Nonenzymatic nitrite sensor based on a titanium dioxide nanoparticles/ionic liquid composite electrode

• We constructed a nonenzymatic nitrite sensor instead of protein-based biosensors.
• We detected nitrite by oxidation instead of reduction.
• The TiO2/IL composite electrode showed good electrocatalytic activity to nitrite.
• The proposed sensor could be applied for determination of nitrite in sausage samples.

A titanium dioxide nanoparticles/ionic liquid composite electrode was prepared and used for selective and sensitive determination of nitrite. The electrochemical behavior of the modified electrodes and the mechanism of the oxidation of nitrite were investigated using cyclic voltammetry. The effect of working solution pH, scan rate and the amount of modifier were studied in great detail. The modifier titanium dioxide nanoparticles in the carbon paste increased the effective surface area of the electrode evidently and improved the sensitivity by enhancing peak currents. Moreover, the presence of high conductive ionic liquids promoted the electron transfer rate and decreased the overpotential of the oxidation of nitrite compared with other electrodes. The proposed sensor showed electrocatalytic activity for the oxidation of nitrite and the oxidation peak occurred at low overpotential (0.78 V versus Ag/AgCl). The catalytic peak current was found to be linear with the nitrite concentration in the range of 5 × 10−7–1.5 × 10−3 M, with a correlation coefficient of 0.9977, using linear sweep voltammetry. The detection limit of 2 × 10−7 M was obtained at a signal-to-noise ratio of 3. The sensor had good reproducibility and stability. The proposed method was applied for the voltammetric determination of nitrite in some sausage samples, and satisfactory results were obtained.