Mass spectrometric identification of the N‐monosubstituted N‐hydroxylamino functionality in protonated analytes via ion/molecule reactions in tandem mass spectrometry

Rationale N-Monosubstituted hydroxylamines correspond to an important class of metabolites for many bioactive molecules. In this study, a tandem mass spectrometric method based on ion/molecule reactions was developed for the identification of compounds with the N-monosubstituted hydroxylamino functionality. Methods The diagnostic ion/molecule reaction occurs between protonated analytes with 2-methoxypropene (MOP) inside a linear quadrupole ion trap mass spectrometer. Results Most protonated compounds with N-monosubstituted and disubstituted hydroxylamino and oxime functional groups react with MOP via proton transfer and formation of a stable adduct in a linear quadrupole ion trap mass spectrometer. However, only protonated compounds with N-monosubstituted hydroxylamino groups form the characteristic MOP adduct–MeOH product. Possible mechanisms of this reaction are discussed. Conclusions A method based on functional group-selective ion/molecule reactions in a linear quadrupole ion trap mass spectrometer has been demonstrated to allow the identification of protonated compounds with the N-monosubstituted hydroxylamino functionality. Only N-monosubstituted hydroxylamines react with MOP via formation of an adduct that has eliminated methanol. Copyright © 2015 John Wiley & Sons, Ltd.