Voltammetric detection of the interactions between RNO2 and electron acceptors in aqueous medium at highly boron doped diamond electrode (HBDDE) |
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Authors: | Murilo S da S Julião Elizabeth I Ferreira Silvia HP Serrano |
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Affiliation: | a Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, 748 Bloco 8 Superior, Cidade Universitária, São Paulo, SP, CEP 05508-900, Brazil b Universidade Estadual Vale do Acaraú, Sobral, CE, Brazil c Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, SP, Brazil d Instituto Nacional de Pesquisas Espaciais, INPE, São José dos Campos, SP, Brazil |
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Abstract: | This paper describes the electrochemical behavior of the nitrofurazone (NFZ), in predominantly aqueous medium, in the absence and presence of glutathione (reduced form) (GSH), l-cysteine (Cys) and O2 using a highly boron doped diamond electrode (HBDDE). In presence of Thiol] ≥ 3.7 × 10−2 mol L−1 NFZ is directly reduced to RNO-Thiol adducts in an electrochemical process involving two electrons and two protons. On the other side, O2 acts as a RNO2•− scavenger and the velocity constant for the reaction, kO2, is 60 L mol−1 s−1. The process is catalytic and can be used to the analytical determination of NFZ in the range of 9.9 × 10−7 ≤ NFZ] ≤ 1.1 × 10−5 mol L−1 at pH 8.0, with sensitivity of 2.2 × 106 μA mol−1 cm−2 and detection limit of 3.4 × 10−7 mol L−1. The analytical parameters were similar to those obtained at pH 4.0 using the direct reduction of NFZ to the respective amine derivative in a process involving six electrons and six protons. The characterization of NFZ global reduction process in aqueous medium and at relative low scan rate, 100 mV s−1, was only possible due the intrinsic superficial characteristics of the HBDDE, which stabilize the RNO2 − free radical, allowing to work in a large potential window, without losing the RNO2 − oxidation signal. |
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Keywords: | Highly boron doped diamond electrode (HBDDE) Nitrofurazone free radical Electronic acceptors Voltammetry and catalytic reaction |
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