ISSN:
0887-6134
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Collision-induced dissociations and ion-molecule reactions in a triple-quadrupole mass spectrometer are used to distinguish qualitatively between permethylated D(-)-ribose and D(-)-arabinose isomers. Differences are observed in the [MH]+ daughter ion spectra of each isomer at relatively low ion kinetic energies from 0 eV to 7 eV (laboratory frame of reference) for collisions with inert nitrogen gas. Loss of neutral methanol is favored for the D(-)-ribose isomer. With permethylated D(-)-arabinose, methanol elimination is less likely to occur and the rearrangement ion [H3COCH2CHOCH3]+ exists in significantly greater abundance. At low precursor ion kinetic energies, the D(-)-arabinofuranoside participates in a selective exothermic proton transfer reaction with methyl-amine to yield the [CH3NH3]+ ion. In contrast, the proton transfer reaction with permethylated D(-)-ribose is an endothermic process with a definite translational energy onset. From this measured threshold ion kinetic energy, the proton affinity of methyl-2,3,5-tri-o-methyl-D(-)-ribofuranoside was estimated to be 940 ± 8 kJ mol-1. In additional experiments where both saccharide isomers function as collision gases, a reactive trimethylsilyl ion is used to distinguish successfully between methyl-2,3,5-tri-o-methyl-D(-)-ribofuranoside and methyl-2,3,5-tri-o-methyl-D(-)-arabinofuranoside isomers.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bms.1200180925
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