Enantiomeric separation by capillary electrophoresis using a soluble neutral ?-cyclodextrin polymer

Enantiomers of several racemic basic compounds of pharmaceutical interest and three tryptophan derivatives were investigated by capillary electrophoresis employing a soluble ?-cyclodextrin polymer and native ?-cyclodextrin. The effects of the concentration of the polymer added to the background electrolyte and of the pH of the buffer on the effective mobility and resolution of the studied compounds were examined. The p-cyclodextrin polymer showed a higher stereoselectivity than the parent ?-cyclodextrin. Enantioselectivity and resolution were influenced by the concentration of the ?-cyclodextrin polymer and the background electrolyte. A pH study, carried out in the pH range 2.7-6, showed that an increase in pH caused a general decrease in both resolution and selectivity. The best results for the enantiomeric separation of the basic compounds studied were obtained at pH 2.7.