Chapter 27: Amino Acids, Peptides and Proteins
Ninhydrin Test
Amines (including
a
-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
a
-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.
