A novel and sensitive electrochemical sensor based on nanoporous gold for determination of As(III)

Three-dimensional porous gold nanoparticles (NPG) were synthesized in situ on indium-doped tin oxide (ITO) substrates by a green and convenient one-step electrodeposition method to achieve super-sensitive As(III) detection. The introduction of NPG method not only greatly improves the electron transfer capacity and surface area of sensor interface but provides more active sites for As(III) enrichment, thus boosting sensitivity and selectivity. The sensor was characterized by scanning electron microscopy, energy dispersion spectroscopy, differential pulse anode stripping voltammetry (DPASV), and electrochemical impedance to evaluate its morphology, composition, and electrochemical performance. The wall thickness of NPG was customized by optimizing the concentration of electroplating solution, dissolved electrolyte, deposition potential, and reaction time. Under optimal conditions, the electrochemical sensor showed a wide linear range from 0.1 to 50 μg/L As(III), with a detection limit (LOD) of 0.054 μg/L (S/N = 3). The LOD is far below 10 μg/L, the recommended maximum value by the world health organization for drinking water. Stability, reproducibility, and repeatability of NGP/ITO were determined to be 2.77%, 4.9%, and 4.1%, respectively. Additionally, the constructed sensor has been successfully applied to determine As(III) in three actual samples, and the results are in good agreement with that of hydride generation atomic fluorescence spectrometry (AFS).