Ninhydrin Test

Ninhydrin Test
• A biochemical test for detecting amino acids and proteins.
• Reacts with free amino groups to produce a colored compound.
Principle
• Ninhydrin reacts with α-amino acids to form a deep blue or purple complex called Ruhemann’s purple.
• Involves decarboxylation and deamination of the amino acid, releasing CO₂ and ammonia.
Reagents Required
1. Ninhydrin solution (0.1% in ethanol or acetone).
2. Buffer solution (optional, to maintain pH).
3. Distilled water.
Procedure
1. Add 1 mL of test solution (containing the amino
acid or protein) in a test tube.
2. Add 1 mL of ninhydrin reagent to the solution.
3. Heat the mixture in a boiling water bath for 2-3 minutes.
4. Observe the color change after cooling.
Observation
• Positive test: Appearance of a purple or blue color indicates the presence of free amino groups.
• Negative test: No color change or light yellow color indicates the absence of free amino groups.
Applications
1. Detection of amino acids in samples.
2. Qualitative analysis of proteins.
3. Used in forensic science to detect fingerprints (amino acids in sweat).

[@jayprakashbind8566]

Well explanation sir 😊