Problems with CO2 on Alltech's CTR I column

[Shelleyincolorado]

Greetings,
I am runing CO2 analysis on Alltech's CTR I column. The CO2 is tailing and there are no leaks in the system. Alltech says that the CO2 is have a chemical reaction with the porous polymer column and that is why its not coming completely off. Has anyone experienced this or been able to solve this problem??

Thank you,
Shelley

[Answer Man]

Shelley: Have you ever been successful at using this column for your analysis? Are other compounds chromatographing OK?

[Shelleyincolorado]

The other compounds I'm looking for (O2, CH4, N2) are resolving beautifully. The CO2 peak is extremely unpredictable: most injections (we are manually injecting with a syring) result in a tailing appearance, but every 20 or so injections - the peak with be normal with no observable reason. Both Alltech and Restek say that the CO2 is chemical reacting with the porous polymer - both either offer suggestions to stop/mitigate the problem.

Shelley

[Answer Man]

It's a shame that Alltech cannot provide you support on their column. The only other solution I can think of is to have a separate, different column for CO2 analysis - something like a Restek ShinCarbon.

http://www.restek.com/fantasia/pdfCache/59519a.pdf

[chromatographer1]

Shelley in Colorado

You have not indicated a matrix at which you are looking at CO2 but any porous solid phase support can be contaminated and if the pores are partially blocked, the result is exactly what you have described.

The solutions to CO2 analysis by Gc are rather limited. Almost all use gas solid chromatography to perform the separation.

If oxygen and nitrogen are to be separated, as well as CO2, the limitations are even greater.

Molecular Sieve 13X will perform the analysis at room temperature or even higher (70°C) temperatures.

Using Carboxen 1000 and ambient temperatures a 15ft to 30ft 1/8 inch OD column will perform nicely. A temperature oven ramp is required for a shorter time analysis.

Alternately, a Carboxen 1004 1/16 inch OD column, 3 to 9 meters long will provide H2/O2/N2/CO/methane/CO2 separation and not be affected by water in your sample.

These are available from my company, Supelco.

Rodney George
Senior Research and Development Scientist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

1-800-359-3041 Technical Service
techservice@sial.com