A New Determination Method of Nitrite in Foods

Nitrite(NO2) can oxidize potassium iodide(KI) reagent into iodine(I2) under acidic condition,and I2 can react with starch into iodine-starch blue color complex.Consequently,based on these reactions a new absorption photometry was established for determining nitrate in the food.The experimental results showed that the optimum reaction conditions are as follows:pH 5,1.0×10-2 g/ml KI solution 10 ml,0.3% starch solution 3 ml and reaction time 6 min,and the maximum absorption wavelength of iodine-starch blue color complex is 540 nm.Under these above conditions,the linear range of this new method is 8.0×10-4 to 7.0×10-6 g/ml,the detection limit of nitrite is 5.0×10-8 g/ml and the relative standard deviation is 0.7%.Therefore,this new method is simple,rapid,sensitive and accuracy,and has enormous application value in food safety determination.