Separation and analysis of cyclodextrins by capillary zone electrophoresis

alpha-, beta-, and gamma-Cyclodextrins were separated by capillary zone electrophoresis using indirect UV photometric detection. The cyclodextrins are separated and detected after complexation with benzoic acid or benzoic acid derivatives using a constant electroosmotic flow. Enhanced resolution of mixtures of cyclodextrins was obtained by adjusting the pH of the electrolyte and the concentration of benzoic acid. High pH conditions resulted in short analysis times with a low selectivity, whereas high benzoic acid concentrations resulted in long analysis times with a high selectivity. Detection limits were found at 50 mu M for alpha-, beta-, and gamma-cyclodextrins, respectively. The method allows the separation and analysis of cyclodextrins in complex samples such as fermentation broth, urine, plasma, and pharmaceutical formulations with minimal sample pretreatment. (C) 1997 Elsevier Science Ltd.