Varian GC 3800 - Saturn 2200

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

7 posts Page 1 of 1
Dear all,

Does anyone know if nitrogen can be used as carrier gas in replacement of Helium or Hydrogen?
In fact, I just arrived in a lab, and I have to work on a GC-MS (3800-Saturn 2200) that has been off for years. Since we can't get helium and are not able to work with hidrogen, I'm trying to use nitrogen as the carrier gas, but I get a very bad mass resolution, and I wonder if it's because of nitrogen use or a leak on GC...
Thank you for your answer!

Regards,
Charlotte
Generally speaking, you can use N2 as a carrier gas, but your resolution will suffer for doing so. No Hydrogen?!? What will you use for make-up gas?

Why the decision not to use hydrogen? It's actually a much better choice for a substitute carrier than nitrogen is for most applications.
Thanks,
DR
Image
You can do the chromatography with nitrogen - it will take longer and you will lose some sensitivity, but other wise it works fine. The problem is with the ion trap MS, which is set up only to work with helium at a specific residual pressure.

Peter
Peter Apps
If you use FID or TCD, nitrogen is fine. As already mentioned, resolution and sensitivity will suffer. With MS, you will likely KILL the masspec within hours.
You can get hydrogen cheap and pure. It's not that dangerous as often perceived. It (H2) works OK with mass filter (quadrupole) instruments. Ion traps, however, are designed to use He as damping medium.
If your need is rather urgent, we might be able to help.
Alexei Gapeev
Millis Scientific, Inc.
gapeev@millisscientific.com
Tel. 877-844-2635
Thank you for your answers.
I don't want to use Hydrogen because the GC-MS has been off for years and no one in the lab knows if the appartus is OK, or if it's been problems during the last uses.
Anyway, our gas supplier can finely find me a bottle of Helium so it's gonna be easier to start up the GC-MS, check it and work with it....
DR wrote:
Generally speaking, you can use N2 as a carrier gas, but your resolution will suffer for doing so. No Hydrogen?!? What will you use for make-up gas?

Why the decision not to use hydrogen? It's actually a much better choice for a substitute carrier than nitrogen is for most applications.


Dr:
Please, help me.
I will operate with a CP-3800 Varian GC / FID. Is it necessary to adjust it to replace the drag gas? I want to change from N2 to H2.
Search this forum or use your favorite search engine - there are many articles that talk about what to consider when making the switch from one carrier gas to another.

I am not an expert on this. In general, FID should be a good candidate for moving from N2 to H2 but you will have to increase flow rate and the result should be shorter run times, higher signal to noise ratio and better resolution.
Thanks,
DR
Image
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