HIGH-ENERGY COLLISION-INDUCED DISSOCIATION OF CERAMIDE IONS FROM PERMETHYLATED GLYCOSPHINGOLIPIDS

Ceramide fragments from permethylated glycosphingolipids (GSLs) were s tudied by high-energy collision-induced dissociation (CID). In compari son with ceramide fragments of underivatized GSLs, many more product i ons including charge-remote fragment ions were observed. These ions pr ovided detailed structural information on the ceramides. The relative intensity and the mass interval between the L and M ions were used to assign the position of the double bond. The position of the hydroxyl g roup was assigned with the Ln and K ions. Because the ceramide fragmen ts and not the pseudomolecular ions were selected as the precursor ion s, the size of GSLs had little effect on the quality of the product io n spectra. The sensitivity of this approach was in the range of picomo les.