A comparison of phosphated and sulfated beta-cyclodextrins as chiral selectors for capillary electrophoresis

The enantioseparation capabilities of three different functionalized beta - cyclodextrins, two sulfated beta -cyclodextrins with 4 and 15 nominal degre es of substitution and a phosphated beta -cyclodextrin with 8 degrees of su bstitution, were compared. While anodic detection was used with both sulfat ed cyclodextrins, the phosphated cyclodextrin required cathodic detection s uggesting either lower ionization of the phosphated cyclodextrin or general ly lower affinity of the analytes for the phosphated cyclodextrin. The effe cts of several experimental parameters were evaluated with respect to enant ioseparation. The degrees of substitution of the cyclodextrin, pH of the ba ckground electrolyte as well as the concentration of the functionalized bet a -cyclodextrin, each had a significant influence on the successful enantio meric separation of the chiral drugs investigated.