In the field of analytical chemistry, Nitrogen determination comes with a long history. The Kjeldahl method was introduced in 1883 first by Johan Kjeldahl. He developed a faster and much more accurate method to determine the content of nitrogen while studying protecting during malt production compared to the then existing methods. The Kjeldahl Analysis method is known for its extreme versatility as it can take care of a complete range of samples ranging from beverages, food & feed, chemical, pharmaceutical industries and environmental. In the modern days, Kjeldahl nitrogen is a needed parameter for regulation reports at various water treatment plants. As a surrogate for protein in food samples, Total Kjeldahl nitrogen is used.
Main steps of the Kjeldahl analysis
The nitrogen in organic samples is decomposed with the help of a concentrated acid solution. By boiling a homogenous sample inside concentrated sulphuric acid, this is achieved. Finally, an ammonium sulfate solution is obtained.
In this process, an excess base is added to the acid digestion mixture for converting NH4+ to NH3 which is followed by condensation and boiling of the ammonia NH3 gas in a receiving solution.
For measuring the amount of ammonia inside the receiving solution, titration is done.
In the modern days, several scientific associations have given approval to the Kjeldahl method like the AACC (Association of American Cereal Chemists), AOAC International (Association of Official Analytical Chemists), ISO (International Standards Organization), EPA (Environmental Protection Agency), and others.
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