Determination of trace copper, lead, cadmium, and iron in environmental and biological samples by flame atomic absorption spectrometry coupled to flow injection on-line coprecipitation preconcentration using DDTC-nickel as coprecipitate carrier

A flow injection on-line coprecipitation system with diethyldithiocarbamate (DDTC) nickel (II) being used as a carrier was coupled to the flame atomic absorption spectrometry (FAAS) for the determination of trace copper, lead, cadmium and iron in environmental and biological samples. Metal ions were on-line coprecipitated with DDTC-Ni (II) in 0.3 mol.l(-1) nitric acid, and the precipitate was collected in a knotted reactor. The precipitate was then dissolved by isobutyl methyl ketone (IBMK), and the concentrated zone was transported directly into the nebulizer-burner system of a FAAS. Enhancement factors of 60, 58, 65, and 59 were obtained for copper, lead, cadmium and iron, respectively, at the sampling frequency of 60 h(-1). The detection limits (3 sigma) were 0.5 mu g.l(-1) for copper, 2.7 mu g.l(-1) for lead, 0.2 mu g.l(-1) for cadmium, and 2.5 mu g.l(-1) for iron respectively, and a relative standard deviations (n=10) were 3.0% for 40 mu g.l(-1) copper, 2.0% for 80 mu g.l(-1) lead, 3.5% for 10 mu g.l(-1) cadmium, and 2.8% for 60 mu g.l(-1) iron. The developed method was applied to determination of the metals in waters and environmental reference material of soil, and biological reference materials of mussle and human hair. Satisfactory results were obtained.