SPECIATION OF INORGANIC MERCURY(II) AND METHYLMERCURY BY VESICLE-MEDIATED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY COUPLED TO COLD VAPOR ATOMIC-ABSORPTION SPECTROMETRY

A novel high-performance liquid chromatography (HPLC) separation coupl ed to cold vapour atomic absorption spectrometry (CVAAS) detection for the speciation of inorganic mercury(II) and methylmercury is describe d. The mercury species can be successfully separated within 8 min by u sing a vesicular-mobile phase of didodecyldimethylammonium bromide (DD AB) in acetate buffer containing 5% v/v of modifier, methyl cyanide (a cetonitrile), and 0.005% v/v of 2-mercaptoethanol. The stationary phas e is a C-18-bonded silica column previously modified by the passing of a solution of DDAB. Detection limits of 0.1-0.2 mu g l(-1) of mercury were achieved after off-line preconcentration of the aqueous samples using C-18 Sep-pack cartridges modified with 2-mercaptoethanol solutio ns. This vesicle-enhanced HPLC-CVAAS approach has been applied to the speciation of inorganic mercury(II) and methylmercury in spiked sea-wa ter and human urine. Recoveries obtained ranged between 91-103% both f or the inorganic and organic mercury species.