What is ammonia nitrogen in water and how should it be measured

Nitrogen in water bodies is the culprit of eutrophication, so it is often the focus of scientific research and engineering technology in the water pollution control industry, and its importance is no less than that of organic pollutants. 1. What is ammonia nitrogen? Ammonia nitrogen refers to ammonia in the form of free ammonia (or non-ionic ammonia, NH3) or ionic ammonia (NH4+). The higher the pH, the higher the proportion of free ammonia; conversely, the higher the proportion of ammonium salts. Ammonia nitrogen is a nutrient in water, which can lead to eutrophication. It is the main oxygen-consuming pollutant in water and is poisonous to fish and some aquatic organisms. The main harmful effect of ammonia nitrogen on aquatic organisms is free ammonia, which is dozens of times more toxic than ammonium salt, and increases with the increase of alkalinity. The toxicity of ammonia nitrogen is closely related to the pH value and water temperature of the pool water. In general, the higher the pH value and water temperature, the stronger the toxicity. Two colorimetric methods of approximate sensitivity commonly used to determine ammonia are the classic Nessler's reagent method and the phenol-hypochlorite method; titration and electrode methods are also commonly used to determine ammonia; distillation can also be used when the ammonia nitrogen content is high -titration. (The national standard includes Nessler's reagent method, salicylic acid spectrophotometry, distillation-titration method) 2. What instrument should be used to measure ammonia nitrogen in water? In the presence of an alkaline environment and a sensitizer, the ammonia nitrogen in the form reacts with a salicylic acid chromogenic reagent to form a colored complex. The analyzer detects the color change and converts the change into ammonia The ammonia value is output. The amount of colored complex generated is equivalent to the amount of ammonia nitrogen. Technical parameters Method basis: Salicylic acid spectrophotometry Execution standard: HJ101-2019 Measuring range: (0-500) mg/L (expandable) lower limit of quantification: ≤0.15mg/L (indication error ± 30%) low concentration Drift: ≤0.02 mg/L High concentration drift: ≤1.0% Indication error: When the standard solution concentration is 2.0 mgL: ±8.0% When the standard solution concentration is 5.0 mgL: ±5.0% When the standard solution concentration is 8.0 mg/L: ±3.0% memory effect When the concentration of the standard solution is 2.0 mgL: ±0.3 mg/L When the concentration of the standard solution is 8.0 mgL: ±0.2 mg/L The actual water sample is compared to the concentration of the test water sample<2.0 mg/L: ≤0.2 mg/L Water sample concentration ≥2.0 mg/L: ≤10.0% Extended range performance: indication error: ±3.0%, repeatability: ≤5.0%, high concentration drift: ≤2.0% repeatability : ≤2%PH interference experiment: ±6.0% Measuring period: The measuring period is 20 minutes, according to the site environment, the color development time can be modified arbitrarily within 5-120min Sampling period: time interval (109999min arbitrarily adjustable) and whole point measurement mode . Calibration cycle: 1 to 99 days, any interval, any time, adjustable maintenance cycle:>720h/time output: RS-232, RS-485, 4-20mA (optional) Environmental requirements: Indoors with adjustable temperature, the recommended temperature is +5 ~ 28°C; humidity ≤ 90% (no condensation) Power supply: AC220 soil 10%V, 50±10%Hz, 5A