Test for Lipids

Edexcel AS-level BiologyBiological MoleculesLesson 16 of 25

Lipids are detected with the emulsion test. It relies on the fact that lipids dissolve in ethanol but not in water.

Method:
1. Add about 2 cm³ of ethanol to the sample in a clean, dry test tube (crush a solid sample first).
2. Shake thoroughly so that any lipid dissolves in the ethanol.
3. Pour the ethanol solution into a second test tube containing about 2 cm³ of water, and shake gently.

Result: if lipid is present, a cloudy white emulsion forms. If there is no lipid, the mixture stays clear.

More in Biological Molecules

• Fatty Acids and Glycerol
• Triglycerides
• Phospholipids
• Unit Membrane
• Amino-acids
• Hydrogen Bonding
• Disulfide Bridges
• Ionic Bonds

All 25 lessons in Biological Molecules · All Edexcel AS-level Biology topics