How to test for lipids

Written by carrie perles | 13/05/2017

The two main ways to test for lipids in a sample substance is through the Sudan Red test and the Grease Spot test. Sudan Red is a dye that is lipid soluble. Therefore, when Sudan Red is added to a sample that contains lipids, the dye will colour the lipids red. The Grease Spot test can also be used identify the presence of lipids in a sample. Lipids make unglazed paper, such as the outside of a paper bag, translucent.

Things you need

  • Sample for Testing

  • Beakers or Droppers

  • Sudan Red

  • Brown Paper Bag

  • Oil

  • Water

Use a cotton swab to apply a few drops of the sample to the paper bag.

Allow the sample to dry on the bag for several minutes.

Hold the paper bag up to a light after the sample has dried completely. If a grease spot remains, the sample contains lipids.

Measure 2ml of oil and 2ml of water.

Add the oil and water to the test tube.

Add 3 drops of Sudan Red.

Shake the test tube and observe. The Sudan Red will colour any lipids in the sample.

Tips

  • During the Grease Spot test, make sure to allow all spots to dry thoroughly. Otherwise, you may think that a wet spot is really a grease spot.

Warnings

  • Be careful with the Sudan Red, because it can stain clothing.

Tips and Warnings

  • During the Grease Spot test, make sure to allow all spots to dry thoroughly. Otherwise, you may think that a wet spot is really a grease spot.
  • Be careful with the Sudan Red, because it can stain clothing.

Things you need

  • Sample for Testing
  • Beakers or Droppers
  • Sudan Red
  • Brown Paper Bag
  • Oil
  • Water

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