Electrospray mass spectrometric decomposition of some glucuronic acid-containing flavonoid diglycosides

Mass spectrometric fragmentation patterns of herbacetin 3-O-glucopyranoside-8-O-glucuronopyranoside (1), gossypetin 3-O-glucopyranoside-8-O-glucuronopyranoside (2) and takakin 7-O-glucopyranoside-8-O-glucuronopyranoside (3) were elucidated from mass spectra obtained with electrospray ionisation. The usefulness of the fragmentation patterns observed in the positive and negative mode for structural elucidation of the studied compounds is discussed. The fragmentation of 3 was substantially different from 1 and 2, especially in the negative mode. In order to explain these differences, theoretical calculations were performed.