Electrochemical sensing platform for the determination of arsenite and arsenate using electroactive nanocomposite electrode

Arsenic is a major water contaminant, threat to human health and country’s economy. Arsenic can occur in different oxidation states (−3, 0, +3 and +5) out of which arsenite (As3+) and arsenate (As5+) are highly toxic. Identification and quantification of such toxicant has become a major challenge. Towards this, a highly electro catalytic ruthenium bipyridine – graphene oxide ([Ru(bpy)3]2+-GO) nanocomposite electrode is utilized. The nanocomposite modified screen printed electrode (SPE) shows an enhanced surface area and electron transfer due to the π-π stacking interactions of nanocomposite. Metal-to-ligand charge transfer (MLCT) property of the composite and its role in detecting arsenic species have been studied. Differential pulse voltammetric response of [Ru(bpy)3]2+-GO modified SPE exhibits three oxidation peaks at 0.38, 0.67 and 0.97 V. The challenge of thermodynamic limitation due to inner layer As(0) deposition is overcome. The nanocomposite modified electrode exhibits high catalytic activity towards the oxidation of As(III) and As(V) with the detection limits of 21 and 34 nM in the wide linear range of 0.08–15 µM. The developed sensing element is selective and exhibits good repeatability and reproducibility at a mean response of 32 µA with a relative standard deviation (RSD) of 2.67 and 2.84% respectively. The selective nature of [Ru(bpy)3]2+-GO nanocomposite in quantifying arsenite and arsenate helps in water quality assessment.