The Ninhydrin Test
Shows positive test for:
Alpha amino acids and proteins that contain free amino acid groups
How to perform the test:
Prepare a solution or suspension of the sample by placing ~0.2 g in 10 ml of water. Three drops of 1% solution of ninhydrin in ethanol is added to 1 ml of the solution and the solution heated for five minutes in a boiling water bath.
A positive test is indicated by:
the formation of red, blue or purple color.
a negative test (left) and a positive test (right)