Ammonia 15N/50N/100N


Test Method Technical Information


Tests For: Ammonia in Natural, Sea and Wastewater
Test Range:0–15 mg/L (15N), 0–50 mg/L (50N), 100 mg/L (100N)
Reagent Chemistry Used: Nessler
Basis of Test Method: Standard Method 4500-Ammonia-C
Method Detection Limit/Limit of Quantification:

Test Range Method Detection Limit (MDL)* (mg/L) Limit of Quantification (LOQ)** (mg/L)
15N 0.10 0.32
50N 0.70 2.24
100N 1.02 3.05
*The Method Detection Limit (MDL) is defined as the minimum measured concentration of a substance that can be reported with 99% confidence to be different from the method blank results.
**The Limit of Quantification (LOQ) is the smallest quantity that can be detected with reasonable certainty for a given analytical procedure.

Testing for Ammonia

Ammonia occurs as a breakdown product of nitrogenous material in natural waters. It is also found in domestic effluents and certain industrial waste waters. Ammonia is harmful to fish and other forms of aquatic life and the ammonia level must be carefully controlled in water used for fish farms and aquariums. Ammonia tests are routinely applied for the monitoring of natural water, sea water; and for pollution control on effluents and waste waters.

The Palintest Tubetests Ammonia (Nessler) test provides a simple method of measuring ammonia (ammoniacal nitrogen) over the three ranges offered.

Reagent Chemistry

The Palintest Tubetests Ammonia (Nessler) tests iare based on the Nessler method. Nessler’s reagent (potassium tetraiodomercurate (II)) reacts rapidly with ammonia under alkaline conditions to form an orange-brown product. Turbidity due to hardness salts is prevented by adding the sample to a solution of Rochelle salt prior to adding the Nessler reagent.

The intensity of the colour produced in the test is proportional to the ammonia concentration and is measured using a Palintest Photometer.


Sufficient Rochelle salt is present to prevent turbidity due to at least 1,000 mg/L hardness.

The test can be used on sea or salt water without the need for pre-treatment of the sample.

Best Practice Advice for Testing

  • Nessler’s reagent is toxic. Handle with care. This reagent is for use in professional water testing applications only.
  • Nessler’s reagent is sensitive to air. Replace cap when not in use.
  • Used Ammonia (Nessler) tubes contain alkaline mercury salts – which are toxic. Care must therefore be exercised in their disposal. The tubes must be disposed of in accordance with current waste legislation and consent limits. Used tubes must always be treated using a proper waste disposal system.
  • Ammonia concentrations can be expressed in several different ways. The following factors may be used for the conversion of readings:
    To convert from N to NH4 – multiply by 1.3
    To convert from N to NH3 – multiply by 1.2

EPA, Definition and Procedure for the Determination of the Method Detection Limit, Revision 2, Dec 2016.
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”).