Analyttca Chtmrca Acta, 273 (1993) 289-296 Elsevler Science Publishers B V , Amsterdam 289 Voltammetry of Cu(II) in the presence of polymethacrylate JosC Manuel Diaz-Cruz, Crlstma Ariiio, Mlquel Esteban and Enrrc Casassas Departament de Quimrca Analhca, Facultat de Quhca, Unrvemtat de Barcelona, Av Dugonalb47,08028 Barcelona (Spain) (Received 1stJune 1992) A systematic studyof the voltammetnc reductionof Cu(II) In the presence of polymethacryhc acid (PMA) was camed out by means of sampleddirect current, normal pulse, dlfferentlalpulse and reverse pulse polarography, cyclic voltammetry and dtierential pulse anodic stnppmg voltammetry Titrations of Cu(II) wth partially neutrahzed PMA allow the deternunation of the apparent formation constant, K, of the Cu-PMA system Keywords Polarography, Stnppmg voltammetry, Voltammetry, Copper, Metal-polyacid complexes, Polymethacrylate Determmatlons of heavy metal ions are of the highest interest m envlronmental analysis Voltarnmetrlc techniques m general and stnppmg voltamrnetry m particular have been extensrvely used for this purpose, because, m prmaple, they allow direct determmatlon m natural samples at very low metal concentration levels [l] Voltammetnc determmatlons of natural sys- tems mvolves the complexatlon of metal ions with macromolecular hgands These studies usually present dlfficultles derived from the polyelec- trolytlc and polyfunctlonal character of the macromolecules In this respect, model homo- functional polyelectrolytes of known composition and structure have been intensively investigated m order to understand the behavlour of natural polyelectrolytes Polyacryhc acid (PAA) and poly- methacryhc acid (PMA) are among the most pop- ular model polyelectrolytes, and their complexa- tlon wth several metal ions has been widely stud- led by voltammetrlc techmques [2] Correspondence to M Esteban, Departament de Quirmca Analitlca, Facultat de Qu’mca, Umversltat de Barcelona, Av Diagonal 647,08028 Barcelona (Spam) Recently, a rigorous voltammetrlc model [3] has been developed for the reduction of a metal ion m the presence of a macromolecular hgand, including both the kmetrcs of complexatlon and the dtierent moblhtles of the species involved The apphcatlon of this model to the Cd(II), Zn(II)-PAA, PMA systems [4-61 yielded satlsfac- tory results and further studies improved the ex- perunental methodology [7,8] and the data treat- ment [9] m order to apply the theoretical model under the optnnum experunental condltlons The use of such methodology [lo] perrmtted clanfica- tlon of some problematic aspects of the Pb(II)- PAA and Pb(II)-PMA systems [4] Previous polarographlc studies of the complex- atlon between Cu(I1) and several polyelectrolytes [ill showed rather complex behavlour, Hrlth the appearance of pre-waves and post-waves m the polarograms, which were not mterpreted The arm of this paper IS to study the voltam- metric reduction of Cu(I1) m the presence of the model polyelectrolyte PMA For this purpose, sampled direct current polarography (DCP), nor- mal pulse polarography (NPP), differential pulse polarography (DPP), reverse pulse polarography 0003~X70/93/$06 00 0 1993 - Elsewer Science Pubhshers B V All nghts reserved