Well, well – I have now analysed my GC-MS data from the first batch of 13C malonic acid doped snow samples that I have incubated for one week now. No luck so far. Because of their heterogeneous and complex nature, the number of peaks was huge (160 in a 21 min run). I have tried to browse through the large peaks as well as the tiny humps in the baseline in order not to miss anything.
What I had hoped for was a compound spectrum that could still be correctly identified by the NIST Mass Spectral Database or that I know from past runs with one of the masses shifted from n to n+1, due to the 13C doping. However, this implies that the metabolite originates from a defined biochemical process and that it is an end-product of this pathway. This is pretty steep to begin with and probably I should dig more into the literature, although so far I have not found anything of relevance (especially for real life samples with unknown end-products).
Should more than processes metabolise the 13C, or should there be more than one end-product, then things get tricky, because the characteristical fragment that I am looking out for will be a lot less intense.
Anyway – more work and more measurements ahead. Wish me luck and patience 😉
