Seperating Green Tea

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Solid-liquid extraction and liquid-liquid extraction of caffeine from tea leaves

Andrew Jensen
Lab partners: Jamie Pawluk, Joe Luong
230105559
Chem 250 L2
Oct,4,2012

Introduction:
Extraction is the experimental procedure of obtaining a desired compound with the use of a solvent from either a liquid or solid mixture. Solid-liquid extraction involves the removal of organic compounds from solid material. This method of extraction may be achieved through extraction of the organic compound at the boiling point of a polar solvent such as water. Using water as the solvent will typically result in a 61-85 percent extraction efficiency of caffeine from green tea¹. By heating the system, the excess energy will lead to an increase in the extraction rates¹. Liquid-liquid extraction is an extraction method which helps to better purify the organic compound from left over inorganic compounds and the original solvent. This method requires a very precise solvent which will be immiscible with the first solvent, but soluble in the desired compound. Both of these extraction methods can be applied to biological compounds in everyday life such as tea. Green tea is one of the most popular beverages in the world partly due to its potential health benefits and stimulus effects. What provides this stimulus effect is caffeine, a naturally found alkaloid within green tea². Caffeine is built up of the chemical formula 1,3,7 trimethylxanthine². Using solid-liquid and liquid-liquid extractions, caffeine can be removed from green tea leaves in its crude form. The average percent caffeine extracted in the experiment was determined to be 0.9864±1.3. Procedures:

9.9902 grams of tea leaves was added to a 250ml beaker. 75ml of hot water was added to the green leaves as well as 2.0124 g of calcium carbonate. This mixture was left to gently boil for 20 minutes. Remove the solid residue via vacuum filtration with a Buchner funnel. The obtained liquid in the Buchner funnel was removed to a...
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