A Highly Sensitive and Selective Spectrofluorimetric Method for the Determination of Nitrite in Food Products

This paper describes a simple, sensitive, and selective spectrofluorimetric method to determine trace amount of nitrite in food products using 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate (DAF-FM DA) as a fluorescent probe. The reaction of DAF-FM DA with nitrite in acidic medium resulted in triazolofluorescein (DAF-FM T), a highly fluorescent reagent in neutral medium. The fluorescence enhancement was proportional to nitrite concentration in the range of 5.0 × 10−8 to 1.5 × 10−6 mol L−1 with a detection limit of 3.3 × 10−8 mol L−1 (S/N = 3). The proposed method has been applied to the determination of nitrite in real food samples, with relative standard deviation (RSD) (n = 6) less than 5.1 % and recoveries in the range of 86.4 ~ 102.9 %.