红外光谱因具有快速、 无损的优点, 特别适合于不同中药的鉴别研究。 基于红外光谱和聚类分析法对两类党参(共49个样本)进行鉴别。 结果表明: 在一维红外光谱中, 两者红外光谱图非常相似, 仅在1 738和935 cm-1处有细微的差异, 说明两者化学组分基本一致。在二阶导数红外光谱中, 显示了更多的红外指纹特征, 特别是1 747, 1 515, 1 468, 1 368, 1 264, 1 163, 1 147, 1 108和936 cm-1等峰的指纹特征更加明显。 进一步采用高分辨率的二维相关红外光谱对两类党参(纹党参和白条党参)进行鉴别, 在1 510~1 170 cm-1范围内, 纹党参的自动峰和交叉峰形成明显的3×3矩阵, 在1 459, 1 298和1209 cm-1处有三个强自动峰, 其中1 209 cm-1的自动峰强度最大; 而白条党参仅在1 450 cm-1处有1个强自动峰, 其余1 340, 1 260, 1 209 cm-1等3个自动峰都极弱。 此外, 还采用K-means聚类分析技术对两类党参共49个样本进行快速分类研究, 结果令人满意。 因此, 红外三级鉴定法结合K-means聚类分析技术在相似药物的鉴别中能起到重要的作用, 且有利于确保药物临床治疗安全有效。

Middle-infrared (MIR) spectroscopy is a well-known, rapid and non-destructive technique suitable for analyses of many different herbal medicines. In this work, MIR combined with clustering analysis was used to develop a novel method for the analysis of two kinds of Codonopsis pilosula. Altogether 49 samples were collected and analyzed. Their entire FT-IR spectra in the range of 4 000~400 cm-1 were generally similar except for small differences around 1 738 and 935 cm-1, indicating that they had similar chemical components. In the second derivative spectra (SD-IR), more distinct fingerprint features were revealed, especially peaks at 1 747, 1 515, 1 468, 1 368, 1 264, 1 163, 1 147, 1 108 and 936 cm-1. Furthermore, the 2D-IR spectra provided obvious differences of “Wen Dangshen” (WDS) and “Bai Tiao Dangshen” (BTDS). In the range of 1 510~1 170 cm-1, WDS had a strong 3×3 peak cluster, including three auto-peaks at 1 459, 1 298 and 1 209 cm-1, and the strongest auto-peak located in 1 209 cm-1. Whereas BTDS had only one very strong auto-peak at 1 450 cm-1 and three weak auto-peaks at 1 340, 1 260 and 1 209 cm-1. Moreover, the two species (49 samples) has been objectively classified with K-means pattern recognition technique. In conclusion, the three-step infrared macro-fingerprint identification method combined with K-means pattern recognition technique is simple, rapid and non-destructive, which plays an important role in discriminating similar natural products to ensure safe and effective clinical treatments.