Lipids In Milk Lab Report

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Introduction
The purpose of this lab was to identify the lipids in an egg yolk and to identify the amount of lipids in milk [1]. To extract the lipids from the egg yolk, the egg yolk needed to be combined with an organic solvent such as a mixture of CHCl3/MeOH. An organic solvent was needed to carry the extracted lipids up the TLC plate because the plate was polar, due to the presence of silica gel (silanol groups). To compare relatively similar lipids to the ones found in the egg yolk, the egg yolk extract was compared to lipids such as cottonseed oil, cholesterol, phosphatidyl choline, phosphatidyl ethanolamine, and sphingomyelin. The lipids in the egg yolk extract were identified by the distance they travelled relative to the known lipids. The Rf value between the unknown lipids and the lipids aids
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The Rf values were obtained by reacting the lipids on the TLC plates with iodine, to visually show how far the lipids moved up the TLC plate. For the identification of the amount of lipids in milk, the milk was combined with an organic mixture of CHCl3/MeOH, to isolate the lipid layer. By centrifuging the organic solvent with milk the heavy lipids sink to the bottom while the water layer which contain water soluble carbohydrates, peptides and small amino acids float to the top. Since the organic solvent had low boiling points the lipids from the organic layer were easily obtained by evaporation.

Methods
Refer to page 1.2-1.3 in the BCEM 341 Manual Lab 1: Lipids. [1]

Results
Refer to the attached sheets.

Discussion
TLC plates are used to determine the polarity of different molecules. TLC plates work around the principle that polar molecules will move higher up the plate than non-polar molecules. The polarity of the plate is due to the polar silica gel which covers the plate. The egg yolk was combined with the

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