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Determination of octanol‐water partition coefficients for carbonate esters and other small organic molecules by microemulsion electrokinetic chromatography
Author(s) -
Østergaard Jesper,
Hansen Steen Honoré,
Larsen Claus,
Schou Christian,
Heegaard Niels H. H.
Publication year - 2003
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.200390120
Subject(s) - microemulsion , chemistry , lipophilicity , partition coefficient , electrokinetic phenomena , octanol , chromatography , heptane , micellar electrokinetic chromatography , substituent , analytical chemistry (journal) , carbonate , capillary electrophoresis , organic chemistry , pulmonary surfactant , biochemistry
Abstract Microemulsion electrokinetic chromatography (MEEKC) was assessed as a tool for determination of octanol‐water partition coefficients using 34 solutes encompassing 8 carbonate esters. It was confirmed that microemulsions containing 1.44–2.88% w/w SDS, 6.49% w/w 1‐butanol, and 0.82% w/w n ‐heptane constitute a good model of octanol‐water partitioning in the pH range of 1.4–7.4. Use of the migration index concept led to improved repeatability of the MEEKC method compared to the use of retention factors. Using a dynamical coating, a high electroosmotic flow at pH 1.4 and 4.75 was achieved expanding the practical pH working range of the MEEKC system. The correlation obtained between the migration index and log P was unaffected by pH indicating that the properties of the microemulsion droplets and, thus, partitioning are independent of pH. No evidence for congeneric behavior was found for the sample set comprising solutes with different hydrogen bonding properties suggesting that simple reference compounds can be used as calibrators. Lipophilicity estimates for the series of carbonate esters were obtained. The increase in lipophilicity with chain length was smaller than expected from the Hansch substituent constant, π.