ARGININE TEST (Test for Guanidine Group):

Significance:

Arginine test is specific for Arginine and indicates the presence of guanidine group in the arginine molecule.

Reagents:

• Protein solution
• 5% sodium hydroxide
• 1% alcoholic α-naphthol
• sodium hypobromite (NaOBr)

PROCEDURE:

• Take 1 ml of original solution (protein solution) in a test tube.
• Add 1 ml of 5% sodium hydroxide to the test tube.
• And add 2 drops of 1% alcoholic α-naphthol.
• Mix it and add 3 drops of sodium hypobromite (NaOBr) reagent.
• Mix it thoroughly.
• A bright red colour is formed. This confirms the presence of arginine.

Observation:

When bright red colour forms, it mean arginine is present in the solution.

Precautions:

• Wash the apparatus before and after the experiment.
• Carefully handle all the chemicals while performing the experiment.