Application of field desorption and secondary ion mass spectrometry for glycolipid analysis

Field desorption (FD) and secondary ion mass spectrometry (SI-MS) mass spectra of several glycolipids are presented to demonstrate their potential for the analysis of glycolipids. FD and SI-MS give useful information on molecular weight, ceramide structure and sugar sequence. In general, FD provides clearer fragment ion peaks for the analysis of sugar sequence than SI-MS. For underivatized acidic glycolipids such as gangliosides, sulfatide and seminolipid, SI-MS provides quasimolecular ions which are hardly produced by FD. In contrast to underivatized gangliosides, permethylated samples give molecular ion species of high intensity in both FD and SI-MS, but no fragment ions pertinent to carbohydrate sequence could be observed in FD spectra. SI-MS spectra of permethylated samples provide good information on sugar chain structure. Thus FD and SI-MS mass spectra complement each other, and the combination of these ionization methods will provide powerful tools for glycolipid analysis.