User guide

250 Advanced User Guide
8 Inlets
16
If you need more response, repeat steps 10 through 15 to
increase to larger volume. See the next section. Try
performing 5 x 5 uL injections, then 5 x 50 uL injections.
Multiple injections with the PTV inlet
The preferred technique for concentrating analytes in the inlet
liner is to use a single, large volume injection. Using a high
capacity syringe and one septum puncture reduces the
possibility of contamination and generally improves results
when compared against a multiple septum puncture technique.
However, if needed, you can perform multiple septum punctures
during the vent time. This technique requires an Agilent data
system and automatic liquid sampler.
Data system requirements
An Agilent data system is necessary for multiple injection
because the needed parameters are not available through the
GC keyboard.
GC ChemStation Software revision B.04.01 SP1 or later.
MSD ChemStation Software revision E.02.00 SP2 or later
EZChrom Software revision 3.3.2 or later
Setting parameters for the inlet in solvent vent mode
Set or configure the following parameters in the data system's
7890A GC method editor.
Syringe size — Verify the syringe size is configured correctly.
The configured syringe size changes the available choices for
injection volume.
Injection volume — Select the injection volume, then enter a
number of injections. The total injection volume will be
displayed.
Multiple Injection Delay — A pause time, in seconds, between
injections. This is added to the minimum hardware cycle time.
Preinjection washes and pumps are performed only before the
first injection of a multiple injection set.
Postinjection washes are performed only after the last injection
in a multiple injection set.