Biuret

The biuret test, also known as Piotrowski's test, is a chemical test used for detecting the presence of peptide bonds. In the presence of peptides, a copper(II) ion forms mauve-colored coordination complexes in an alkaline solution The deeper the purple color, the higher is the number of peptide-copper complexes.

Procedure:

1. Pour 5 mL of your test substance into a test tube.

2. Add 5 drops of Biuret reagent to your test tube. (Caution: Biuret reagent contains NaOH, a strong base. If spilled, wash off immediately with water. Call the teacher for assistance.) Biuret changes color to a blue/violet in the presence of proteins.

3. Gently shake/swirl the contents of the test tube. Look for any color change in the test substance.

4. Clean your test tubes thoroughly.

Sources:

Biuret Test for Protein: Biochemistry

Aryal

https://microbenotes.com/biuret-test-for-protein/