User`s guide

Theory of Thermal Desorption
304
Upon finishing the leak test, SV1 and SV3 open and the sample tube
is purged with carrier gas for the duration of the purge time. During
the purge time, air is purged from the tube to reduce the risk of
adsorbent oxidation during desorption. See Carrier Gas Purge of the
Sample Tube on page 310.
After the purge time has elapsed, the tube oven is brought into
contact with the sample tube and the primary desorption begins.
Primary (Tube) Desorption—During tube desorption, the tube
oven is brought into contact with the sample tube and the desorb
time begins. SV1 and SV3 remain open. Analytes, released from the
tube, are transferred to the cold trap.
Figure 88 Primary (Tube) Desorption
If you have enabled the Inlet Split option SV5 opens. The inlet split
flow must be adjusted either manually or set electronically, prior to
beginning your analysis. The sample can be split by activating the
Transfer Line t
o GC
Sample
Tube
SV2
Carrier Supply
Carrier
Pressure
SV1
Desorb Supply
SV4
Outlet Split
SV5
Inlet Split
SV3
Desorb Vent
Leak
Pressure
Inlet Split/
Tube Condition Vent
A
Trap
Outlet Split
Vent
Desorb Flow
Vent
Pressure
Regulator
Supply
PR
Valve A
Position B
2
3
4
1