CAPILLARY ZONE ELECTROPHORESIS FOR SEPARATION OF DRUG ENANTIOMERS USING CYCLODEXTRINS AS CHIRAL SELECTORS - INFLUENCE OF EXPERIMENTAL PARAMETERS ON SEPARATION

Enantiomeric separations in cyclodextrin-modified capillary zone electrophoresis (CZE) can be tuned by many experimental conditions, such as the cyclodextrin type, concentration and degree of substitution, pH and separation voltage. The enantiomers of rac-terbutaline, rac-terbutaline mononsulphate, rac-bambuterol, rac-propranolol, rac-ephedrine and rac-brompheniramine were used as model substances to study the effect of the above factors on separation parameters using an uncoated fused-silica capillary. The cyclodextrins used in the experiments were alpha-cyclodextin, beta-cyclodextrin, dimethyl-beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin. The results were compared with those predicted by theoretically derived models. The most effective parameters for optimizing resolution were pH and cyclodextrin type and concentration. The applied voltage was the most effective in tuning the separation time. The quality of the cyclodextrins used for the separation is of importance as both the degree of substitution of modified cyclodextrins and the position of substitution were found to affect the separations.