Nanomaterial/Ionophore-Based Electrode for Anodic Stripping Voltammetric Determination of Lead: An Electrochemical Sensing Platform toward Heavy Metals

Abstract

A novel nanomaterial/ionophore-modified glassy carbon electrode for anodic stripping analysis of lead (Pb(2+)) is described. Nanosized hydroxyapatite (NHAP) with width of 20-25 nm and length of 50-100 nm has been prepared and used to improve the sensitivity for detection of Pb(2+) because it provides unique three-dimensional network structure and has strong adsorption ability toward Pb(2+). An ionophore, usually used in ion-selective electrodes, is utilized here for its excellent selectivity toward Pb(2+). Nafion, a cation-exchange polymer, is employed as the conductive matrix in which NHAP and the ionophore can be tightly attached to the electrode surface. Such a designed NHAP/ionophore/Nafion-modified electrode shows remarkably improved sensitivity and selectivity to Pb(2+). The electrode has a linear range of 5.0 nM to 0.8 microM with a 10 min accumulation time at open-circuit potential. The sensitivity and detection limit of the proposed sensor are 13 microA/microM and 1.0 nM, respectively. Interference from other heavy metal ions such as Cd(2+), Cu(2+), and Hg(2+) associated with lead analysis can be effectively diminished. The practical application of the proposed sensor has been carried out for determination of trace levels of Pb(2+) in real water samples.