Simultaneous determination of Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe in water samples by differential pulse stripping voltammetry at a hangingmercury drop electrode

A highly sensitive and selective voltammetric procedure is described for th e simultaneous determination of eleven elements (Cd, Pb, Cu, Sb, Bi, Se, Zn , Mn, Ni, Co and Fe) in water samples. Firstly, differential pulse anodic s tripping voltammetry (DPASV) with a hanging mercury drop electrode (HMDE) i s used for the direct simultaneous determination of Cd, Pb, Cu, Sb and Bi i n 0.1 M HCl solution (pH = 1) containing 2 M NaCl. Then, differential pulse cathodic stripping voltammetry (DPCSV) is used for the determination of Se in the same solution. Zn is subsequently determined by DPASV after raising the pH of the same solution to pH 4. Next, the pH of the medium is raised to pH 8.5 by adding NH3/NH4Cl buffer solution for the determination of Mn b y DPASV. Ni and Co are determined in the same solution by differential puls e adsorptive stripping voltammetry (DPAdSV) after adding DMG (1 x 10(-4) M) . Finally, 1 x 10(-5) M 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br -PADAP) is added to the solution for the determination of Fe by DPAdSV. The optimal conditions are described. Relative standard deviations and relativ e errors are calculated for the eleven elements at three different concentr ation levels. The lower detection limits for the investigated elements rang e from 1.11 x 10(-10) to 1.05 x 10(-9) M, depending on the element determin ed. The proposed analysis scheme was applied for the determination of these eleven elements in some ground water samples.