Electrochemical Determination of Iron(III) in River Water by Differential Pulse Voltammetry (DPV) Using a Poly(3,4-Ethylenedioxythiophene)–Polystyrene Sulfonate co-Polymer/Gold Nanoparticle Modified Gold Microelectrode

An electrochemical sensor based upon a poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT-PSS) co-polymer film with gold nanoparticles (AuNPs) modified microelectrode is reported for the determination of Fe(III). Scanning electron microscopy images showed that the AuNPs were immobilized on gold (Au) microelectrode by formation of a nanofilm with PEDOT-PSS. The individual particles and their cluster-like aggregates provide a larger active electrochemical area and higher conductivity, which facilitates the determination of Fe(III). Electrochemical impedance spectroscopy (EIS) shows the AuNPs/PEDOT-PSS/Au microelectrode possesses high conductivity. A low detection limit of 0.01 µM Fe(III) was obtained using the modified microelectrode by differential pulse voltammetry (DPV) due to its large specific surface area, high conductivity, and the presence of more active sites. The optimized pH of the supporting acetate buffer was 2.0. The AuNPs/PEDOT-PSS/Au provided a linear range from 0.0119 μM to 7.14 μM. The modified electrode was successfully employed for the the determination of total dissolved iron in river water from Three Gorges with satisfactory results.