What type of organic compounds cannot be Kjeldahlised ?

Explanation

**Step-by-Step Solution:**

1. **Understanding Kjeldahlization**: The Kjeldahl method is a chemical procedure used to determine the nitrogen content in organic compounds. It involves converting nitrogen in the sample into ammonium sulfate, which can then be quantified.

2. **Identifying Organic Compounds**: Organic compounds can be classified based on their structure and functional groups. Some contain nitrogen atoms, which is relevant for the Kjeldahl method.

3. **Compounds That Cannot Be Kjeldahlized**:
- **Nitrogen-Containing Rings**: Organic compounds that have nitrogen atoms incorporated into a ring structure (e.g., pyridine, pyrrole) cannot be effectively Kjeldahlized. This is because the nitrogen in the ring is not readily converted into ammonium sulfate.
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