4.1 (d) To conduct a qualitative test for protein

Before you start get or make a copy of this Table of results SampleInitial colourFinal colour A – Protein solution B – Water

Step 1 Label two boiling tubes A and B.

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

Step 3 Place 2 ml water into tube B.

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

Step 5 Swirl both tubes. Observe colour change

Expected Result Positive: lilac / violet Negative: blue

Step 6 Table of results: SampleInitial colourFinal colour A – Protein solution B – Water

END