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Ternary nanocomposite-based reduced graphene oxide/chitosan/Cr2O3 for the simultaneous determination of dopamine, uric acid, xanthine, and hypoxanthine in fish meat

A voltammetric non-enzymatic sensor based on a reduced graphene oxide/chitosan/chromium oxide nanocomposite-modified glassy carbon electrode (GCE/rGO/CS/Cr2O3) was investigated for the synchronous determination of dopamine (DA), uric acid (UA), xanthine (XN), and hypoxanthine (HXN). The as-synthesized rGO/CS/Cr2O3 was characterized via field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) and Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible spectroscopy (UV-Vis). As a result, the modified electrode showed high sensitivity for the simultaneous determination of DA, UA, XN, and HXN. Compared to bare GCE, GCE/rGO/CS/Cr2O3 results in a strongly increased voltammetric current of DA, UA, XN, and HXN. Investigation into the effect of the experimental parameters, such as the pH and scan rate, showed that at pH = 7, the maximum current was achieved by a diffusion mechanism. A linear range in the simultaneous measurement of DA, UA, XN, and HXN is present in succession in the range from 5 to 160 μM, 10 to 500 μM, 10 to 400 μM and 2 to 300 μM with the detection limits of 0.65 μM, 0.80 μM, 1.20 μM, and 0.85 μM, respectively. The applicability of the sensor for the analysis of DA, UA, XN, and HXN in fish meat was successfully demonstrated.