Which of the following tests cannot be used for identifying amino acids?
Show Hint
- Ninhydrin test
- Barfoed test
- Xanthoproteic test
- Biuret test
The Correct Option is B
Solution and Explanation
Xanthoproteic test: amino acids with an aromatic ring (Tyr, Phe, Trp) give yellow/orange colour with conc. HNO3.
Biuret test: gives violet colour with peptide bonds / proteins; it is conventionally listed among the tests used for amino acids and proteins.
Barfoed test: copper acetate in acetic acid, used to distinguish reducing monosaccharides from disaccharides. It has nothing to do with amino acids.
Answer: (2) Barfoed test
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