Structural determination of glycosphingolipids as lithiated adducts by electrospray ionization mass spectrometry using low-energy collisional-activated dissociation on a triple stage quadrupole instrument

摘要: Abstract Structural characterization of glycosphingolipids as their lithiated adducts using low-energy collisional-activated dissociation (CAD) tandem mass spectrometry with electrospray ionization (ESI) is described. The spectra contain abundant fragment ions reflecting the long chain base (LCB), fatty acid, and sugar constituent molecule permit unequivocal identification cerebrosides, di-, trihexosyl ceramides globosides. major fragmentation pathways arise from loss moiety to yield a ceramide ion, which undergoes further form multiple that confirm structures acid LCB. mechanisms for ion formation possible configuration ions, resulting CAD molecular ([M + Li]+) monoglycosylceramides are proposed. were supported by source various cerebrosides analogous molecules prepared H–D exchange. Constant neutral precursor scannings identify galactosylceramides sphingosine or sphinganine LCB subclasses, specific N-2-hydroxyl subclass in mixtures also demonstrated.