Electrochemical determination of lead based on metal–organic framework MIL-101(Cr) by differential pulse anodic stripping voltammetry

Abstract

Green octahedral crystals of MIL-101(Cr) were synthesized and used for the determination of Pb²⁺ at the trace level by differential pulse anodic stripping voltammetry (DPASV) because of their good adsorption capability for Pb²⁺. The synthesized MIL-101(Cr) was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Parameters affecting the electrochemical process, such as the pH of the electrolyte solution, the volume of the MIL-101(Cr) suspension, the potential and the time for accumulation, were investigated in detail. Under optimal conditions, the electrochemical sensor had a linear response over the concentration range of 1.0 × 10⁻⁹ to 1.0 × 10⁻⁶ mol L⁻¹ (R² = 0.999) with a detection limit of 5.0 × 10⁻¹⁰ mol L⁻¹ (S/N = 3). The method was successfully applied to the determination in real samples and good recoveries are obtained from different spiked samples.