Estimation of log Pow values for neutral and basic compounds by microchip microemulsion electrokinetic chromatography with indirect fluorimetric detection (μMEEKC-IFD)

Microchip microemulsion electrokinetic chromatography with indirect fluorimetric detection (mu MEEKC-IFD) was used to obtain log P octanol/water (log P-ow) values for neutral and basic compounds. Six compounds, with log P-ow values between 0.38 and 5.03, were used to create a calibration curve relating the log of retention factors (log k) obtained from mu MEEKC-IFD with the known log P-ow values. The log P-ow values for six additional compounds were determined using the log k values obtained by mu MEEKC-IFD and the linear relationship between log P-ow and log k established for the standard compounds. The mu MEEKC-IFD buffer was composed of 50 mM 3-[cyclohexylamino]-1-propane-sulfonic acid (CAPS) buffer (pH 10.4) containing 1.2% n-heptane (v/v), 2% sodium dodecylsulfate (w/v), 8% 1-butanol (v/v) and 4 mu M 5-carboxytetramethyl-rhodamine (TAMRA) as the fluorophore probe for indirect detection. The mu MEEKC-IFD provided an accurate method for estimating log P-ow values and also a means for analyzing compounds that are non-fluorescent. (c) 2004 Elsevier B.V. All rights reserved.