904 provides a choice of three criteria by which a titration can be considered to have reached an endpoint successfully. 9.1.2.1 Stability Time When this termination criteria is selected, a titration is considered to have reached an endpoint when the electrode potential stays below the specified endpoint potential for a period of time called the stability time. Typical endpoint stability times range between 5 and 15 seconds. 9.1.2.
METHODS OPTIMIZATION 9.1.2.2.2 Absolute Drift Stop Under this criteria, a titration reaches an endpoint successfully when the drift falls below a predefined threshold called the absolute drift stop value. When setting the absolute drift threshold, a balance must be struck between the titration speed and accuracy. Choosing a threshold slightly higher than the initial drift rate will result in high reproducibility and relatively slow titrations.
METHODS OPTIMIZATION 9.2 The Sample 9.2.1 Proper Sampling Procedure Proper sampling is essential for accurately determining the water content of bulk materials, particularly with non-homogeneous samples. Many standard methods detail instructions to ensure proper sampling. As a general rule, the following guidelines should be followed: 1. The sample must be representative. The water content of the sample taken is the same as the average water content of the bulk material. 2.
METHODS OPTIMIZATION 9.2.4 Liquid Samples The water contained in liquid samples must be available to react with the KF reagent. It is important to select a reagent or co-solvent with which the sample is miscible. Liquids are typically added through the septum in the sample port via a syringe and needle using the following steps: 1. Attach a long needle (approximately 6” long, 21-gauge) to a syringe large enough to hold at least one complete sample volume. 2.
METHODS OPTIMIZATION 9.2.5 Sample Preparation Techniques While many samples can be introduced directly into the titration vessel (see section 6.5 Sample Addition), others require preparatory steps. It is critical that samples are not contaminated with additional water or lose water during the preparation phase. The steps required for the most common sample preparation techniques are outlined below.
METHODS OPTIMIZATION An outline of a general procedure follows: 1. Determine the mass of an extraction bottle or flask equipped with a septum. 2. Add the extraction solvent to the bottle and determine the mass of the bottle and the solvent. In order to maximize the effectiveness of the extraction, the water content of the solvent should be as low as possible. When choosing an extraction solvent, one must carefully consider the limit of water saturation for a possible solvent. 3.
METHODS OPTIMIZATION The heating temperature is sample specific and can be found in applicable standard methods. The temperatures are chosen to be as high as possible without decomposing the sample, which can result in contamination of the titration vessel. 9.3 Karl Fischer Reagent System A wide variety of Karl Fischer reagents exist on the market today, each designed and formulated for specific sample matrices and titration conditions.
METHODS OPTIMIZATION 9-12
APPENDIX 3 A3-2
A3-6 APPENDIX 3 MAN HI904 09/13
APPENDIX 1 Appendix 1. Contents A1 TECHNICAL SPECIFICATIONS ..............................................................
APPENDIX 1 A1-2
APPENDIX 1 A1 TECHNICAL SPECIFICATIONS Range Resolution Result Units Sample Type Determination Pre-Titration Conditioning Background Drift Correction Endpoint Criteria 1 ppm to 5% 0.
APPENDIX 1 Reagent Handling System Type Desiccant Type Bottle Thread Type Glass Connection Reagent/Waste Tubing Peripheral Devices PC USB Flash Drive Laboratory Analytical Balance Printer Monitor Keyboard Sealed system with integrated diaphragm air pump Molecular Sieves GL-45 Standard Taper 19 (using supplied adapter) PTFE Transfer methods and reports via USB connection to a PC using the HI 900 PC Software Methods and reports can be easily transferred between devices using a USB Flash Drive.
APPENDIX 2 Appendix 2. Recommended Reagents A2 RECOMMENDED REAGENTS ................................................................ A2-3 A2.1 Reagents for Generators with Diaphragm ......................................... A2-3 A2.2 Reagents for Generators without Diaphragm .................................... A2-3 A2.3 Water Standards .................................................................................
APPENDIX 2 A2-2
APPENDIX 2 A2 RECOMMENDED REAGENTS A2.1 Reagents for Generators with Diaphragm Sigma-Aldrich® 34836 34726 34868 34843 34820 Coulomat Coulomat Coulomat Coulomat Coulomat HYDRANAL® AG (anolyte) E (anolyte) Oil (anolyte) AG-H (anolyte) AK (anolyte) 34840 34840 34840 34840 34821 Coulomat Coulomat Coulomat Coulomat Coulomat CG (catholyte) CG (catholyte) CG (catholyte) CG (catholyte) CG-K (catholyte) General Purpose Ethanol-based Hydrocarbons/Oils Hydrocarbons/Oils Ketones/Aldehydes A2.
APPENDIX 2 A2-4
APPENDIX 3 Appendix 3. Accessories A3 TITRATOR COMPONENTS ....................................................................
APPENDIX 3 A3-2
APPENDIX 3 A3 TITRATOR COMPONENTS HI 900561 Titration Vessel (Glass only) HI 900182 Reagent Adapter Holder (Glass only) HI 76330 Detector Electrode HI 900511 Generator Electrode with Diaphragm HI 900560 Titration Vessel Assembly HI 900512 Generator Electrode without Diaphragm HI 900180 Air Pump HI 900181 Reagent Adapter Holder Assembly A3-3
APPENDIX 3 HI 900568 Reagent Exchange Adapter HI 900564 Desiccant Cartridge for Generator Electrodes HI 900537 Bottle Top Assembly (with molecular sieves) HI 900542 O-ring set HI 900538 Desiccant Cartridge for Reagent/Waste Bottles HI 900534 Waste Bottle HI 900535 2 x Tubing for Reagent/ Waste Handling HI 900536 2 x Tubing for Air Pump HI 900566 Open-top GL18 Cap HI 900563 Glass Stopper, Standard Taper 19 A3-4 HI 900551 Molecular sieves, 150 g HI 900940 Calibration Key HI 900946 24 V Power Supp
APPENDIX 3 HI 900804 Manual (English) for HI 904 HI 900900U PC Application on USB Flash Drive HI 920013 USB Cable HI 900567 Septum Kit (5 pcs) HI 900543 Glass Joint Grease HI 900931 Generator Cable A3-5
A3-6 APPENDIX 3 MAN HI904 09/13
GENERAL APPLICATIONS BROCHURE HI 904 KARL FISCHER COULOMETRIC TITRATOR www.hannainst.
Method ID: HI9001EN Titrator Validation with 1.0 mg/g Water Standard Description: Method for validation of titrator accuracy. The results are expressed in mg/g and shouldmatch the certified value (within the uncertainty limits) provided by the manufacturer of the standard. Electrode: HI 76330 Double Platinum Pin Electrode HI 900517 Generator with Diaphragm -or HI 900518 Generator without Diaphragm Reagents: General Purpose Coulometric Karl Fischer Reagent 1.
Method ID: HI9301EN Moisture Determination in Solvent for external dissolution or extraction Description: Method for the determination of moisture in extraction/dissolution solvent. The results are expressed in mg/g and should be less than 1.00 mg/g. Extractions/dissolutions of substances with low water contents may require very dry solvents (<0.100 mg/g).
Method ID: HI9901EN Bromine Index of Aromatic Hydrocarbons Adaptation of ASTM D1492-08 Description: Method for the determination of bromine index of bromine-reactive substances. This method typically applies to aromatic hydrocarbons with only trace amounts of olefins (alkenes) and having bromine indexes less than 1000. For samples with a bromine index greater than 1000, it is recommended to dilute the sample with a suitable solvent.
Method ID: HI9901EN Bromine Index of Aromatic Hydrocarbons Adaptation of ASTM D1492-08 Results: Titration Report Method Name: BrIndex of Aromatics Time & Date: 12:00 Jan 01, 2013 Sample Size: 0.4978 g Bromine Consumed: 1.609 mg Result: 323.33 mg/100g Titration Duration: 4:36 [mm:ss] Generator Electrode Type: HI 900518 Titration went to Completion Operator Name: Analyst Signature: _______________________ Titrator Application Methods: General Applications – r. 1.
TITRATION THEORY TITRATION THEORY Principles HI 904 KARL FISCHER COULUMETRIC TITRATOR Revision 1.0 www.hannainst.
TITRATION THEORY 2
TITRATION THEORY Contents 1 1.1 1.2 1.3 GENERAL REVIEW OF TITRATION THEORY ................................................ 5 Introduction to Titrations ............................................................................ 5 Uses of Titrations .........................................................................................5 Advantages and Disadvantages of Titrations ............................................. 6 2 TYPES OF TITRATION ........................................................
TITRATION THEORY 4.3.2.2 Dispensing Errors............................................................................................... 22 4.3.3 4.3.4 Chemical Reaction Errors ................................................................................22 End Point Determination Errors .......................................................................22 5 CALCULATIONS .......................................................................................... 23 5.
TITRATION THEORY 1 GENERAL REVIEW OF TITRATION THEORY 1.1 Introduction to Titrations A titration is a quantitative, volumetric procedure used in analytical chemistry to determine the concentration of an analyte (the species being measured) in solution. The concentration of the analyte is determined by slowly adding a titrant (reagent) to the solution. As the titrant is added, a chemical reaction occurs between the titrant and the analyte.
TITRATION THEORY 1.3 Advantages and Disadvantages of Titrations Some advantages of titrations, as an analytical technique, are: • More precise results than many instrumental methods, such as measurement by electrode, the accuracy of the measurement is up to 0.1%; • Simple methods, reasonable capital costs, and easy training; • Suitability to measure major components of a mixture or product; • Automation can reduce time and labor spent on each analysis.
TITRATION THEORY 2 TYPES OF TITRATIONS 2.1 Titrations According to The Measurement Method 2.1.1 Amperometric Titrations An amperometric titration is performed by placing two electrodes (often a metal electrode and a reference electrode) into the sample solution and holding the potential of the metal electrode at a selected voltage. The current that flows, due to the oxidation or reduction of a reactant or product, is plotted vs.
TITRATION THEORY Potentiometry is the measurement of a potential under conditions of zero current flow. The measured potential can then be used to determine the analytical quantity of interest, generally a component concentration of the analyte solution. The potential that develops in the electrochemical cell is the result of the free energy change that would occur if the chemical phenomena were to proceed until the equilibrium condition has been satisfied.
TITRATION THEORY 2.2 Titrations According to The Reaction Type 2.2.1 Karl Fischer Titrations This method is based on a well-defined chemical reaction between water and the Karl Fischer reagent. The chemistry provides excellent specificity for water determination. The method can be used to determine free and bound water in a sample matrix.
TITRATION THEORY of reaction decreases and titration endpoint become increasingly difficult to reach. If the pH exceeds 8, side reactions begin to occur between iodine and hydroxide or methylate ions, changing the titration stoichiometry. While solvents not containing alcohols can be used for Karl Fischer analysis, they also have an effect on reaction stoichiometry. When alcohols are not present, the reaction resembles the Bunsen reaction stoichiometry where the consumption ratio of water to iodine is 2:1.
TITRATION THEORY The amount of current that passes through the generator can easily and accurately be measured by the electronics of the titrator. Therefore, coulometric Karl Fischer titrations are considered absolute - standardization is not necessary. Water standards can be titrated as a system check to ensure proper system functioning. 2.2.1.3.1 Generator Electrodes with Diaphragm The first coulometric Karl Fischer titrators used a diaphragm cell.
TITRATION THEORY 2.2.1.4 Visual Indication of Karl Fischer Titrations Visual methods, originally used by Karl Fischer, are limited in application, require a high degree of skill and have been made obsolete by electrometric indication. For successful visual indication, titration samples must be colorless. Additionally, the solution coloration varies between polar and non-polar titration media. After the titration equivalence point all of the water in the titration solution has been reacted.
TITRATION THEORY Bivoltametric indication involves measuring the voltage required to maintain a constant current flow between electrode elements. A small direct or alternating current called a polarization current (Ipol) is applied between the electrode pins or rings and the resulting voltage is measured in order to monitor the titration progress.
TITRATION THEORY Figure 3 shows a traditional titration curve. The curve is obtained by plotting the pH value against the volume of NaOH added. pCl Figure 3. 2.2.3 Argentometric Titrations Argentometric titrations use silver (nitrate) as the titrant and are generally precipitation titrations, as many silver salts are insoluble. These titrations are commonly used to titrate and determine the concentration of bromide, chloride, cyanide, iodide, and sulfide.
TITRATION THEORY 2.2.4 Complexometric Titrations A complex is a species where a central metal ion is covalently bonded to one or more electron donating groups called ligands. In a complexometric titration, metal ions are titrated using a titrant that binds strongly to it. Often these titrants contain EDTA or CDTA, polydentate ligands that form very stable coordination compounds with metal ions. The complexation reaction must be fast in order to be useful for direct titration.
TITRATION THEORY Titration of Acids Weak acids with pKa’s up to about 11 can be titrated in non-aqueous solvents. These include carboxylic acids, enols, phenols, imides, sulfonic acids, and inorganic acids. Water or lower alcohols are suitable for titrating medium to strong acids (pKa less than 5). Titrating a weaker acid with a strong base titrant requires a solvent less acidic than water or ethanol/methanol.
TITRATION THEORY Figure 6. Figure 7. Visual indicators such as Ferrion are also available. The oxidized and reduced form of the indicator will have different colors and can be used to determine the end point. Various reductants can be determined by titrants with oxidants such as potassium permanganate, potassium chromate or iodine. Commonly used reductants that are used as titrants include sodium thiosulfate, and ferrous ammonium sulfate.
TITRATION THEORY Potential, glass electrode, mV Figure 8.
TITRATION THEORY 3 INTRODUCTION TO TITRATION APPARATUS AND TYPICAL TITRATION PROCEDURE 3.
TITRATION THEORY 3.2 Automatic Titration Automatic titrators are high-precision analytical instruments that deliver the titrant, monitor the physical change associated with the titration reaction, automatically stops at the endpoint and calculates the concentration of the analyte. Automatic titrators are best for repetitive titrations and high-accuracy analyses. An automatic titrator must have an accurate liquid dispensing system.
TITRATION THEORY 4 TITRATION RESULTS 4.1 Accuracy The factors most critical to achieving accurate results with the HI 900 titration systems are the concentration of the sample, size of the sample and having an optimized set of method parameters. 4.2 Repeatability Repeatability, or the agreement between replicate determinations, is expressed quantitatively as the relative standard deviation (RSD). 4.3 Sources of Error One of the advantages of volumetric analysis is excellent accuracy and precision.
TITRATION THEORY 4.3.2.2 Dispensing Errors Incorrect dispensing due to: • Dead valve volume and leaking valve; • Inaccuracy in motor drive and gear lash/ backlash; • Poor burette/ piston seal; • Non-uniform diameter of burette glass cylinder; • Chemical incompatibility with tubing or bubble generation; • Density/ temperature changes in titrant. • Inadaquate volume to cover electrode. 4.3.
TITRATION THEORY 5 CALCULATIONS 5.1 Equations Used in Volumetric Karl Fischer Titrations 5.1.1 Calculation of water content as % mass from samples measured by mass C sample V titrant Titer m sample Concentration of Sample (% w/w) Volume of Titrant (mL) Titrant Titer (mg/mL) Mass of Sample (g) 5.1.
TITRATION THEORY 5.1.5 Calculation of water content in External Dissolution Samples C sample m solvent m sample C solution C solvent Concentration of Sample (% w/w) Mass of Solvent (g) Mass of Sample (g) Water Content of Dissoluted Sample (w/w) Water Content of Solvent (w/w) 5.1.
TITRATION THEORY 5.1.9 Calculation of Titer (water equivalent of the titrant) using water standards C titrant m sample C standard V titrant Titrant Titer (mg/mL) Mass of Sample (g) Water Content of Standard (mg/g) Volume of Titrant (mL) 5.2 Equations Used in Titrations The main variables used in calculating a result from a titration are the sample volume, the concentration of the titrant, and the volume of titrant required to reach the equivalence point.
TITRATION THEORY By Mass C titrant m standard Ratio FW standard V titrant Titrant Concentration (N) Mass of Standard (g) Equivalence ratio of titrant/standard (eq titrant/ mol standard) Formula Weight of the Standard (g/mol) Volume of Titrant (L) By Volume C titrant V standard C standard V titrant Concentration of titrant (N) Volume of Standard (mL) Concentration of standard (eq/L) Volume of Titrant
TITRATION THEORY C sample1 C sample2 C sample3 V titrant 1 V titrant 2 V titrant 3 C titrant Ratio FW analyte 1 FW analyte 2 FW analyte 3 m sample Sample 1 Concentration (g/100g) Sample 2 Concentration (g/100g) Sample 3 Concentration (g/100g) Volume of titrant required to reach the first end point (L) Volume of titrant required to reach the second end point (L) Volume of
TITRATION THEORY 6 GLOSSARY Acid A chemical species that can donate one or more protons (hydrogen ions). Acid-Base Titration Stoichiometric neutralization titrations, based upon the reaction that occurs between an acid and base. Activity A physical property corresponding to the concentration of all ions in a solution. Electrodes respond to activity.
TITRATION THEORY End point The point where a titration is stopped because a physical change in the solution has indicated a completed titration. Titration end points typically coincide with the equivalence point. A fixed value end point (pH or mV), can be used as well. The titration will stop at the desired point regardless if the titration is complete. Equivalence point The point where the quantity of titrant is stoichiometrically equal to the quantity of analyte.
TITRATION THEORY Neutralization A chemical reaction where an acid and a base react to form a neutral salt and water. Non-aqueous A solution that does not contain water. Non-aqueous Titration A titration that is preformed in non-aqueous solutions. Typically used to titrate very weak acid and bases to eliminate the leveling effect water has on all acids and bases dissolved in it. Normal The concentration of a solution which accounts for any stoichiometric difference between the various species in a solution.
TITRATION THEORY Spectrophotometric Titration A titration in which the end point is marked by a change in the color and/or color intensity. Stoichiometry The quantitative relationship of the reactants and products in a chemical reaction. Titrant The chemical added in a titration that causes the given reaction to occur. Titration A quantitative, volumetric procedure used in analytical chemistry to determine the concentration of an analyte in solution.
TITRATION THEORY Titr THEORY 904 07/13 32
