Determination of the lipophilicity (log P o/w) of organic compounds by microemulsion liquid chromatography.

Four microemulsion liquid chromatography (MELC) systems and one micellar liquid chromatography (MLC) system have been evaluated as potential high-throughput screening platforms capable of modeling the partitioning behaviors of drug compounds in an n-octanol/water system and predicting their lipophilicity (i.e., log P values). The microemulsion mobile phases is consisted of sodium dodecyl sulfate (SDS), butanol, octane, heptanes, octanol and water. A linear solvation energy relationship (LSER)-based method was used to compare the MELC and MLC systems, as well as several other biochemical systems, and to identify the optimal system by comparing their Euclidean distances with the LSER coefficients. The most effective MELC system had a mobile phase consisting of 3.0% (w/w) SDS, 6.0% (w/w) butanol, 0.8% (w/w) octanol, and 90.2% (w/w) water (pH 6.4). The results showed that it gave superior results to the other chromatographic systems in terms of its ability to predict the log P values of drug compounds.