Measuring Very Dilute Concentration (<0.5%)

CVO 4 months ago

Hi everyone,

Our lab recently purchased a microGC 990 (it has a TCD detector) with an OpenLab software. We want to measure CO2 concentration in ambient air (<500 ppm or <0.05%). We have the PORAPLOT U column.

Can this very dilute concentration be measured by adjusting some parameters? I tried increasing injection time; that seems to help. Are there any other parameter(s) that I can play with?

I'm thinking of playing with injection temperature, and column temperature.

Any suggestion or advice would be much appreciated.

Thank you

0 kbeard 4 months ago

Yes, the 990 is capable of less than 10 ppm detection limit for CO2. You will need a column temperature around 50C, and helium or hydrogen carrier gas.
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0 CVO 4 months ago in reply to kbeard

Hi kbeard, thank you for your reply. I tried it, put the column temperature, injection temp and sampling temp to 50 deg C. I got as low as 1000 ppm. I was trying to make calibration curve. I'm gonna try to see if I can make calibration gas and measure it for below 1000 ppm.
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