Estimation of partition coefficients by MEKC Part I: Potential pharmaceuticals based on 2-quinolone and 2-indolone

Abstract

The octanol-water partition coefficients of 18 potential pharmaceuticals derived from 2-quinolone and 2-indolone were measured by means of MEKC. Their values range from 2.2 to 4.7 (expressed in logarithmic form). The critical micelle concentration (CMC) of SDS was determined conductometrically and the partial specific volumes of the micelles in the buffer (25 mM sodium borate, pH 9.5) were calculated from density data. The values were used for determination of the phase ratio and for estimation of the micelle-water (K mw ) and octanol-water (K ow ) partition coefficients. Direct calculation of K ow from the easily measurable capacity factors (K') gives results comparable with those laboriously determined from K mw . Extrapolation of the micellar time from the set of migration times of alkylbenzene standards proved to be viable alternative to measurements using a marker.