Anodic stripping voltammetric analysis of trace arsenic(III) enhanced by mild hydrogen-evolution at a bimetallic Au-Pt nanoparticle modified glassy carbon electrode

A glassy carbon electrode (GCE) modified with electrodeposited bimetallic Au-Pt nanoparticles (Au-PtNPs) was applied to sensitively detect As(III) by linear sweep anodic stripping voltammetry (ISASV). In 0.5 M aqueous H2SO4, atomic hydrogen and molecular hydrogen were easily electrogenerated at the Pt sites on Au-PtNPs/GCE, which can chemically reduce As(III) to As(0) and enhance the cathodic preconcentration of As(0) at both the Pt sites and the neighboring Au sites. Since the As(0)-Au affinity is weaker than the As(0)-Pt affinity, the preconcentrated As(0) can be rapidly oxidized on/near the surface Au sites of Au-PtNPs/GCE, yielding sharper and higher LSASV current peaks. Under optimum conditions (700 s preconcentration at -0.1 V, 5 V s(-1)), the LSASV peak current for the As(0)-As(III) oxidation responded linearly to As(III) concentration from 0.005 to 3.0 mu M with a limit of detection (LCD) of 3.7 nM (028 ppb) (S/N = 3), while that for the As(III)-As(V) oxidation was linear with As(III) concentration from 0.01 to 3.0 mu M with a LCD of 6.0 nM (0.45 ppb) (S/N = 3). This method was applied for analysis of As(III) in real water samples. (C) 2015 Elsevier B.V. All rights reserved.