Advanced Techniques of Analytical Chemistry

Kjeldahl Method

Author(s): Kamya Goyal*, Navdeep Singh, Shammy Jindal, Rajwinder Kaur, Anju Goyal and Rajendra Awasthi

Pp: 105-112 (8)

DOI: 10.2174/9789815050233122010011

* (Excluding Mailing and Handling)


This method was introduced by Johan Kjeldahl in 1883 for the quantitative
estimation of nitrogen in a compound which becomes a classical and widely employed
method in analytical chemistry and has been extensively utilized from over more than
130 years. The presence of nitrogen in organic compounds and in other protein
materials was identified by this technique. The amount of protein was calculated from
the different varieties of material including food for human beings, some fertilizers,
fossil fuels and other water waste. The process in this method to oxidize the
compounds containing carbon dioxide or hydrogen atoms are changed in water. The
ammonium ions are further transformed into ammonia gas when they dissolve in
oxidized solution. The three step principle was describing the process of nitrogen
estimation, in which the first step is digestion, which deals with the conversion of
nitrogen in the food material into ammonia. In second step, the process of
neutralization started, in which ammonium sulphate changed into ammonia gas. The
third last step of titration was started and a suitable indicator was used to detect the end
point of reaction. The first step in the procedure of this method is digestion and this
process was done for at least 60-90 minutes. The second step deals with the distillation
process in which the nitrogen is separated and the third step deals with the titration in
the presence of acid and this will give us the determination of ammonia compound in
the sample. In this chapter, we highlight the basic fundamentals, principle, procedure,
applications and also recent advancements were covered.

Keywords: Ammonia, Applications, Catalyst, Digestion Flask, Distillation, Fertilizers, Fossil fuels, Human food, Hydrogen ion concentration, Indicator, Johan Kjeldahl, Kjeldahl method, Neutralization, Nitrogen Estimation, Principle, Procedure, Protein, Recent advancements, Titration, Waste water.

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