Effect of alkali metal cationization and multiple alkali metal exchange onthe collision-induced dissociation of loganic acid studied by electrosprayionization tandem mass spectrometry

Under electrospray ionization conditions loganic acid undergoes alkali meta l (Li, Na and ii) exchange and alkali metal cationization. Multiple exchang es of up to four alkali metal ions are observed. Different populations of m etal exchanged species are produced during electrospray ionization, Collisi on-induced dissociation of ammonium cationized species is compared with tha t of metal cationized species to study the effect of metal cationization, G lycosidic cleavage and ring cleavages of aglycone and sugar moieties are th e major fragmentation pathways observed during collision-induced dissociati on. The fragmentations of the highly metal exchanged species indicate the o pening of the pyran ring, Collision-induced dissociation of the various met al exchanged and metal cationized species also reveals the nature of the di fferent populations. Copyright (C) 2000 John Whey & Sons, Ltd.