There are several papers available. Try this one it is available on WEB

J Chromatogr Sci (2013) doi: 10.1093/chromsci/bmt042

Headspace method (SPME) interfaced with GC-MS are best suited to carry out analysis under investigation at your side. 

Have a read to following literature

http://www.sciencedirect.com/science/article/pii/S0038071704004109

SPME is a good technique, but can be selective or can become overloaded depending on the mix of volatile compounds you're looking at. You should find a local lab who uses thermal desorption tubes for sampling - you can use three (sorbent) bed tubes for screening - and sensitivity is really good. The kind of labs that will have this technology are those that do (EPA) TO17 analysis. Where is your university?

Shenyang Agricultural university, Liaoning, China 

Hello Jamil. I have sent your contact details (as much as I can glean) to colleagues in China - they will be in touch to let you know if there are laboratories nearby that have the relevant technology. Please come back to me if you do not hear from them.

Thank you very much sir Matt Bates, I'm waiting for their response.

Please could you give me an email address to contact you on Jamil?

Thanks, Matt.