Chromatography Forum

Hi,

If my GC has a vaporiser, is there any difference in area count whether I'm using Gas Cal and Liq Cal to test for CO/CO2? It will pass through a methanizer and the cal blend balance is ethylene (gas) and propylene (liq).

Both cal blend have 10 ppm of CO and CO2 and the parameters are all same, but seems like both cal give a lot difference in area count.

By the way, does ethylene have any impact if it pass through the methanizer and vaporiser?

If my GC has a vaporiser, is there any difference in area count whether I'm using Gas Cal and Liq Cal to test for CO/CO2? It will pass through a methanizer and the cal blend balance is ethylene (gas) and propylene (liq).

Yes. mole v/v and liquid v/v will give differing results.

Both cal blend have 10 ppm of CO and CO2 and the parameters are all same, but seems like both cal give a lot difference in area count.

By the way, does ethylene have any impact if it pass through the methanizer and vaporiser?

Hi,

Yes, it will carbonize the methanizer catalyst and reduce the conversion of the CO and CO2 if not eliminate it.

best wishes,

Rod

Hi Rod,

Thanks for your prompt reply. But the question is the certificate of the cal blend give both in mole ppm (10ppm).

Any difference then is in the homogeneity of the samples and if CO reacts with anything in the matrix, or the metal in the vaporizer.

Your gas sample SHOULD be without a doubt the most accurate. But that all depends upon the manufacturer's accuracy and competency. It is all too easy for the CO to enter the headspace of the liquid blend and have a lower concentration than expected. Does your liquid blend had a dipstick or a syringe?

Rod

My liq is in piston... Charged with helium.. My area count was like 80 for CO2 in propylene bal n 180 for CO2 in ethylene gas cylinder