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REACTION OF CARBOHYDRATE BY: DR. BEENISH ZAKI INSTRUCTOR DEPARTMENT OF BIOCHEMISTRY.

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Presentation on theme: "REACTION OF CARBOHYDRATE BY: DR. BEENISH ZAKI INSTRUCTOR DEPARTMENT OF BIOCHEMISTRY."— Presentation transcript:

1 REACTION OF CARBOHYDRATE BY: DR. BEENISH ZAKI INSTRUCTOR DEPARTMENT OF BIOCHEMISTRY

2 P ROCEDURE

3 E QUIPMENT REQUIRED Each student needs: Test Tube rack Test tube holder Test tube (4 in number)

4 MOLISCH’S TEST PROCEDURE Take 2ml of solution in a test tube. Add two drops of Molish’s reagent. Mix it well. Under the cooling conditions incline the test tube and add 2 ml concentrated H 2 SO 4 slowly along the sides of the test tube. Don’t mix the content

5 H 2 SO 4 is sulphuric acid. Sulphuric Acid is the most corrosive acid. This reaction is exo-thermic reaction. Acid and Water don’t go well together. Please be CAREFUL!!

6 BENEDICT’S TEST PROCEDURE Take 5ml of Benedict’s reagent Add 8 drops of solution to it. Mix well. Boil it for 2 minutes. Cool under tap water.

7 S ELIWANOFF ’ S T EST PROCEDURE Take 3 ml of Seliwanoff’s reagent. Add 3ml of carbohydrate solution. Mix well and heat for 3 minutes. Cool under tap water.

8 IODINE TEST PROCEDURE Take 2ml of solution in a test tube. Add 2 drops of iodine solution Mix well

9 As you get your results start writing your observation in the observation column. The principle and inference will be discussed at the end of the session. D OCUMENTATION Molisch's Test PrincipleObservationInference

10 B EFORE Y OU S TART Please button up your laboratory coats. Girls tie your hairs Check the temperature of the water bath. (>90) Cool for no more than half a minute under tap water.

11 D ISCUSSION

12 P RINCIPLE O F M OLISCH ’ S T EST General test for carbohydrates Molisch Reagent composition : 5% alcoholic α- napthol. Carbohydrates in the presence of hot mineral acids undergo dehydration forming hydroxy - methyl furfurals. This condenses with α-napthol to form a purple ring at the junction of the two layers.

13 M OLISCH ’ S TEST ObservationInference A purple ring is observed at the junction of the two layers Indicates the given solution is a carbohydrate solution General test for carbohydrates

14 C ONTENT ’ S OF B ENEDICT ' S REAGENT Copper sulfate: provide cupric ions Sodium Citrate: Prevents the precipitation of cupric ions Sodium Carbonate: Provides an alkaline medium

15 P RINCIPLE OF BENEDICT ’ S TEST In an alkaline medium carbohydrates form enediols. Enediols reduce cupric ions to cuprous forming a colored complex. It is called as semi quantitative test which gives an approximate percentage of sugar present in the urine of a diabetic person

16 BENEDICT’S TEST ObservationInference Colour of the solution changes from blue to green, yellow, orange Indicates the presence of a reducing sugar.

17 INTERPRETATION OF BENEDICT’S TEST ColourPercentage of sugar Green0.5 (+) Yellow1.0 (++) Orange1.5 (+++) Red2.0 (++++)

18 I MPORTANCE OF THE B ENEDICT ' S T EST Used in the preparation of Urostix for diagnosing glucose in urine Used by Diabetics to check their glucose status.

19 P RINCIPLE OF S ELIWANOFF ' S TEST Seliwanoff's Reagent composition : Resorcinol in Concentrated HCL Principle: In acidic medium carbohydrates form furfurals which react with resorcinol to give a cherry red colour.

20 S ELIWANOFF ' S TEST ObservationInference Cherry red colour is observed Indicates the presence of a ketohexose i.e fructose.

21 P RINCIPLE OF I ODINE TEST Principle: Starch a polysaccharide forms a complex with iodine which gives a blue colour.

22 IODINE TEST ObservationInference Light blue colour is observed Indicates the presence of starch

23 ANY QUESTIONS?

24


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