benzene determination

[Krashan]

Hello everyone,
I will determine some VOC in workplace atmosphere (incl. benzene) with desorption from sorbent using carbon disulfide. I use GCMS system and I can observe peak for benzene present in CS2. This is purity with low benzene level (<1 ppm). It is of course not proper for my application. Do you know better CS2 purity (without benzene) and its supplier? Is it typical that benzene is present in CS2?
Regards
Robert

[djletin]

Yes. CS2 typically contains low concentrations of Benzene and is a problem if you are doing trace benzene in air analysis with CS2 desoprtion of sorbent tubes as you describe. Alfa Aesar and Sigma-Aldrich, among others offer "low" benzene CS2 but don't know how pure it is. You will need to check.

[Krashan]

Thank you,
I used exact Sigma Aldrich CS2 and Alfa Aesar has also 1 ppm max. It is too large for me. The problem is CS2 is the best desorption solvent for my analysis (methanol and other solvents are to poor). Perhaps I will try thermodesorption without any solvent.
Best regards
Robert