Chromatography Forum

Hey guys,

a have a problem concerning the Varian CP-3800 with a 8400 autosampler connected to a MS (but outlet pressure is still atm) and I would be so greatful of you could help me.
I tried to start a new method and here are some key data (if you need more, let me know):
- 20 m column with 0.18 mm ID
- N2 carrier gas
- using pressure pulse for the injection at 35 psi
- oven start temperature: 70 °C
Every parameter is reaching its set point execpt for the column flow. I selected constant column flow and I tried values from 0,4 - 1,0 mL/min and the pressure program is changing all right but the system will still not go to ready. Do you have any idea why this is?

Thanks!

Column flow cannot be measured by instrument, only total flow.
System checks the pressure and evaluates column flow, maybe system still believes the column output is in vacuum?

Thank you for your reply!
I meant the column flow is a set value, depending on which the Varian creates a pressure program. If I change the column flow value, the pressure also changes.
I already changed the vacuum setting, so thats probably not it. Still, thanks a lot!