Abstract:

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.

Key words: food, nitrite, iodine, starch