how can ı do alifatic and aromatic hydrocarbon analysis in soil sample. ı have to do separate according to carbon number. Especially carbon number; EC5>EC9, EC9>EC16, EC16>EC35.(TNRCC method 1006).
And also ı want to learn extraction method. Because every compenents have different boilng point. Can ı see this analysis in single chromotgram? should ı use carbon marker?
Dear Ömer,
besides the fact that there exist several protocols for hydrocarbon extraction - surely you know some of them - I prefer the following ones:
1) Soxhlet extraction with hexane and purification of the extract with florosil to get rid of polar humic substances.
2) Very quick: Extraction with an acetone:hexane 1:1 mixture on a vortex mixer (acetone mediates soil moisture and hexane) -> centrifugation -> addition of water to the supernatant (acetone will be washed out of the non-polar phase), injection of the upper non-polar phase to GC. This is more to get an overview of what you might expect and to optimize your GC.
Please don't forget to run C9, C16 and C45 as standard to be able to identify your integration limits. n-Alkanes degrade faster in soil than all others, which results in a "hump" of an unresolved complex hydrocarbon mixture (UCM, http://dx.doi.org/10.1021/es020656n) so it might be hard to identify n-alkane-peaks in the samples.
Good example chromatograms of petroleum products and soil extracts (fresh and biologically aged hydrocarbon mixtures) you may find here: http://www.hlnug.de/fileadmin/dokumente/altlasten/handbuch/hba35_web.pdf It's in German but I'm sure you will figure out what they say.
For quantification of total hydrocarbon fractions GC-FID will suffice. For particular aromatics in soil extracts I would prefer GC-MS using their specific mass traces anyway.
Best regards
Thomas
The US Environmental Protection Agency has several chemical analysis methods posted online. You can search the internet for some chemical with "EPA method" to find them. I have attached a couple that are relevant to your question.
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