Method for olefin and paraffin analysis

Chromatography Forum: GC Archives: Method for olefin and paraffin analysis
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, July 15, 2003 - 06:07 am:

Does anyone have an idea as to how to separate olefins and parrafins (many long chain alkanes) in a mixture, and quantify them? Is this possible by LC?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, July 15, 2003 - 07:48 am:

Bollocks and crap!


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Chris Pohl on Tuesday, July 15, 2003 - 12:36 pm:

Although this is possible by reversed phase, the long chain alkanes can only be detected using a refractive index detector which is not compatible with the gradient (which you will need if you have a complex mixture). Silver loaded stationary phases will enable a class separation of olefins from alkanes but you won't be able to get both separation and quantitation of individual compounds this way. If I were you, I would use GC.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, July 15, 2003 - 03:57 pm:

How would i use GC to quantify what are olefins and paraffins>?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Wednesday, July 16, 2003 - 04:12 am:

olefins: unsaturated hydrocarbons
paraffins: saturated hydrocarbons

I've heard about a bromine test/bromine number too, anyone any ideas?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Wednesday, July 16, 2003 - 08:27 am:

If I remember right there was a LC/GC-combination on the market (10-15 years ago? Philips -- but not sure).First step: class separation, second:GC-individual separation.
Alkanes you can get in steps of 10 units up to Hexacontane (MW 843),about olefin standards I don't know.
Peter


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Sunday, July 20, 2003 - 06:35 pm:

It is possible with a dry silica column and hexane as the mobile phase. The paraffins elute first - unretained, and the olefins elute a bit later, all in a broad peak. This is a simple group separation. If you want to separate them into a multiplicity of peaks, you need reversed-phase, preferentially non-aqueous reversed-phase.


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