Use of ?-cyclodextrin polymer as a chiral selector in capillary electrophoresis

Enantiomers of several basic compounds of pharmaceutical interest were successfully separated by capillary electrophoresis using a modified ?-cyclodextrin polymer. As the cyclodextrin contained carboxylic groups, the chiral selector could be used in either an uncharged or a charged mode, selecting the appropriate pH of the background electrolyte. The effect of the pH of the background electrolyte on the effective mobility, resolution and selectivity was studied in the range 2.6-6.2 for the enantiomer resolution of ?-hydroxyphenylethylamine, norphenylephrine, terbutaline, ephedrine, norephedrine, ketamine, epinephrine and propranorol. Very good enantiomeric resolution was achieved for all the compounds except for ephedrine and norephedrine (R < 0.5). An increase in the pH of the electrolyte caused an inversion of mobility for either terbutaline and propranolol owing to strong complexation with the negatively charged polymer.