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 4000~400 cm-1 were generally similar ex-cept for small differences around 1738 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 1747,1515,1468,1368,1264,1163,1147,1108 and 936 cm-1 .Furthermore,the 2D-IR spectra pro-vided obvious differences of "Wen Dangshen"(WDS)and "Bai Tiao Dangshen"(BTDS).In the range of 1510~1170 cm-1 ,WDS had a strong 3 × 3 peak cluster,including three auto-peaks at 1459,1298 and 1209 cm-1 ,and the strongest auto-peak located in 1209 cm-1 .Whereas BTDS had only one very strong auto-peak at 1450 cm-1 and three weak auto-peaks at 1340,1260 and 1209 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.%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1738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1747,1515,1468,1368,1264,1163,1147,1108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1510~1170 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1459,1298和1209 cm-1处有三个强自动峰,其中1209 cm-1的自动峰强度最大;而白条党参仅在1450 cm-1处有1个强自动峰,其余1340,1260,1209 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.
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