Electrochemical sensor based on Fe3O4@Au/MOF-P2W17V composite modified glassy carbon electrode for food nitrite detection

Excessive consumption of nitrites can be harmful to human health. Therefore, the design of novel electrocatalysts for efficient electrochemical quantification of nitrite is important. In this paper, a magnetic metal-organic framework (Fe₃O₄@Au/MOF) was synthesized by a self-assembly method using waste orange peel as the reducing agent, and vanadium-substituted tungsten phosphate (K₇P₂W₁₇VO₆₂-18H₂O, P₂W₁₇V) and Fe₃O₄@Au/MOF were loaded on glassy carbon electrodes for the first time by layer-by-layer self-assembly and electrodeposition. Then, a nitrite sensor based on Fe₃O₄@Au/MOF-P₂W₁₇V nanocomposites was prepared. The composites' characterization reveals that the combination of P₂W₁₇V with Fe₃O₄@Au/MOF not only inhibits nanoparticle agglomeration but also offers high catalytic activity and electrical conductivity when compared to pure Fe₃O₄@Au/MOF and P₂W₁₇V. Under the optimal conditions, the Fe₃O₄@Au/MOF-P₂W₁₇V sensor's linear range for detecting nitrite was 0.01–100 mM, with a sensitivity of 11.682 μA·μM⁻¹·cm⁻² and a detection limit as low as 0.532 μM. In 100 cycle stability trials and 30 d reproducibility experiments, the current peak retained more than 95 % of its initial value. Furthermore, the sensor demonstrated good selectivity and has been successfully applied to detect nitrite in ham sausage, squash, milk and brined quail eggs, and the results were basically consistent with those of the naphthylenediamine hydrochloride method. The effective fabrication of Fe₃O₄@Au/MOF-P₂W₁₇V opens up a new avenue for determining low amounts of nitrite in analytical applications that is viable for practical use.