从茶叶中提取咖啡因不同实验方法对照研究

目的探讨从茶叶中提取实验量咖啡因的最佳方法。方法按照实验室常用的方法（提取-升华法和提取-萃取法），用乙醇和水作溶剂，采用不同的装置及回流时间，从5g茶叶中提取咖啡因。结果醇提取-升华法，回流时间60，90，120min，得白色咖啡因量8．4，11．9，13．7mg；水提取-升华法煮沸15min，得白色咖啡因量4．1mg；提取-萃取法（分2种反应体积），煮沸15min，得黄色咖啡因量37mg，23．6mg。结论从时间、产量、环保、成本等综合因素考虑，水提取-升华法提取咖啡因是较理想的实验方法。

Contrastive analysis of extraction of caffeine from tea leaves

Objective To investigate the most preferable method of caffeine extraction from tea leaves.Methods In accordance with the commonly used laboratory methods(extraction-distillation and extraction-extraction),ethanol and water were used as solvents to extract caffeine from 5 g of tea leaves,with different devices and at different time points of backflow.Results By alcohol extraction-sublimation method,at the backflow time of 60 min,90mim and 120 min,the mass of white crystallized caffeine obtained was 13.7 mg,...