NEW DERIVATIVES OF CYCLODEXTRINS AS CHIRAL SELECTORS FOR THE CAPILLARY ELECTROPHORETIC SEPARATION OF DICHLORPROP ENANTIOMERS

alpha-, beta- and gamma-cyclodextrins (CDs), as well as some of their chemical derivatives, have been tested as chiral resolving agents for the capillary zone electrophoretic resolution of the racemic herbicide dichlorprop, (+/-)-2-(2,4-dichlorophenoxy)propionic acid, of which on ly the (+)-isomer is herbicidally active. The complexation constants o f the herbicide enantiomers with the cyclodextrin host molecules have been calculated from the electrophoretic migration time data at variab le cyclodextrin concentration. The experimental results showed that se veral of the investigated CDs allowed dichlorprop enantiomer resolutio n. In particular, a newly synthesised ethylcarbonate derivative of bet a-CD showed the best enantiomer resolution properties among the tested compounds, while the remaining ones showed inferior or no performance s at all. The calculated inclusion constants allowed identification of the best conditions for enantioresolution, and an explanation of the different complexation properties of the investigated compounds has be en proposed on the basis of molecular modeling. (C) 1998 Elsevier Scie nce B.V. All rights reserved.