Experiment 23 Determination of Nitrate in Drinking Water by UV Spectrophotometry

Experiment 23 Determination of Nitrate in Drinking Water by UV Spectrophotometry 

Your instructor has prepared a 50 ppm stock solution of nitrogen in water by dissolving 0.361 g of KN03 in 1000 mL of solution. 

Prepare calibration standards that are 0.5, 1.0, 3.0, 5.0, and 10.0 ppm N in 50-mL volumetric flasks by diluting the stock standard with distilled water. After diluting to the mark, pipet 1.0 mL of 1 N HC1 into each flask and shake well. 

Filter the water samples if necessary. Then prepare them for measurement by adding 1 mL of 1 N HC1 to 50 mL of each. This can be done by filling (rinse first) 50-mL volumetric flasks with the samples to the 50-mL mark and then pipetting 1.0 mL of the HCl into these flasks. Shake well. Prepare the control sample and a blank (distilled water) in the same way as the samples. 

Zero the UV spectrophotometer with the blank at 220 nm. Measure all solutions (calibration standards, unknowns, and control) as follows using quartz cuvettes. Measure the absorbances at 

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