采用红外光谱、 二阶导数光谱和二维相关红外光谱对来自黑龙江、 吉林、 辽宁三省的老鹳草中药材进行了分析。 不同产地的老鹳草的红外光谱都具有1 730和1 337 cm-1等表征鞣质类成分的特征吸收峰和1 618和1 318 cm-1波数表征草酸钙的特征峰。 其中还发现在1 370 cm-1的C—H弯曲振动区和1 230 cm-1的C—O伸缩振动区三产地老鹳草具有一定的差异性。 在高分辨的二阶导数谱中, 1 509, 1 204, 764和763 cm-1附近的表征鞣质类成分的吸收峰更明显, 三产地老鹳草在CO羰基伸缩振动区表征了脂肪类化合物的不同; 尤其是在二维相关光谱上, 各自的自动峰具有显著的差异性, 黑龙江的老鹳草出现了7个自动峰, 其中1 621 cm-1处自动峰最强; 而在吉林和辽宁产地的老鹳草中同样出现了4个自动峰, 前者1 580 cm-1处的自动峰最强, 后者在1 649 cm-1处自动峰最强。 该方法直观、 简单、 方便、 快速, 可以作为鉴别和鉴定同种不同产地老鹤草的一种新方法。

Tri-step infrared spectroscopy (Fourier transform infrared spectroscopy (FTIR) combined with second derivative spectra and two-dimensional correlation infrared spectroscopy (2D-COS) ) was employed to identify and analyze the main components of Heilongjiang (HLJG), Jilin (JLG), Liaoning (LNG) genuine Herba Geranium. The emergence of several characteristic absorption peaks of tannins including 1 730 and 1 337 cm-1 and peaks around 1 618 and 1 318 cm-1 belonging to calcium oxalate suggested that Herba Geranii contained tannins and calcium oxalate. Differences near 1 370 and 1 230 cm-1 were found among the three Herba Geranii. In light of second derivative spectra, four more peaks of tannin components around 1 509, 1 204, 764 and 763 cm-1 and evident differences around CO stretching bands (1 750～1 600 cm-1) were observed. By 2D-COS spectra with further improved resolution, the three genuine Geraniums were visually distinguished due to their significant differences in auto-peak profile. HLJG has 7 auto peaks with a strongest peak around 1 621 cm-1, while JLG and LNG both have only 4 auto peaks with a strongest peak around 1 580 and 1 659 cm-1, respectively. It was demonstrated that the Tri-step infrared spectroscopy was successfully applied to fast analyze and identify genuine Geraniums from different geographical regions and subsequently would be applicable to the study of Chinese medicinal resources and quality standards.