茶多酚中咖啡因的近红外光谱分析

Near Infrared Determination of the Content of Caffeine in Tea Polyphenol

采用近红外光谱分析技术对茶多酚中咖啡因进行了光谱及定量分析,原始光谱表明咖啡因在近红外波段有着很强且较为明显的吸收峰。通过对样品的漫反射原始吸光度光谱进行导数、散射校正及相关分析更清晰地给出了咖啡因在近红外光谱波段的光谱特性,为建立快速稳健的定标模型创造了条件。该技术能够解析出咖啡因中各主要基团在近红外波段的吸收特性,结合定标过程定量快速检测咖啡因在茶多酚中的含量,定标分析结果显示在很大的浓度范围内有很好的线性相关性,定标标准差SEC为0.49%,相关系数(r)为0.993,证实了近红外光谱分析技术作为一种新的快速分析茶多酚中咖啡因含量手段的可行性及优越性。

In the present paper the caffeine in the tea polyphenol was analysed spectrally and quantitatively by using near infrared spectroscopy. From the original absorbance of caffeine in the tea polyphenol an obvious and strong peak can be viewed. By using second derivative, MSC（multiple scatter correction） and correlation analysis the spectral characteristics of caffeine in the near infrared region can be seen very clearly, thus the robust calibration model can be set up easily. The result obtained shows that through this technique the abscorptive characteristic of those primary fundamentals of caffeine can be looked through easily, meanwhile, calibration test was performed to quantitatively measure the weight percent of caffeine in the tea polyphenol, and fine precision of the result was obtained in a comparatively very large range of concentration. The SEC（standard error of calibration） is 0.49%, and the correlation coefficient r is 0. 993. The result shows that NIR is feasible and superior in analyzing the content of caffeine in tea polyphenol.