ENANTIOMERIC SEPARATION OF LOCAL-ANESTHETIC DRUGS BY MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY WITH TAURODEOXYCHOLATE AS CHIRAL SELECTOR

The enantiomeric separation of local anaesthetic analogues, by means o f micellar electrokinetic chromatography (MEKC), using taurodeoxychola te (TDC) both as chiral selector and as surfactant was studied. In thi s system the analytes are migrating with the micellar phase towards th e anode. When a mixed micellar phase between TDC and Brij-35 [polyoxye thylene(23)-dodecanol] was used, the migration direction and migration order of the enantiomers were reversed due to a decreased distributio n of the analytes to the micellar phase. The separation time with the mixed micelles is significantly shorter than with neat TDC as the mice llar phase. The success of the chiral separation is strongly dependent on the concentration of TDC, there is an optimal concentration of the surfactant for each enantiomer pair in accordance with a proposed the ory for the association between the analytes and TDC. In the mixed mic ellar phase optimum chiral resolution for each analyte was achieved at different ratios of TDC and Brij-35. It is further shown that the aff inity of the [S-(+)]-enantiomers for TDC was higher than that of the [ R-(-)]-forms.