Fragmentation characterization and differentiation of isomeric diglycosyl flavonoids using ultra-high-performance liquid chromatography electrospray ionization quadrupole time-of-flight tandem mass spectrometry in negative ion mode

Flavonoids exhibit a wide range of biological activities and the fragmentation characterization and differentiation of isomeric diglycosyl flavonoids is an important area of research. In this study, ultra-high-performance liquid chromatography electrospray ionization quadrupole time-of-flight tandem mass spectrometry was used to identify two pairs of isomeric diglycosyl flavonoids: naringin/narirutin and neohesperidin/hesperidin. The two pairs of flavonoids were identified by product ion tandem mass spectra of the precursor ions [M - H](-). The results showed that characteristic product ions distinguishing flavonoids glycosylated with rhamnosyl-(alpha 1 -> 2)-glucosyl from isomeric flavonoids glycosylated with rhamnosyl-(alpha 1 -> 6)-glucosyl were the precursor ion [M - H](-) and its characteristic product ions Y-0(-) and [X-0,2(0) - H](-).