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

ABSTRACT

A new chemically modified carbon paste electrode by 2,2ʹ-((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 acetonitrile–ethanol mixture at 25°C show that the ML complexes have formed. The formation constants of complexes were calculated from the computer fitting of the molar conductance–mole 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 μg L⁻¹ and 0.0782 μg L⁻¹ for cadmium and mercury ions, respectively, and the linear range for both metal ions were from 1 to 100 μg 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 97–101%.

KEYWORDS:

• Modified carbon paste electrode
• conductometry
• formation constants
• CV
• DPV
• AAS

Disclosure statement

This research is sponsored by Payame Noor university, in which we have a business interest. We have disclosed those interests fully to Payame Noor university, and have in place an approved plan for managing any potential conflicts arising from this arrangement.