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Structural characterization of product ions of regulated veterinary drugs by electrospray ionization and quadrupole time‐of‐flight mass spectrometry. Part 3: Anthelmintics and thyreostats
Author(s) -
Nuñez Alberto,
Lehotay Steven J.,
Lightfield Alan R.
Publication year - 2016
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.7508
Subject(s) - chemistry , mass spectrometry , veterinary drug , electrospray ionization , ion trap , quadrupole ion trap , tandem mass spectrometry , chromatography , veterinary drugs , analyte , quadrupole time of flight , analytical chemistry (journal) , electrospray , characterization (materials science) , nanotechnology , veterinary medicine , medicine , materials science
Rationale Previously, we have reported a liquid chromatography/tandem mass spectrometry method for the identification and quantification of regulated veterinary drugs in food animals. The method uses three selected transition ions per analyte but structural characterization is also needed. This work is a continuation of two previous publications in which we propose structures of the selected transition ions of 130 veterinary drugs altogether. Methods In this work, 24 additional veterinary drugs were analyzed by infusion into a high‐resolution quadrupole time‐of‐flight (QTOF) mass spectrometer using electrospray ionization (ESI) in positive or negative mode. The TOF analyzer was calibrated to achieve low error mass accuracy in the MS and MS/MS modes. Also, the MS 2 and MS 3 spectra were obtained by using a Q‐Trap mass spectrometer to further determine the possible pathways of ion formation. Results The low error mass spectrometry analysis allowed the elucidation of the ion formulae of selected transition ions for qualitative identification. The rational interpretation of data including a review of the published literature led to the proposed structures of the MS/MS product ions of 24 compounds covering two classes of regulated veterinary drugs (anthelmintics and thyreostats). In addition, the use of MS 2 and MS 3 experiments led to the establishment of fragmentation patterns. Conclusions The identification and quantification of veterinary drug residues is helpful information for regulatory monitoring programs in defense of regulatory enforcement actions. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.