ANALYTICAL RELATED PROBLEMS IN METAL AND TRACE-ELEMENTS DETERMINATIONIN INDUSTRIAL-WASTE LANDFILL LEACHATES

The periodic analytical control of waste landfill leachate is of funda mental importance not only to check the presence of possible toxic sub stances, but also to assess changes in concentration levels and behavi our with time. This work identifies some of the difficulties which ari se during the analysis of some heavy metals and trace elements in leac hate samples from a controlled industrial wastes landfill located in n orth Italy. The analytical problems encountered using both electro-the rmal atomic absorption spectroscopy (ETAAS) and neutron activation ana lysis (NAA) for the determination of a series of elements, Cu, Cd, Pb, Ni, Mn, V, As, Se, Sb, Th, Sn, Cs, W, Cr, with concentration often at nanogram levels, are presented and evaluated. To solve these problems two selective chemical procedures have been developed to separate and to eliminate the matrix interfering compounds or elements (i.e., orga nic matter, complexing agents, Cl-, Br-, S2- , Na+) which reduce and i n some cases impair the sensitivity of the technique. For the analyses by ETAAS a preliminary preconcentration and separation procedure, bas ed on the ion exchange resin Chelex-100 has been developed to determin e Pb, Cd, Co, Cu, Ni and Sn. In the case of NAA a specific radiochemic al separation had to be studied for the analysis of Sn, V, W, Mn, Cr, As, Sb, Se, Th in presence of high bromine and sodium concentrations. Procedures blanks and yields have been controlled and evaluated and qu ality assurance measurements have been carried out analyzing, with the proposed methods, standard reference materials from BCR and NIST. Fur thermore, different mineralization procedures using both microwave and Teflon bomb have been compared and evaluated.