Separation of Aromatic Sulfides by Electrokinetic Chromatography with Micellar S olution

Abstract

When a DC high voltage is applied between the both ends of an open-tubular capillary filled with an ionic surfactant solution, the whole solution is transported by the electroosmotic flow, while the charged micelle migrates with a different velocity from that of the solution because of an electrophoretic effect. In other words, electroosmotic and electrophoretic effects cause the differential migration between the micelle and the surrounding aqueous phase. A solute added into the surfactant solution distributes itself between the micelle and the aqueous phase. Electrokinetic chromatography, which is based on the combination of the electrokinetic migrations and the micellar solubilization phenomenon, was applied to the separation of seven alkyl phenyl sulfides whose alkyl groups were methyl, ethyl, propyl, isopropyl, butyl, isobutyl and s-butyl, and four alkyl benzyl sulfides whose alkyl groups were methyl, ethyl, propyl and isopropyl. The ten sulfides among the eleven were separated by a 0.05 mm i. d. × 900 mm fused silica tube filled with a 0.02 mol·dm^-3 sodium dodecyl sulfate solution (pH 7.0) at ambient temperature. Distribution coefficients of the sulfides in micellar solubilization were calculated for sodium dodecyl sulfate and sodium tetradecyl sulfate solutions at 35°C. The use of a mixed solution of 80% of a 0.03 mol·dm^-3 sodium dodecyl sulfate solution (pH 7.0) and 20% of methanol gave also successful separation of the ten aromatic sulfides among the eleven. The unresolved pair was different from that observed with a O.02 mol·dm^-3 sodium dodecyl sulfate solution.