Total Kjeldahl Nitrogen
Encyclopedia
Total Kjeldahl Nitrogen or TKN is the sum of organic nitrogen
, ammonia
(NH3), and ammonium
(NH4+) in the chemical analysis of soil, water, or wastewater (e.g. sewage treatment plant effluent). To calculate Total Nitrogen (TN), the concentrations of nitrate-N and nitrite-N are determined and added to TKN.
TKN is determined in the same manner as organic nitrogen
, except that the ammonia is not driven off before the digestion step.
The original TKN method was developed by the Danish chemist Johan Kjeldahl
in 1883. Today, TKN is a required parameter for regulatory reporting at many plants but is also used to provide a means of monitoring plant operations.
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
(NH3), and ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
(NH4+) in the chemical analysis of soil, water, or wastewater (e.g. sewage treatment plant effluent). To calculate Total Nitrogen (TN), the concentrations of nitrate-N and nitrite-N are determined and added to TKN.
TKN is determined in the same manner as organic nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, except that the ammonia is not driven off before the digestion step.
The original TKN method was developed by the Danish chemist Johan Kjeldahl
Johan Kjeldahl
Johan Gustav Christoffer Thorsager Kjeldahl , was a Danish chemist who developed a method for determining the amount of nitrogen in certain organic compounds using a laboratory technique which was named the Kjeldahl method after him....
in 1883. Today, TKN is a required parameter for regulatory reporting at many plants but is also used to provide a means of monitoring plant operations.