Analysis of glycolipids by fast atom bombardment mass spectrometry

The positive and negative ion fast atom bombardment (FAB) mass spectra of four glycolipids obtained from microbial cultures are reported. The spectra of the glycolipids in the positive ion mode are characterized by abundant [M + Na]+, [M + Na + matrix]+ and [M + 2Na - H]+ species. In negative FAB conditions the molecules yield [M - H]-. Our understanding of the FAB behaviour of glycolipids in both positive and negative modes has been considerably aided in the structure elucidation, without any derivatization or degradation reaction of the compounds studied. The technique allows unambiguous molecular weight determination of low-microgram amounts of these glycolipids purified from biological sources and provides useful fragmentation information.