Determination of Hg22+Ions Using a Modified Glassy Carbon Electrode with 2,2':6':2''-Terpyridine

Abstract

A glassy carbon electrode (GCE) modified with 2,2':6':2”-terpyridine (2,2':6':2”-TPR) using a spin coating method was applied for the highly selective and sensitive analysis of a trace amount of <TEX>$Hg_2^{2+}$</TEX> ions. Various experimental parameters, which influenced the response of the 2,2':6':2”-TPR modified electrode to <TEX>$Hg_2^{2+}$</TEX> ions, were optimized. The linear sweep and differential pulse voltammograms for the 2,2':6':2”-TPR modified electrode deposited with Hg show a well-defined anodic peak at +0.65 V (vs. Ag|AgCl). After a 25 min preconcentration time in an <TEX>$Hg_2^{2+}$</TEX> ion solution (0.1 M acetate buffer, pH 5.0), differential pulse voltammetry(DPV) with 2,2':6':2”-TPR modified electrode shows a linear response between <TEX>$1.0\;{\times}\;10^{-6}M\;and\;2.0\;{\times}\;10^{-7}M$</TEX>. The least-square treatment of these data produce an equation of I[<TEX>${\mu}A$</TEX>] = 0.031 + 0.005C with r = 0.980(n = 5). The detection limit of this electrode with linear sweep voltammetry and differential pulse anodic voltammetry were <TEX>$2.0\;{\times}\;10^{-6}M\;and\;8.0\;{\times}\;10^{-8}M$</TEX>, respectively. The presence of Pb, Fe, Cd, Ti, Ni, Co, Mg, Al, Mn, and Zn did not interfere in the analysis of the <TEX>$Hg_2^{2+}$</TEX> ion. The 2,2':6':2”-TPR modified GCE has been successfully applied in determination trace amounts of Hg in a human urine sample.