Electrochemical detection of uric acid and xanthine in human urine using the Co/UiO-66 modified glassy carbon electrode

UiO-66 based materials (University of Oslo-66), with large surface area and abundant active sites, exhibit high water/solution stability due to a strong interaction between zirconium ion and the oxygen atom in carboxylate linkers. Therefore, they are potential electrode modifiers for electrochemical analysis because most of the electrochemical sensors have been used in aqueous media. In the present study, a potential electrochemical technique to detect uric acid (URA) and xanthine (XAN) is described using a Co/UiO-66 modified glassy carbon electrode. The Co/UiO-66 materials with different Co/Zr molar ratios were synthesized by hydrothermal process and were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption isotherms. The characterization showed a low loading and high dispersion of doped Co onto UiO-66 matrix. It was also found that the doped Co element may be grafted into the lattice of UiO-66. Co/UiO-66 exhibited better electrochemical activity toward URA and XAN detection. Under optimum conditions, 0.08Co/UiO-66/GCE demonstrated the best response compared to other material of different Co/Zr ratio, with three linear calibration ranges of 5–10 µM, 10-49.5 µM, and 49.5–327.1 µM and the limit of detection of 0.544 and 0.547 µM for URA and XAN, respectively. This proposed sensor offers a simple and low-cost pathway to quantify URA and XAN and was successfully employed to simultaneously determine URA and XAN in human urine with exceptional recoveries (97.61 to 104.79