Anodic stripping voltammetry analysis of mercury(II) on a pyridine-Au/pyridine/glassy carbon electrode

We report the simple preparation of a pyridine (Py)-stabilized Au modified glassy carbon electrode (GCE) for high-performance anodic stripping voltammetry (ASV) analysis of Hg(II). A monolayer-scale ultrathin Py film was covalently modified on a GCE by electroreduction of 4-cyanopyridine (cPy) in 0.1 M aqueous H2SO4 (Py/GCE), and then the electroreduction of a synthesized cPy-Au(III) complex generated a Py-Au nanocomposite on the Py/GCE surface (Py-Au/Py/GCE). It was found that the electrogenerated Au(0) can catalyze the electroreduction of cPy. The materials and electrodes were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and electrochemical techniques. The gold sites on Py-Au/Py/GCE are highly active and well protected by the Py groups, and the Au-Hg amalgamation effect and the Py-Hg2+ coordination effect can make the cathodic preconcentration of Hg highly efficient, thus the Py-Au/Py/GCE offers very high sensitivity and stability for ASV analysis of Hg(II), giving a limit of detection of 12 ppt (S/N = 3). The Py-Au/Py/GCE was used for Hg(II) analysis in real water samples with satisfactory results.