Capillary electrophoretic separation of enantiomers using the single isomer heptakis-(2,3-dimethyl-6-sulfato)-beta-cyclodextrin as chiral resolving agent in methanol-water background electrolytes

The utility of the sodium salt of the single isomer heptakis-(2,3-dimethyl- 6-sulfato)-beta-cyclodextrin as chiral resolving agent in methanol-water ba ckground electrolytes was studied by capillary electrophoresis. The effecti ve mobilities of neutral, weak acid and weak base enantiomers were measured as a function of the methanol concentration in the 0 to 50% (v/v) range, w hile the heptakis-(2,3-dimethyl-6-sulfato)-beta-cyclodextrin concentration was simultaneously varied in the 0 to 100 mM range. The addition of methano l improved the solubility and decreased the effective mobility of the analy tes. The methanol-induced reduction in the extent of binding of the analyte s to the charged cyclodextrin could be compensated for by increasing the co ncentration of the charged cyclodextrin in the background electrolyte. Sepa ration selectivities closely followed the theoretical predictions of the ch arged resolving agent migration model of enantiomer separations. (C) 1998 E lsevier Science B.V. All rights reserved.