Characterization of Single-Isomer, Heptasulfated β-Cyclodextrins by Electrospray Ionization Mass Spectrometry and Indirect UV Detection Capillary Electrophoresis

摘要

The molecular weight, the purity, and the degree of substitution for several newly synthesized single-isomer, heptasulfated β-cyclodextrin derivatives, heptakis-6-sulfato-β-cyclodextrin, heptakis(2,3 -diacetyl-6-sulfato)-β-cyclo-dextrin, and heptakis(2,3-dimethyl-6-sulfato)-β-cyclodex-Win, were determined by electrospray ionization mass spectrometry and indirect UV detection capillary electrophoresis. The main fragmentation mechanism of these single-isomer, fully sulfated cyclodextrins involves dissociation of the sulfate groups. The extent of desulfation increases with the skimmer-collimator voltage bias and the number of charges oh the electrospray ions. By reducing the skimmer-collimator voltage bias, the loss of sulfate groups could be reduced, though not completely eliminated, for the doubly charged molecular ions. Thus, ESI-MS can be used to confirm the degree of substitution for the most sulfated isomer, but not to determine the exact concentration distribution for the lower substituted isomers in a mixture.