Influence of Composition on the Selectivity of a Mixed-micellar Buffer in Micellar Electrokinetic Chromatography

Abstract

The solvation parameter model is used to study the influence of composition of mixed micelles containing sodium N-dodecanoyl-N-methyltaurine and the neutral polyether surfactant Brij 35 on selectivity in micellar electrokinetic chromatography. The addition of Brij 35 to the anionic surfactant affects mainly the phase ratio and reduces the hydrogen-bond acidity of the mixed micelle but otherwise has only minor influences on selectivity. The addition of organic solvent to the bulk electrolyte produces small and predictable changes in selectivity similar to those observed in reversed-phase liquid chromatography. An interphase model is suggested to account for the observed changes in retention characteristics of the mixed micelles.