Chromatography Forum

I'm having an issue coordinating the start of my GC run with the thermal desorber. Last week, the ATD was desorbing from the cold trap before the GC oven was at temperature. So I increased the cycle time. For some reason, the thermal desorber seems to be starting before the the GC is ready. Any basic thoughts? I have the method setup for "external device" and to my knowledge the PE technician installed everything correctly last week. Is there a certain way the pins need to be configured with the remote start cable? This morning I received another "fatal sequence" error.

Finally, does it matter if I trigger the sequence first on the turbomatrix software or the chemstation sequence? I remember when we had a Markes Unity thermal desorber, there were some weird things you had to do (i.e. purge time of 999.99). Maybe I'm just missing something with the PE ATD - Agilent 6890 configuration.

Any thoughts would be greatly appreciated.

Thanks,
Aaron

Normally you hardwire the ready output from the 6890 to the ready input of an autosamper (or Thermal Desorber in your case). This prevents any external device from performing the injection (or any time critical steps in preparation to the injection) until the GC oven and other thermal or pressure control loops are ready and the stabilisation time has elapsed.

How exactly the hardwiring is done between these two specific devices needs to be extracted from the manuals of the GC and Thermal Desorber.

Jan Willem Mol
Applied Instruments