This oxidation requires that dissolved oxygen be available in the water. Ammonia is an additional source of nitrogen as a nutrient which may contribute to the expanded growth of undesirable algae and other forms of plant growth that overload the natural system and cause pollution. The range is dependent on the path length used. The range listed above is based on a path length of 1.8 cm. Method Ammonia forms a colored complex with Nessler's Reagent in proportion to the amount of ammonia present in the sample.
Rochelle salt is added to prevent precipitation of calcium or magnesium in undistilled samples.
Interferences Sample turbidity and color may interfere. Turbidity may be removed by a filtration procedure. A calibration curve must be generated using this LaMotte reagent system before testing. See Creating a Calibration Curve instructions for directions. Procedure Set colorimeter or spectrophotometer to a wavelength of 420 nm.