2879200 Free Ammonia Reagent Set, 0.01-0.50 mg/L NH₃-N

Free Ammonia Reagent Set measures free ammonia nitrogen in the range of 0.01-0.50 mg/L NH₃-N and monochloramine 0.04-4.50 mg/L Cl₂ in finished chloraminated water. The product uses Indophenol method (10200). Article 2879200 can be used to conduct analysis of 50 samples. The product can be evaluated using all Hach instruments except DR820.

Free Ammonia Reagent Set includes:

• Free Ammonia Chlorinating Reagent Solution (p/n 2877436)
• Monochlor F Reagent Powder Pillows (p/n 2802299)

Before starting analysis:

• It is required to collect the sample in clean glass bottles.
• It is recommended to analyze the sample immediately after collection.
• It is necessary to measure the reagent blank value for each new reagent lot.

Procedure for NH₃-N measurement

Add 10ml of the collected sample in two sample cells. Label the first sample сell as monochloramine cell and the second sample cell as free ammonia cell. Insert the monochloramine cell in the spectrophotometer or colorimeter and select ZERO. Remove the monochloramine cell and pipet one drop of Free Ammonia Chlorinating Solution to the free ammonia cell. Close and invert free ammonia cell several times. After that add Monochlor F Reagent Powder Pillow to each sample cell. Install the stopper and shake the content of each sample cell. After 5 minutes, insert the monochloramine cell into the cell holder and press READ. Remove the monochloramine cell, insert free ammonia cell in the instrument and push READ.

Summary of method

Added hypochlorite combines with free ammonia forming more monochloramine. In the presence of a cyanoferrate catalyst, monochloramine in the sample enters into reaction with substituted phenol forming intermediate monoimine compound. The intermediate couples with excess substituted phenol forming green-colored indophenol that is proportional to the amount of monochloramine present in the sample. Free ammonia is determined by comparing the color intensities, with and without added hypochlorite.