Dear Sir. Concerning your inquiry about the best detector and column in GC analysis for methane CO2 in air or atmosphere. These gases can be measured using GC by a variety of detectors (methanizer and FID). Typical gas samples are contained within a matrix of atmospheric air, requiring chromatographic separation. Often, samples contain water, which can interfere with the chromatographic separation or detection mechanism or damage a detector. Shimadzu Scientific Instruments has designed a variety of GC systems for the quantitative analysis of gases. system utilizes three detectors, four 1/16th inch valves and six columns. It is designed to analyze the

these gases in a matrix of atmospheric air containing water vapor. Maximum sensitivity is achieved by simultaneously injecting 1 ml of sample using fixed loops. Methane and Carbon Dioxide are quantitatively analyzed using two valves: a ten-port valve for loop injections and pre-column back-flush to vent, then a six-port column switching valve. The sample is injected on to the Haysesep T pre-column where the air, CO2 and CH4 are separated from water. The systems are described in the following below links and the attached file which may help you in your analysis:

http://www.ssi.shimadzu.com/products/literature/gc/SSI_GC_Green_Gases_Lo.pdf http://commons.emich.edu/cgi/viewcontent.cgi?article=1064&context=mcnair

Thanks

I appreciate your help.

Mr. Eldin has given maximum info regarding this question. I would like to add one more piece information that Shimadzu also offers an excellent detector BID for the trace analysis of these gases. BID is 100 times more sensitive than TCD and 2 times more sensitive than FID.