ENANTIOSEPARATION OF LOCAL-ANESTHETIC DRUGS BY CAPILLARY ZONE ELECTROPHORESIS WITH CYCLODEXTRINS AS CHIRAL SELECTORS USING A PARTIAL FILLING TECHNIQUE

The enantiomers of prilocaine were successfully resolved with alpha-cy clodextrin, and those of mepivacaine and bupivacaine, with methyl-beta -cyclodextrin as chiral selectors, by means of capillary zone electrop horesis (CZE) employing a partial filling technique. By this separatio n mode, a discontinous separation zone is formed in the capillary. Pri or to application of the actual drug substance, the capillary is parti ally filled with the separation solution. During the enantioseparation both ends of the capillary are dipped into the running buffer solutio n, i.e., without chiral selector. The consumption of chiral selector i s thus very low, less than a microliter per run. The repeatibility of the electrophoretic mobility of the enantiomers was better than 1.2% r elative standard deviation (RSD). The effect of the length of the sepa ration zone on the resolution of the enantiomers was studied. The appl ication time of the chiral selector, instead of the selector concentra tion, was varied in order to improve and regulate the enantioresolutio n and reduce consumption of the chiral selector as much as possible. I t was found that the enantioseparations were directly affected by the length of the separation zone, and there was a minimal plug length whe re complete enantioresolution was achieved.