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Ethanol emulsion test for lipids

An emulsion test allows you to check whether a substance might be a lipid. The test uses the fact that lipids can dissolve in ethanol but not water:

  • Grind the sample and place in a clean, dry test tube.
  • Pour 95% ethanol into the tube. Shake vigorously.
  • Lipids can dissolve in ethanol but not water.

  • Pour this solution into another test tube of distilled water.

If the sample contains lipids, the lipids will form tiny lipid globules in the mixture called an emulsion. This appears as a cloudy white layer in the mixture.

If the mixture doesn't contain lipids, the mixture will stay colourless.

The cloudy white emulsion has a milky appearance.
The cloudy white emulsion has a milky appearance.