Electrochemical sensor for simultaneous determination of ascorbic acid, uric acid and folic acid based on Mn-SnO2 nanoparticles modified glassy carbon electrode

• Simultaneous determination of ascorbic acid, uric acid and folic acid has been achieved using Mn SnO2 NPs modified /GCE.
• The proposed sensor exhibits wide linear range, low detection limit, good stability and high reproducibility.
• The sensor was successfully applied to the analysis of pharmaceutical products, fruits and human urine samples.

A highly sensitive and selective electrochemical sensor was fabricated based on Mn doped SnO2 nanoparticles (NPs) modified glassy carbon electrode (Mn-SnO2/GCE) for simultaneous determination of ascorbic acid (AA), uric acid (UA) and folic acid (FA) for the first time. The Mn-SnO2 NPs synthesized by microwave irradiation method were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. The Mn-SnO2/GCE exhibited excellent electrocatalytic activity towards the oxidations of AA, UA and FA in phosphate buffer solution (pH 6.0) and the corresponding electrochemical signals have appeared as three well resolved oxidation peaks with significant peak potential differences of 0.141 V (AA–UA), 0.345 V (UA–FA) and 0.486 V (AA–FA). For selective determination, the linear responses of AA, UA and FA were in the concentration ranges of 1 to 900, 1 to 860 and 0.5 to 900 μM for AA, UA and FA with detection limits of 56, 36 and 79 nM respectively. For simultaneous determination by synchronous change of the analyte concentrations, the linear response ranges were between 5 and 500 μM for UA and 1–500 μM for FA with the lowest detection limits of 25 and 38 nM respectively in the presence of AA. The proposed sensor was proved to be applicable for the determination of the target analytes in pharmaceuticals and urine samples.

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