Which of the following compounds is strictly UNSUITABLE for the estimation of nitrogen using Kjeldah — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Kjeldahl's method is not applicable to compounds where nitrogen is part of a heterocyclic ring (like Pyridine or Quinoline), or present in nitro ($-NO_2$), nitroso ($-NO$), or azo ($-N=N-$) groups. In these structures, the nitrogen is not quantitatively converted to $(NH_4)_2SO_4$ upon digestion with concentrated $H_2SO_4$.