Extraction of Caffeine From Tea

Extraction of Caffeine from Tea Experiment 1

Introduction:

The purpose of this experiment is to extract caffeine from Tea leaves and to determine the percentage of crude caffeine in Tea leaves.

Procedure:

A mixture of two tea bags with 50mL and 2.4g of calcium carbonate were poured in a 150mL beaker. The mixture was boiled gently for 15 minutes. The mixture was then cooled to about 55oC  – 60oC and using a Buchner funnel and a filter flask, a vacuum filtration was performed, refer to Figure 1. After another beaker was marked at the 12mL level, the tea solution was poured into it and it was boiled until the solution reached the 12mL mark. Then the solution was transferred to a centrifuge tube and was cooled for a couple of minutes. 2mL of dichloromethane was then added to the centrifuge tube. The tube was shaken vigorously, mixing the blend and then it was centrifuged for about a minute. A pipet was then inserted to draw the lower organic layer and transferred to another centrifuge tube. The Tea solution was still in the first centrifuge tube. The above extraction process was repeated 3 more times. After this was done, anhydrous magnesium sulfate was added to the combined dichloromethane/caffeine solution. The solution was occasionally swirled for about 5-8 minutes. A micro funnel was prepared and clamped on to a 25mL Erlenmeyer flask. The dried dichloromethane/caffeine solution was then transferred throug h the micro funnel to the flask, see Figure 2. The remaining magnesium sulfate was rinsed with about 0.5mL of dichloromethane and this rinse was transferred to the micro funnel. The dichloromethane was then evaporated using a hot plate in the hood, leaving behind a greenish white residue of crude caffeine.

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Results and Calculations:

Mass (g)

4.581 2.401 17.371

Two Tea bags CaCO3 25mL Erlenmeyer Flask Mass of Erlenmeyer Flask with Crude Caffeine

17.417

Mass of Crude Caffeine: 17.417 g  17.371 g  0.046 g  



Percent of Crude Caffeine in Tea Leaves: Mass of Crude Caffeine Mass of Tea Leaves 0.046 g  

*100%

4.581 g 



1.00%

Discussion:

There are grave discrepancies with the results from the experiment. There could be many causes for these inconsistencies. An explanation for such differences could be due to systematic errors in the equipment, such as inaccuracies caused by the disposable Pasteur pipets, for instance, which would contribute to the inaccuracy of amount of crude caffeine we obtained at the end. In order to remove the caffeine from tea leaves, the other components must be extracted from the leaves. Flavonoids and all the other components except Cellulose due to its insolubility in water, are extracted into hot water. However, for caffeine and the chlorophyll and theophylline to be isolated, they are extracted into the dichloromethane. Dichloromethane is able to produce an almost pure form of  caffeine. At the end of the experiment, we were left with a greenish white residue, which was the nearly crude caffeine and chlorophyll. Conclusion:

In conclusion, the tea leaves was found to contain about 1% of crude caffeine; it contained about 46mg of caffeine in about 4.581g of tea leaves. The experimental data obtained seems to be sufficient and corresponds to the theoretical data of tea leaves having 1% of crude caffeine. At the end of the lab, a greenish, white residue formed at the bottom of the 25-mL Erlenmeyer flask. The residue had a very strong coffee odor .

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Figure 1

Figure 2

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