BATCH AND FLOW INJECTION SPECTROPHOTOMETRIC DETERMINATION OF NITRITE AND NITRATE IN WASTEWATER SAMPLES OF ERBIL CITY

Two simple and direct batch spectrophotometric methods for the determination of nitrite and nitrate and two simultaneous spectrophotometric flow injection methods developed for the determination of nitrite and nitrate in wastewater samples. The methods based on the direct reaction between nitrite with barbituric acid (BBA) and/or thiobarbituric acid (TBA) and the absorbance's are measured at 536 and 589 nm respectively. The reaction is selective for nitrite and provides a basis for a new spectrophotometric determination. In Batch method nitrate was reduced to nitrite using Jones reductor and analyzed as nitrite, while simultaneous flow system based on on-line nitrate reduction using Jones reductor column. The optimized chemical and physical conditions gave linear calibration range between 1.3-53 and 0.3-40 μg/ml using BBA and TBA in batch method, and gave linear range between 6.5-43 and 3.0-40 μg/ml using BBA and TBA in flow injection method. The methods developed were applied to the determination of nitrite and nitrate in waste water samples of Erbil city. Keywords: Spectrophotometric; Batch; Flow injection analysis; Nitrite, Nitrate; Simultaneous determination; Wastewater