Simultaneous determinations of Cu, Cd and Pb in river-water samples by multielement isotope dilution/ICP-MS with the aid of chelating resin preconcentration

The simultaneous determinations of Cu, Cd and Pb in river-water samples were investigated by multielement ID (isotope dilution)/ICP-MS (inductively coupled plasma mass spectrometry). A mixed and enriched spiked solution of Cu (Cu-63, 0.3%; Cu-65, 99.7%), Cd (Cd-110, 0.63%; Cd-111, 96.44%; Cd-112, 1.82%; Cd-113, 0.43%; Cd-114, 0.59%; Cd-116, 0.10%) and Pb (Pb-204, 0.0342%; Pb-206, 92.1497%; Pb-207, 6.5611%; Pb-208, 1.2550%) was added into the river-water samples, and kept standing overnight to achieve isotope equilibria. Since the concentrations of Cu, Cd and Pb in river water were extremely low, they were preconcentrated using a chelating resin (Chelex 100) at pH 9 before an isotope ratio measurement. The isotope ratios of Cu-63/Cu-65, Cd-114/Cd-111 and Pb-208/Pb-206 were then simultaneously measured for the spiked and standard solutions, respectively. Polyatomic ion interferences of (MoO)-Mo-95-O-16 and (MoO)-Mo-98-O-16 with Cd-111 and Cd-114, respectively, could be avoided by chelating resin preconcentration, because Mo was hardly recovered in the preconcentration, while Cd could be recovered by almost 100%. As a consequence, Cu, Cd and Pb in a river-water certified reference material (JAC 0031, issued from the Japan Society for Analytical Chemistry) and a river-water sample collected from the Kiso River were determined with fairly good precision by the present multielement ICP-MS method, simultaneously.