Spectrophotometric Determination of Nitrite and Nitrate in Water, Meat and Vegetables

Spectrophotometric Determination of Nitrite and Nitrate in Water, Meat and Vegetables

Abdulla Fathe Eid Abdulla Fathe Eid Supervisors Dr. Nidal A. Zatar  Prof. Maher A. Abu-Eid 1998 A method for spectrophotometric determination of nitrite and nitrate in water, meat and vegetables is described. This method is based on the reduction of phosphomolybdic acid to phosphomolybdenum blue complex by sodium sulfide. The obtained phospholybdenum blue complex is oxidized by the addition of nitrite causing a reduction in the intensity of the blue color. The decrease in the absorbance of the blue color is found to be directly proportional to the concentration of nitrite present. The absorbance of the phospholybdenum blue complex is monitored spectrophotometrically at 814 nm and related to the concentration of nitrite present.  On the other hand nitrate can be reduced to nitrite using modified jones reductor and determined using the same procedure as for nitrite.  The effect of different factors such as: acidity, stability of the complex, time, temperature, phosphate concentration, molybdenum concentration, sodium sulfide concentration and the tolerance amount of other ions have been reported.  Maximum absorbance amount of other ions have been reported.  Maximum absorbance is a 814 nm and Beer's law is obeyed over the range 0.23-3.00 ppm with molar absorptivitiy of 1.1X1041.mol-1.cm-1 and relative standard deviation of 2.60% for five measurements.  The method is applied for determination of nitrite and nitrate in water, meat products and vegetables. Zajel / An-Najah National University