核磁共振法无损伤测定茶叶中咖啡因含量研究型实验教学初探

Preliminary study of research-oriented experimental teaching based on non-damage detecting the caffeine's content in tea by NMR

开展研究型实验教学是实践教学改革的重要方向。在研究型实验核磁共振法无损伤测定茶叶中咖啡因含量的教学过程中,学生独立查阅文献,改进实验装置及操作方法,提高咖啡因的收率和纯度;通过核磁共振法建立一系列梯度浓度的咖啡因含量与氢谱积分面积的工作曲线。利用甲醇浸提冷冻干燥技术将不同产地、不同品种的茶叶制成样品,测定其氢谱,通过工作曲线求解咖啡因含量,以期建立快速准确、无损伤,预处理简便的茶叶中咖啡因含量的检测方法。

Developing research- oriented experimental teaching is an important direction of a new mode of teaching reform of higher education. In the process of research-oriented experiment ＂ non- damage determination of caffeine＇s content in tea by NMR＂, the students utilize the literature review to put forward the improvement to the unreasonable experimental apparatus and methods for extracting caffeine from tea to enhance the yield and purity of caffeine by themselves. Determined through a series of graded concentrations of caffeine 1H NMR spectra, the work curve about the integral area of hydrogen atom and caffeine＇s content is established. The caffeine＇s content in tea from different origin or varieties are obtained through the calibrati fast and accurate, non-damage, on curve by the methanol freeze-drying technology, in order to build simple pretreatment methods of detection caffeine＇s content in tea.