VESICLE-MEDIATED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY COUPLED TO ATOMIC DETECTION FOR SPECIATION OF TOXIC ELEMENTS

High-performance liquid chromatographic (HPLC) separation followed by element-specific detection by plasma emission or atomic absorption is shown to be a synergic combination through the use of surfactant vesicles as mobile phases for metal speciation. Several species of As, Se and Hg of environmental and toxicological concern were separated by using vesicular mobile phases of the surfactant didodecyldimethylammonium bromide (DDAB) on a C-18 reversed-phase column which was previously modified by DDAB molecules. A mobile phase of the surfactant dihexadecyl phosphate (DHP) containing methanol was used for the speciation of butyltin compounds. The usefulness of the proposed vesicle-mediated methods has been demonstrated for the separation and determination of As species in tap water and urine and Hg species in seawater. The fundamental basis of this emerging new strategy of vesicle-mediated coupling of HPLC separation to atomic detection is also discussed.