傅里叶红外光谱结合化学计量学的渣驯优劣鉴别研究

Identification of Tibetan Medicine Zhaxun by Infrared Spectroscopy Combined With Chemometrics

渣驯通常分为4个等级,藏医传统用药经验认为色黑、质重、粪便少的渣驯质量更优。不同等级渣驯外观性状差异较小,成膏后更不易区分。傅里叶红外光谱技术(FTIR)具有快速无损的优点,已广泛用于药材鉴别领域。以4个等级渣驯为研究对象,探究傅里叶红外光谱技术鉴别不同等级渣驯的可行性。收集渣驯药材及代用品共56批,按粪便比例和外观形态将药材分为4个等级,采用《六省区藏药标准》中炮制方法将各批次药材加工成干膏。采集不同样品4000~400 cm^(-1)范围的红外光谱信息,以不同化学计量学方法建立模型。预处理方式采用Saitzky-Golay(S-G)平滑、纵坐标归一化、二阶导数转化,渣驯红外光谱主要吸收区域为3500~3200,3000~2800,1800~1350,1350~900和900~400 cm^(-1),代用品吸收峰的波数差异较大。1779 cm^(-1)附近仅有Ⅰ等级渣驯和Ⅱ等级渣驯的吸收峰,1768 cm^(-1)附近Ⅰ等级渣驯和Ⅱ等级渣驯峰强度明显强于Ⅲ等级渣驯和渣驯代用品,1660 cm^(-1)附近仅代用品渣驯无吸收峰,1257 cm^(-1)仅代用品具有吸收峰,均可作为不同等级渣驯的鉴别依据;(3)号区域内及(7)号区域吸收峰差异均与传统分级相关,品质越好的峰强度越大,可作为多批次渣驯验证区域。根据SIMCA软件统计结果,主成分分析(PCA)较难区分不同等级渣驯;偏最小二乘法(PLS-DA)能更好地区分4个等级药材,外部验证结果表明该模型能很好地区分不同等级渣驯;通过SPSS21.0软件统计,系统聚类(HCA)可以区分部分Ⅲ等级渣驯及代用品渣驯。傅里叶变换红外光谱结合化学计量学能快速鉴别渣驯优劣,区分代用品,为渣驯质量评价提供一种快速有效的方法。

Zhaxun is usually divided into four grades.Zhaxun is of better quality with black color,heavy quality and fewer feces,according to the experience of traditional Tibetan medicine.Different grades have little difference in appearance,and it is more difficult to distinguish after boiling into pastes.Fourier transform infrared spectroscopy(FTIR)has the advantages of being fast,and nondestructive and has been widely used in medicinal material identification.They were exploring the feasibility of FTIR to identify Zhaxun of different grades with FTIR.56 batches of medicinal materials and substitutes were collected and divided into four grades according to the proportion of feces and morphology.Each batch was processed into dry pastes according to the Tibetan medicine standard of six provinces.Different chemopmetric methods established models according to different samples in the range of 4000~400 cm^(-1).Preconditioning methods contain Saitzky-Golay(S-G)smoothing,ordinate normalization,and second derivative transformation for preprocessing,and the main absorption regions of Zhaxun are 3500~3200,3000~2800,1800~1350,1350~900,900~400 cm^(-1).There are great differences in the indices of the absorption peaks of substitutes.Only Zhaxun of gradeⅠand gradeⅡhave absorption peaks near 1779 cm^(-1).The intensity of Zhaxun of gradeⅠand gradeⅡnear 1768 cm^(-1)is significantly stronger than gradeⅢand substitutes.Only substitutes near 1660 cm^(-1)have no absorption peak,and substitutes at 1257 cm^(-1)have an absorption peak.These can be used as the identification of Zhaxun’s different grades.Changes absorption peaks in area(3)and area(7)are related to the traditional classification that the stronger peak intensity is related to quality.Principal Component Analysis(PCA)is difficult to distinguish Zhaxun of different grades.However,Partial Least Squares Discriminant Analysis(PLS-DA)can better distinguish medicinal materials of four grades and results of external verification show that the model can well distinguish Zhaxun of different grades according to the statistical chart of results of SIMCA.The hierarchical cluster method(HCA)can distinguish some batches of Zhaxun of gradeⅢand substitutes through SPSS21.0.FTIR combined with chemometrics provides a rapid method for the quality evaluation of Zhaxun that can quickly identify the grades of Zhaxun and distinguish the substitutes.