种子类中药材黑豆和牵牛子都含有大量的油脂和蛋白质, 因此两种药材的一维红外光谱极其相似, 为了区别科属不同的两种药材, 采用红外光谱三级鉴定法对黑豆和牵牛子进行分析鉴定。 经典红外光谱中, 黑豆和牵牛子均有1 745 cm-1表征油脂类的特征吸收峰, 以及1 656和1 547 cm-1表征蛋白质酰胺Ⅰ带和酰胺Ⅱ带的特征吸收峰。 其中油脂特征吸收峰与蛋白质特征吸收峰的相对高度不同, 说明二者的相对含量不同。 同时, 一维红外光谱对两种中药材主体成分的分析结果, 即含有大量的油脂和蛋白质, 与文献所报道的一致。 在二阶导数红外光谱中, 牵牛子中存在1 712 cm-1属于有机酸类的特征吸收峰, 然而黑豆中却没有此吸收峰的存在。 此外导数光谱中两种药材峰形和峰强度的差别更为明显。 二维相关红外光谱中, 黑豆和牵牛子自动峰的峰位置和峰强度等均具有显著差异。 在1 500~1 700 cm-1波数范围内, 黑豆有2个明显自动峰, 牵牛子有3个明显的自动峰。 在2 800~3 000 cm-1波数范围内, 黑豆和牵牛子均有2个强自动峰, 但最强自动峰的位置不同。 运用红外光谱三级鉴定法, 可以更直接快速简便的分辨出主体成分相同的两种种子类中药材, 为今后的研究打下基础。

Semen Glycines Nigrae and Semen Pharbitidis containing a large amount of fats and proteins are commonly used in Chinese herbal medicine. Tri-step infrared spectroscopy was applied to fast analyze and identify the two samples. In the conventional infrared spectroscopy, the samples both have obvious characteristic absorption peaks at 1 745 cm-1 assigned to the stretching mode of CO in esters. Furthermore, the two kinds of herbs have the peaks at 1 656 and 1 547 cm-1 assigned to the amide Ⅰ and Ⅱ bands of protein. Obviously, the infrared spectra of herbs demonstrate that protein and fat is the major component in two kinds of herbs, and the relative intensity of the peaks assigned to fat and protein indicate their relative content is different. And the result is consistent with the reported. In the second derivative spectra, Semen Pharbitidis has a peak at 1 712 cm-1 assigned to the organic acid, however, Semen Glycines Nigrae has not this absorption peak. In addition, in the second derivative spectra, appeared more differences between the two samples in shape and intensity of the peaks. In two-dimensional correlation infrared spectra, the two samples were visually distinguished due to their significant differences in auto-peak position and intensity. In the region of 1 500~1 700 cm-1, Semen Glycines Nigrae has two autopeaks and Semen Pharbitidis has three autopeaks. In the region of 2 800~3 000 cm-1, the samples both have two autopeaks, but the position of the strongest autopeak is different. It was demonstrated that the Tri-step infrared spectroscopy were successfully applied to fast analyze and identify the two kinds of samples containing the same major component, and made sure the foundation for future researches.