A mesoporous silver-doped TiO.sub.2-SnO.sub.2 nanocomposite on g-C.sub.3N.sub.4 nanosheets and decorated with a hierarchical core-shell metal-organic framework for simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid

An electrochemical sensor is described for the simultaneous voltammetric determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). An indium-tin oxide (ITO) electrode was modified with a hierarchical core-shell metal-organic framework and Ag-doped mesoporous metal-oxide based hybrid nanocomposites on g-C.sub.3N.sub.4 nanosheets. The morphology, structural and chemical composition of the hybrid nanocomposite was characterized using different analytical methods. The modified ITO showed superior electrocatalytic performance towards the oxidation of AA, DA and UA due to the enhanced surface area, synergistic effects and well-organized porous assembly. Figures of merit, include (a) linear responses from 0.1 to 200 [mu]M, 2.5 to 100 [mu]M and 2.5 to 625 [mu]M; (b) detection limits (at S/N = 3) of 0.02, 0.01 and 0.06 [mu]M, and (c) well separated oxidation peaks near -50, 186 and 390 mV (vs. Ag/AgCl) for simultaneous sensing AA, DA and UA, respectively. The sensor was evaluated by analysing spiked serum samples and gave data with precision, with recoveries of >98%.