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 color 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.
- Sample for Testing
- Beakers or Droppers
- Sudan Red
- Brown Paper Bag
- Oil
- Water
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Instructions
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1
Use a cotton swab to apply a few drops of the sample to the paper bag.
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2
Allow the sample to dry on the bag for several minutes.
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3
Hold the paper bag up to a light after the sample has dried completely. If a grease spot remains, the sample contains lipids.
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4
Measure 2ml of oil and 2ml of water.
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5
Add the oil and water to the test tube.
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6
Add 3 drops of Sudan Red.
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7
Shake the test tube and observe. The Sudan Red will color any lipids in the sample.