Skip to main content
[ "article:topic", "showtoc:no", "license:ccbysa", "authorname:burrananddesrochers" ]
Biology LibreTexts

Part 3: Testing for lipids

  • Page ID
    16576
  • Testing for lipids

    A. Paper test

    Paper turns translucent (gets a grease spot) in presence of lipids

    Test samplesdistilled water, vegetable oil, cream, and unknown.

    1.  Put a drop of each substance on a brown paper towel.  Rub in the cream.

    2.  Put the towel off to the side and let it sit for 10 minutes.

    3. Record the appearance of the bag where you placed the spots in the table below.

    sample appearance after drying conclusion
    water    
    oil    
    cream    
    unknown    

    B. Sudan IV test

    Two layers form in presence of lipids.  Red dye concentrates in top layer.

    Test samplesdistilled water, vegetable oil, cream, and unknown.

    1. Label tubes

    2.  Add 3 ml (0.75 inch) distilled water to each tube

    3.  Add 3 ml (0.75 inch) of sample to the tube (total of 6 ml per tube)

    4.  Add 9 drops of Sudan IV and shake (must mix well)

    5.  Add 2 ml (0.5 inch) water

    6. Record results in the table below

    tube sample appearance after Sudan IV conclusion
    1 water    
    2 oil    
    3 cream    
    4 unknown