User guide

266 Advanced User Guide
8 Inlets
Total f l ow 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 Flow through the septum purge vent, at least 15
mL/min.
Gas saver On to reduce split vent flow at Saver time.
Saver flow Flow through the split vent after Saver time.
These instructions apply to both column defined and not defined.
1 Press [Front Inlet] or [Back Inlet].
2 Scroll to Mode: and press [Mode/Type]. Select Splitless.
3 Set the interface temperature and a sampling end time.
4 If your column is defined, enter a Purge time and Purge flow.
Turn Gas saver on if desired. Set the Gas saver time after the
purge time and enter a Gas saver flow.
5 If your column is not defined, enter a Purge time (Purge flow is
not available). Set Total flow greater than column flow plus
septum purge flow to guarantee adequate column flow.
6 Make certain Auto Prep Run is On (see “Pre Run and Prep Run”
on page 171) or press [Prep Run] before introducing a sample.
About the VI direct mode
Direct sample introduction permits a quantitative transfer of
analyte without risking contamination to the pneumatic system.
It provides the sensitivity required for air toxic analyses. The
interface’s minimal dead volume also eliminates the potential
interaction of solutes with poorly swept, active surfaces.
To operate in the direct mode, you must physically disconnect
the split vent and reconfigure the GC.
Before Pre Run
The interface is forward pressure controlled; pressure is sensed
downstream from the flow proportional valve.