Molisch's test

To test the presence of carbohydrates in the given solution

1. Aim :- To Test the presence of carbohydrates in the given sample using Molisch’s Test Lecture by:- Dr. Mohan Kumar Assistant professor Gyan Joyti Collage of Pharmacy, Hazaribag Email:- [email protected]

2. Experiment:-1 Aim :- To Test the presence of carbohydrates in the given sample using Molisch’s test. Theory: The word carbohydrate is formed from the words carbon and hydrogen. Carbohydrates are combinations of the chemical elements carbon and hydrogen plus oxygen. In the natural world, carbohydrates are the most common chemical compounds used for food. Molisch’s test is a general test for carbohydrates. This test is given by almost all of the carbohydrates. In this test concentrated sulfuric acid converts the given carbohydrate into furfural or its derivatives, which react with α- naphthol to form a purple coloured product.

3. Materials required: Molisch’s reagent Glucose solution Concentrated sulfuric acid Test tubes Measuring cylinder Test tube holder Test tube stand Dropper Stirrer Pipette Distilled water

4. Procedure: First prepared the Molisch’s reagent by adding α- naphthol in 10% alcoholic solution. Take 2ml of given sample solution in a clean test tube. Add 2-3 drops of Molisch reagent slowly. Now add concentrated sulfuric acid along the sides of the test tube. The acid layer forms a layer at the bottom. If there is formation of violet ring then the presence of carbohydrate is confirmed.

5. Take sample of sugar solution Add Molisch’s reagent Add conc.H2SO4 Formation of violet ring

6. Observations: Test Glucose Lactose Sucrose Starch Molisch’s test Purple ring Purple ring Purple ring Purple ring

7. Results and Discussions: The given organic compound is a reducing sugar. Precautions: Handle the acids like concentrated sulfuric acid with care. Always use droppers to take reagents from the reagent bottles.