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Identification of isobaric product ions in electrospray ionization mass spectra of fentanyl using multistage mass spectrometry and deuterium labeling
Author(s) -
Wichitnithad Wisut,
McManus Terence J.,
Callery Patrick S.
Publication year - 2010
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4673
Subject(s) - chemistry , isobaric process , isobar , mass spectrometry , fragmentation (computing) , deuterium , hydrogen–deuterium exchange , ion , electrospray ionization , analytical chemistry (journal) , tandem mass spectrometry , collision induced dissociation , isobaric labeling , mass spectrum , chromatography , protein mass spectrometry , organic chemistry , atomic physics , physics , computer science , thermodynamics , operating system , nucleon
Isobaric product ions cannot be differentiated by exact mass determinations, although in some cases deuterium labeling can provide useful structural information for identifying isobaric ions. Proposed fragmentation pathways of fentanyl were investigated by electrospray ionization ion trap mass spectrometry coupled with deuterium labeling experiments and spectra of regiospecific deuterium labeled analogs. The major product ion of fentanyl under tandem mass spectrometry (MS/MS) conditions ( m/z 188) was accounted for by a neutral loss of N‐ phenylpropanamide. 1‐(2‐Phenylethyl)‐1,2,3,6‐tetrahydropyridine (1) was proposed as the structure of the product ion. However, further fragmentation (MS 3 ) of the fentanyl m/z 188 ion gave product ions that were different from the product ion in the MS/MS fragmentation of synthesized 1, suggesting that the m/z 188 product ion from fentanyl includes an isobaric structure different from the structure of 1. MS/MS fragmentation of fentanyl in deuterium oxide moved one of the isobars to 1 Da higher mass, and left the other isobar unchanged in mass. Multistage mass spectral data from deuterium‐labeled proposed isobaric structures provided support for two fragmentation pathways. The results illustrate the utility of multistage mass spectrometry and deuterium labeling in structural assignment of isobaric product ions. Copyright © 2010 John Wiley & Sons, Ltd.