Rapid determination of nitrite in foods in acidic conditions by high‐performance liquid chromatography with fluorescence detection

In this study, a simple, rapid, and sensitive method for the determination of nitrite (NO₂^?) in food samples by high‐performance liquid chromatography with fluorescence detection in acidic conditions had been developed. The derivatization of the nitrite with 2,3‐diaminonaphthalene was performed in acidic conditions to yield the highly fluorescent 2,3‐naphthotriazole, which was directly analyzed by high‐performance liquid chromatography with fluorescence detection without adjusting the solution to alkaline. The analysis column was reversed‐phase C₈ column. A constant flow rate of 1.0 mL/min was employed using water/acetonitrile as the mobile phase in isocratic mode (70:30, v/v). Fluorescence was monitored with excitation at 375 nm and emission at 415 nm. The standard calibration curves were linear for nitrite in different matrixes in the concentration range of 0–100 μg/L, and the correlation coefficients ranged from 0.9978 to 0.9998. The limits of detection and quantification were in the ranges of 0.012–0.060 and 0.040–0.20 mg/kg, respectively. The recoveries of nitrite from samples spiked at three different concentrations were 74.0–113.2%, and the relative standard deviations of the recovery results (n = 6) were 1.67–10.8%. The proposed method has good repeatability and is very sensitive and simple. It has been successfully used to determine nitrite in foods.