Speciation of inorganic mercury(II) and methylmercury by vesicle-mediated high-performance liquid chromatography coupled to cold vapour atomic absorption spectrometry

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Abstract
A novel high-performance liquid chromatography (HPLC) separation coupled to cold vapour atomic absorption spectrometry (CVAAS) detection for the speciation of inorganic mercury(II) and methylmercury is described. The mercury species can be successfully separated within 8 min by using a vesicular mobile phase of didodecyldimethylammonium bromide (DDAB) in acetate buffer containing 5% v/v of modifier, methyl cyanide (acetonitrile), and 0.005% v/v of 2-mercaptoethanol. The stationary phase is a C18-bonded silica column previously modified by the passing of a solution of DDAB. Detection limits of 0.1–0.2 µg l–1 of mercury were achieved after off-line preconcentration of the aqueous samples using C18 Sep-pack cartridges modified with 2-mercaptoethanol solutions. This vesicle-enhanced HPLC–CVAAS approach has been applied to the speciation of inorganic mercury(II) and methylmercury in spiked sea-water and human urine. Recoveries obtained ranged between 91–103% both for the inorganic and organic mercury species.