I am using MSTFA, O-Methoxyamine in Dry pyridine to derivatize my samples. Usually I try to analyse the samples as soon as possible after derivatizing them. But I want to know whether I can store these derivatized samples for further use, as in to analyse them in a different coloumn or to re run the sample?
Thank you!!
If I am keeping them capped and wrapped and in a dry place then?
Actually one of my colleagues stores her samples and she says that she gets the same peaks in those stored samples just that her derivatization method is different and she is not doing GCMS, but only GC.
It depends on the volume and storage conditions. If you keep them dry and prevent evaporation you may be able to store them for a couple of days. We do derivatization on-line (i.e. automatically just before injection) and in 50µl total volume. Under these conditions you see already significant effects if you repeatedly measure a batch of (lets say 40) samples. Simply due to evaporation/concentration changes. So if you frequently need to re-run samples try to work in larger volumes to minimize evaporation effects.
Hello,
As nicely mentioned by Dr. Jan Lisec, one of the Pioneers in GC-MS-based metabolomics research, I can vouch that upto 24-48 hours the stability is OK.
What has worked for me is: Up to 48 hours for MSTFA derivatives under lots of dried silica, in zip-lock bags, each vial parafilmed, put in -80 C.
MS is far more sensitive than GC only, so the other person might not notice changes in concentrations- but in GC-MS it would be affected. Better NOT to store at all, but derivatize in batches of 6-12 so that the runs finish in 12-24 hours. Never ever store, unless one has to ship them or analyze at a remote site not accessible.
I also see that MTBSTFA derivatives a bit more stable (literature says 100-1000 times more) and have seen negligible variations up to 60-72 hours as well.
Thanks,
Biswa
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