Mercury speciation in environmental samples by cold vapour atomic absorption spectrometry with in situ preconcentration on a gold trap

A method has been developed for the determination of total and organic mercury in biological materials and sediments. A microwave assisted mineralization of the organic mercury, after its extraction from the matrix, is described. This procedure warrants complete transformation of Hg(II) and, consequently, the quantitative reduction to Hg(0). The conditions for mercury reduction were optimized by a central composite design. The preconcentration of the analyte has been achieved by amalgamation on a trap system, consisting in a pyrolytic graphite platform wound by a gold wire. Mercury was determined by cold vapour atomic absorption spectrometry. The method was validated by the analysis of two certified reference materials and applied to the determination of total and organic mercury species in mussel tissues and sediments. The method is simple and practical, and offers the advantage of not requiring special equipment to measure inorganic and organic mercury simultaneously.