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Accurate mass measurement at enhanced mass‐resolution on a triple quadrupole mass‐spectrometer for the identification of a reaction impurity and collisionally‐induced fragment ions of cabergoline
Author(s) -
Paul Gary,
Winnik Witold,
Hughes Nicola,
Schweingruber Hans,
Heller Rexford,
Schoen Alan
Publication year - 2003
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.952
Subject(s) - chemistry , mass spectrometry , mass , ion , analytical chemistry (journal) , hybrid mass spectrometer , mass spectrum , monoisotopic mass , impurity , triple quadrupole mass spectrometer , selected reaction monitoring , chromatography , tandem mass spectrometry , organic chemistry
In this study, accurate mass measurements were made by electrospray ionization (ESI) on a triple quadrupole mass spectrometer operating in enhanced mass‐resolution mode (peak width = 0.1 u FWMH), to give qualitative information relating to the pharmaceutical, cabergoline. Accurate mass determinations by ESI‐MS were performed on a protonated impurity formed during cabergoline storage. The accurate mass measurement resulted in only one proposed elemental composition for the impurity, using reasonable elemental limits and mass tolerance for the calculation. This information was sufficient to propose a structure for the impurity where ESI‐MS/MS proved consistent. The difference between the accurate mass measurement and the exact mass calculated for the proposed structure was 0.8 mmu, with a standard deviation of 0.7 mmu for replicate accurate mass determinations. Accurate mass determinations in ESI‐MS/MS provided information on cabergoline fragment ions formed through collisionally‐induced dissociation. Since the potential formation of isobaric ions exists for two major cabergoline fragment ions, accurate mass measurement allowed for the determination of the most probable fragment ion structures. The differences between the accurate mass measurements and exact masses calculated for the proposed fragment ions were 1.9 and 2.1 mmu, with standard deviations of 0.4 and 0.8 mmu, respectively, for replicate determinations. Copyright © 2003 John Wiley & Sons, Ltd.