Simultaneous Electrochemical Determination of Dopamine, Acetaminophen, and Caffeine with a PVP/rGO-Modified Electrode

The simultaneous and cost-effective determination of Dopamine (DA), Acetaminophen (APAP), and Caffeine (CAF) could be useful in several areas such as pain management, clinical diagnostics, and pharmaceutical quality control. In this study, reduced graphene oxide (rGO) was synthesized from graphite and graphene oxide (GO) using ascorbic acid as reducing agent. The rGO was characterized using FT-IR spectroscopy, Raman spectroscopy, scanning electron microscopy, and thermogravimetry. rGO and polyvinylpyrrolidone (PVP) were then combined to modify a glassy carbon electrode (rGO-PVP/GCE), which was studied using cyclic voltammetry, electrochemical impedance spectroscopy, and square-wave voltammetry (SWV). The modified electrode rGO-PVP/GCE exhibited favorable electron transfer kinetics and electrocatalytic activity in the oxidation of DA, APAP, and CAF compared to GO/GCE, PVP/GCE, and rGO/GCE. The SWV results showed three distinct anodic peaks at 0.44, 0.63, and 1.49 V (vs Ag/AgCl 3 M KCl), corresponding to the oxidation of DA, APAP, and CAF, respectively. The responses showed good linearity in the investigated concentration ranges and the limits of detection for DA, APAP, and CAF were 0.81, 0.16, and 19.6 μM, respectively. Finally, the proposed sensor was applied to simultaneously determine DA, APAP, and CAF in artificial urine, a pharmaceutical syrup, and an energy beverage.