Interfacial engineering of TiO2-WO3@MWCNTs nanocomposites for ultrasensitive and highly selective electrochemical nitrite sensing in food samples.

Nitrite ions are extensively utilized in the food industry to enhance preservation, flavor, and colorants; however, their excessive intake poses serious health risks, including mutagenic and carcinogenic effects. In this work, a novel electrochemical sensor platform providing high sensitivity and high selectivity was constructed using TiO2-WO3@MWCNTs-modified carbon paste electrodes (CPEs). The synergistic combination of TiO2-WO3 bi-metal oxide nanostructures with multi-walled carbon nanotubes significantly enhanced electrochemical reactivity and electrocatalytic activity of the electrode interface. The fabricated nanocomposite was systematically characterized through Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) to identify all acquired features. After assay optimization and mechanistic investigation, the modified electrode exhibited an ultralow detection limit of 0.003 µM and a wide linear detection range of 0.01-210 µM for nitrite detection using chronoamperometry, with excellent selectivity. The sensor's practical applicability was validated through analysis of real food samples, yielding high recovery values and confirming its accuracy and reliability.