Chiral separations by capillary zone electrophoresis with the use of cyanoethylated-β-cyclodextrin as chiral selector

The uncharged beta-cyclodextrin derivative, cyanoethylated-beta-cyclodextrin, was successfully used, as chiral selector, in capillary zone electrophoresis in a polyacrylamide coated capillary. Several basic and acidic analytes belonging to different classes of compounds of pharmaceutical interest were analyzed and their enantiomers resolved. The chiral resolution was strongly influenced by the concentration of the cyclodextrin as well as by the pH of the background electrolyte and the capillary temperature. Compared with the results previously obtained for the separation of naproxen enantiomers employing trimethylated-beta-CD, the use of cyanoethylated-beta-CD caused an inversion of migration order [R-(-)-naproxen faster than the S-(+)-isomer]. H-1 NMR spectra of R,S-naproxen without cyclodextrin and R,S- and S-naproxen in the presence of the chiral selector revealed a strong interaction between the methyl group and H proton of the aromatic moiety of naproxen and the cyanoethylated-beta-cyclodextrin. (C) 1998 Elsevier Science B.V. All rights reserved.