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Estimation of Nitrogen BY Kjeldahl Method

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The  Kjeldahl method  in  analytical chemistry  is a method for the quantitative determination of  nitrogen  contained in  organic substances  plus the nitrogen in inorganic ammonia and ammonium (NH 3 /NH 4 + ). Other forms of inorganic nitrogen, for instance  nitrate , are not included in this measurement. This method was developed by  Johan Kjeldahl  in 1883 The method consists of heating a substance with  sulphuric acid , which decomposes the organic substance by oxidation to liberate the reduced nitrogen as  ammonium sulphate . In this step  potassium sulphate  is added to increase the  boiling point  of the medium (from 337 °C to 373 °C) .  Chemical decomposition  of the sample is complete when the initially very dark-coloured medium has become clear and colourless. The solution is then distilled with a small quantity of sodium hydroxide, which converts the ammonium s...
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