Simultaneous determination of hydroquinone and catechol using Cu-nanoparticles incorporated glycine film modified electrode

Hydroquinone (HQ) and catechol (CC) are two isomers of dihydroxybenzenes, widely used in many fields, such as cosmetic, dye, pesticides, medicines, and pharmaceutical industries, which are announced as environmental contaminant by the European Union and the US Environmental Protection Agency [1,2]. In the case of electrochemical analysis of HQ and CC, due to the same electroactive phenolic groups, their redox peaks overlap, rendering them to be hardly resolved by conventional electrodes. Therefore, chemically modified electrodes (CMEs) which differentiate between HQ and CC were used as excellent resolving devices. In this letter, a novel method has been developed for the simultaneous determination of HQ and CC based on graphene oxide nanosheets/ copper NPs/ glycine nanocomposite was deposited on glassy carbon electrode by cyclic voltammetry. The surface morphology of the electrodes was characterized by scanning electron microscopy. Bare electrode fails to resolve the voltammetric signals of HQ and CC in a mixture. However, the modified electrode not only separates the voltammetric signals of HQ and CC, but also shows higher oxidation current for these molecules and simultaneous determination of HQ and CC was performed by differential pulse voltammetry. The catalytic peak currents were linearly dependent on the concentrations of HQ and CC in the range of 5.0–300 and 5.0–200 μM, with detection limits of 0.32 and 0.21 μM, respectively. The sensitivity, stability and reproducibility of the constructed sensor were studied and it was successfully applied to the analysis of HQ and CC in tap, lake and synthetic waste water sample as the real samples.