Characterization of gangliosides by direct inlet chemical ionization mass spectrometry

Permethylated derivatives of N-acetylneuraminic acid-containing G(M3), N-glycolylneuraminic acid-containing G(M3), G(D1a), and G(D1b), were analyzed by direct inlet ammonia chemical ionization (CI) mass spectrometry. These compounds were found to yield simple fragmentations, prominent fragment ions in the high mass region, and characteristic fragment ions corresponding to the cleavage of glycosidic linkages. This method also provides detailed information on the carbohydrate sequence and lipophilic composition in gangliosides.