Rapid determination of logarithmic partition coefficients between n-octanol and water using micellar electrokinetic capillary chromatography.

Micellar electrokinetic capillary chromatography (MECC) was evaluated as a rapid screening tool for the determination of logarithmic partition coefficients between n-octanol-water (log P(OW)). The technique is performed by electrochromatographing a mixture of standards of known log P(OW). The logarithmic capacity factor of each standard was plotted against its log P(OW) to form a linear calibration curve for a given set of chromatographic conditions. The log P(OW) of an unknown is calculated by using its chromatographically determined capacity factor and extracting the log P(OW) value from the calibration curve. The method was evaluated with a set of model compounds with known log P(OW). The accuracy of the method was examined and found to be within the limits required for screening purposes. The correlation of log P(OW) values determined using HPLC and MECC for some novel compounds was examined. This technique allows the screening of log P(OW) at a rate of four samples per hour with minimal sample requirements (< microgram) and with extremely small solvent waste generated.