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.Various tests exist to chemical test carbohydrate and once carbohydrate is detected, advanced tests could be carried out to categorize and distinguish it from other compounds. Chemical test carbohydrate include, The Molisch Test, The Iodine/Potassium Iodide Test, Benedict’s Test, Barfoed’s Test, Seliwanoff’s Test and Bial’s Test.
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 which results in the formation of an aldehyde which is compressed with two phenol molecules that displays 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.The appearance of a purple ring at the border between the acid and the test layers suggest a positive reaction.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 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.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 carry out chemical test carbohydrates to examine the different reactions of carbohydrates with the reagents to categorize and detect its compounds.
