Zirconium oxide-porous carbon derived from metal-organic frameworks as a new sensing platform: application to simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid

In this study, a new sensor was designed for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) by calcination of zirconium metal–organic frameworks (Zr-MOF). The characterization of the calcination product (ZrO 2 -PCs) was characterized by SEM and TEM showed a uniform distribution of nano-sized ZrO 2 in the carbonaceous network. Deposited nanocomposite on a glassy carbon electrode (ZrO 2 -PCs/GCE) showed high selectivity and excellent electrocatalytic activity in simultaneous determination of AA, DA and UA in phosphate buffer solution (0.1 M, pH 7). Cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy were used to investigate the electrochemical properties of the fabricated electrode. At the optimized experimental conditions, wide linear ranges were obtained in ternary mixtures of AA, DA, and UA, i.e., 1–6000, 0.5–221, and 0.5–271 µM, respectively. The modified electrode showed good repeatability, reproducibility and long-term stability. In addition, ZrO 2 -PCs/GCE was successfully applied to simultaneous determination of AA, DA and UA in human blood serum and urine samples. The good performance of the proposed electrode was attributed to catalytic properties of ZrO 2 and its uniform distribution in the highly conductive carbonaceous matrix, resulted from metal–organic frameworks.