preparation of a new electrochemical sensor for individual and simultaneous determination of ascorbic acid, dopamine and uric acid using zirconium oxide-porous carbon nanocomposite derived from metal-organic frameworks

Abstract: ascorbic acid (aa), dopamine (da) and uric acid (ua) are among biomolecules that have very important physiological functions in the metabolic system of living organisms. in the present study, a porous carbonaceous platform containing zirconium oxide (zro2-pcs) was synthesized by calcination of a metal-organic framework for the simultaneous determination of aa, da and ua. the morphology and structure of zro2-pcs was characterized by xrd, ft-ir, sem, tem, edx and nitrogen adsorption/desorption methods. in addition, cv, dpv and eis were used to investigate the electrochemical properties of the fabricated electrode. considering the influence of ph on the results, pbs (0.1 m, ph 7.0) was selected for the simultaneous analysis of aa, da and ua. three well-separated dpv peaks were observed on zro2-pcs/gce for the three bio-molecules. at the optimized conditions, wide linear ranges, i.e., 1-5998.08, 0.5-220.87 and 0.5-270.88 μm for aa, da, and ua in ternary mixture were obtained, respectively. the respective detection limits were 0.33, 0.16 and 0.16 μm. repeatability and reproducibility of the method were calculated as relative standard deviation (rsd%) with maximum values of 2.0, 2.22, 4.71 and 2.59, 4.48, 1.37 for aa, da, ua respectively. the method was applied to the simultaneous detection of aa, da and ua in human serum samples by dpv using standard addition method, successfully. these performance improvements can be attributed to the catalytic effect of zro2 nanoparticles and increase in active surface area of the electrode surface. in addition, defect structures (oxygen vacancies) of zro2 play an important role in improving catalytic activity and can significantly reduce the oxidation potential of analytes [1, 2]. on the other hand, excellent electrical conductivity of porous carbon accelerates electron transfer during electrochemical reactions [2, 3].