Competitive binding of cadmium by plant thiols: an electrochemical study assisted by multivariate curve resolution |
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Authors: | Rui Gusm?o Cristina Ari?o José Manuel Díaz-Cruz and Miquel Esteban |
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Institution: | (1) Departament de Química Analítica, Universitat de Barcelona, Martí i Franquès 1–11, 08028 Barcelona, Spain |
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Abstract: | Multivariate curve resolution with alternating least squares (MCR-ALS) has been applied to voltammetric data obtained from
analysis of the competitive binding of cysteine (Cys) and cysteine–glycine (Cys-Gly) by Cd(II) as a first approach towards
mixtures of phytochelatins and related compounds in natural media. From different starting points, the possibilities of formation
of mixed complexes and/or displacements between ligands are investigated. Analysis of the resulting unitary voltammograms
and concentration profiles of the resolved components by MCR-ALS suggests that the strongest ligand (Cys-Gly) is able to displace
the weakest (Cys) from its metal complexes, whereas this does not happen in the opposite direction. On the other hand, no
evidence of Cd mixed-ligand complexes was found.
Figure Differential pulse polarograms measured in the independent titrations of 1 × 10-5 mol L-1 Cys, 1 × 10-5 mol L-1 Cys-Gly, and a mixture of Cys-Gly (0.5 × 10-5 mol L-1) and Cys (1 × 10-5 mol L-1) with Cd2+, at TRIS-HNO3 buffer (0.1 mol L-1 and PH 7.5) in the presence of 0.1 mol L-1 KNO3 |
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Keywords: | Plant thiols Cadmium Competitive binding Multivariate curve resolution with alternating least squares Differential pulse voltammetry ESI-MS |
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