Kinetic-spectrophotometric determination of trace amounts of nitrite ion based on its reduction reaction with thionine in adidic media

A simple, sensitive and rapid method for determination of traceamounts of nitrite ion in real samples is reported. The reaction is initiated byadding known volumes of a nitrite ion solution of identified concentration toacidic solutions of thionine which causes decolorization of reagent with time. Theabsorbance changes is then monitored spectrophotometrically at lmax = 602 nmat 25 ـC. Calibration curve is linear in the range 0. 005-1. 500 mg mL-1 of nitriteion. Many of cations and anions have no interfering effect but iodide, Mo (VI), W (VI) and S2O32- ions do interfere. The effect of interfering ions have been elimi-nated by the use of proper masking agents. This method was used to determinenitrite ion concentration in Karoon river water and foodstuffs such as susages.