期刊
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
卷 12, 期 11, 页码 1193-1204出版社
AMER CHEMICAL SOC
DOI: 10.1016/S1044-0305(01)00305-1
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Negative ion electrospray-tandem mass spectrometry has been employed to study chloride adducts of saccharide molecules. Decompositions of [M + Cl](-) obtained under identical low-energy collision conditions allow the approximate ranking of chloride affinities and gas-phase acidities of a series of isomeric monosaccharides. The ketohexoses are found to be more acidic than the aldohexoses. Chloride adduct decompositions are examined for a glucopyranosyl fructose and a glucopyranosyl glucose series. For each disaccharide series, the linkage position is shown to markedly influence the favored pathways of [M + Cl](-) decompositions, initiated either by loss of neutral HCl to form [M - H](-) and possibly leading to further (consecutive) decompositions, or by loss of M to form Cl-. Upon formation of [M - H](-), both cross-ring cleavages and glycosidic bond decompositions were observed in varying degrees for the two series of disaccharides. Remarkably, for three non-reducing polysaccharides that each contain a terminal sucrose group at the downstream end, chlorine-containing product ions arising from cleavage of the Glcalpha-2Fru linkage have been observed. Apart from Cl-, chlorine-containing product ions are not observed for any of the other disaccharides investigated, and they appear to be specifically diagnostic of a terminal Glcalpha-2Fru linkage. Their appearance is rationalized based upon a substantially reduced tendency for HCl loss from these non-reducing polysaccharides. (C) 2001 American Society for Mass Spectrometry.
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