Factors Affecting the Determination of Ammonia Nitrogen by Online Monitoring with Nessler’s Reagent Spectrophotometry
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Hello everyone, ammonia nitrogen is measured using an online testing instrument (Nessler’s reagent spectrophotometry). Samples were taken from the dilution combined tank, the hydrolysis-acidification tank, and Tank O; measurements showed that the ammonia nitrogen levels in the combined tank and the hydrolysis-acidification tank were significantly too low. However, the value for pool O is close to that measured by the national standard method. I don’t know the reason, but in 1. the PH comprehensive tank and hydrolysis-acidification tank, the pH of the water samples is 7.5–8, while it is neutral in tank O. However, research shows that acidic water samples can result in lower ammonia nitrogen levels. So, the effect of PH is ruled out. 2. Influence of substances in the water sample. No additional substances are added between these steps; oxygenation is increased in tank O. Question: Does the oxygen content affect the results of ammonia nitrogen measurement using this method? No information was found. Is it the influence of other substances in the water? I’d like to ask the friends from Sichuan – thank you! Also: Should my diluted sample be left for a while before testing, or should it be tested right after dilution (in terms of result accuracy)?
If nitrate bacteria are present and there is sufficient dissolved oxygen, at temperatures above 15°C, most of the ammonia nitrogen is oxidized to nitrate salts; when the concentration of organic matter is low, the removal rate of ammonia nitrogen exceeds 90%.
Thank you for your reply. However, that’s not where my problem lies.