hi to all,
i know that it could be a stupid question. I am analysing by means of mass spectrometry a molecule having various O- moieties. interestingly, in ESI- I observe both MH- but also a 22 Da mass shift, compatible with a Sodium addition to the molecule. i am wandering on what kind of interaction there is between the molecule and the Na. is it an ion adduct? is Na bound to the O- by means of an ionic bond? thank you in advance
Hi,
I'd also assume that you're looking at sodium adducts via an ionic interaction between O and Na; these do not contribute to the charge of your molecule of interest, but do contribute to the overall mass observed by MS.
Have you tried looking at the fragmentation of the +22 Da species? I know from experience with glycan analysis that protonated and sodiated species fragment completely different (in positive ion mode, that is..).
Hope this helps!
Sodium ions usually substitute dissociable protons, e.g. in carboxylate moieties. Yes, it is an ion adduct.
Hi,
If I get this correctly following scenario might have occurred, one of the O-H moiety deprotonated and a Na adduct took place; R-O-Na. while one of the other O-H also lost its proton and became a negative charge carrier; O-.
I do not know your molecule exactly but this is one scenario.
Regards.
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