Determination of Nitrite and Sulfite in Foods by Phenolic Acid-based Gold Nanoparticles Electrode

Based on the good reducibility and non-pollution of phenolic acid, the phenolic acid-based gold nanosensor system was established to realize sensitive detection of nitrite and sulfite. Different phenolic acids were used to reduce chlorauric acid to prepare gold nanoparticles (AuNPs). The optimal phenolic acid was gallic acid (GA) by ultraviolet spectrum and electrochemical impedance spectrum method. The GA@AuNPs@Au electrodes were prepared by electrodeposition and the electrochemical behaviors of nitrite and sulfite were characterized by linear scanning voltammetry (LSV). The optimized system conditions were as follows: GA concentration 1 mmol/L, incubation temperature 70 ℃, reaction time 60 min, pH6.0 phosphate buffer solution concentration 0.15 mol/L. The concentration of nitrite and sulfite in the range of 0.001 to 7 mmol/L showed a good linear relationship with the peak oxidation current (R2>0.994), and the detection limits were 0.20 μmol/L and 0.24 μmol/L (S/N=3), respectively. The modified electrode has good reproducibility and stability, and it can be used for the simultaneous determination of nitrite and sulfite in real samples.