A stable electrochemical sensor for the detection of ascorbic acid based on Fe3O4/ZrO2 nano composite modified carbon paste electrode

Abstract

Magnetite and zirconium oxide (Fe3O4/ZrO2) nano composite, Fe3O4 and ZrO2 nanoparticles were synthesized by a chemical co-precipitation method and hydrothermal decomposition of zirconium metal organic framework, respectively. The structural and morphological properties of the as-synthesized materials were characterized by X-ray diffraction and scanning electron microscope. Electrochemical properties of carbon paste electrode (CPE) modified by Fe3O4, ZrO2 and Fe3O4/ZrO2 nano composites were studied using cyclic voltammetry and electrochemical impedance spectroscopy in the presence of 2 mM K3Fe(CN)6/0.1 M KCl aqueous solution. Voltammograms acquired on Fe3O4/ZrO2/CPE showed an enhancement of the oxidation current density compared to the other modified electrodes. By applying the Randles-Sevcik equation, the CPE modified by Fe3O4/ZrO2 nano composite resulted in an electroactive surface area of 0.0978 cm2; about twice to that of the unmodified CPE (0.0458 cm2). The electrochemical sensor was used for the detection of ascorbic acid (AA). Under optimized condition (pH 4) the sensor exhibits sensitivity of 10 µA/µM; LOD of 0.46 µM; LOQ of 1.53 µM and a linear range of 1-6 μM AA. The Fe3O4/ZrO2/CPE has also shown accepted reproducibility (% recoveries 93.54%); RSD of 2.4% and stable response of 96.91% of the initial current after 30 days of storage. KEY WORDS: Ascorbic acid, Carbon paste electrode, Electrochemical sensor, Nano composite Bull. Chem. Soc. Ethiop. 2024, 38(5), 1205-1223. DOI: https://dx.doi.org/10.4314/bcse.v38i5.2