(i) Dumas method: A known mass of organic compound is heated with excess of CuO in an atmosphere of CO2, when nitrogen of the organic compound is converted into N2 gas, the volume of N2 gas thus obtained is converted into STP and the percentage of nitrogen is determined by the formula.
(ii) Kjeldahl's: A known mass of organic compound is heated with conc. H2SO4 in presence of K2SO4 and little CuSO4 or Hg in a long necked flask called Kjeldahl's flask. When nitrogen present in the compound is quantitatively converted into (NH4)2SO4.(NH4)2SO4 thus obtained is boiled with excess of NaOH solution to liberate NH3 gas which is absorbed in a known excess of a standard acid such as H2SO4 or HCl
