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Improvement of microemulsion electrokinetic chromatography for measuring octanol–water partition coefficients
Author(s) -
Xia Zhining,
Jiang Xuemei,
Mu Xiaojing,
Chen Hua
Publication year - 2008
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200700104
Subject(s) - microemulsion , analyte , electrokinetic phenomena , partition coefficient , chemistry , chromatography , tracing , electric field , analytical chemistry (journal) , logarithm , octanol , physics , mathematics , mathematical analysis , pulmonary surfactant , computer science , biochemistry , quantum mechanics , operating system
Microemulsion electrokinetic chromatography (MEEKC) has been used to indirectly measure octanol–water partition coefficients (log P ow ) of compounds. In order to obtain an accurate log P ow value, the electrophoretic mobilities of the microemulsion phase ( μ me ) and the analyte ( μ eff ) in MEEKC must be accurately required. However, in conventional MEEKC, the shortage of obtaining μ me with a tracing method was discovered, and the influences of concentration, injection volume of analyte, and high electric field on measuring μ eff were also found. In this paper, a novel method called improved MEEKC (I‐MEEKC) was developed to avoid the problems mentioned above. In I‐MEEKC, a nonlinearity fitting program was used to obtain μ me to avoid the error from tracing μ me ; the extrapolating method was used to eliminate the effects of concentrations and injection volumes of analytes on μ eff measurement, and an enough stable microemulsion was selected to eliminate the effect of high electric field on μ eff measurement. Then the novel method was applied to estimate log P ow of uncharged compounds and charged pharmaceuticals compared to the conventional MEEKC. The log P ow of all analytes obtained by I‐MEEKC agreed with those obtained by classical shake flask or literature values, the errors between them were within 0.1 logarithm units, better than the ones by conventional MEEKC.