REMOVAL OF INSTRUMENTAL INTERFERENCES IN EVALUATING SOLID-WASTE INTERACTION WITH SOIL

A survey on the nature and amount of waste production, control and cha racterization of the composition of both fresh and aged waste leaching s must be carried out in order to clarify one of the most important pr oblems: solid waste interaction with soils. Dedicated analytical metho ds are required in all cases and the aim of this communication is to e lucidate the problems met in the optimization of analytical procedures and to describe the approaches developed to solve them. Attempts were devoted both to metal and anion determination, the instrumental techn iques were: Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Hydride Generation f or metal analysis, and ion Chromatography (IC) for anion determination s. Analysis of leachings needs some attention because of sample dissol ution and matrix effects; literature data show that results from diffe rent laboratories have given overall coefficients of variation up to 2 00%. With respect to the optimisation of sample dissolution a detailed study was made on Reference Materials of the European Community to op timise time of dissolution and analysis for different kinds of sample. The removal of matrix and spectral interferences in the determination of metals and nonmetals (e.g. As, Bi, Se) is shown as well as pretrea tments enabling the detection of the total anion content. Four procedu res were compared, namely: solid extraction, basic (NaOH) and acid (HN O3) digestion, radical-oxidant digestion (UV-H2O2). The clean-up and c hromatographic procedures proposed are now applied for the survey of t he leachings produced by different waste dumps.