How long are swab samples viable for if stored in viral transport medium (VTM) in a -80C freezer? I've been doing RNA extraction and PCR on swabs that have been stored in VTM for over two years in a -80C freezer. However, my PCR results have yielded lots of primer dimers.
It could be my method of RNA extraction that's the problem, however, my question is, does VTM not preserve samples for long periods of time?
It is better used RNA later for storage samples.
Primer dimer is irrelevant to extraction at all, mostly problem is due to design of primers.
Yeah, I agree that RNA later is optimal vs VTM. I was just curious as to the storage life of VTM in -80C of samples as the samples are already in VTM. Thanks though, I appreciate your feed back!
for RNA whuch is less fixable than DNA , it important not to store it at deep freezer (-80 or over) for long time (2-4 weeks) , wherease DNA can stored at -20 for 6 month to 1 year.
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