表儿茶素类单质红外光谱特性研究

儿茶素类物质的测定对茶叶品质检测有重要作用，本工作利用傅立叶红外光谱技术对表儿茶索、表没食子儿茶素、表儿茶素没食子酸酯和表没食子儿茶素没食子酸酯4种儿茶素类单质进行了中红外光谱实验研究，得到了对应单质的红外吸收光谱。结果表明，3147~3498cm^-1范围内的宽带吸收来自于苯环上羟基的伸缩振动吸收，而400～1750cm^-1范围内多峰结构吸收，对应于骨架振动和取代基的变形振动吸收；对应中红外吸收光谱的多峰结构谱段高频端表儿茶素没食子酸酯和表没食子儿茶素没食子酸酯与对应儿茶素相比都多了一强吸收峰，对应波数分别为1681cm^-1和1692cm^-1，这是由于前两者都相应多出了-C=O结构。这些结果对于茶叶品质的光谱检测有重要的参考价值。

Study on Epicatechins by Infrared Spectroscope

The determination of catechin is important to the tea estimation quality. In this work, Fourier transform infrared spectroscopy （FTIR） is used to analyze the characteristics of the epicatechin, epi-gallocatechin, epi-catechin-3-gallate and epi-gallocatechin-3-gallate, and gained the infrared absorption spectra. The characterization results clearly showed that the absorption bands detected around 3147~3498 cm-1are due to the stretching modes of the hydroxy of the benzene ring, while 400~1750 cm-1 are due the rocking and wagging modes of skeleton vibration and substituents, respectively. Compared to the epicatechin and epi-gallocatechin, the other two strong peaks at 1681 cm-1 and 1692 cm^-1 were observed in epi-catechin-3-gallate and epi-gallocatechin-3-gallaet, respectively, which could be attributed to the extra -C=O structure. These results have very important reference value to the spectrum detection of the quality of tea.