A study of the interaction between enantiomers of zolmitriptan and hydroxypropyl-beta-cyclodextrin by capillary electrophoresis

The enantioresolution of zolmitriptan was performed using cyclodextrin (CD)-modified capillary zone electrophoresis (CZE) with hydroxypropyl-beta-CD (HP-beta-CD) as the chiral selector. The influence of experimental conditions on the enantioseparation of zolmitriptan, such as pH, temperature, applied voltage, and concentrations of running electrolyte and CD, was systematically investigated, obtaining a baseline separation of two enantiomers by the use of a 25 mM sodium dihydrogen phosphate (SDPH) running electrolyte (pH 2.4) containing 30 mM HP-beta-CD at 15 degrees C. Binding constants for each enantiomer-HP-beta-CD pair at different temperatures, as well as thermodynamic parameters for binding, were calculated. A nonlinear van't Hoff plot was obtained, indicating that the thermodynamic parameters of complexation were temperature-dependent for zolmitriptan enantiomers. The significant contribution of the enthalpy difference to the Gibbs free energy change suggested a stereomeric barrier mechanism for chiral recognition.Biochemical Research MethodsChemistry, AnalyticalSCI(E)EI13ARTICLE1313-32039