The electrochemical sensor based on electrochemical oxidation of nitrite on metalloporphyrin-graphene modified glassy carbon electrode

In this study, 5-(4-aminophenyl)-10,15,20-triphenylporphyrin]Mn(iii) (MnNH₂TPP) and graphene oxide (GO) composite materials (GO-MnNH₂TPP) were successfully used to modify a glassy carbon electrode (GC) by the drop casting method. The GO-MnNH₂TPP/GC composite electrode was used to investigate the electrocatalytic oxidation features of nitrite ion by cyclic voltammetry (CV) and amperometric I-T curve techniques. These experimental results show the GO-MnNH₂TPP/GC composite electrode has excellent electrocatalytic performance for the detection of nitrite. The oxidation peak current of nitrite ion at the GO-MnNH₂TPP/GC composite electrode has shifted negatively and the intensity of the oxidation peak current increased greatly compared with that at the GC, GO/GC and MnNH₂TPP/GC electrodes. A linear relationship has been established between the oxidation current and the nitrite ion concentration. The detection limit of the GO-MnNH₂TPP/GC composite electrode for the detection of nitrite ion was found to be 1.1 μM and 2.5 μM (S/N = 3) using CV and amperometric I-T curve techniques, respectively. The GO-MnNH₂TPP/GC electrode possesses excellent electrocatalytic activity, rapid response time, low detection limit, high selectivity for nitrite and was applied to the detection of nitrite in real water samples.