Voltammetry of metal ions in mixtures of ligands .2. Application to successive labile complexes

被引:14
作者
Berbel, F [1 ]
DiazCruz, JM [1 ]
Arino, C [1 ]
Esteban, M [1 ]
机构
[1] UNIV BARCELONA,DEPT QUIM ANALIT,BARCELONA 08028,SPAIN
来源
JOURNAL OF ELECTROANALYTICAL CHEMISTRY | 1997年 / 432卷 / 1-2期
关键词
D O I
10.1016/S0022-0728(97)00230-1
中图分类号
O65 [分析化学];
学科分类号
070302 ; 081704 ;
摘要
In previous work, a model was proposed for the voltammetric study of metal ions in mixtures of macromolecular and simple ligands, with the assumption that the complexes formed are totally labile or totally inert. In this paper, the general equations of that model are applied to the study by reverse pulse polarography (RPP) of the system Cd(II) + polymethacrylic acid + iodide, which is taken as a model of labile complexation with the simple ligand forming successive 1:m complexes. In general terms, there is good agreement between the experimental set of current data and the theoretical predictions. In contrast, the influence of the electrodic adsorption on the potential data was too high to obtain results close to the theoretical ones. According to theoretical predictions, an experimental strategy was developed for the estimation of the stability constants of simple complexes which adsorb onto the electrode. The methodology is based on the use of RPP as a well-known tool for minimizing adsorption. However, and in contrast with the DeFord-Hume method, it considers only current measurements and not potential values, since previous papers showed that RPP potentials can be much more affected by adsorption than RPP currents. As expected, the application of the method to the Cd(II) + I- complexes yielded results much closer to the potentiometric values reported in the literature than those obtained by the application of the DeFord-Hume method. (C) 1997 Elsevier Science S.A.
引用
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页码:243 / 251
页数:9
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