A simple gold plate electrode modified with Gd-doped TiO₂ nanoparticles used for determination of trace nitrite in cured food

Abstract

A simple gold plate electrode (GPE) based on a gadolinium-doped titanium dioxide (Gd/TiO₂) ultrathin film was successfully constructed by using a surface sol-gel technique, and used for the detection of trace amounts of nitrite in cured foods. The Gd/TiO₂ nanoparticles were synthesised and characterised via scanning electron microscopy (SEM) and X-ray diffraction (XRD), indicating that the Gd-doped TiO₂ formed an anatase phase through roasting at 450°C, generating actively interstitial oxygen at the interface of the surface of TiO₂ lattice surrounded by Gd³⁺. The electro-catalytic effect for oxidation of nitrite on the modified electrode was investigated by cyclic voltammetry in 0.10 mol l⁻¹ sulfuric acid media solution, showing that the modified electrode exhibited excellent response performance to nitrite with good reproducibility, selectivity and stability. The catalytic peak current was found to be linear with nitrite concentrations in the range of 8.0 × 10⁻⁷ to 4.0 × 10⁻⁴ mol l⁻¹, with a detection limit of 5.0 × 10⁻⁷mol l⁻¹ (S/N = 3). The modified electrode could be used for the determination of nitrite in the cured sausage samples with a satisfactory recovery in the range of 95.5–104%, showing its promising application for food safety monitoring.

Keywords:

• gold plate electrode
• Gd doped
• TiO₂ nanoparticle
• nitrite
• electrochemical analysis

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Numbers 21075011, 21275022 and 21105005), the Hunan Provincial Natural Science Foundation of China (Numbers 09JJ3016 and 10JJ5002), the National Science & Technology Support Program of China during the Twelfth Five-Year Plan Period (Number 2012BAC17B01), the Foundation of Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation of China (Numbers 2012CL04 and 2012CL09), and the Program for New Century Excellent Talents in University (Number NCET-10-0138), Ministry of Education of the People's Republic of China.