Briefly explain how to test for protein in a given solution using the Biuret test.

To test for protein in a given solution using the Biuret test, you would first add a small amount of the solution to a test tube. Then, add a few drops of Biuret reagent to the test tube and mix gently. If protein is present in the solution, the mixture will turn from blue to purple. The intensity of the purple color can indicate the concentration of protein in the solution.

Biuret Test for Protein:

1. Add Sample to Solution: Add a small amount (1-2 drops) of the test solution to a test tube.

2. Add Biuret Reagent: Add 1-2 mL of Biuret reagent to the test solution. Biuret reagent contains copper sulfate and sodium hydroxide.

3. Mix: Gently mix the solution.

4. Observe Color Change:

- Positive Test: A violet to deep blue color develops, indicating the presence of protein.
- Negative Test: The solution remains colorless or slightly green, indicating the absence of protein.

Principle:

The Biuret test relies on the reaction between peptide bonds in protein molecules and copper ions in the Biuret reagent. This reaction forms a colored complex, producing the characteristic blue color. The intensity of the color change correlates with the concentration of protein in the solution.