User guide

212 Advanced User Guide
8 Inlets
• Start with the inlet temperature cold, near but slightly
below the solvent boiling point. For example, if using
methylene chloride (boiling point 39 °C), start with a
temperature of 30–39 °C.
• Use Splitless mode.
• Ramp to the normal split/splitless inlet temperature
5 Note the response achieved.
6 Next, change the inlet mode to Solvent Vent.
7 Check the injector timings.
a Install an empty sample vial in the injector turret or tray.
b Input the injection rate (Draw, Dispense, and Inject rates)
for the injector and increase the injection volume to 5 uL.
c Enter draft Solvent Vent parameters:
• Set a Vent Flow of 100 mL/min as a starting point.
• Keep the inlet isothermal for now
• Enter a Vent Pressure of 0 psi (0 kPa) until 0.1 min.
• Make an injection using the empty vial. Use a
stopwatch or your GC's timer feature to time how long
the needle is in the inlet.
8 Enter revised Solvent Vent mode parameters.
• Set the method's Vent Time to be about 0.05 min longer
than the time the needle spends in the inlet.
• Set the inlet temperature initial Hold Time to be about
0.05 min longer than the vent pressure until time.
• Program the inlet to ramp quickly to the injection
temperature. Make sure the ramp starts after the vent
pressure until time.
• Set the Purge Flow to Split Vent to 30 mL/min. Set the
purge time to be the vent pressure until time + 1 minute.
9 Make a 5 uL injection of your standard. You should see 5
times the response.
If the response of all analytes is too low:
• The dispense speed is too fast. Liquid was injected into
the inlet and pushed out the vent.
• The vent time is too long. The inlet started to heat
while the vent was open.
If the response of early eluters is too low:
• The inlet temperature is too high.