Microemulsion electrokinetic chromatography: comparison with micellar electrokinetic chromatography

Abstract

The fundamental characteristics of microemulsion electrokinetic chromatography (MEEKC) were studied in comparison with micellar electrokinetic chromatography (MEKC). A microemulsion consisting of heptane-sodium dodecyl sulphate-butanol-buffer (pH 7.0) (0.81:1.66:6.61:90.92) was mainly employed. The separation selectivity of MEEKC was compared with that of MEKC with SDS micelles by using three different test mixtures. The microemulsion showed a stronger affinity to non-polar compounds than the SDS micelle. The migration-time window in MEEKC was easily extended owing to an increase in the electrophoretic mobility of the microemulsion by increasing the SDS fraction in the microemulsion. The efficiency in MEEKC was also compared with that in MEKC. The plate heights in MEEKC were higher than, but less than double, those in MEKC. The effect of microheterogeneity was not significant but the effect of sorption-desorption kinetics seemed more serious in MEEKC than in MEKC.