Characterization of partitioning behavior of cephalosporins using microemulsion and micellar electrokinetic chromatography.

Electrokinetic chromatography (EKC) was introduced to determine the partitioning behavior of various cephalosporins (cefpim, cefpirom, cefaloridin, cefaclor, cephalexin, cefuroxim, cefotaxim) in microemulsions (ME) and micellar (MC) systems. The partitioning behavior of cephalosporins in microemulsions was characterized calculating the capacity factor. The required parameters for the determination of the capacity factor (micro(aq) and micro-me are the electrophoretic mobilities of the solutes in the aqueous phase and the microemulsion phase, micro(eff) is the effective mobility in the microemulsion solution) were measured by EKC using cationic and anionic microemulsion systems consisting of the surfactants/n-heptane/1-butanol/10 mM phosphate buffer solution, pH 7.0. Electrokinetic chromatography was shown to be a useful method to quantify the partitioning behavior of drugs in oil/water microemulsion. The logarithm of the capacity factor was correlated with the logarithm of the 1-octanol/water partitioning coefficients.