What GC Method for Gaseous CO2 Analysis (1-20% v/v)?

[chemengineerd]

Hello GC enthusiasts,

My goal is to evaluate CO2 concentration in gaseous samples mixed with CO2/Air/Freon.
Expected concentrations will range from 1-20% CO2 v/v.

I'm currently using a GC-MS that is configured with a gas sampling valve, He carrier, LN2 cooling, and a RTX-1 column to identify impurities in Halon 1301 samples.

I also have a TCD and FID available to use.

My initial intuition suggests using the current setup (GC-MS, RTX-1, ~-30C oven temp), and setting the AMU mass range on the MS between 44-145 in order to pick up the CO2 m/z of 44.

It seems that would quantify CO2 (and freon) with this approach, but not the air. Therefore, I would be short of calculating the CO2 concentration.

I'm not sure if that is correct, and if there may be a better option with what I have available.

What would you advise? I am open to purchasing new equipment, if necessary (budget <$10K).

[AICMM]

If you have a TCD available, you would be advised to use that for the CO2. GC/MS for the fixed gases can be challenging and TCD with helium carrier would be simple pursuit. Column like a Q polymer should work well.

Other option is FID with a methanizer but at those high levels a TCD would be the first choice.

Clarify, as well, you want to do the air as well? In the Halon 1301?

Best regards,

[Consumer Products Guy]

We used packed-column GC with TCD decades ago to determine CO2 levels in sealed food pouches. It was straightforward.

There might also be specialized equipment for CO2 these days.

[James_Ball]

For CO2 on MS you would need to begin the scan range at least at 43m/z, since the exact mass can drift between scans a little and if you run it at exactly the mass you need it can drift in and out and you will have clipping of the signal sporadically.