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

The octanol-water partition coefficients of 18 potential pharmaceuticals de rived 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 (CIVIC) of SIDS was determined conductometrically an d 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 o f K-ow from the easily measurable capacity factors (le) gives results compa rable with those laboriously determined from K-mw. Extrapolation of the mic ellar time from the set of migration times of alkylbenzene standards proved to be viable alternative to measurements using a marker.