Analytica Chimica Acta 404 (2000) 231–240 Determination of Ag(I), Hg(II), Cu(II), Pb(II), Cd(II) by stripping voltammetry in aqueous solutions using complexing polymers in conjunction with membrane filtration E.A. Osipova a , V.E. Sladkov a , A.I. Kamenev a , V.M. Shkinev b,∗ , K.E. Geckeler c a Department of Chemistry, Moscow State University, 119899 Moscow, Russia b Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin str., 117975 Moscow, Russia c Institute of Organic Chemistry, University of Tuebingen, Tuebingen, Germany Received 23 March 1999; received in revised form 7 September 1999; accepted 12 September 1999 Abstract The electrochemical behavior of a series of metal ions (Ag(I), Hg(II), Cu(II), Pb(II), Cd(II)) and the ternary Cu(II)–Pb(II)– Cd(II) system in the solutions of water-soluble complexing polymers poly(ethylenimine) (PEI), poly(1-vinyl-2-pyrrolidone) (PVP), their thiourea-containing derivatives poly(ethyleneimine)methylthiourea (PEI-TU) and poly(1-vinil-2-pyrrolidone) methylthiourea (PVP-TU) was investigated using cyclic and anodic stripping voltammetry (ASV) at different carbon elec- trodes. The optimum conditions were selected for the stripping voltammetric determination of Ag(I), Hg(II), Cu(II), Pb(II) and Cd(II) in a concentration range from 10 −6 to 10 −5 M in the presence of water-soluble polymers at the carbon-paste electrode (the relative standard deviation did not exceed 10%). The stability of metal complexes with PEI was established to decrease in the following order: Hg(II) > Cu(II) > Ag(I) > Cd(II) > Pb(II). The hydrophilic polymer PEI is shown to reduce the intermetallic interactions of components of the Cu(II)–Pb(II)–Cd(II) ternary system on the electrode surface. The different complex stabilities of Pb(II), Cd(II) and Cu(II) with PEI allow to determine Pb(II) and Cd(II) in the presence of a larger excesses of Cu(II) (100/1 and 10/1, respectively) compared to a procedure without PEI (10/1 and 0.33/1, respectively). The conditions were optimized for the simultaneous stripping voltammetric determination of the components of the divalent Pb(II)–Cu(II)–Cd(II) system in 2% aqueous solutions of PEI. Finally, the possibility of determining Cu(II) and Pb(II) in tap water after preconcentration as PEI complexes using membrane filtration was demonstrated. ©2000 Elsevier Science B.V. All rights reserved. Keywords: Anodic stripping voltammetry; Carbon electrodes; Complexing polymers; Membrane filtration; Metal ions ∗ Corresponding author. Present address: Vernadsky Institute of Geochemistry and Analytical Chemistry RAS 19 Kosyin str., 117975 Moscow, Russia. Fax: +95-938-2054. E-mail address: vshkinev@mail.ru (V.M. Shkinev). 1. Introduction The problem of determination of heavy metal ions in multicomponent natural and industrial ob- jects and new materials engineering remains actual. Highly-sensitive electroanalytical methods, such as stripping voltammetry, allows to determine heavy 0003-2670/00/$ – see front matter ©2000 Elsevier Science B.V. All rights reserved. PII:S0003-2670(99)00713-8