CHARACTERIZATION OF SINGLE-ISOMER, HEPTASULFATED BETA-CYCLODEXTRINS BY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY AND INDIRECT UV DETECTION CAPILLARY-ELECTROPHORESIS

The molecular weight, the purity, and the degree of substitution for s everal newly synthesized single-isomer, heptasulfated beta-cyclodextri n derivatives, heptakis-6-sulfato-beta-cyclodextrin, eptakis(2,3-diace tyl-6-sulfato)-beta-cyclodextrin, and eptakis(2,3-dimethyl-6-sulfato)- beta-cyclodextrin, were determined by electrospray ionization mass spe ctrometry and indirect UV detection capillary electrophoresis. The mai n fragmentation mechanism of these single-isomer, fully sulfated cyclo dextrins involves dissociation of the sulfate groups. The extent of de sulfation increases with the skimmer-collimator voltage bias and the n umber of charges on the electrospray ions. By reducing the skimmer-col limator voltage bias, the loss of sulfate groups could be reduced, tho ugh 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 di stribution for the lower substituted isomers in a mixture.