Isolating and Comparing the Caffeine Content in Black, Green, and Oolong Tea

Caffeine is a substance found in many different foods and drinks, such as tea. Different teas contain different amounts of caffeine, so the purpose of this experiment was to compare the caffeine content in black, oolong, and green tea. Dichloromethane (CH2Cl2) and sodium carbonate (Na2CO3) was used to separate the caffeine from the tea. Two distinct layers were then created with the use of a centrifuge: a layer that contained dichloromethane and caffeine, and a layer that contained the tea. The solution containing the dichloromethane and caffeine was isolated, and solid sodium sulfate (Na2SO4) was added to absorb water that might have been present in the solution. The solution was then left in a fume hood overnight to evaporate dichloromethane, leaving crude caffeine.

After thirty trials, the amount of caffeine isolated was compared using an ANOVA test. The black tea yielded the highest average amount of caffeine, with the green tea at the lowest. The ANOVA test yielded a p-value of 4.0963 x 10-17, leading to a conclusion that there is a relationship between amount of caffeine isolated and the darkness of tea. This led to the acceptance of the initial scientific hypothesis, which stated that black tea will contain the highest mean average amount of caffeine. This experiment is important because people turn to tea as a source of caffeine. With the knowledge gained from this experiment, people can know which tea is fit for them, and limit the amount of caffeine in their diet.

Research Conducted By:

Seth Fillar
Fraser High School

Daniella Toma
Warren Mott High School

 

 

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