Soraya Pashaei Marandi Section 521 Assignment 3 Lipid Tests Lipid solutions contain many biomolecules and in order to separate the mixture thinlayer chromatography is used to yield a chromatogram The molecules react with both the mobile phase solvent and stationary phase silica gel to obtain a clear separation of each molecule The separation of the molecules is dependent on their adsorption affinity to silica gel and their polarity For this experiment the hypothesis was that the most non polar molecules would end up being the furthest away from the point of origin The null hypothesis was that the solvent would have no adverse affect on the distance moved by a molecule This experiment was conducted by obtaining a silica gel strip and placing a drop of the mixed lipid mixture on a the center line The strip was then placed into the solvent jar until the solvent front neared the top It was then sprayed with Amido black solution and placed in a jar that contained iodine crystals The lipid molecules absorbed the iodine vapor and turned a yellow color The strip contained the separated molecules from bottom to top as phospholipids saturated fatty acids and triglycerides Lipid Size mm2 Distance from Origin Rf Phospholipid 10 18 0 375 Fatty Acid 10 25 0 521 Triglycerides 11 33 0 688 In order to test for the presence of lipids an emulsification test is used The test is based on the fact that lipids are decanted in water but are soluble in ethanol A positive result would show a cloudy emulsion of dispersed liquid droplets The hypothesis was that substances that contained lipids would turn a murky white color in ethanol while substances that did not contain lipids would remain clear The null hypothesis was that ethanol would have no affect on the results obtained from this experiment Also the presence of oils in lipids was tested by adding Sudan IV and a positive result stained the oil droplets red The substances that were used for both of these test were vegetable oil distilled water olive oil milk and salad dressing The vegetable oil was used as the positive control while the distilled water was used as the negative control Below are the results for both experiments Substance Emulsion Test Result Sudan IV Test Result Vegetable Oil Distilled Water Olive Oil Milk Salad Dressing
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