Analysis of C6+ in ppm range in high pressure natural gas

Chromatography Forum: GC Archives: Analysis of C6+ in ppm range in high pressure natural gas
Top of pagePrevious messageNext messageBottom of pageLink to this message  By John Malcolm on Wednesday, August 2, 2000 - 07:08 pm:

We need to qualitatively and quantitaively analyze a high pressure natural gas stream for heavy hydrocarbons and aromatics from C6 to C18. The gas stream is essentially 30% CO2 and 68% methane with the remainder made up of C2 to C5 and C6+. GCs at the plant (Daniel and Chandler) analyze the C6+ as a single C6+ component. The total C6+ concentration is in the 100 to 400 ppm range so the 20 or 30 components comprising the C6+ are in the low ppm range. Is there a GC or GCMS method that can analyze this gas to accurately measure the total C6+ concentration and the composition of the C6+?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Jason Ellis on Thursday, August 3, 2000 - 08:49 am:

You should be able to separate out your compounds on a 100% dimethylpolysiloxane phase using either FID or MSD. I'd say that a 30m x 0.25mm ID, 0.50um film would be a good starting point. The difficult thing will be to resolve the C6/C7 range from the matrix material on a liquid phase column. You will have to start cool (i.e. 30-40C) to improve separation. Going to a thicker film would improve resolution at the light end, but it might end up hurting you on the heavy end due to excess retention and column bleed.


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