A chemical test is a quantitative or qualitative process that is intended to prove the presence or to assess 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.
The Molisch’s Test is a highly responsive chemical test carbohydrate which was discovered by the Austrian botanist Hans Molisch. Sulfuric acid desiccates the carbohydrate to produce 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 suggest a positive reaction.
Carbohydrates and monosaccharides will display 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.
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. 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. 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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