Measurement of gas component by GC

Chromatography Forum: GC Archives: Measurement of gas component by GC
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Canny on Wednesday, February 13, 2002 - 02:48 am:

I am a student in Netherlands.Now I'm do my traineeship in a company,my work is to measure some component in gas,i want to know some detail information about how to measure them by GC.
Thank you!


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Rodney on Wednesday, February 13, 2002 - 06:35 am:

Dear Canny

Your desire for detailed information is good. But due to the lack of detailed information given it is difficult to give you a good answer, however:

Gas sample components are usually measured by mole percent.

They are injected using a fixed loop valving system with the loop equilibrated to atmospheric pressure.

They are calibrated using commercial standards.

If I have not been as helpful as you wished, sorry, but please give the forum a few more details next time.

best wishes,

Rodney George
Supelco


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Canny on Thursday, February 14, 2002 - 02:13 am:

The normal GC refers to GLC,but I know GSC is a way to measure the component in gas,especially the low-molecular-mass gases,such as air component,carbon dioxide,nitric oxides.

The information I found from Internet is almost about GLC, who know something about GSC or are there some experience in doing such experiment to measure gas by GC?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, February 14, 2002 - 06:05 am:

Canny,
If you have a specific application in mind you might try posting here what the components are you are trying to separate. Also J&W Scientific is a good source for columns and excellent technical info (at www.JandW.com). Also Alltech and Supelco are good players at www.alltechweb.com and www.sigma-aldrich.com.

Regards,
Mark


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Rodney on Thursday, February 14, 2002 - 08:39 am:

Canny

Call Supelco Technical service and we can help you with your column requirements.

It is a free phone call or email. We have offices all over the world.

techservice@sial.com

1-800-359-3041

Rodney George
Gas Separations Research
Supelco


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Bruce Freeman on Thursday, February 14, 2002 - 01:04 pm:

"Permanent gas" separations can be complicated. For example, molecular sieve has been used to the components of air, but if I recall correctly it cannot separate oxygen from argon, and irreversably adsorbs carbon dioxide and many other gases.

Since this sort of separation has been in use for decades now, your best bet would be to contact a column manufacturer or distributor, such as Supelco (see above) or Alltech Associates (www.alltechweb.com). They can be very helpful and save you a lot of trouble.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Friday, February 15, 2002 - 06:20 am:

True, packed Mol Sieve columns won't separate oxygen/argon at ambient temperature, but capillary PLOT 5A columns will ( on a good day, at 25C). Even at 60C I get a reassuring 0.9% result for partially resolved argon in air. As you say CO2 is absorbed. C1 - C3 hydrocarbons are OK. C4 is a struggle, seems to be mostly absorbed. C5 and up are 100% absorbed in my experience. I use porous polymers for C3 - C6 hydrocarbons.

I support advice to contact suppliers/column manufacturers and see test chromatograms on their websites. Canny, if you can do this, take advantage of the most up-to-date information. Solutions are extremely dependent on which gases are present and in what ratios. Since you have still not said what the application is, it is difficult for anyone here to give detailed advice.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Friday, February 15, 2002 - 06:27 am:

True, packed Mol Sieve columns won't separate oxygen/argon at ambient temperature, but capillary PLOT 5A columns will ( on a good day, at 25C). Even at 60C I get a reassuring 0.9% result for partially resolved argon in air. As you say CO2 is absorbed. C1 - C3 hydrocarbons are OK. C4 is a struggle, seems to be mostly absorbed. C5 and up are 100% absorbed in my experience. I use porous polymers for C3 - C6 hydrocarbons.

I support advice to contact suppliers/column manufacturers and see test chromatograms on their websites. Canny, if you can do this, take advantage of the most up-to-date information. Solutions are extremely dependent on which gases are present and in what ratios. Since you have still not said what the application is, it is difficult for anyone here to give detailed advice.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By canny on Tuesday, March 12, 2002 - 02:12 am:

If the components are O2,H2O,CO,CO2,from ASTM i know they can be detected by TCD,what kind of column is matched to TCD,the packed one or capillary one?Are there any specific requirement for it?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Rodney George on Tuesday, March 12, 2002 - 05:27 am:

Canny,

The problem separation here is O2 and CO.

Packings in general which separate these gases do not tolerate water or the water peak is partially or completely absorbed.

Many times analysts will measure water by difference, assuming no non-measured gases are present, the sum of measured gases subtracted from 100% gives you the water content.

It is possible to measure these at the same time if you have a trap valve to catch the O2/N2/CO peak while allowing the other gases to pass through. Normally water is backflushed so the sieve column will not contact the 'backround' amount of water. If water is to be measured a short 'R' porous polymer packed column or a 'U' capillary would be preferred with a 2m column of Carboxen 1000 60/80 mesh packed column or a capillary Carboxen 1006 column to separate N2/O2 - C1 - CO fully used as a trap column.
If N2 is to be separated from O2 (because of possible leaks in the system or to confirm its absence, a long trap 'water tolerant' packed column or a subambient C-1006 capillary will perform this separation.

email me at rgeorge@sial.com if you have questions. I will be glad to advise you further.

Rodney George
Senior Research Chemist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

814-359-5737 voice
814-359-5702 fax
rgeorge@sial.com


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