CHELATING RESIN PRECONCENTRATION AND HG(II) ASSISTED ELUTION FOLLOWEDBY DIFFERENTIAL-PULSE ANODIC-STRIPPING VOLTAMMETRY FOR THE DETERMINATION OF CD, EU, AND PB IN SEAWATER

A new and efficient HE(II) back-elution method for the desorption of C d, Cu, and Pb from Chelex-100 chelating resin was developed. A smaller eluent volume and shorter elution time can be achieved using an Hg(II ) containing eluent rather than pure nitric acid. Owing to the remaini ng Hg(II) ion in the effluent, a mercury thin-film electrode is formed in-situ during the anodic stripping voltammetric determination withou t any further addition of Hg(II). The results indicate that all the an alytes in seawater matrix can be completely adsorbed on Chelex-100 res in from the sample at pH 6.5, and subsequently eluted from the resin W ith an acid solution of 5 x 10(-4) mol/L Hg2+ + 1 mol/L HClO4. The det ection limits obtained from the differential-pulse anodic (mu g L-1 to ng L-1) stripping voltammetry are at sub-ppb to ppt (mu g L-1 to ng L -1) levels permitting to determine Cd, Cu and Pb traces in seawater, T he analytical reliability was confirmed by the analysis of the certifi ed reference material CASS-II (open ocean seawater).