同步-异步二维中红外相关谱检测掺假芝麻油

将同步-异步二维中红外相关谱和多维偏最小二乘判别法相结合定性分析掺假芝麻油。分别配置40个纯芝麻油和含有玉米油不同体积分数(3%~60%)的掺假芝麻油样品40个。室温下,分别采集所有样品的常规一维中红外光谱(650~4 000cm-1)。在研究纯芝麻油和掺假芝麻油的一维中红外光谱的基础上,以芝麻油中掺假的玉米油浓度为外扰,进行相关计算,得到同步和异步二维中红外相关谱矩阵,并对其进行标准化。分别提取标准化的同步和异步二维中红外相关谱主对角线上部分和下部分元素进行融合,得到同步-异步二维中红外相关谱矩阵。在此基础上,分别基于同步-异步二维中红外相关谱矩阵、同步二维中红外相关谱矩阵和异步二维中红外相关谱矩阵建立了三个定性分析掺假芝麻油的多维偏最小二乘判别模型对预测集未知样品进行预测,其识别正确率分别为100%,96.2%和96.2%。结果表明:相对于同步和异步二维中红外相关谱,同步-异步二维中红外相关谱不仅包含了完整的掺假油特征信息,而且剔除了冗余信息,因此能取得更好的判别结果。

Detection of Adulterated Sesame Oil Based on Synchronous-Asynchronous Two-Dimensional Mid-Infrared Correlation Spectroscopy

An innovative method for classification of adult erated sesame oil was applied by using synchronous-asynchronous two-dimensiona l (2D) mid-infrared correlation spectroscopy in combination with way partial l east squares discriminant analysis (NPLS-DA).40 pure sesame oils and 40 adulte rated sesame oils with corn oil (3％～60％) were prepared and one-dimensional (1D)infrared absorption spectra(650～4 000 cm-1) were measured at room tempe rature.1D spectral characteristics of pure and adulterated sesame oil were stud ied.Under the perturbation of the concentration of corn oil in sesame oils,the synchronous and asynchronous 2D mid-infrared correlation spectra were calculat ed and normalized.Synchronous-asynchronous 2D mid-infrared correlation matrix was obtained by computing the sum of the upper triangular part of the normalize d synchronous 2D mid-infrared correlation matrix and the strictly lower triangu lar part of the normalized asynchronous 2D mid-infrared correlation matrix.The qualitative analysis NPLS-DA models were constructed to classify adulterated s esame oil by using synchronous-asynchronous 2D mid-infrared correlation spectr a,synchronous 2D mid-nfrared correlation spectra,and asynchronous 2D mid-nfr ared correlation spectra.For samples in prediction set,the rate of correct cla ssification was 100％ by using synchronous-asynchronous 2D mid-infrared correla tion spectra,versus 96.2％ by using synchronous and asynchronous 2D mid-infrar ed correlation spectra.Compared with synchronous,or asynchronous 2D mid-infra red correlation spectra,synchronous-asynchronous 2D mid-infrared correlation spectra not only contain more integrated characteristic information of adulterat ed oil,but also eliminate redundancy.Therefore,synchronous-asynchronous 2D m id-infrared correlation spectra can provide better classification results.