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Effect of metal cationization on the low‐energy collision‐induced dissociation of loganin, epi ‐loganin and ketologanin studied by electrospray ionization tandem mass spectrometry †
Author(s) -
Madhusudanan K. P.,
Raj K.,
Bhaduri A. P.
Publication year - 2000
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/1096-9888(200007)35:7<901::aid-jms18>3.0.co;2-b
Subject(s) - chemistry , dissociation (chemistry) , loganin , protonation , electrospray ionization , collision induced dissociation , tandem mass spectrometry , molecule , mass spectrometry , fragmentation (computing) , ion , medicinal chemistry , analytical chemistry (journal) , organic chemistry , chromatography , computer science , operating system , high performance liquid chromatography
The effect of alkali metal and silver cationization on the collision‐induced dissociation (CID) of loganin (1), epi ‐loganin (2) and ketologanin (3) is discussed. Their protonated molecular ions fragment mainly by glycosidic cleavages. The epimeric pairs (1 and 2) show differences in the abundances of the resulting fragment ions. Lithium cationization induces new dissociation pathways such as the retro‐Diels–Alder (RDA) fragmentation followed by rearrangement. Unlike the dissociation of protonated molecular ions, the dissociation of lithiated molecules also provides lithiated sugar fragments. The CID of dilithiated molecules is substantially different from that of the monolithiated precursors. RDA reaction appears to be favoured by the presence of the additional lithium atom in the molecule. In addition, other ring cleavages are also induced. The abundances of the various fragment ions are different in the CID spectra of the epimeric pairs. Extensive D labelling and 6 Li labelling experiments confirmed many of the ion structures proposed. The CID spectra of the sodiated ions are generally weaker, although similar to those of the corresponding lithiated species. Higher alkali metal ion (K + , Rb + and Cs + ) adducts generated only the corresponding metal ions as products of CID. Similar fragmentations were also observed in the CID of the [M + Ag] + ions of these compounds, the epimeric pairs showing characteristic differences in their CID behaviour. Copyright © 2000 John Wiley & Sons, Ltd.