白蜂蜡和黄蜂蜡的拉曼光谱研究

Research on Raman Spectroscopy of White and Yellow Beeswaxes

利用532 nm和633 nm波长的激发光对18份不同来源的白蜂蜡和黄蜂蜡进行拉曼光谱分析,并用化学计量学工具探索造成差异的关键因素。所有蜂蜡样品的拉曼峰在532 nm下的强度均比633 nm高,但在633 nm下白蜂蜡的荧光信号明显比黄蜂蜡小。将数据按照不同激光波长分组进行主成分(PCA)以及正交偏最小二乘(OPLS)分析能进行明显的聚类,并通过变量投影重要性分析(VIP)得知蜂蜡样品中的碳氢键易受激光波长的影响。将数据按照白、黄蜂蜡分组进行PCA及OPLS分析,发现633 nm激光无法区分这两种蜂蜡,但可在532 nm下用OPLS区分。通过变量投影重要性分析得出造成蜂蜡差异的8个标志峰。

In this research,eighteen samples of paraffin waxes with different sources were analyzed with Raman spectrometry under laser wavelengths of 532 nm and 633 nm,and chemometrics tools were utilized to explore the key factors causing the differences.Peak intensities under 532 nm were higher than those under 633 nm,but the fluorescent signals of white beeswaxes were significantly lower than those of yellow beeswaxes.By classifying the data according to different laser wavelengths and performing principal component analysis(PCA)and orthogonal partial least squares(OPLS)analysis,the observations in the plots can be clearly discriminated,and by further variable importance in projection(VIP)analysis it can be inferred that C—H bond was sensitive to the change of laser wavelength.By classifying the data according to white and yellow beeswaxes and performing PCA and OPLS analysis,the samples couldn’t be distinguished under the irradiation of 633 nm laser.However,they could be discriminated from the refined samples through 532 nm-OPLS model.Eight marker peaks possibly responsible for the classification of these two beeswax types were found through VIP analysis of the 532 nm-OPLS model.