Fig. 2.

ESI Q-TOF-MS¹ spectra of GlcCer and GalCer from human plasma. The spectra were prepared from silica gel extracts of primulin-stained monohexosylceramides after TLC separation as borate complexes in alkaline solvent. MS¹ spectra of GlcCer (upper panel) and GalCer (lower panel) were recorded in the positive ion mode. Dotted frames in the insets, which show the orcinol stain of a TLC plate, indicate the silica gel positions from which primulin-detected GlcCer and GalCer were extracted, respectively. Lane a: Reference GlcCer, 7 µg; lane b: neutral GSL mixture corresponding to 34.7 mg of human plasma protein; lane c: reference GalCer, 10 µg. Unassigned ion species, which originate most likely from coextracted lipids are marked with asterisks and were not further analyzed. Major [M+Na]⁺ ions of monohexosylceramides and their proposed structures are listed in Table 2.