Characterization of trimethylsilyl derivatives of cerebrosides by direct inlet-chemical ionization mass spectrometry.

Submicrogram quantities of trimethylsilyl derivatives of cerebrosides obtained from the spleen of a patient with Gaucher's disease and from bovine brain were analyzed by direct probe inlet-chemical ionization mass spectrometry, using isobutane as the reagent gas. Quasimolecular ions (QM+, M + 73) and other recognizable fragment ions produced by the successive elimination of trimethylsilanol and sugar residue gave useful information about fatty acid compositions. These ions could also be utilized for qualitative analyses of the molecular species of cerebrosides. Cerebrosides with non-hydroxy and hydroxy fatty acids could be discriminated from each other by comparing the intensities of their quasimolecular ions. Cerebrosides with saturated and monounsaturated fatty acids could also be discrimnated from each other, because the mass number decreased by two mass units in cerebrosides with monounsaturated fatty acids. It was concluded that structural information and molecular species determination could be obtained from small amounts of purified cerebrosides.