Simultaneous detection of uric and ascorbic acids by AuNPs electrodeposited on the GCE surface.

Simultaneous determination of small biologically important molecules is more significant for monitoring several diseases at physiological pH. Uric acid (C₅H₄N₄O₃) and ascorbic acid (C₆H₈O₆), for instance, were once regarded as crucial components in the physiological processes of humans since they coexist in numerous biological matrices regularly, and monitoring their concentrations simultaneously indicates diseases like gout. In the present work, the gold nanoparticles (AuNPs) were assembled on a glassy carbon electrode (GCE) using electrodeposition of Au³⁺ ions for the simultaneous determination of C₅H₄N₄O₃ and C₆H₈O₆. The deposited AuNPs were characterized using UV–visible spectroscopy, XPS, XRD, and AFM. Morphological analysis depicted that the particles are spherical with a size of 32 nm, and the particles are uniformly distributed on the electrode surface. The formation of gold oxide and its reduction peaks in cyclic voltammetry revealed the effective deposition of AuNPs on the GCE surface. The catalytic activity AuNPs modified GCE was analyzed by probing the oxidation of C₅H₄N₄O₃ and C₆H₈O₆ at physiological pH (pH 7.2). The present modified electrode greatly enhanced the oxidation peak currents, and the potential of oxidation is also shifted to less positive potential compared to bare GCE. The AuNPs/GCE was used to determine C₅H₄N₄O₃ in the presence of a 50-fold high concentration of C₆H₈O₆. The detection of 40 nM C₅H₄N₄O₃ was achieved using amperometry and a detection limit of 1.8 × 10^–9 M (Signal/Noise = 3) was observed for the determination of uric acid in the concentration range from 4 × 10^–8 to 4 × 10^–5 M. [ABSTRACT FROM AUTHOR]