Electrochemical determination of copper(ii) using co-poly (cupferron and β-naphthol)/gold nanoparticles modified glassy carbon electrodes

Abstract

A novel, simple and reliable method for the determination of trace copper on glassy carbon electrodes (GCEs) modified with co-poly(cupferron and β-naphthol)/gold nanoparticles (GNPs) is reported. The present work realized the application of principle of organic co-precipitation in solution into electrochemical analysis. First, the co-poly(cupferron and β-naphthol) was electrochemically deposited on the prepared GNPs/GCE by CV scanning in order to obtain co-poly(cupferron and β-naphthol)/GNPs/GCE. Then, the chelating ligand cupferron on the surface of the modified electrode and copper ion in the solution form the chelate complex (Cu(II)-Cpf), at the same time, the Cu(II)-Cpf was induced to be adsorbed by the carrier β-naphthol on the surface of the modified electrode by the principle of organic co-precipitation. Thus, the Cu²⁺ of the coprecipitated complexation can be detected at the co-poly(cupferron and β-naphthol)/GNPs/GCE. Therefore, preconcentration-separation and electrochemical detection of trace copper were simultaneously and synchronously carried through. After optimization, two linear responses were obtained in the concentration range from 9.0 × 10⁻¹⁰ to 4.5 × 10⁻⁸ M and 5.0 × 10⁻⁸ to 1.5 × 10⁻⁶ M, with a low detection limit of 5.0 × 10⁻¹¹ M. This modified GCE does not present any significant interference from Cd²⁺, Ag⁺, Fe³⁺, Pb²⁺, Cr³⁺, Zn²⁺, NO₃⁻, Cl⁻, SO₄²⁻ and EDTA. No deterioration was observed in the electrode response during at least 3 weeks of successive measurements. And the modified electrode shows high selectivity, sensitivity and stability. The proposed method provides a new way for the separation, enrichment and electrochemical detection of trace copper ion.