Nitrogen is the major element next to
Carbon,hydrogen and oxygen and oxygen found in living things.Nitrogen occurs in amino acids,purine and pyrimidine bases,vitamins,amino sugars,alkaloids,
Compound ligids,etc.However,the major nitrogen source is proteins .A method for the quantitative determination of nitrogen in food is developed by johan kjeldahl.In modern times the Kjeldahl method is largely automated and makes use of specific catalysts to speed up the decomposition.The Kjeldahl method consists of three steps,which have to be carefully carried out in sequence