Test for carbohydrates
Place 2cm cubed of the substance in a test tube.
Add two drops of iodine solution and shake.
The colour change to a blue-black colouration indicates the presence of carbohydrates.
Test for lipids
Add 5cm cubed of ethanol to 2cm cubed of the substance being tested.
Shake the tube to completely dissolve the lipid in the solution.
Add 5cm cubed of water and shake gently.
If the solution turns cloudy, a lipid is present.
Test for proteins
The test for proteins is called the Biuret test.
Add an equal amount of sodium hydroxide solution to the sample.
Add a few drops of dilute copper sulfate solution and mix gently.
A purple colouration indicates the presence of proteins.