Determination of solute-micelle association constants for a group of benzene derivatives and polycyclic aromatic hydrocarbons with sodium dodecyl sulphate by micellar electrokinetic chromatography

Micellar electrokinetic chromatography was applied to determine solute-micelle association constants for a group of benzene derivatives and polycyclic aromatic hydrocarbons using sodium dodecyl sulphate as surfactant. Among the different buffers studied, only those of pH greater than or equal to 9 [2-(N-cyclohexylamino)ethanesulphonic acid and ammonium acetate] gave an electroosmotic flow high enough to allow the elution of all compounds studied. Determination of association constants was achieved under different experimental conditions and the resulting errors were evaluated. The effect of the nature and concentration of the buffer and the alcohol (n-propanol and n-butanol) on the values obtained by this technique for solute-micelle association constants was studied. It was observed that these factors do not affect the association constants under the experimental conditions used. The values of the solute-micelle association constants and the errors in their determination were also compared with those obtained previously by micellar liquid chromatography.