Do you know that tea contains caffeine ? We tried following procedure in our lab to extract the caffeine content from tea leaves. Here is the procedure.
Boil 20g of dry leaves in 500ml beaker and 250ml water added to it and was boiled for 25minutes. The solution is filtered through a buchner funnel without using a filter paper. To the clear filtrate,with stirring 60ml of 10% lead anhydride was added to precipitate tannins (naturally occuring polymers). The mixture was left undisturbed for 2-3 days. After this period,the solution was filtered through a glass wool and the solution was concentrated on a sand bath to about 30ml. The solution was cooled and extracted it thrice with 25ml portions of chloroform. The chloroform extracts were combined and most of the chloroform was removed by distillation.
The residue was cooled and 40ml of petroleum ether is added and stirred for 5min. Now the crude caffeine was filtered.
Here the organic solvent chloroform is used to extract caffeine from aqueous extract. Because it is more soluble in chloroform then in water. Chloroform caffeine mixture can be separated on the basis of different densities of chloroform and water, because chloroform is much denser than water and insoluble in it.
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