Determination of Paraquat by Square-Wave Voltammetry at a Perfluorosulfonated Ionomer/Clay-Modified Electrode

Abstract

A novel Nafion/clay-modified electrode (NCME) was developed for the determination of paraquat by square-wave cathodic stripping voltammetry. The clay that showed the best performance for the fabrication of the NCME is nontronite (SWa-1, ferruginous smectite). The electrochemical behavior of paraquat showed that the cathodic peak at -0.70 V vs Ag/AgCl permits adequate quantification of the analyte. Linear calibration curves are obtained over the 0-80 ppb range, with a detection limit of 0.5 ppb in pH 8 phosphate buffer solution for 4 min preconcentration time. Various factors influencing the determination of paraquat were thoroughly investigated in this study. The practical analytical utility is illustrated by selective measurements of paraquat in real water samples.

Estudo eletroanalítico do herbicida paraquat em soluções aquosas por voltametria de onda quadrada utilizando ultramicroeletrodos

“…Por exemplo, Zen 14 e colaboradores utilizaram eletrodos modificados com Nafion® e observaram, para valores de freqüênci-as superiores a 90 s -1 , o surgimento de uma corrente residual muito elevada, o que dificultava as análises. Walcarius e Lamberts 6 empregaram o HMDE para analisar o paraquat.…”

Estudo do comportamento eletroquímico do herbicida ametrina utilizando a técnica de voltametria de onda quadrada

“…A utilização da SWV tem sido utilizada com sucesso para o estudo do comportamento eletroquímico e determinação analítica de pesticidas em diferentes amostras [5][6][7][8]. Assim, o objetivo deste trabalho foi estudar o comportamento eletroquímico do herbicida ametrina utilizando-se eletrodo de mercúrio e voltametria de onda quadrada e ainda se avaliar os limites de detecção em águas para futuras aplicações em amostras reais.…”

Voltammetric Analysis of Pesticides

“…The working electrode consisted of a carbon paste electrode chemically modified by a synthesized Ca-hydroxyapatite. Many other unique applications of square wave voltammetry include the use of non-modified (Liu & Lin, 2005) and modified (Parham & Rahbar, 2010) carbon paste electrodes for the sensing of organophosphate pesticides, the quantification of pesticides in real water samples using ionomer clay-modified electrode (Zen et al, 1996) and even on non modified electrodes (Garrido et al, 1999(Garrido et al, , 2001. Some recent advances and applications of SWV were described, for which the stripping voltammetry was combined with solid-phase extraction often used in separation science (Gong et al, 2009(Gong et al, , 2010.…”