How to Determine Ammonia Nitrogen (TAN) using Salicylate Method

Ammonia nitrogen (TAN), a major pollutant in wastewater, consists of non-ionized ammonia (NH3) and ammonium ions (NH4 +), which are pH- and temperature-dependent. To determine its presence in water is important because of its harmful effects on both humans and aquatic organisms.

In the nitrogen cycle with sufficient oxygen, ammonia nitrogen can be converted into nitrite and nitrate, which may cause cancer in the human body. Dissolved ammonia can also be toxic to fish, and discharge of ammonia nitrogen into the water may lead to eutrophication and reduction of the amount of dissolved oxygen. Either case may result in aquatic organisms' deaths.

Using Salicylate method to determine Ammonia nitrogen (TAN)

In the Salicylate method, Ammonia compounds are initially combined with hypochlorite to form monochloramine (1), which then reacts with salicylate to form 5-aminosalicylate (2)

Ammonia Nitrogen Using Salicylate Method

Oxidation of 5-aminosalicylate is carried out in the presence of a catalyst, nitroprusside or Fe(CN)5NO2– (also called nitroferricyanide), which results in the formation of indosalicylate, a blue-colored compound. The blue color is masked by the yellow color (from excess nitroprusside) causing a green-colored solution. The intensity of the color is directly proportional to the ammonia concentration in the sample.

Ammonia Nitrogen Using Salicylate Method

Steps of Salicylate method

Using Rocker WD 100 Reader and HACH Nitrogen-Ammonia Reagent Set, TNT, AmVer (Salicylate) as an example.

  1. Select the appropriate concentration (LR: 0.02-2.5 mg/L ; HR: 0.4-50 mg/L) of reagent according to the NH3-N concentration of the sample.
  2. Add sample to reagent vial as the test sample. Adding volume is suggested as: LR: 2 ml, HR: 0.1 ml.
  3. Add Ammonia Salicylate and Ammonia Cyanurate powder pillow into each vial.
  4. Close the vials and shake until all powders are finely dissolved.
  5. Wait 20-min for reaction to complete.
  6. Insert the sample vial into the W100 colorimeter and get results.

W100 Multiparameter Colorimeter

W100 Multiparameter Colorimeter

  • Supports COD, Total Phosphorus, Total Nitrogen, and Total Ammonia Nitrogen reading
  • Ideal for multiple users
  • Fast detection
  • High-efficiency measurement
  • User-friendly setting
  • CE certification

 

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