Analytical Sciences

Voltammetric Detection of Lead Using Chitosan-tripolyphosphate Crosslinked Electrode

Mônika G. HEINEMAN,* Bruna L. GONÇALVES,** Juliano R. M. VICENTI,** and Daiane DIAS*

*Laboratório de Eletro-Espectro Analítica (LEEA), Escola de Química e Alimentos, Universidade Federal do Rio Grande, Av. Itália, km 8, Rio Grande, 96203-900, RS, Brazil
**Laboratório de Físico-Química Aplicada e Tecnológica (LAFQAT), Escola de Química e Alimentos, Universidade Federal do Rio Grande, Av. Itália, km 8, Rio Grande, 96203-900, RS, Brazil

This paper discusses about the improvement of electrochemical characteristics of graphite paste electrode chemically modified with chitosan through physical crosslinking of the biopolymer with sodium tripolyphosphate. Biopolymer characterizations were performed by scanning electron microscopy, Fourier transform infrared spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical characterization of Pb with graphite paste electrode modified with chitosan crosslinked with sodium tripolyphosphate (GPE-CTS-TPP) showed that the process is quasireversible, controlled by adsorption and involves the transfer of two electrons. Additionally, the physical crosslinking process decreased the electrode resistance as well as improved the electron transfer rate. Once the GPE-CTS-TPP showed enhanced morphological and electrochemical characteristics, it was applied for Pb determination by square wave anodic stripping voltammetry. The method presented appropriate accuracy (recoveries from 95 to 108% and concordance with comparative method between 90 and 107%), high sensitivity (limit of detection and quantification of Pb were 0.73 and 2.44 μg L⁻¹, respectively) and could be applied to analytical determinations.

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