Triterpenoid saponins from Symplocos chinensis have been investigated by positive ion electrospray ionization multi-stage tandem mass spectrometry (ESI-MS^n) in a new linear ion trap mass spectrometer. It has been found that the fragmentation patterns of these given saponins significantly vary in accordance with different derivatization in the glucuronyl residue of oligosaccharide chains. The product ions show that the carboxyl group and the free hydroxyl group at the C-3' position of the glucuronyl residue are the key sites for determining the fragmentation pathways of these given triterpenoid saponins.The described results in this paper confirm the mechanisms previously postulated for cross-ring cleavage process for the metal coordinated species. Furthermore, the experimental results can benefit the determination of the minute compounds of this type in crude plant extracts and give some aid for the studies of similar glycoconjugates.
