A fragmentation study of a flavone triglycoside, kaempferol-3-O-robinoside-7-O-rhamnoside

A mass spectrometric method based on the combined use of electrospray ionization, collision-induced dissociation and tandem mass spectrometry has been applied to the structural characterization of the flavone triglycoside, robinin (3,5,7,4-tetrahydroxyflavone-3-O-robinoside-7-O-rhamnoside). The deprotonated molecule fragments by loss of the rhamnose glycan residue to yield the Y-7(-) ion (m/z 593) and by scission of the robinose glycan residue to yield the radical anion [Y-3,Y-0-H](-) (m/z 430). The Y-7(-) ion fragments by scission of the robinose glycan residue to yield the radical anion of Y-7[Y-3,Y-0-H](-) (m/z 284). The [Y-3,Y-0-H](-) radical anion fragments by loss of the rhamnose glycan residue to yield the radical anion Y-7[Y-3,Y-0-H](-) (m/z 284) and by scission to yield [Y-7-H][Y-3,Y-0-H](-) (m/z 283). A fragmentation mechanism has been proposed. Copyright (C) 2004 John Wiley Sons, Ltd.