How to test for lipids

Written by carrie perles Google
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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.

Skill level:

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Things you need

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

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  1. 1

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

  2. 2

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

  3. 3

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

  1. 1

    Measure 2ml of oil and 2ml of water.

  2. 2

    Add the oil and water to the test tube.

  3. 3

    Add 3 drops of Sudan Red.

  4. 4

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

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.

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