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Applications of fast atom bombardment mass spectrometry and fast atom bombardment mass spectrometry—mass spectrometry to the maduramicins and other polyether antibiotics
Author(s) -
Siegel Marshall M.,
McGahren William J.,
Tomer Kenneth B.,
Chang Ted T.
Publication year - 1987
Publication title -
biomedical and environmental mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0887-6134
DOI - 10.1002/bms.1200140108
Subject(s) - fast atom bombardment , chemistry , mass spectrometry , adduct , protonation , mass spectrum , polyatomic ion , molecule , ion , organic chemistry , chromatography
Fast atom bombardment mass spectrometry (FAB MS) and fast atom bombardment mass spectrometry‐mass spectrometry (FAB MS/MS) were used to study the monovalent glycoside polyether antibiotics maduramicin α, β and δ and the maduramicin α salts, their derivatives and degradation products. Also, representative compounds from three major classes of polyether antibiotics were studied: the monovalent polyethers, nigericin and monensin A, the divalent polyether lasalocid A and the monovalent glycoside polyethers septamycin, BL580 δ, etheromycin and carriomycin. The respective FAB fragment and decomposition ions were correlated with the known structures. The FAB spectra of all the polyethers contained metal‐adduct molecular ions. Protonated molecular ions were absent. All the polyethers having a β‐hemiketal carboxylic acid group produced an abundant ion, often the base peak of the spectra, 62 daltons less than the corresponding metal‐adduct molecular ion. The gas phase mechanism proposed for the formation of this fragment ion is an unusual unimolecular reaction which is initiated by an intramolecular proton transfer from the carboxylic acid to the hydroxy group of the β‐hemiketal, and, then followed by the concerted losses of water and carbon dioxide to produce the corresponding polyether olefin.