Electrochemical sensor for sensitive nitrite and sulfite detection in milk based on acid-treated Fe3O4@SiO2 nanoparticles

In this work, a simple electrochemical sensing platform based on acid-treated Fe 3 O 4 @SiO 2 nanoparticles was successfully prepared for nitrite and sulfite detection. Fe 3 O 4 @SiO 2 nanoparticles were synthesized through the sol–gel and hydrothermal methods. Fe 3 O 4 @SiO 2 presented positive charges after acid treatment, which could enhance the electrostatic attraction between Fe 3 O 4 @SiO 2 and nitrite and sulfite. The Fe 3 O 4 @SiO 2 (acid-treated) modified magnetic glassy carbon electrode (MGCE) was applied to detect nitrite and sulfite using differential pulse voltammetry and cyclic voltammetry. Under optimized conditions, the developed electrochemical sensor presented good analytical properties for nitrite and sulfite detection with detection limits of 3.33 μmol/L and 31.57 μmol/L, respectively. The good recoveries varied from 85.18% to 111.02%, with a relative standard deviation of 0.23–4.80%. Furthermore, the Fe 3 O 4 @SiO 2 (acid-treated) modified MGCE showed better selectivity, reproducibility, and repeatability in nitrite and sulfite detection. Therefore, this proposed electrochemical sensor provides a new method for developing a nitrite and sulfite detection sensor.