2 Background introduction The extraction of caffeine from tea can be done by soaking method. Soaking method is a liquid-solid extraction. In the laboratory, a Soxhlet extractor can be used for such extraction The Soxhlet extractor for solid-liquid extraction involves three key points: the solvent reflux, dissolution and siphon, and these allow the solid tea to be extracted by a pure solvent each time Soxhlet extractor ilt Siphon The specific process is: heating the three-necked bottle will volatilize the solvent, and the solvent vapor will meet the condensate and drop back to the Soxhlet extractor, which can dissolve the caffeine from the tea. When the liquid level of Soxhlet extractor exceeds the height of the siphon, pressure caused by different liquid levels of the siphons two ends can make the solvent sucked back into the three-necked bottle Extraction device• The extraction of caffeine from tea can be done by soaking method. Soaking method is a liquid-solid extraction. In the laboratory, a Soxhlet extractor can be used for such extraction. • The Soxhlet extractor for solid-liquid extraction involves three key points: the solvent reflux, dissolution and siphon, and these allow the solid tea to be extracted by a pure solvent each time. • The specific process is: heating the three-necked bottle will volatilize the solvent, and the solvent vapor will meet the condensate and drop back to the Soxhlet extractor, which can dissolve the caffeine from the tea. When the liquid level of Soxhlet extractor exceeds the height of the siphon, pressure caused by different liquid levels of the siphon’s two ends can make the solvent sucked back into the three-necked bottle . Background introduction Soxhlet extractor Siphon Extraction device