Chromatography Forum

Hi everyone

We have some trouble with our GC MS system concerning the MS part. It will take some time to fix the problem, probably one to three weeks depending on availavility of exchange parts and service technician.

I am not sure on what is the best option for the GC. I removed the coloumn from the MS and capped the transfer line so no helium can accumulate and harm the photodiode detector. I let the column connected to the injector and the end freely in the oven with low helium flow and no temperature.
Is it better to remove the column entirely and seal the inlet?
Or do I need to take everything apart such as gas filter and seal it?
Even if it is just for three weeks?
I would highly appreciate some input from more experienced users.

Thanks for your help
Kathy

Hello

You have 2 options:

1.If you're not going to use GC for next three weeks just remove column from inlet, plug both ends with septa and switch off GC. You can plug inlet but it is not critical.

2.If you want to use GC (you have other detectors) just plug MSD with blank nut and switch it off, you can still use GC without MSD.

Regards

Tomasz Kubowicz

...I am not sure on what is the best option for the GC. I removed the coloumn from the MS and capped the transfer line so no helium can accumulate and harm the photodiode detector. I let the column connected to the injector and the end freely in the oven with low helium flow and no temperature.
Is it better to remove the column entirely and seal the inlet?
Or do I need to take everything apart such as gas filter and seal it?
Even if it is just for three weeks?
I would highly appreciate some input from more experienced users.

Thanks for your help
Kathy

Oh Kathy, why haven't you simply switched your GC and MS off ?

Hello

You have 2 options:

1.If you're not going to use GC for next three weeks just remove column from inlet, plug both ends with septa and switch off GC. You can plug inlet but it is not critical.

2.If you want to use GC (you have other detectors) just plug MSD with blank nut and switch it off, you can still use GC without MSD.

Regards

Tomasz Kubowicz

Thanks a lot for your quick response.
I need to go with option 1.
Is it no problem (with diffusing air) to leave the gasfilter unsealed with no helium flow?
Best wishes
Kathy

...I am not sure on what is the best option for the GC. I removed the coloumn from the MS and capped the transfer line so no helium can accumulate and harm the photodiode detector. I let the column connected to the injector and the end freely in the oven with low helium flow and no temperature.
Is it better to remove the column entirely and seal the inlet?
Or do I need to take everything apart such as gas filter and seal it?
Even if it is just for three weeks?
I would highly appreciate some input from more experienced users.

Thanks for your help
Kathy

Oh Kathy, why haven't you simply switched your GC and MS off ?

From what I heard it is not recommend to leave the system without any gasflow but open to air for couple of days to weeks? You'd say this is no problem, especially for the column?
(My experience is limited that's I was asking for some input)

Thanks a lot for your help and regards
Kathy

Leave the column in, set the flow to 1 ml/min and the split ratio to 1:1 with no gas saver. Turn all the heated zones off. Everything will stay clean.

Peter

....
I need to go with option 1.
Is it no problem (with diffusing air) to leave the gasfilter unsealed with no helium flow?
Best wishes
Kathy

When you leave helium cylinder valve open and GC shut down you won't damage gas trap. It will be pressurized because GC electro valve will be closed - there is no need to leave helium flowing.

Leave the column in, set the flow to 1 ml/min and the split ratio to 1:1 with no gas saver. Turn all the heated zones off. Everything will stay clean.

Peter

I'm with Peter on this one. I would rather spend a couple dollars a day and leave a very small flow of helium through the GC and column so that when I start up again I have no worries about air or moisture in the system.

If is it not a vacuum problem on the MS, I would also leave it capped and under vacuum. I hate waiting for all the air and moisture to be pulled out of the internal parts if it is allowed to collect there for days or weeks. If I begin a repair and can't finish it, I will always seal the analyzer and pull vacuum until I can go back in and finish the repair. Takes less time to shut down properly than it does to bake everything out if left without vacuum.