INTRODUCTION OF MIGRATION INDEXES FOR IDENTIFICATION - CHIRAL SEPARATION OF SOME BETA-BLOCKERS BY USING CYCLODEXTRINS IN MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY

Because of the different physiological impact that stereoisomers may h ave, it is often vital to separate these forms from one another. Becau se of their structural similarity, the separation is usually difficult to achieve and zones may elute very close to each other. This is a pa rticular problem in capillary electrophoresis, where the repeatability of absolute migration times is fairly poor, mainly due to the irrepro ducibility of the electroosmotic flow. The separation is usually repea table, however, and when the disturbing effects are eliminated by usin g a migration index system incorporating two marker compounds the iden tification of the enantiomers becomes extremely good. Relative standar d deviation (RSD) values less than 0.1% for the migration index of eac h enantiomer were obtained in both intra-day and day-to-day (6 days) s tudies. The best separation was achieved with the electrolyte solution made of 40 mM berate, 32 mM sodium dodecyl sulfate (SDS), 12 mM beta- cyclodextrin (beta-CD), and 6 mM alpha-cyclodextrin (alpha-CD) at pH 9 .3.