拉曼光谱-聚类分析快速鉴别掺伪芝麻油

目的建立快速鉴别掺伪芝麻油的拉曼光谱-聚类分析方法。方法以不同产地、不同品牌的多批次芝麻油、大豆油、玉米油、菜籽油、精炼棕榈油、精炼棉籽油及精炼地沟油为样品,在780 nm和532 nm激光光源下,扫描和比较其普通、扩展及导数拉曼光谱的形态。结果在532 nm激光光源的扩展光谱及一阶导数光谱中,芝麻油与低价植物油及精炼地沟油光谱的信息量最大,样品间光谱形态的差异显著。基于此全波段光谱信息和形态建立的多步聚类分析模型对芝麻油、低价植物油、仿冒芝麻油和精炼地沟油的判别正确率均为100%;对5%、10%、20%、30%和50%掺假芝麻油的判别正确率分别为72%、92%、100%、100%和100%;对5%、10%和20%掺杂芝麻油的判别正确率分别为97%、100%和100%;对5%、10%和20%掺杂植物油的判别正确率分别为94%、100%和100%。样品测量时无需制备样品及消耗化学试剂,测量和分析一份样品仅耗时5 min左右。结论所建立的拉曼光谱-聚类分析模型既可准确鉴定芝麻油,还可准确鉴定各种类型的掺伪芝麻油,可实现对掺伪芝麻油的快速、无损和准确鉴别。

Rapid detection of adulterated sesame oil by Raman spectrum-cluster analysis

Objective To establish a Raman spectrum cluster analysis method for rapid detection of adulterated sesame oil. Methods The shapes of full-range, extended-range and the 1st derivative Raman spectra were scanned and compared, based on the multiple batches of sesame oil, soybean oil, corn oil, rape seed oil, refined palm oil, refined cotton seed oil and refined bio-waste oil with various producing areas and brands, under both 780 nm and 532 nm laser sources. Results The extended-range and the 1st derivative Raman spectra under 532 nm showed the most abundant information and significantly distinct patterns among sesame oil, low-price vegetable oil and bio-waste oil. A multi-steps identification model of Raman spectrum cluster analysis was developed based on the spectral information and patterns. The discriminant rate was 100% for sesame oils, low-price vegetable oils, counterfeit sesame oils and refined bio-waste oils. The discriminant rates were 72%, 92%, 100%, 100%, and 100% for sesame oils mixed with 5%, 10%, 20%, 30%, and 50% low-price vegetable oil, 97%, 100%, and 100% for sesame oils mixed with 5%, 10%, and 20% bio-waste oil, and 94%, 100%, and 100% for vegetable oils mixed with 5%, 10%, and 20% bio-waste oil, respectively. Conclusion This Raman spectrum cluster analysis model can identify the sesame oil as well as kinds of adulterated sesame oils in a rapid, non-destructive and accurate way.