Mass spectrometric methods for the characterisation and differentiation ofisomeric O-diglycosyl flavonoids

Tandem mass spectrometric methods have been evaluated for the characterisat ion of the type and the differentiation of the interglycosidic linkage of i someric flavonoid O-diglycosides. Based on the occurrence of internal monos accharide residue loss and the relative abundances of Y-type ions formed by fragmentation at glycosidic bonds, four pairs of isomeric flavonoid O-digl ycosides can be unambiguously differentiated. The different techniques used , i.e. linked scanning at constant B/E without collisional activation and l ow-energy collision-induced dissociation using methane or helium as collisi on gas, have been shown to be useful for distinguishing the two most common (1, 2- and 1, 6-) interglycosidic linkages, e.g. flavonoid O-neohesperidos ides and O-rutinosides. Copyright (C) 2001 John Wiley & Sons, Ltd.