I'm performing RNA extraction on saliva, and all my samples of neat saliva pipetted onto swabs have worked fine, but now that i've started extraction buccal swabs (so, the swab actually rubbed on the inside of the person's mouth), i've been getting really low peaks and some peaks aren't appearing at all. It looks like RNase contamination, but i've taken all the appropriate steps to avoid this during the procedure (rnase-free disposables, RNaseZap, B-ME, etc), and i've replaced all the reagents and disposal materials with new batches and still got the same results, and i've also changed the swab batch.
Has anyone got any ideas, because i'm all out? or has anyone else experienced this and either found an explanation or not?
Any help would be appreciated!