Sakaguchi test: Objective, Principle, Reagents, Procedure and Result




Sakaguchi test: Objective, Principle, Reagents, Procedure and Result

Objective:

  • to detect amino acid gauanidium group [R-NH-C= (NH2)2+-NH2]. i.e arginine

Principle of Sakaguchi test:

This test is specific for arginine because this reaction is given by guanidinium compound. The arginine reacts with α – napththol and an oxidizing agent  such as bromine water or sodium hypochlorite/sodium hypobromite to give a red colored product. The other guanidinium containing compounds other than amino acid also give this reaction.

Reagents:

  • test solution: 1 % arginine, 1 % glycine, 5 % egg white (albumin)
  • 1 % α naphthol in alcohol
  • Sodium hypochlorite
  • 1 % urea solution
  • Dry test tubes
  • Pipettes

Procedure of Sakaguchi test

  1. Take 1ml test solution in dry test tube.
  2. Similarly, take 1ml distilled water in another test tube as control.
  3. Add 2 drops of α naphthol and mix well.
  4. Now add 2ml sodium hypochlorite to all test tubes.
  5. Immediately add 1ml of urea solution to establish the red complex formed.

Result interpretation:

  • Positive sakaguchi test: Red color ( Arginine)
  • Negative sakaguchi test: no red color ( glycine, albumin)

Sakaguchi test: Objective, Principle, Reagents, Procedure and Result