HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHY FAST-ATOM-BOMBARDMENT (TANDEM) MASS-SPECTROMETRY OF PSEUDOMONAS RHAMNOLIPIDS

Several rhamnolipid preparations from Pseudomonas strains were studied by thin-layer chromatography/fast atom bombardment (TLC/FAB) mass spe ctrometry and TLC/FAB tandem mass spectrometry (MS/MS). The preparatio ns were separated with normal-phase (Silica 60) and reversed-phase (RP -8) chromatography. Silica 60 plates appeared to be very useful in the separation of rhamnolipids according to the number of monosaccharide residues present. Spectra which show characteristic fragment ions coul d be obtained from components of mixtures with a total sample size of less than 200 ng. Chromatography on RP-8 plates gave a good separation of the rhamnolipids based on the length of the fatty acid alkyl chain . MS/MS of the sodium cationized molecules gave information about the sequence of the building blocks. Particularly, heterogeneity in beta-h ydroxy fatty acid composition was determined for the principal as well as minor components present in natural rhamnolipid mixtures.