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