Selective determination of arsenic (III) using a Nafion/α-MnO2@polydopamine modified electrode

Abstract

Abstract A simple strategy for reliable determination of As(III) without strongly acidic media is described by using the gold disk electrode modified with the water-dispersible polydopamine-coated α-MnO2 (α-MnO2@PDA) composites and the Nafion layers. The composites have been synthesized by the in-situ polymerization of dopamine and used to improve the sensitivity for detection of As(III). In this case, the α-MnO2 microrods are used as inorganic matrixes with strong adsorption abilities towards As(III) and the permeable PDA layers are prepared to enhance such adsorption effects by plenty of amino and hydroxyl groups that could work as the active adsorption sites. Nafion has been employed based on its excellent film-forming ability, by which the α-MnO2@PDA modified layer can be tightly attached to the sensor surface. Such a designed electrode shows a remarkably improved analysis performance to As(III). The electrode has a linear range of 10–150 μg L−1 with a sensitivity of 0.13 μA μg−1 L. Moreover, the proposed sensor exhibits a favorable stability and reproducibility in the determination of As(III). Additionally, interferences from co-existing ions can be effectively diminished. Therefore, we believe that the combination of α-MnO2@PDA composite and Nafion could be used to develop electrochemical sensors for the sensitive and selective analysis of As(III).