Chromatography Forum

Hi everybody!

I am looking for an appropriate protocol for sampling and extracting to BTEX, and other volatile and semi-volatile hydrocarbons to monitor the early oil weathering in sea water. We intend to use GCxGC Instrument and therefore, wanna see both volatiles and semivolatiles in single chromatogram; means we don't wanna separately sample and extract for BTEX and other hydrocarbons.

Can we use SPME to extract both BTEX and other hydrocarbons simultaneously? And What about Sorptive Stirr Bar Extraction (I guess, in this case we need to know the partition coefficients which is impossible as we wanna scan around 1000s of compounds in the weathered oil samples)?

I would be thankful for the valuable input from you.

Thanks a lot and best regards,

check the student projects thread where you also posted this question. I put a reply there.

deed11,

If you are looking at weathered hydrocarbons, I would not expect much BTEX to be left since these will digest/evaporate pretty readily. If you really want to look from BTEX to semi-volatile, then I would recommend you look at TX1005 from the TNRCC. Works well for the range you are interested in, especially if you run a thicker film (which will slow things down a bit.) The only disadvantage of the method is that your lab has to be reasonably cool or low altitude.

Best regards.

You can get the BTEX range and well into the higher hydrocarbons doing GCxGC with a PONA column for first dimension and BPx-50 for the second dimension. Carbowax is better in the second dimension for lower boilers, but will not take the heat for the high end. I've done from the butanes to above C30 with the PONA/BPx-50 column set.

Thank you for the valuable input