Chromatography Forum

Hi
I am using a restek Rt-QPLOT column in a 6890 GC.

Currently the flow of He through the column is 0.2ml/min. I want to increase the flow to 1.5 ml/min but when I set this flow, the instrument makes funny noises like a 'beep'.

What could be happening? My guess is that there is a leak and the instrument can't reach the pressure needed for that flow.

THANKS
ITZA

Hi Itza

You are almost certainly correct. Check for leaks and try again.

Peter

Hi Itza,

To try to give you an answer I need some informations:
how long is your column and what's the diameter
are you using the split or do you inject on the splitless mode
what is the pressure when you're at 0,2 ml/mn
do you have a gradient temperature?

Pierre

Hi

I think I found the solution. I had a slow split velocity so whenever I tried to increase the flow in the column the pressure increased and I think it couldn't reach the pressure needed with the conditions of the injector.

The GC is not making noises anymore and I am running the column at 1.5 ml/min and around 40 cm/sec. The injector conditions are split 50:1 with split flow around 80. The column is 30m long and 0.32mmID and the carrier flow is He.


Thank you!

ITZA