Micellar electrokinetic chromatograph micelle

A Fuertoes-Matei, J Li, KC Waldron. Micellar electrokinetic chromatographic study of interaction between enkephalin peptide analogs and charged micelles. J Chromatogr B 695 39-47, 1997. 

Enormous advances and growth in the use of ordered media (that is, surfactant normal and reversed micelles, surfactant vesicles, and cyclodextrins) have occurred in the past decade, particularly in their chromatographic applications. New techniques developed in this field include micellar liquid chromatography, micellar-enhanced ultrafiltration, micellar electrokinetic capillary chromatography, and extraction of bioproducts with reversed micelles techniques previously developed include cyclodextrins as stationary and mobile-phase components in chromatography. The symposium upon which this book was based was the first major symposium devoted to this topic and was organized to present the current state of the art in this rapidly expanding field. 

Micellar Electrokinetic Capillary Chromatography. Surfactants that form micelles in solution are added to the buffer in the capillary. When the solute is injected, it partitions itself between the buffer and the micelle. Migration of the solute depends on the amount of time it spends in the micelle versus the time it spends in the buffer. Therefore, the separation of analytes occurs due to differences in the partition coefficient between the two phases, much like in a chromatographic process. 

The general theory of micellar electrokinetic chromatography represents a confluence of chromatographic and electrophoretic principles. The expressions for electrophoretic mobility under different separation conditions are summarized in Table 8.4 [161,162]. These relationships allow the determination of the critical micelle concentration and equilibrium distribution constants for solute-micelle association complexes under typical conditions for micellar electrokinetic chromatography [60-64,161-164]. These properties change significantly with the composition of the electrolyte solution, and are generally different to common reference values for pure water. 

The apparent electrophoretic mobility of an analyte in micellar electrokinetic chromatography depends on three factors the electroosmotic mobility for the system the fraction of analyte in the electrolyte solution and its electrophoretic mobility and the fraction of analyte in the pseudostationary phase, and the electrophoretic mobility of the micelles (assuming that the mobility of the analyte-micelle complex is the same as the micelle). If we introduce the chromatographic retention factor, defined as the ratio of the number of analyte molecules in the pseudostationary phase to the number in the... 

Explain how micellar electrokinetic chromatography combines electrophoretic and chromatographic separation principles. Why is the MEKC micelle called a pseudostationary phase ... 

With respect to chromatographic techniques, cationic surfactant micelles have been used as mobile phase additives in the well-known micellar liquid chromatography (MLC) [4]. They have also been employed as pseudostationary phases in micellar electrokinetic capillary chromatography (MEKC) [5]. 

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