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The Kjeldahl method for nitrogen estimation relies on converting organic nitrogen into . Which of thQualitative and Quantitative Analysis Chemistry Question

Question

The Kjeldahl method for nitrogen estimation relies on converting organic nitrogen into $(NH_4)_2SO_4$. Which of the following classes of organic molecules generally FAIL to yield their nitrogen quantitatively under standard Kjeldahl digestion conditions?

Answer: A,B,C

💡 Solution & Explanation

The Kjeldahl method does not accurately estimate nitrogen if the compound contains nitrogen in a ring (pyridine, quinoline), in a nitro or nitroso group, or in an azo or diazonium group, as these do not completely convert to ammonium sulphate upon boiling with concentrated $H_2SO_4$. Primary amines, however, are easily estimated.

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