1. 4.1 (d) To conduct a qualitative test for protein

2. Before you start get or make a copy of this Table of results
Sample
Initial colour
Final colour
A – Protein solution
B – Water

3. Label two boiling tubes A and B.
Step 1
Label two boiling tubes A and B.

4. Place 2 ml of protein solution into tube A.
Step 2
Place 2 ml of protein solution into tube A.

5. Place 2 ml water into tube B.
Step 3
Place 2 ml water into tube B.

6. Add 2 ml of Biuret reagent into each tube.
Step 4
Add 2 ml of Biuret reagent into each tube.

7. Swirl both tubes. Observe colour change
Step 5
Swirl both tubes. Observe colour change

8. Expected Result
Positive: lilac / violet
Negative: blue

9. Step 6 Table of results: Sample Initial colour Final colour
A – Protein solution
B – Water

10. END