CHARACTERIZATION OF POSITIONAL AND ANOMERIC ISOMERS OF METHYL 2-O-SULFO-D-GLUCOPYRANOSIDURONIC AND 3-O-SULFO-D-GLUCOPYRANOSIDURONIC ACIDS AND METHYL 2-O-SULFO-D-GLUCOPYRANOSIDES AND 3-O-SULFO-D-GLUCOPYRANOSIDES BY SECONDARY-ION MASS-SPECTROMETRY

Secondary ion mass spectrometry (SIMS) of anomeric pairs of methyl 2-O - and 3-O-sulfo-D-glucopransiduronic acids and methyl 2-O- and 3-O-sul fo-D-glucopyranosides show the deprotonated molecule in the negative-i on mode and ammoniated and sodiated molecules in the positive-ion mode . The four isomers were distinguished from each other by linked scanni ng at constant B/E in negative- and positive-ion SIMS, which gave info rmation characteristic of the position of the sulfate group and even t he configuration of the anomeric methoxy group. The main fragmentation processes correspond to the loss of methanol and the elimination of S O3.