Lipophilicity determination of acidic compounds: MEEKC as a reliable high-throughput methodology

Abstract

In the present study a pressure-assisted MEEKC method with reversed-polarity using a conventional CE instrument with UV detection and uncoated fused silica capillaries is validated as a high-throughput methodology for the lipophilicity determination of the neutral species of acidic compounds (pK_a > 3.5). After the calibration of the system with four standard compounds of known log P_o/w, mass distribution ratios (log k_MEEKC) of new molecules can be directly converted into log P_o/w values by means of a simple linear equation (log P_o/w=a·log k_MEEKC+b). The method was internally and externally validated for a log P_o/w range between -1.54 and 4.75, with higher accuracies than conventional liquid chromatographic methods.