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Quantificação Eletroquímica do Inseticida Metil-Paration Usando Dispositivo Analítico Fabricado em Papel

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Methyl-Parathion (mPRT, Fig. 1A) is an organophosphate pesticide, commonly used in cotton and soy crops, which comercialization is prohibited in Brazil since 2015 due to its high toxicity [1]. In developing countries the restrict access to well established analytical methods has caused human and environmental contamination revealing that the design of new low-cost analytical systems, such as paper-based analytical devices (PAD) for pesticides monitoring, is highly required [2]. In this work, a square-wave voltammetric (SWV) method is proposed to quantify mPRT using an electrochemical PAD with graphite leads as working and counter electrodes and a pseudo-reference electrode fabricated with a silver ink. At the graphite electrode surface, the mPRT shows two pH-dependent oxidation peaks related to the nitro group reduction. The best selectivity was obtained using phosphate buffer pH 2. Recording SW voltammograms at different concentrations (Fig. 1B), a linear analytical curve ranging from 5.00 to 35.0 µmol L"1 (R2 0.991) was obtained with an estimated detection limit of 1.00 µmol L"1. Besides its simplicity, the proposed device is highly promising for analysis of mPRT contamination on site.