Enantiomer separation of denopamine by capillary electrophoresis with charged and uncharged cyclodextrins

Direct separation of enantiomers of denopamine was investigated by capillary electrophoresis employing charged and uncharged cyclodextrin (CD) derivatives. Uncharged beta-type CDs, having hydrophobic groups, were essential for the enantioseparation of denopamine; of these, especially dimethyl-beta-CD was effective. Among charged CDs, gamma-type as well as beta-type CDs were found effective for the enantioseparation of denopamine. Reversal of migration order of R-form (active) and S-form enantiomers was investigated by using two types of coated capillaries: (i) an amine capillary with an inner wall coated with dimethylamino groups, and (ii) a polyacrylamide-coated capillary. Manipulation of migration order could be easily performed by selecting suitable capillaries, buffer pH, and CDs.