ELECTROKINETIC CHROMATOGRAPHY EMPLOYING AN ANIONIC AND A CATIONIC BETA-CYCLODEXTRIN DERIVATIVE

beta-Cyclodextrin, 1, can act as a chiral buffer additive in capillary zone electrophoresis (CZE) owing to its ability to form diastereomeri c complexes with the enantiomers of ionic compounds. Reaction of 1 wit h 2,3-epoxy-propyltrimethylammonium chloride gave preponderantly 6-O-( 2-hydroxy-3-trimethylammoniopropyl) derivatives (2) of varying degrees of substitution (d.s.). Analogous reaction of 1 with 1,3-propanesulto ne yielded 6-O-(sulfo-n-propyl) derivatives (SPE-beta-CD, 3) of varyin g d.s. The purity and the d.s. of 2 and 3 were determined by H-1 NMR a nd electrospray ionization mass spectrometry (ESI-MS). These charged b eta-cyclodextrin derivatives were used for the chromatographic enantio mer separation of a series of neutral barbiturates, of chlorthalidone, terbutaline, warfarin, salbutamol and brompheniramine by cyclodextrin electrokinetic chromatography (CD-EKC). During the separation of chlo rthalidone with 3 as chiral additive, a reversible interconversion of the enantiomers (enantiomerization) was observed at temperatures below 20 degrees C.