Deuterium effect on ionization and fragmentation patterns of monosaccharides ionized by atmospheric pressure chemical ionization

Glucose, galactose, and mannose in H2O and D2O were ionized by an atmospheric pressure chemical ionization (APCI) method. Isotope effects on fragmentation patterns of the monosaccharides were examined by deuterium replacement of the –OH groups to distinguish the isomers with a single mass spectrometer. The most abundant ions were the [M+H2O]+ and [MD5+D+D2O]+ for using H2O and D2O as solvent and eluent, respectively. Major fragment ions were the [M−OH]+ and [M−OH−H2O]+ in H2O, while those in D2O were the [MD5+D−D2O]+ and [MD5+D−2D2O]+. The differences in the product ions generated in H2O and D2O were due to enhancement of the strength of hydrogen bonding by the deuterium replacement. Variations of the ion intensity ratios of the [M−OH]+/[M−OH−H2O]+ and [MD5−OD]+/[MD5−OD−D2O]+ with the fragmentor voltage showed different trends depending on the kind of monosaccharides. By comparing the ion intensity ratios of the [M+H2O]+/M+, [MD5+D+D2O]+/[MD5+D]+, [M−OH]+/[M−OH−H2O]+, and [MD5+D−D2O]+/[MD5+D−2D2O]+, it was possible to distinguish the isomers of monosaccharides.

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