The qualitative or quantitative technique which is implemented to detect the existence or to evaluate 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 which results in the formation of an aldehyde which is compacted 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. 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. The appearance of a purple ring at the border between the acid and the test layers signal a positive reaction.
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 detects the presence of monosaccharides. 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. 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. 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 conducted by researchers to study the various reactions of carbohydrates with the reagents used to classify and identify its compounds.
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