KJELDAHL METHOD process,formula,limitations

 Kjeldahl’s method: 

Kjeldahl  method purpose :

This method can be used for Estimation of Nitrogen in a given Compound.

Kjeldahl's  method procedure:

In Kjeldahl method, Nitrogen is converted into Ammonia. Ammonia produced is directly proportional to Nitrogen.During this conversion, CuSO4 used as Catalyst

17 gram of Ammonia = 14 gram of Nitrogen

Ammonia is quantitatively calculated by using Acid  with known concentration

(N*V) Acid = (N * V) Base 

LIMITATIONS of Kjeldahl's Method:

Kjeldahl  method can't detect Nitrogen in,

(i) organic compounds containing nitrogen in the ring such as pyridine, quinoline, etc.

(ii) Organic compounds containing nitrogen (–NO2) and diazo (–N = N–) groups.