Electrochemical Detection of Ultratrace (Picomolar)\nLevels of Hg²⁺ Using a Silver Nanoparticle-Modified Glassy\nCarbon Electrode

Abstract

Ultratrace\nlevels of Hg²⁺ have been quantified by undertaking\nlinear sweep voltammetry with a silver nanoparticle-modified glassy\ncarbon electrode (AgNP-GCE) in aqueous solutions containing Hg²⁺. This is achieved by monitoring the change in the silver\nstripping peak with Hg²⁺ concentration resulting from the\ngalvanic displacement of silver by mercury: Ag­(np) + 1/2Hg²⁺(aq) → Ag⁺(aq) + 1/2Hg­(l). This facile and reproducible\ndetection method exhibits an excellent linear dynamic range of 100.0\npM to 10.0 nM Hg²⁺ concentration with <i>R</i>² = 0.982. The limit of detection (LoD) based on 3σ\nis 28 pM Hg²⁺, while the lowest detectable level for quantification\npurposes is 100.0 pM. This method is appropriate for routine environmental\nmonitoring and drinking water quality assessment since the guideline\nvalue set by the US Environmental Protection Agency (EPA) for inorganic\nmercury in drinking water is 0.002 mg L^–1 (10 nM).