132 Advanced Operation Manual
3 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 40) 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. Purge timing delay must take into
consideration the volume of the loop or trap in the external
sampler plus the transfer line versus desorb/total flow rate.
Cryo focussing is required for very volatile samples in
splitless mode.
When you introduce a sample, the split valve remains closed
while the sample enters the interface and is transferred to
the column. At a specified time after the sample is
introduced, the split valve opens.
Splitless mode pneumatics
Before Pre Run When the GC is preparing for sample
introduction, total flow to the interface is measured by a
flow sensor and controlled by a proportional valve. Column
flow is controlled via back- pressure regulation. The split
valve is open.
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