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GC conditions while not in use
Posted: Mon Dec 12, 2011 5:39 pm
by sepscientologist
On my LC I have everything shutoff after a sequence. I don't know what to do on my GC though.
I am running an FID and MS so it seems like I might have a method at the end of my sequence that
shuts off the FID and stops or slows gas flows. It that common practice and are there kind of
standard things to do?
Re: GC conditions while not in use
Posted: Mon Dec 12, 2011 6:03 pm
by Axar
Why don't you want to use macro?
It is possible to create a method with zero flows and shuted down heaters and add it in the end of every sequence. But I do not know how it can affect your MS. I heard that it is not good to keep your MS off.
Re: GC conditions while not in use
Posted: Mon Dec 12, 2011 6:25 pm
by aldehyde
If you turn off column flow to the MS it will suck air into your inlet and through the system. Set FID temp to 125 C and turn off the hydrogen and air, set the make up flow to 5 or 10 mL/min.
Set the inlet to 125 C and reduce the split to 5:1 with column flow between 0.5-1 mL/min and turn the oven off. Before running in the morning restore all the temperatures and flows and then do a blank injection or two and let the oven program run.
I prefer to keep idle temps at around 100 C to prevent moisture from getting trapped in the system.