Immobilization of poly(o-aminophenol) film on Pt surface: A robust sensor for detecting As(III) in an acidic medium

Poly(o-aminophenol) film was immobilized onto a platinum surface to develop a arsenic senor in acidic medium via oxidation of As(III). The surface of the electrode was characterized using X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and the linear polarization techniques. The fabrication of the polymeric film on the platinum surface created noble catalytic sites pertaining to As(III) oxidation in acidic medium. The fact is ascertained from the observation of the lowering of onset and peak potential along with the increment of oxidation current in reference to a platinum electrode. The As(III) oxidation reaction follows first -order kinetics with a mixed mechanistic pathway following the conversion into As(V) with two electron transfers. From the assessment of the hydrodynamic voltammogra, the standard rate constant and formal potential were determined to be 1.65x10- 3 cm-1, and 0.62 V, respectively. Comparatively, the rate constant in the rotational mode is almost three times greater than in the static mode, implying a mass transfer-controlled process. From the amperometric investigation, the sensitivity, LOD, and LOQ values were found to be 0.0021 mA.cm- 2 mu M-1, 1.73 +/- 0.031 mu gL-1, and 4.59 +/- 0.043 mu gL- 1 , respectively. The stability and the real time assessment render excellent applicability with firm validation for arsenic detection in water with the PoAP film modified Pt electrode.