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 μM, 1–700 μM, 5–700 μM and 1–600 μM 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 μM, 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