Electrochemical behavior of N-Nitrosodiphenylamine and its determination in synthetic urine samples using a graphite-polyurethane composite electrode

Abstract In this paper, the electrochemical determination of the N-nitrosodiphenylamine was proposed comparing the voltammetric response of two non-modified carbon electrodes: a glassy carbon (GCE) and a solid graphite-polyurethane composite (GPUE). The surfaces of the electrodes were characterized by atomic force microscopy. The electroactive areas of GCE and GPUE were 0.040 and 0.068 cm2, respectively, calculated from chronocoulometry measurements using K4Fe(CN)6 as probe and the integrated form of Cottrell Equation. Cyclic voltammograms obtained for N-nitrosodiphenylamine using both electrodes indicated anodic and cathodic peaks (vs. Ag/AgCl (3.0 mol L−1 KCl), in agreement with the literature. At GCE, the electrochemical reduction of the molecule is a diffusion-controlled process, whereas at GPUE some degree of adsorption was also observed. Square wave and differential pulse voltammetry were explored in order to optimize the best analytical performance for the quantification of the molecule. Under optimal conditions, linear range (sensitivity and limit of detection) for GCE and GPUE of 8.02 to 46.6 μmol L−1 (1.09 μA L μmol−1 cm−2 and 4.54 μmol L−1) and of 2.51 to 17.5 μmol L−1 (5.50 μA L μmol−1 cm−2 and 0.270 μmol L−1) were obtained, respectively. Considering higher sensitivity and lower detection limits values, the GPUE was selected for the quantification of N-nitrosodiphenylamine in synthetic urine samples. The developed method presented a competitive detection limit compared to other sensors reported in the literature, considering the use of a non-modified electrode, with low cost of fabrication, easiness of surface renovation, and sustainability.