Determination of Nitrate Nitrogen in Water by UV-1100 Spectrophotometry - Master's thesis - Dissertation

This method is used to determine the concentration of nitrate nitrogen in water samples using spectrophotometry. The procedure involves preparing a series of standard solutions and comparing their absorbance with that of the sample solution. **Keywords**: Spectrophotometer; Nitrate Nitrogen in Water; Analytical Instrument; V-1100; V-1200 **Experimental Procedure**: 1. Take a 1.00 mL water sample and place it in a 50 mL colorimetric tube. 2. Prepare a set of standard solutions by adding different volumes (0.00, 0.05, 0.10, 0.30, 0.50, 0.70, and 1.00 mL) of nitrate nitrogen standard solution to separate 50 mL tubes and dilute each to 1.00 mL with distilled water. 3. Add 0.1 mL of ammonium sulfamate solution (20 g/L) to each tube, shake well, and let stand for 5 minutes. 4. Then add 0.2 mL of thymol ethanol solution (5 g/L), mix thoroughly, and add 2 mL of silver sulfate sulfuric acid solution (10 g/L). Let the mixture stand for another 5 minutes. 5. Add 8 mL of distilled water, mix again, and then add ammonia solution to achieve the deepest yellow color while dissolving any silver chloride precipitate. Finally, dilute to the 25 mL mark with distilled water and mix well. 6. Measure the absorbance at 415 nm using a 2 cm cuvette, with distilled water as the reference. 7. Calculate the concentration of nitrate nitrogen in the water sample using the formula: $ C_{NO_3^- - N} = \frac{m}{V} $ Where: - $ C_{NO_3^- - N} $ = mass concentration of nitrate nitrogen in water (mg/L) - $ m $ = measured mass of nitrate nitrogen (μg) - $ V $ = volume of the water sample (mL) **Note**: This method is commonly applied in environmental analysis and water quality testing. It is suitable for laboratories equipped with a spectrophotometer such as the V-1100 or V-1200 models.