Determination of octanol–water partition coefficients of pesticides by microemulsion electrokinetic chromatography

Microemulsion electrokinetic chromatography (MEEKC) was evaluated as a screening tool for the indirect measurement of octanol–water partition coefficients (log P o/w) of pesticide compounds. Over 80 pesticide compounds representing a variety of structural characteristics were studied, and good correlation of log P o/w with the logarithm of the retention factor was found. The microemulsion system studied allowed the separation of compounds in the log P o/w range of −1 to 7. In addition, a smaller set of simple organic molecules that vary in structural features was evaluated and compared to the pesticide log P o/w calibration. The pesticide and simple organic molecule log P o/w calibration lines were statistically similar. This suggests that a universal set of standard compounds may be employed for the log P o/w calibration to provide measurements for a variety of compounds with good accuracy.