CHARACTERIZATION AND DIFFERENTIATION OF DIGLYCOSYL FLAVONOIDS BY POSITIVE-ION FAST-ATOM-BOMBARDMENT AND TANDEM MASS-SPECTROMETRY

This study shows that fast atom bombardment (FAB) in combination with collisional activation and tandem mass spectrometric techniques is useful for the characterization of, and the differentiation between, O-diglycosyl, O-C-diglycosyl and di-C-glycosyl flavonoids. A quick differentiation between the three types of glycosyl flavonoids is possible by simply examining FAB mass spectra. Low-energy product ion spectra of [M + H](+) ions have been used for determining the carbohydrate sequence in O-diglycosyl flavonoids and characterizing the terminal monosaccharide in O-C-diglycosyl flavonoids. The data obtained for per-O-deuterated precursor ion species of O-diglycosyl flavonoids indicate that O-linked hydrogen atoms are involved in the formation of Y-n(+) ions. High-energy product ion spectra of [M + H](+) ions enable further characterization and differentiation of isomeric di-6,8-C-glycosides.