Separation of drugs by capillary electrophoresis, Part 10. Permethyl-alpha-cyclodextrin as chiral solvating agent

Following the German-Chinese Drug Screening Program, 86 racemic drugs were investigated in capillary zone electrophoresis in the presence of the chira l solvating agent (CSA) hexakis-(2,3,6-tri-O-methyl)-alpha-cyclodex (TM-alp ha-CD). Of the 86 drugs, 23 were separated into enantiomeric pairs. A compa rison of the migration separation factors (alpha(m)) and the migration reta rdation factors (R-m) with previously published data for native alpha-CD re vealed that the 'upper-rim' hydroxyl groups do not necessarily facilitate t he recognition of the drug enantiomers by the chiral host. In contrast, an overall increase in affinity for the permethylated host led to a higher rat e of successful enantiomer separations. A key substructure (4H) was identif ied in the analyte structure domain, with a crucial influence on the behavi or of a particular drug.