An Electrochemical Sensor for Determination of Ultratrace Cd, Cu and Hg in Water Samples by Modified Carbon Paste Electrode Base on a New Schiff Base Ligand

This paper describes the preparation and electrochemical application of a new chemically modified electrode for simple and highly sensitive simultaneous determination of copper, mercury and cadmium using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Firstly, a new bis-Schiff base ligand, 2,2-((pyridine-2,6-diylbis (azanylylidene)) bis (methanylylidene))bis(4-bromophenol) (ligand L) has been synthesized by reaction of the 2,6-diamino pyridine with 5-bromo salicylaldehyde or salicylaldehyde at ethanol under refluxing. The structure of the synthesized compound resulted from the IR, (HNMR)-H-1, MS, UV spectroscopy and elemental analysis data. Afterwards, a novel, simple and effective chemically modified carbon paste electrode with ligand L was prepared. The electrochemical properties and applications of the modified electrode, including the pH, percentage of modifier, the electron transfer, optimized conditions, linear response and detection limit were investigated. High sensitivity and reproducibility, together with the ease of preparation and regeneration of the electrode surface by simple polishing, make the electrode very suitable for the voltammetric determination of copper, mercury and cadmium in several Merck samples and water samples.