Dear Dr John

Thanks for the reply.

I am doing screening VOCS at the moment by GC/MS. But I need to screen peptides, faty acids, vitamin and ... .

Dear Mohsen

You mean the exsudat of your bacteria or the entire metabolites?

All of your described analytical classes need their own protocol!

However primary metabolites (TCA/sugars/AS/major fatty acids) are well detectable via GC-MS profiling. For peptides and vitamin you need special protocolls and a sensitive LC-MS/MS!

give us more details

christian

actually I am looking for peptides and vitamins.