Chemical Test Carbohydrate
Mar 10th, 2010 by beauty writer
The qualitative or quantitative technique which is implemented to detect the existence or to measure a chemical compound and or chemical group by using a reactant is a chemical test.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.
The Molisch’s Test is a sensitive chemical test carbohydrate which was discovered by the Austrian botanist Hans Molisch. Sulfuric acid desiccates the carbohydrate to produce an aldehyde which is compressed with two phenol molecules that displays a purple or red colored compound. The sample is combined with a small amount of Molisch’s reagent, which is a-naphthol dissolved in ethanol, in a test tube. After it has been mixed, concentrated sulfuric acid, a small amount, is slowly added along the sides of the test tube without mixing to form a bottom layer.If a purple ring appears at the cross point between the acid and the test layers, a positive reaction is indicated.Chemical test carbohydrate will give a rapid positive test result for carbohydrates, monosaccharides while disaccharides and polysaccharides react slower.
The Barfoed’s Test is a chemical test carbohydrate that can be used to identify the existence of monosaccharides in the sample.One ml of the sample solution must be added together with 3 ml of Barfoed’s reagent, an acetic acid solution and a solution of acetetate cupric. The solution must be heated for three minutes in a boiling water bath and the appearance of a reddish precipitate will give out a positive result for monosaccharides.
Discovered by the American chemist Stanley Rossiter Benedict,one of the chemical test carbohydrate utilized to detect the existence of reducing sugars is the Benedict’s test.
Place one ml of the sample solution in a test tube and add 2 ml of Benedict’s reagent which is a solution of sodium citrate and sodium carbonate that is mixed with a solution of copper sulfate.Once the solution is heated in a boiling water bath for three minutes, a reddish precipitate should form within three minutes if it tests positive.
Chemical test carbohydrates are mainly performed by researchers to study the various reactions of carbohydrates with the reagents used to classify and identify its compounds.
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