Heavy metal determination in aquatic species for food purposes

New analytical procedures and sample mineralizations are proposed regarding the determination of arsenic, selenium, copper, lead, cadmium, zinc and me rcury in matrices involved in food chain as mussel, clams and fishes. As re gard As, Se, Cu, Pb, Cd and Zn determinations, H2SO4-HNO3 acidic mixture is used for the digestion of each matrix. In the case of Hg the sample digest ion is performed using a concentrated suprapure H2SO4-K2Cr2O7 mixture and t he results are compared with those from other conventional methods. Differe ntial pulse cathodic (DPCSV) and anodic stripping voltammetry (DPASV) are e mployed for determining simultaneously selenium, arsenic and copper, lead, cadmium, zinc, respectively, while mercury determination is carried out by the cold vapour atomic absorption spectrometry (CV-AAS) with reduction with SnCl2. The voltammetric measurements were performed using a conventional t hree-electrode cell and the ammonia-ammonium chloride buffer (pH 9.3) as su pporting electrolyte. For all the elements, in addition to the detection li mits, precision acid accuracy data are also reported: the former, expressed as relative standard deviation (s(r)), and the latter, expressed as relati ve error (e), are in all cases between 3 to 6%.