Identifiction of the lowest energy dissociation pathway of collisionally activated O-methyl oligosaccharide [M + Na]+ cations by SORI-FTMS

Collisional activation mass spectrometry of oligosaccharide quasimolecular ions is widely applied for sequencing of the primary structure of a carbohydrate. Several mechanisms for glycosidic bond cleavage and fragmentation of the furanose/pyranose ring of the oligosaccharide cations have been proposed to rationalize the gas phase ion chemistry of collisionally activated oligosaccharide ions. In spite of a growing number of mechanistic studies about unimolecular fragmentation of oligosaccharide ions, no thermochemical data are known. A further improvement of gas phase carbohydrate ion chemistry requires understanding of the potential energy hypersurface of these ions. In this study we have probed the lowest dissociation limit of sodium cationized maltoheptose per methyl ether molecules using multiple low energy collisions in an ICR.