Phosphated surfactants as pseudostationary phase for micellar electrokinetic chromatography: Separation of polycyclic aromatic hydrocarbons

A double alkyl chain di(2-ethylhexyl)phosphate (DEHP) is introduced as a potential anionic micellar pseudophase for a wide range of benzene derivatives and/or polycyclic aromatic hydrocarbons (PAHs). Several parameters such as concentration of phosphated surfactant, type and concentration of organic solvents (acetonitrile, isopropanol, and methanol), as well as capillary electrophoresis separation voltage were optimized to enhance resolution, efficiency and selectivity as well as to maximize peak capacities. The migration times and selectivity order for a number of PAHs differ significantly, depending on the type of organic solvent added to the DEHP surfactant. Acetonitrile at a concentration of 30% v/v in combination with 100 mM DEHP gave optimum separation for a mixture of 21 benzene derivatives and PAHs in under 16 min.