Desenvolvimento de sensor eletroquímico à base de óxido de grafeno modificado com porfirina de cobalto para a detecção de 2,6-dicloro-1,4-benzoquinona

The water disinfection process in treatment plants generates toxic subproducts owing to the reaction between chlorinated disinfectants and organic chemicals. Among these subproducts, halobenzoquinones represent a class of chlorinated chemicals with high toxicity to the bladder cells and potential to induce damage to cellular DNA and proteins [1]. The main purpose of this work was to detect 2,6-dichloro-1,4- benzoquinone (DCBQ)on a glassy carbon electrode (GCE) modified with a nanocomposite based on graphene oxide (GO) and cobalt tetramethoxyphenylporphyrin (CoTMPP). The oxidation of DCBQ on GCE is a reversible, diffusioncontrolled and pH-dependent process, which involves 2 electrons and 2 protons. The oxidation peak potential shifted negatively with the increase of pH value, and the highest peak currents were detected at 7.0. The effect of DCBQ accumulation time on the electrode surface was investigated by square wave voltammetry (Figure 1a). Only at the first 6 minutes, the peak current increased linearly with the accumulation time, and indicated saturated adsorption of DCBQ on the modified electrode at further increasing time (Figure 1b). After optimization of the voltammetric parameters, an analytical curve was obtained in a range of concentration from 4.98 μmol/L to 56.6 μmol/L, following the equation: J/mA cm-2 = -0.03113+ (12128.71) [DCBQ]/μmol L-1 , with R2 = 0.9976. The detection and quantification limits were determined as 4.81 μmol/L and 16.04 μmol/L, respectively. Hence, a nanocomposite electrode based on GO and CoTMPPhas been successfully applied to detect DCBQ in aqueous solutions.