I have analyzed a Bezafibrate sample obtained after 90 minutes exposure to UV-radiations on UPLC-MS/MS to identify the formation of byproducts.
Now the TIC I obtained has various peaks corresponding to degradation byproducts beside bezafibrate main peak. I then did mass measurements and on the basis of m/z values estimated their proposed structures.
Now my question is, how can I say that a specific proposed structure corresponds to that specific peak in TIC?
Either I have to see the m/z values? Higher m/z values higher will be the retention time of that structure on TIC?
It's not completely clear what you're working with, e.g., when you mention m/z values does this mean only molecular weight information or does it also include CID spectra. If you're good at interpreting CID spectra, you can probably make some fairly reasonable guesses. In any event, it's not at all easy to be certain of compound identities, i.e., 'guesses' aren't good enough! If you have a well-calibrated high resolution instrument with good mass accuracy, you can be fairly sure of molecular weights and therefore empirical formulas. But a given empirical formula can correspond to many structures; check out ChemSpider (http://www.chemspider.com/). With MS/MS data, you can search for potential matches in databases such as METLIN (http://metlin.scripps.edu/index.php). Even with a good MS/MS match, though - your interpretation or a METLIN hit - you still can't be SURE of a structure unless you have an authentic standard for comparison of CID spectrum and LC retention time (even then an NMR spectrum would be useful). With respect to m/z values and retention times, there's usually no particular correlation unless you're working with homologous series (which may be partly so in your case since you're looking at related compounds).
- Badges
- Science method