Water quality—Determination of Kjeldahl nitrogen
1 Subject content and application scope
1.1 Subject content
This standard specifies a method for the determination of nitrogen by a Kjeldahl-type method. It includes ammonia nitrogen and organic nitrogen compounds that can be converted into ammonium salts under these conditions. Such organic nitrogen compounds mainly refer to organic nitrogen compounds with negative trivalent state of protein, peptone, amino acid, nucleic acid, urea and other synthesized nitrogen. It does not include azide, diazo, azo, hydrazone, nitrate, nitroso, nitro, nitrite, nitrile, oxime and semi-carbazone nitrogen-containing compounds.
1.2 Application scope
This standard is applicable to the determination of Kjeldahl nitrogen in industrial wastewater, lakes, reservoirs and other polluted water bodies.
1.3 Determination range
When the content of Kjeldahl nitrogen is low, more samples are taken, digested and distilled, and finally ammonia is determined by spectrophotometry. When the content is higher, less samples are taken, and finally ammonia is determined by acid titration.
1 Subject content and application scope
2 Principle
3 Reagents
4 Apparatus
5 Sampling and sample storage
6 Procedure
7 Expression of results
8 Explanation of special circumstances
