Abstract

SILVA, N.A.F.; LEITAO, R.A.E.  and  MATOS, M.J.. Bismuth as an electrode material in the simultaneous determination of Pb (II) and Cd (II) in poplar (populus) leaves by SWASV. Port. Electrochim. Acta [online]. 2006, vol.24, n.2, pp.283-293. ISSN 0872-1904.

In this work we tested the performance of the bismuth film electrode in the detection and simultaneous determination of toxic metals on real samples in a complex matrix, by square wave anodic stripping voltammetry. The studied samples were white poplar leaves gathered in "2ª Circular", which is an area of major traffic intensity of the city of Lisbon. The determined metals were Pb (II) and Cd (II). After being dried, the white poplar leaves were submitted to an acid digestion process assisted by microwave technology. A complete optimization study of the voltammetric parameters was made in order to simultaneously determine the metals as well as to decrease the detection limits and improve the method’s repeatability and sensitivity. The working electrode consisted in a bismuth film deposited on a vitreous carbon disc surface. The Ag/AgCl system was used as the reference electrode and a platinum wire as the auxiliary electrode. The concentrations (in mg of metal/kg of dry matter - leaves) obtained for Pb (II) and Cd (II) were of 3.0 and 1.7, respectively. Also, detection limits of 1.80 × 10^-8 mol L^-1 for Pb (II) and 6.90 × 10^-9 mol L^-1 for Cd (II) were estimated. In addition, a well shaped voltammogram obtained in the analysis of real samples opens excellent perspectives for the use of the bismuth electrode as an alternative to toxic metals such as mercurys.

Keywords : bismuth electrode; toxic metals; stripping voltammetry; poplar leaves.

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