Lesson 8 : Laboratory Tests for Lipids Flashcards
Lipids are __________________ that encompass ___________ and ____________ such as _________, ____________, ____________, and _____________.
amphipathic molecules
fatty acids
derivatives
diglycerides, triglycerides, phospholipids and cholesterol
Roles of Lipid in the body
- Provide energy for the body
- Act as chemical messenger
- Involved in the maintenance of body temperature
- Involved in membrane layer formation
- Involved in the formation of prostaglandins and mediation of inflammation
Categories of Lipids
Triglycerides
Phospholipids
Steroids
Waxes
Principle in Lipids
Many Phospholipids are __________ in ___________ and they __________ out where as _____________, _____________,__________ are ____________ in ____________.
insoluble
acetone
precipitate
triglycerides, sterol, pigments
soluble
acetone
Egg and egg yolk is very important sources of ____________ which is a generic term to designate any group of_________________ occurring in ________ and ____________, which are _____________– they attract both water and fatty substances (and so are both ___________ and _____________), and are used for ___________, _________, _______________, and _______________ .
Lecithin
yellow-brownish fatty substances
animal
plant tissues
amphiphilic
hydrophilic
lipophilic
smoothing food textures, dissolving powders (emulsifying), homogenizing liquid mixtures, and repelling sticking materials
Lecithin can easily be extracted __________ using solvents such as __________, _________, ___________, ________, _________, etc., or extraction can be done __________
chemically
hexane, ethanol, acetone, petroleum ether, benzene
mechanically
Procedure for Acrolein Test
- Get 3 test tubes and label with clarified butter, vegetable oil and linseed oil. Add 2mL of each to their respective tube
2.Add small amount of Potassium bisulphate crystals to each tube - Heat the mixture directly on a burner
- Observe the formation of a gas and odor that will be produced
- Record this as your observation.
Acrolein test is used to detect the presence of ________ or _________. When fat is treated strongly in the presence of a _________________ like ______________, the glycerol portion of the molecule is dehydrated to form an _____________, _____________ that has a pungent irritating odor.
glycerol or fat
dehydrating agent
potassium bisulphate (KHSO4)
unsaturated aldehyde
acrolein
Acrolein Test Results
Positive result: If glycerol present in the sample, it will give a pungent smell.
Negative result: If glycerol is absent in a sample, it will not produce a pungent smell.
Liebermann-Burchard Test Procedure
- Get a test tube with 2 ml of cholesterol dissolved in chloroform
- Add 2 mL of acetic anhydride to the cholesterol solution and mix completely
- Add 5 drops of concentrated sulfuric acid to the previous mixture by tilting the test tube and dropping on the side of the test tube then gently mix the solution
- Observe for a bluish-green color
- Record this as your observation.
Liebermann-Burchard Test Objective
To detect the presence of cholesterol
Principle of Liebermann-Burchard Test
A chemical estimation of ____________, reacts as a __________ with a _____________ and the product are _______________.
cholesterol
typical alcohol
strong concentrated acids
colored substances
In Liebermann-Burchard Test, ___________ are used as _________ and ____________.
Acetic anhydride
solvent
dehydrating agents
Results of Liebermann-Burchard Test
Positive result: It indicates cholesterol in a sample by giving bluish-green color to the solution.
Negative result: The color of the solution will not change.
Copper Acetate Test Procedure
- Get 2 test tubes and label with olive oil and oleic acid. Add 2mL of each to their respective tube
- Add petroleum ether to both test tubes
- Shake test tubes to mix the content
- Add copper acetate solution to both test tubes
- Shake vigorously both test tubes
- Observe for blue-green color
- Record this as your observation.
Unsaturated fatty acid: ____ layer appearance -
upper layer color _________ and the lower layer color _______.
Saturated fatty acid: ____ layer appearance – appearance of _________ at the bottom of the upper layer.
2 layer
green
blue
2 layer
white blue precipitate
Copper Acetate Test Principle
This test used to distinguish between _____ or _______ and ___________ and ___________. The _____________ solution does not react with the _________, while saturated and unsaturated fatty acids react with copper acetate to form __________. unsaturated fatty acids can only be extracted by __________.
oil or neutral fat and fatty acid saturated and unsaturated
copper acetate
oils
copper salt
petroleum ether
Spot/Translucent Test Procedure
- Prepare a filter paper and drop the Clarified butter on it then press another filter paper on top of the other
- Hold the filter paper against a light source
- Then repeat the process with Vegetable oil and Linseed oil
- Record your observations.
Spot/Translucent Test Principle
A translucent spot test is a preliminary test for the ______, which is characterized by a __________ and ________.
lipids
translucent and greasy spot
Spot/Translucent Test Results
Positive result: Translucent spot will appear on the filter paper.
Negative result: Translucent spot will not appear on the filter paper.
Test for Unsaturation Procedure
- Prepare 5 test tubes and label with Olive oil, Coconut oil, Corn oil, Palm oil and Sunflower oil. Add 1mL of each to their respective tube
- Add few drops of Bromine Water to each tube one by one and make sure to replace the lid of the container
- Shake each test tube vigorously
- Note if the color of Bromine water disappeared.
- Record your observation.
Unsaturated Test Principle
Unsaturation test is used to detect the _________ or ________ in a lipid sample. All the neutral fat contains ____________ of fatty acids. Double bonds are found in the _______________, which becomes saturated by taking up either __________ or __________. If the lipid contains more ___________ or _____________, it will take more ___________.
unsaturated fatty acids or double bond
glycerides
structure of unsaturated fatty acids
bromine or iodine
unsaturated fatty acids or more double bonds
iodine
Unsaturated Test Result
Positive result: Pink color will disappear by the addition of unsaturated fatty acids.
Negative result: Pink color will not disappear.
