SPECIATION OF CU, PB, CD AND HG IN WATERS OF THE OPORTO COAST IN PORTUGAL, USING PRECONCENTRATION IN A CHELAMINE RESIN COLUMN

Sea water was collected monthly between January and March 1996 from th e shore of the Oporto coast at three different representative sampling points and speciation of Cu, Pb, Cd and Hg were carried out. For the purpose, total particulate (retained on a 0.45 mu m pore-size filter), particulate sorbed to inorganic matter, total dissolved, and dissolve d and operationally labile metal was discriminated. The filters were d igested by microwaves. The filtered water was pre-concentrated on a mi crocolumn of Chelamine, eluted with 5 ml of 2 mol l(-1) HNO3 and analy sed by flame atomic absorption spectrometry (F-AAS) or mercury cold va pour (MCV-AAS) for Hg. Spike recovery percentages did not differ signi ficantly (P>0.05) from 100% for any metal studied. The organic matter (OM) destruction was performed by UV photolysis. For quality control o f the results, determination of Cu, Pb and Cd total dissolved concentr ation by differential pulse anodic stripping voltammetry was also perf ormed; for Hg only the pre-concentration in the column was changed to partial evaporation of the sea water, followed by MCV-AAS. No statisti cally significant difference was observed between the results provided by the comparative methods. Online pre-concentration with Chelamine s howed to be expeditious and effective for extraction of the heavy meta ls in coastal waters. The distribution of each metal in the different fractions, including ascertainment of significant correlation between pairs of metal fractions and the respective partition coefficients, is discussed. (C) 1997 Elsevier Science B.V.