User guide

256 Advanced User Guide
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.
Table 51
summarize some issues to consider when choosing an
operating mode. Specifications for the interface are also listed.
Table 51 Overview of the volatiles interface
Mode Sample
concentration
Sample to
column
Comments
Split High Very little, most is
vented
Splitless Low All Can switch to split
mode electronically.
Direct Low All Must physically
disconnect split vent,
plug the interface, and
reconfigure the GC.
Maximizes sample
recovery and eliminates
possibility of
contamination to
pneumatic system.
Table 52 Specifications of the volatiles interface
Specification Value/Comment
Deactivated flow path
Volume 32 µL
Internal dimensions 2 mm by 10 mm
Maximum flow to interface 100 mL/min
Split range Depends on column flow
Typically no split to 100:1
Temperature range 10 °C above ambient (with oven at
ambient) to 400 °C