Development of electrochemical sensors for the determination of selenium using gold nanoparticles modified electrodes

Electrochemical sensors have been developed for the determination of selenium (Se (IV)) using glassy carbon electrodes modified with gold nanoparticles (AuNPs) obtained electrochemically (GC/AuNPs/E) and chemically (GC/AuNPs/C) using square wave anodic stripping voltammetry (SWASV). GC/AuNPs/E was characterized by cyclic voltammetry (CV), atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray dispersion spectrometry (EDS). The results indicate a homogeneous distribution of AuNPs with a 75 ± 20 nm particle size distribution. The chemically prepared AuNPs were characterized by transmission electron microscopy (TEM) and UV-vis spectroscopy (Surface Plasmon Band), and the results indicate that the AuNPs have a spherical shape (7.4 ± 1.3 nm). GC/AuNPs/C was prepared using a drop coating technique and was characterized by CV. The optimum conditions for the prepared electrodes were as follows: accumulation potential of −0.80 V (Eacc), accumulation time (tacc) of 120 s, and a frequency of 15 Hz. A linear range was observed from 10 to 50 μg L−1 with a limit of detection (LOD) of 0.120 μg L−1 for GC/AuNPs/E, and a linear range was observed from 15 to 55 μg L−1 with a LOD of 0.175 μg L−1 for GC/AuNPs/C. The proposed procedure was validated with the TM-15 certified reference material, and good accuracy and precision were observed. In addition, this approach was applied to seawater samples with satisfactory results.