Introduction

              Lipids are substances that are insoluble in water and can be broken down to their basic fatty acid components. They are classified according to their structures. Triacylglycerols, which consist of the commonly known fats and oils, are esters of fatty acids and glycerol. Waxes are esters of long-chain fatty acids and long-chain monohydrolic alcohols. Sphingolipids contain sphingosine as its structural backbone, an unbranched C-18 alcohol and amino and hydroxyl groups. Phospholipids are esters of fatty acids and phosphoglycerol. Steroids contain a structural backbone with isoprene-relate units and four fused rings. Lipid vitamins contain an isoprenoid-related structural backbone that contains long hydrocarbon chains or fused rings. The first four are saponifiable lipids, the lasst two are not.

             The formation of soaps or the salts of fatty acids, also called saponification is a method used in determining an unknown fat or oil. The saponification number is the number of mg KOH required to saponify 1.0 g of fat or oil. The larger the number, the smaller the average chain length of the fatty acids in the unknown fat or oil.  Determining the iodine number is useful in characterizing the degree of unsaturation of the unknown fat or oil. It is defined as the number of grams of I2 taken up by 100 g of fat or oil. IBr is added which reacts with the double bonds through an addition reaction. Adding Ki releases iodine from the unreacted IBr. The released iodine is then titrated with standard sodium thiosulfate.
 

Procedure :
A. Saponification number
 

B. Iodine number
 
 

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Chemistry 145.1
Human Genome Project and Bioinformatics
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Experiment No. 3
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Experiment No. 12
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