Selection Of GC column for CO2...

[rajtorrent]

Hi Guys,

We have a GC currently equipped with an MXT volatiles column (RESTEK) and two detectors (an FID & a PID). We are able to analyze BTEX with the present configuration. But now that we want to analyze Co2 also, kindly suggest as to which column should we purchase to this end. Is there any column which can separate all the above gases (Benzene, toluene, Ethyl Benzene, Xylene & Co2) , eliminating the use of two different columns?...

[larkl]

Pretty doubtful, maybe not impossible. What's the sample matrix? You'd need a PDD or TCD to measure the CO2, wouldn't you? I'd think that most columns that will separate the CO2 from the permanant gases or whatever else is present won't handle these heavy components.

[chromatographer1]

This is a very easy but very old separation if you use a TCEP packed or SCOT column (Supelco) Look at the Supelco packed application guide and you will see the separation demonstrated. The CO2 will be essentially an unretained peak but will be clearly separated from Benzene. m- p- xylenes will coelute. A SCOT column will separate much better than the packed column but requires a smaller sample and requires more care in handling.

best wishes,

Rodney George
Consultant