Test Ammonia Levels in Water
Method of measuring ammonia nitrogen in water
There are various methods to know the ammonia nitrogen content in water. One is the Nasser reagent spectrophotometry. Take an appropriate amount of water sample first. If the water sample is turbid or colored, it needs to be pretreated to remove interference. Add an appropriate amount of potassium sodium tartrate solution, which can mask metal ions such as calcium and magnesium. After dripping the Nasser reagent, ammonia will react with the Nasser reagent to form a yellow-brown complex. Set a spectrophotometer to measure its absorbance at a specific wavelength, and according to the standard curve prepared in advance, the ammonia nitrogen content can be calculated.
The second is the salicylic acid-hypochlorite spectrophotometry. After the water sample is properly treated, add an appropriate amount of sodium hydroxide to adjust the pH. Add salicylic acid and sodium hypochlorite solution in turn. Ammonia reacts with salicylic acid and hypochlorite under the catalysis of sodium nitroso ferricyanide to form a blue compound. Similarly, use a spectrophotometer to measure the absorbance at the corresponding wavelength, and obtain the ammonia nitrogen concentration from the standard curve.
There is a titration method. After the water sample is pretreated, add an appropriate amount of magnesium oxide to make it slightly alkaline, heat distillation, ammonia escapes with water vapor, and is absorbed in boric acid solution. After distillation, titrate the absorption solution with sulfuric acid standard solution, and indicate the end point with a mixed indicator of methyl red and methylene blue. According to the dosage of sulfuric acid standard solution, the ammonia nitrogen content can be known by calculation.
The above methods have their own advantages and disadvantages. The Nessler reagent spectrophotometry is relatively simple to operate and has high sensitivity. However, mercury salts are toxic, so the waste liquid needs to be properly disposed of. The salicylic acid-hypochlorite spectrophotometry has no worries about mercury pollution, and the sensitivity is also good, but the stability of the reagent is slightly inferior. The titration method is suitable for water samples with high ammonia nitrogen content, which does not require high equipment, but the operation is slightly complicated and easily disturbed. In practical application, when the appropriate method is selected to measure ammonia nitrogen in water according to the characteristics of the water sample, analytical requirements and laboratory conditions.
There are various methods to know the ammonia nitrogen content in water. One is the Nasser reagent spectrophotometry. Take an appropriate amount of water sample first. If the water sample is turbid or colored, it needs to be pretreated to remove interference. Add an appropriate amount of potassium sodium tartrate solution, which can mask metal ions such as calcium and magnesium. After dripping the Nasser reagent, ammonia will react with the Nasser reagent to form a yellow-brown complex. Set a spectrophotometer to measure its absorbance at a specific wavelength, and according to the standard curve prepared in advance, the ammonia nitrogen content can be calculated.
The second is the salicylic acid-hypochlorite spectrophotometry. After the water sample is properly treated, add an appropriate amount of sodium hydroxide to adjust the pH. Add salicylic acid and sodium hypochlorite solution in turn. Ammonia reacts with salicylic acid and hypochlorite under the catalysis of sodium nitroso ferricyanide to form a blue compound. Similarly, use a spectrophotometer to measure the absorbance at the corresponding wavelength, and obtain the ammonia nitrogen concentration from the standard curve.
There is a titration method. After the water sample is pretreated, add an appropriate amount of magnesium oxide to make it slightly alkaline, heat distillation, ammonia escapes with water vapor, and is absorbed in boric acid solution. After distillation, titrate the absorption solution with sulfuric acid standard solution, and indicate the end point with a mixed indicator of methyl red and methylene blue. According to the dosage of sulfuric acid standard solution, the ammonia nitrogen content can be known by calculation.
The above methods have their own advantages and disadvantages. The Nessler reagent spectrophotometry is relatively simple to operate and has high sensitivity. However, mercury salts are toxic, so the waste liquid needs to be properly disposed of. The salicylic acid-hypochlorite spectrophotometry has no worries about mercury pollution, and the sensitivity is also good, but the stability of the reagent is slightly inferior. The titration method is suitable for water samples with high ammonia nitrogen content, which does not require high equipment, but the operation is slightly complicated and easily disturbed. In practical application, when the appropriate method is selected to measure ammonia nitrogen in water according to the characteristics of the water sample, analytical requirements and laboratory conditions.

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