Recommendation on carrier gas for GOW MAC 350/TCD?

Discussions about GC and other "gas phase" separation techniques.

5 posts Page 1 of 1
Hi everyone,

We're installing a GOW MAC 350 w/TCD for the analysis of fixed gases (ie. CO2, CO, N2, etc). The GC can use either Helium, Nitrogen or Argon as the carrier gas, just wondering if anyone had any recommendations on this.

I know as a general rule that I cannot detect (ie. analyte) the same compound that makes up the carrier gas. For example, if I use N2, I cannot detect N2.

But aside from this, are there any other factors I should consider in selecting a gas? Limits of detection, etc?

On the cost side, I'm assuming He would be the most expensive carrier gas to use.

He & H2 are the most ideal gases so some diffusion effects should not be observed.
Best regards,
Dmitriy A. Perlow
Thanks dap!

I was not sure if I could use Hydrogen as carrier gas - the GOW-MAC manual states to use Helium or Argon. See!AjglVmUkgtjLp2PCMA_KI-KA8386.

But if this is the case, I'll use my hydrogen generator. The GOW MAC requires a min pressure of 15psi and my generator can make up to 55psi so this would work perfectly.

Hopefully I can use H2. Thanks again!
Helium and hydrogen will give you better sensitivity on the TCD for N2, CO, and CO2. I am assuming you are only trying to measure low percent or so? Hydrogen can be used on TCD but the effect on filaments is of concern to some people especially if they are shooting air samples since the reaction at the filament could be of concern.

Best regards
Thanks AICMM for your input, I think H2 would be a good option. My only concern was safety since the tungsten filament on the TCD is heated (ie. explosion).

But you do bring up an important issue, namely the injection of air. We will be injecting ~1mL air samples into the packed column for analysis (ie. CO, CO2, H20, etc). I didn't think of the H2 reacting with the filament, good point!

In either case, I'll look into N2 or He, I'm not sure how low of a detection I'll need at this point as I'll be analyzing at exhaust gases (not car exhaust).

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