Simultaneous determination of catechol and hydroquinone based on poly(sulfosalicylic acid)/functionalized graphene modified electrode

A glassy carbon electrode (GCE) modified with poly(sulfosalicylic acid) (PSA) and poly(diallyldimethylammonium chloride)-graphene (PDDA-GN) was prepared by a simple self-assembly method. The formation of films was ascribed to the electrostatic force between negatively charged PSA and positively charged PDDA-GN as well as the pi-pi stacking interaction between PSA and PDDA-GN. The as prepared films were characterized by scanning electron microscopy (SEM), Raman spectroscopy and electrochemical methods. Under the optimized condition, the modified GCE showed two well-defined redox waves for catechol (CT) and hydroquinone (HQ) in cyclic voltammetry (CV) with a peak potential separation of 111 mV, which ensured the anti-interference ability of the electrochemical sensor and made simultaneous determination of dihydroxybenzene isomers possible in real samples. The corresponding oxidation currents increased remarkably compared with those obtained at the bare GCE, PSA/GCE and PDDA-GN/GCE, respectively. Differential pulse voltammetry (DPV) was used for the simultaneous determination of CT and HQ. The anodic peak current of CT was linear in the concentration from 1 x 10(-6) to 4 x 10(-4) M in the presence of 3 x 10(-5) M HQ, and the detection limit was 2.2 x 10(-7) M (S/N = 3). At the same time, the anodic peak current of HQ was linear in the concentration from 2 x 10(-6) to 4 x 10(-4) M in the presence of 2 x 10(-5) M CT, and the detection limit was 3.9 x 10(-7) M (S/N = 3). The proposed method was applied to simultaneous determination of CT and HQ in tap water with satisfactory results. These results indicated that PSA/PDDA-GN is a promising modified material with great potential in electrocatalysis and electrochemical sensing.