Electrocatalytic determination of Cd2+ and Pb2+ using an l-cysteine tungstophosphate self-assembled monolayer on a polycrystalline gold electrode

Abstract

In this study, a novel sensitive surface based on an L-cysteine tungstophosphate-modified polycrystalline gold electrode (Au-(Cys)PW) was developed for the electrochemical detection of Cd²⁺ and Pb²⁺ in trace amounts. The electrocatalytic effect of this modified electrode toward Cd²⁺ and Pb²⁺ was evaluated by square wave voltammetry (SWV) as a sensitive method in the presence of the two analytes with bare and Au-(Cys)PW electrodes. The experimental conditions were optimized in order to evaluate the best analytical parameters of the sensor. A linear range of 0.01–0.2 μmol L⁻¹ for both analytes and detection limits of 9.0 nmol L⁻¹ and 4.0 nmol L⁻¹ for Cd²⁺ and Pb²⁺, respectively, were determined based on a signal-to-noise ratio (S/N) equal to 3. Reproducibility and repeatability studies were also performed, and the Au-(Cys)PW electrode was employed for the determination of Cd²⁺ or Pb²⁺ in an industrial wastewater sample, which revealed the potential application of the modified electrode.