Desenvolvimento de método eletroquímico para análise voltamétrica de tetradifona em eletrodo de carbono vítreo

• Ano de defesa: 2012
• Autor(a) principal: Aleixo, Herbert
• Orientador(a): Okumura, Leonardo Luiz
• Banca de defesa: Fontes, Edimar Aparecida Filomeno , Suarez, Willian Toito , Saczk, Adelir Aparecida
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Tetradifona; Voltametria; Pulso diferencial; Pimentão verde
• Palavras-chave em Inglês: Tetradifon; Voltammetry; Differential pulse; Green peppers
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://locus.ufv.br/handle/123456789/2118

Tetradifon, a potentially carcinogenic and mutagenic pesticide, contributes to environmental and human contamination when applied to green bell pepper crops. In this context, in this work, a reliable and sensitive method for determination of tetradifon in Brazilian green bell pepper samples involving a differential pulse voltammetry (DPV) technique on a glassy carbon electrode is proposed. The electrochemical behavior of tetradifon as followed by cyclic voltammetry (CV) suggests that its reduction occurs via an irreversible five electron transfer vs. Ag|AgCl, KCl 3 μmol L-1 reference electrode. Very well resolved diffusion controlled voltammetric peaks have been obtained in a supporting electrolyte solution composed of a mixture of 40% dimethylformamide (DMF), 30% methanol, and 30% NaOH 0.30 mol L 1 at 1.43 V, 1.57 V, 1.73 V, 1.88 V, and 2.05 V. The proposed DPV method has led to good linear response in the 3.00 10.0 μmol L−1 range, with a limit of detection (LD) of 0.756 μmol L−1 and 0.831 μmol L−1 in the absence and in the presence of the matrix, respectively. Moreover, improved LD results (0.607 μmol L−1) have been achieved in the absence of DMF from the supporting electrolyte solution. Recovery has been evaluated in five commercial green bell pepper samples, and recovery percentages ranging from 91.0 to 109% have been obtained for tetradifon determinations. The proposed voltammetric method has also been tested for reproducibility, repeatability, and potential interferents, and the results obtained for these three parameters are satisfactory for analytical purposes.