Simultaneous voltammetric determination of ascorbic acid, dopamine, acetaminophen and tryptophan based on hybrid trimetallic nanoparticles-capped electropretreated graphene

A novel nanocomposite sensor based on trimetallic nanoparticles of (Au/Ag/Pd)NPs uniformly capped electropretreated graphene oxide (EPGrO) was fabricated. The investigation and characterization of the (Au/Ag/Pd)NPs/EPGrO nanocomposite were studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) techniques. Cyclic voltammograms (CVs) of the nanocomposite electrode displayed obvious and sharp oxidation peaks for each ascorbic acid (AA), dopamine (DA), acetaminophen (AP) and tryptophan (TP) as compared to their responses at EPGrO and bare electrodes. An efficient electron mediating behavior of the nanocomposite electrode with large separation peak potentials for AA-DA, DA-AP, and AP-TP were estimated to be 0.16, 0.18 and 0.29 V, respectively. In addition, differential pulse voltammograms (DPVs) of the nanocompsite electrode showed simultaneous determination of AA, DA, AP and TP with linear calibration plots from 5-650 mu M, 1-700 mu M, 5-700 mu M and 1-600 mu M where their detection limits were calculated to be 0.24 +/- 0.03, 0.02 +/- 0.01, 0.12 +/- 0.04 and 0.03 +/- 0.01 mu M, respectively. Finally, the practical application of the (Au/Ag/Pd)NPs/EPGrO nanocomposite electrode was successfully conducted for the analytical determination of AA, DA, AP and TP in real sample of human blood serum.