DETERMINATION OF BETA-CYCLODEXTRIN INCLUSION COMPLEX CONSTANTS FOR 3,4-DIHYDRO-2-H-1-BENZOPYRAN ENANTIOMERS BY CAPILLARY ELECTROPHORESIS

Chiral separation of 3,4-dihydro-2H-1-benzopyran derivatives by capillary zone electrophoresis was achieved by employing beta-cyclodextrin (beta-CD) as chiral selector. The effects of electrolyte composition (beta-cyclodextrin concentration, ionic strength and pH of the buffer) on the migration time, enantioselectivity, peak efficiency and resolution were investigated. As expected, there was an optimum beta-CD concentration (C-opt) which gave maximum enantioselectivity. The stability constant for the beta-CD inclusion complex was determined for each enantiomer of two 3,4-dihydro-2H-1-benzopyran derivatives. For each solute, the experimental value of C-opt agreed well with the value calculated from the equation [C](opt) = 1/(KRKS)(1/2), where we used experimental values for the inclusion complex constants (K-R,K-S). The enantiomeric separation of three 3,4-dihydro-2H-1-benzopyran derivatives was achieved using this optimization method, and baseline separation was obtained in less than 15 min with an efficiency of between 300 000 and 600 000 theoretical plates.