Highly sensitive determination of lead(ii) and cadmium(ii) by a large surface area mesoporous alumina modified carbon paste electrode

Abstract

Nanosized mesoporous γ-alumina (M-γ-Al₂O₃) was first prepared and then modified into a carbon paste to fabricate a novel modified carbon paste electrode. The prepared alumina has pores with an amorphous wall and large surface area. The electrochemical behavior of the modified carbon paste electrode was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The modified carbon paste electrode was employed to determine Pb²⁺ and Cd²⁺ simultaneously by a differential pulse voltammetry (DPV) method. Amperometric determination was carried out in 0.1 mol L⁻¹ NaAc–HAc buffer solution (pH 6.0) after enriching for 360 s at −1.0 V. The oxidation peak currents of Pb²⁺ and Cd²⁺ were proportional to their concentration in the range of 0.001–10 μmol L⁻¹ and 0.01–10 μmol L⁻¹, respectively. The detection limits of Pb²⁺ and Cd²⁺ were 0.20 nmol L⁻¹ and 2.0 nmol L⁻¹ (S/N = 3), respectively. The modified carbon paste electrode shows good stability, repeatability and sensitivity. The proposed method was applied to the determination of Pb²⁺ and Cd²⁺ in water samples with satisfactory results.