Electroanalysis of Heavy Metals in the Cork of Quercus Suber Tree. Preliminary Study: Electroanaliticity of Pb(II)

J.C.A.C. Ponte e Sousa^a)*, J.M. Ginja Teixeira^a), A.M. Neto Vaz^a),b)

^a) Departamento de Química, Universidade de Évora. R. Romão Ramalho, 59, 7000-671 Évora.

^b)CECUL Fundação da Faculdade de Ciências da Universidade de Lisboa. Edifício C8, R. Ernesto de Vasconcelos, 1749-016 Lisboa

Received 15 November 2002; accepted in revised form 09 January 2003

 

Abstract

This will enable Pb(II) determination optimisation, regarding environmental aspects of the perpetuation of Quercus suber Montado (similar to Forest). It will also allow a more profound toxicological quality control of corks (barks). These two last referred aspects are very related ones, once accepted that the more advanced could the certification of the quality patterns of corks (barks) be, more will be the sustainability of Quercus suber ecosystem. Which we believe can be done, amongst other vectors, by studying such an important environmental issue as heavy metals. It is shown that Pb(II) quantification in the cork (bark) of Quercus suber tree (Cork Oak) is possible, using Differential Pulse Anodic Stripping Voltammetry (DPASV). The samples digestion was made in a mixture of H₂O₂ and HNO₃ 1:8, in a closed recipient at approximately 90 ºC. The measures were made in NaCl 0.1 M, using a Hanging Mercury Drop Electrode, a Glassy-Carbon Rod Counter Electrode, and an Ag/AgCl/KCl 3M reference electrode, after a 180 s deposition step. The results have shown the determination of a coherent stripping potential of -0.405 V (SD=0.0005 V), and a fine linear adjustment after the standard addition method (R² = 0.997). They have also revealed the interest of further studies. The need to test other electroanalysis requisites was understood, and imposed by the proof of the complex nature of the matrix.

Keywords: cork (bark), Quercus suber tree (cork oak), Pb(II), Differential Pulse Anodic Stripping Voltammetry (DPASV), environment

 

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* Corresponding author. E-mail address: joaoponteesousa@clix.pt, jcps@uevora.pt.