Electrochemical sensor based on EDTA-functionalized polyorthophenylene diamine g-C3N4 nanocomposite for determination of melamine in milk

Melamine has little acute oral toxicity, but excessive consumption of melamine can be harmful to human health, and the development of a rapid and accurate detection method for melamine is very important. Since the electrochemical activity of melamine is very low, potassium ferrocyanide was used as a redox probe to help detect melamine using a modified carbon paste electrode. In this study, we present a novel, simple, sensitive, and low-cost electrochemical sensor for the rapid detection of melamine. The sensor was based on electrochemically synthesized polyorthophenylene diamine and graphitic-carbon nitride (g-C3N4) nanocomposite (g-C3N4/POPD), which was additionally functionalized by ethylenediaminetetraacetic acid (EDTA) in order to get structure (g-C3N4/POPD /EDTA) with advanced selectivity towards melamine. The synthesized g-C3N4/POPD/EDTA nanocomposite was characterized by FE-SEM, EDS, Mapping, ATR-IR, Raman, AFM, BET, and EIS techniques. Cyclic voltammetry and differential pulse voltammetry were used for the investigation of the electrochemical behavior of the modified electrode in the presence of melamine. The oxidation peak currents of ferrocyanide were linear with the concentration of melamine in the range from 0.01 µM to 0.1 µM with a linear coefficiency of 0.996. The detection limit was 9.0 nM. The sensor was successfully applied to the determination of melamine in milk products and showed high selectivity, sensitivity, and reproducibility.