Chapter 27: Amino Acids, Peptides and Proteins

Ninhydrin Test

• Amines (including α-amino acids) react with ninhydrin to give a coloured product.
• It can be used qualitatively (e.g. for chromatographic visualisation) or quantitatively (e.g. for peptide sequencing).
• The α-amino acids typically give a blue-purple product.
• Proline, a secondary amine, gives a yellow-orange product.
• The test is sensitive enough that ninhydrin can be used for the visualisation of fingerprints.

© Dr. Ian Hunt, Department of Chemistry