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At room temperature ammonia (NH3) is a colorless, toxic gas. It is very soluble in water that turns increasingly into the ammonium ions (NH4+) as the pH decreases to less than 9.25, the pKa of ammonia/ammonium. To determine the ratio it is necessary to know the pH of the water and then use the Henderson-Hasselbach equation.
In nature, the level of ammonium in the water varies. Typically, in groundwater ammonium comes from the bacterial degradation of plants and animals. In surface waters, it can be indicative of pollution due to landfills or natural causes. In aquaculture ammonia/ammonium is monitored along with pH due to the toxicity of ammonia for fish. As pH increases above 8.25 the ammonium is converted to ammonia gas, which is more toxic than ammonium.
One of the main uses of ammonia is the production of nitric acid (HNO3). Ammonium is used in many applications, for example as a base for fertilizers, detergents, bleaching in the paper industry, and in hair dyes. It is also important to measure ammonium levels when disinfecting with chlorine (bleach) as free chlorine reacts with ammonium and organic compounds to form chlorine compounds. This results in diminished disinfecting capabilities compared with free chlorine. One of the main uses of ammonia is the production of nitric acid (HNO3). Ammonium is used in many applications, for example as a base for fertilizers, detergents, bleaching in the paper industry, and in hair dyes. It is also important to measure ammonium levels when disinfecting with chlorine (bleach) as free chlorine reacts with ammonium and organic compounds forming chlorine compounds. This results in diminished disinfecting capabilities compared with free chlorine.
The products on this page are for measuring ammonium ion activity in the field only. The ammonium ion activity is measured by liquid membrane ISE without an ISA. The ammonium ISE does not measure ammonia so at pH’s within 1 pH of the pKA ( > pH 8.25) there will be ammonia present that is not measured. The products found on the ammonia parameter page measure both species as ammonia. Portable and benchtop photometers can also display results as ammonia-nitrogen or ammonium. Methods available include both colorimetric and laboratory ISE measurements.
We offer multi-parameter, portable meters that measure pH, ORP, dissolved oxygen, conductivity, ammonium, chloride, and nitrate. The multi-parameter portables can be ordered with probes that can also measure turbidity and meters that have built-in GPS for data mapping.
The ammonium Ion-Selective Electrode (ISE) is a liquid membrane electrode. The ISE is used without an Ionic Strength Adjuster (ISA). The activity coefficient is based on typical surface water conductivity values. Water with very high conductivity will have a higher ion concentration due to other minerals being present. The actual measurement will be influenced by a change in ion activity. The ammonium ISE is specific for ammonium and at pH’s greater than 8.25 there will begin to be a shift to ammonia, which is not measured.
Solutions for ammonium measurement include ISE standards for calibration.
To empower customers to achieve quality
by supplying intuitive, accurate, and reliable analytical instruments with exceptional customer service and value.
We take pride in every product we build. From an original idea, to a completed product ready for testing. We oversee every aspect of the manufacturing process. It is this level of attention to detail that sets us apart.
To empower customers to achieve quality by supplying intuitive, accurate, and reliable analytical instruments with exceptional customer service and value.
We take pride in every product we build. From an original idea, to a completed product ready for testing. We oversee every aspect of the manufacturing process. It is this level of attention to detail that sets us apart.
To empower customers to achieve quality by supplying intuitive, accurate, and reliable analytical instruments with exceptional customer service and value.
We take pride in every product we build. From an original idea, to a completed product ready for testing. We oversee every aspect of the manufacturing process. It is this level of attention to detail that sets us apart.
