Synthesis and characterization of an Au nanoparticles/graphene nanosheet nanocomposite and its application for the simultaneous determination of tramadol and acetaminophen

In this study, we aimed to prepare a selective and sensitive electro-chemical sensor through modifying a carbon paste electrode (CPE) with a gold nanoparticle graphene nanosheet (AuNPs/GN) nanocomposite and 4-hydroxyl-2-(triphenylphosphonio)phenolate (HTP). The AuNPs/GN nanocomposite was synthesized and characterized by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and scanning electron microscopy (SEM) and then was used for the modification of CPE. This modified electrode was successfully applied for the determination of tramadol (TRA) and simultaneous detection of TRA and acetaminophen (AC). The results showed that the TRA peak potential at HTP-AuNPs/GN-CPE shifted to less positive values in comparison with that of unmodified CPE. Kinetic variables including electron transfer coefficient (alpha) and heterogeneous electron transfer rate constant (k ') for the electrocatalytic oxidation of TRA at the HTP-AuNPs/GN-CPE surface were calculated. The differential pulse voltammetry (DPV) technique showed that the plot of the electro-catalytic current versus TRA concentrations is composed of two linear segments. Moreover, the detection limit of 0.82 mu M for TRA was obtained. The analytical function of this sensor was assessed to detect TRA and AC in human urine and pharmaceutical samples with acceptable results.