Simultaneous electro-catalytic oxidative determination of ascorbic acid and folic acid using Fe3O4 nanoparticles modified carbon paste electrode

• Simultaneous voltammetric determination of ascorbic acid and folic acid.
• Synthesis of Fe3O4 nanoparticles by hydrothermal method.
• Fe3O4 modified carbon paste electrode for ascorbic acid and folic acid analysis.
• Ascorbic acid and folic acid in pharmaceuticals, blood serum and lemon juice.

The fabrication of magnetite (Fe3O4) nanoparticles modified carbon paste electrode (Fe3O4-CME) enabled facile electrochemical determination of ascorbic acid (AA) and folic acid (FA) using differential pulse voltammetry. Fe3O4 nanoparticles were synthesized by solution route and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometer and scanning electron microscopy. The nanoparticles were found to have an average diameter of 22 nm. The electrochemical signals showed that Fe3O4-CME enhanced the rate of oxidation of AA and FA by increasing the peak current with a corresponding decline of peak potential compared to carbon paste electrode which makes the oxidation process thermodynamically more favorable. The modified electrode had a good sensitivity toward simultaneous determination of AA and FA in a linear working range of 9.09 × 10−7–4.70 × 10−3 M and 6.50 × 10−8–9.80 × 10−5 M with corresponding detection limits of 2.51 × 10−7 M and 2.01 × 10−9 M for AA and FA respectively. Electrochemical impedance spectroscopy was employed to understand the enhancement of the Fe3O4 nanoparticles modified carbon paste electrode over plain carbon paste electrode.