CONTROL OF SELECTIVITY IN MICELLAR ELECTROKINETIC CHROMATOGRAPHY BY MODIFICATION OF SODIUM DODECYL-SULFATE MICELLES WITH ORGANIC HYDROXY COMPOUNDS

Modification of micellar phases with solubilized solutes was examined to control the separation in micellar electrokinetic chromatography (MEKC). The addition of organic hydroxy compounds (1-hexanol, cyclohexanol and phenol) as modifiers to a micellar solution of sodium dodecyl sulfate specifically decreased the capacity factor of some aromatic analytes possessing hydrophilic functional groups. The effect of phenol was different in selectivity to that of 1-hexanol and cyclohexanol. The effects of these modifiers were mainly explained in terms of the saturation of the micellar palisade layer with the modifiers and the hydrogen-bond interaction between the modifier and analyte molecules in the micellar phase. Such micellar modification were applied to improve the MEKC separation.