Tailoring of L-cysteine conjugated chitosan carbon electrode for selective and sensitive monitor of copper in the water

Copper has been widely used in bacteriostatic materials and pesticides, which make it as a potential threat for human health. The development of an electrochemical sensor with high selectivity and sensitivity to copper ions as well as the practicability is an urgent need. In this work, novel chitosan grafted L -cysteine (Cys-CTS) was prepared and characterized by NMR, FT-IR spectra, Raman spectra, XRD . Functionality of Cys-CTS was explored by the CV, and EIS . Presence of sulfur and copper in conjugation and Cys-CTS/Cu(II) composite was confirmed by SEM and EDX analysis. In electrochemical characterizations, the Cys-CTS exhibited higher electron transfer ability than CTS. Then, the Cys-CTS, as the functional monomer, was used to fabricate an ion-imprinted electrode while the electrode had been modified with nitrogen-doped reduced graphene oxide (N-RGO) before. The introduction of N-RGO allowed the detection current of copper ions to be increased significantly. Under the optimal parameters, the modified electrode has a wide linear detection range (0.25–140 μmol L −1 ) and a low detection limit (0.1 μmol L −1 ). Tailoring of L -cysteine conjugated chitosan carbon electrode has better detection performance than CTS alone in the same conditions. In the detection tests of tap water and drinking water, the excellent accuracy and recovery rate (varied from 92.1% to 103.4%) was obtained. The current work can be used for detection of heavy metal in soil as well in water.