Chemical Test Carbohydrate : The Proper Method to Examine Carbohydrate
Saturday, February 6th, 2010A chemical test is a quantitative or qualitative process that is intended to prove the existence or to evaluate a chemical compound and or chemical group with the help of a reactant. To chemical test carbohydrate, there are a number of tests that can be conducted to determine if a sample contains carbohydrates and if it does, there are further tests that can be carried out to classify and identify it. The Molisch Test, The Iodine/Potassium Iodide Test, Benedict’s Test, Barfoed’s Test, Seliwanoff’s Test and Bial’s Test are chemical test carbohydrate.
Named after Austrian botanist Hans Molisch, the Molisch’s Test is a sensitive chemical test carbohydrate. Sulfuric acid desiccates the carbohydrate which results in the formation of an aldehyde which is compressed with two molecules of phenol that results in a purple or red colored compound. Next, the Molisch’s reagent,naphthol dissolved in ethanol, is mixed with the sample in a test tube. A small amount of concentrated sulfuric acid is gradually poured to the mixture along the wall of the test tube without mixing to generate a bottom layer. If a purple ring appears at the cross point between the acid and the test layers, a positive reaction is indicated.
Carbohydrates and monosaccharides will show a rapid positive test result in chemical test carbohydrate although disaccharides and polysaccharides has a much slower reaction. The Barfoed’s Test is a chemical test carbohydrate that detects the presence of monosaccharides. Placing one ml of a sample solution in a test tube, 3 ml of Barfoed’s reagent, a solution of acetic acid and acetate cupric solution are added. Heat the solution in a boiling water bath for three minutes and if a formation of a reddish precipitate appears, it tests positive for monosaccharides.
Named after the American chemist Stanley Rossiter Benedict,the Benedict’s test is a chemical test carbohydrate used as a test for the presence of reducing sugars. One ml of the sample solution should be placed in a test tube with a 2 ml solution of the Benedict’s reagent which contains sodium citrate and sodium carbonate mixed with a copper sulfate solution. A reddish precipitate should appear within the three minutes if any reducing sugars are present when the solution is heated in a boiling water bath for three minutes. Primarily, researchers conduct chemical test carbohydrates to examine the different reactions of carbohydrates with the reagents to categorize and detect its compounds.
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