Question:easy
Ninhydrin test is used for the detection of?
Ninhydrin test is used for the detection of?
Show Hint
Ninhydrin gives Ruhemann's purple with the free alpha-amino group of amino acids.
Updated On: Jun 24, 2026
- Bile salts
- Amino acids
- Nucleic acid
- Lipids
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: Ninhydrin is a classic qualitative reagent, and the task is to recall what it lights up.
Step 2: When ninhydrin meets the free alpha-amino group of an alpha-amino acid, it strips the nitrogen and yields an intense blue-violet pigment, Ruhemann's purple. Imino acids like proline instead give a yellow shade.
Step 3: This makes ninhydrin the go-to spray for revealing amino acid spots after paper or thin layer chromatography, and it is even used to develop latent fingerprints owing to skin amino acids.
Step 4: The distractors each have their own chemistry: bile salts give the Pettenkofer reaction, nucleic acids respond to diphenylamine or orcinol, and lipids stain with Sudan dyes. So ninhydrin pins down amino acids.
\[\boxed{\text{Amino acids}}\]
Step 2: When ninhydrin meets the free alpha-amino group of an alpha-amino acid, it strips the nitrogen and yields an intense blue-violet pigment, Ruhemann's purple. Imino acids like proline instead give a yellow shade.
Step 3: This makes ninhydrin the go-to spray for revealing amino acid spots after paper or thin layer chromatography, and it is even used to develop latent fingerprints owing to skin amino acids.
Step 4: The distractors each have their own chemistry: bile salts give the Pettenkofer reaction, nucleic acids respond to diphenylamine or orcinol, and lipids stain with Sudan dyes. So ninhydrin pins down amino acids.
\[\boxed{\text{Amino acids}}\]
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