Conductometric studies and application of new Schiff base ligand as carbon paste electrode modifier for mercury and cadmium determination

A new chemically modified carbon paste electrode by 2,2'-((pyridine-2,6-diylbis(azanylylidene))bis(methanylylidene))diphenol (L) ligand has been made and used as a sensor for determination of trace mercury and cadmium ions with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Complexation studies of the ligand with Cu2+, Zn2+, Hg2+, Ni2+ and Cd2+ ions by conductometric method in acetonitrileethanol mixture at 25 degrees C show that the ML complexes have formed. The formation constants of complexes were calculated from the computer fitting of the molar conductancemole ratio data, and the stability of the resulting complexes varied in order of Cd2+ > Hg2+ > Cu2+ > Zn2+ > Ni2+. Then a simple and effective chemically modified carbon paste electrode with L was prepared, and the electrochemical properties and applications of the modified electrode were investigated. Under the optimal conditions, the detection limit was 0.0494 mu g L-1 and 0.0782 mu g L-1 for cadmium and mercury ions, respectively, and the linear range for both metal ions were from 1 to 100 mu g L-1. The electrode shows high sensitivity, reproducibility and low cost, and was successfully applied to determination of Cd2+ and Hg2+ ions in water samples with recovery in the range of 97101%.