I must say i have not used or analise them ever. But in some vegetable analysis (as onions ) we can see in GC-MS several thio ethers and others thio oxygen compounds as very well resolved peaks - most of them have relatively small mass. You probably should use cold on collumn injection tecnhiques if the compounds are termally unstable, but you say litle about your compounds.

HPLC method G L Newton et al 1981 Anal.Biochem 114 383 387