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 Yn+ ions. High-energy product ion spectra of [M+H]+ ions enable further characterization and differentiation of isomeric di-6,8-C-glycosides.