A Surface Network Based on Reduced Graphene Oxide/Gold Nanoparticles for Selective Determination of Norepinephrine in Real Samples

A spontaneous modification of glassy carbon electrode (GCE) by reduced graphene oxide (rGO) doped peripherally with gold nanoparticles (AuNPs) was fabricated and characterized by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). The electron transfer kinetics of surface materials was evaluated by fitting the charge transfer resistance (R ct) data in the presence of a redox probe such as [Fe(CN)6]3-/4-. The developed sensor (AuNPs.rGO-GCE) exhibited a large enhancement on the electrochemical oxidation of norepinephrine (NOR) than other arrays of surface assemblies. The voltammetric behavior of NOR at the present (AuNPs.rGO-GCE) modified surface was confirmed to follow a quazi-reversible reaction mechanism. Moreover, the apparent diffusion coefficient (D app) and the heterogeneous rate constant (k s) parameters of NOR species were collectively calculated using the classical irreversible electrochemical theory. The sensor showed excellent sensitivity and selectivity on NOR quantification in the presence of large concentration of ascorbic acid (AA) and the limit of detection of NOR (DL3σ ) is lowered to 57 nM (10 ppb). The analytical performance of the proposed system was validated successfully for pharmaceutical (injection ampoule) and biological (plasma blood) samples with tolerable recovery percentages.