植物原油与地沟油拉曼光谱谱图的分析研究

Research to distinguish hogwash oil from raw vegetable oil based on Raman spectra

目的建立一种简便、快速、准确的鉴别植物原油与地沟油的检测方法。方法以10个品种(大豆、葵花籽、玉米、茶籽、花生、菜籽、橄榄等原油以及初榨棕榈油、初榨棕仁油、初榨芝麻油)的106份正常植物原油和11批次的精炼地沟油为样品,通过扫描样品的拉曼光谱,比对谱图的形态特征,谱图一阶导数处理和数据分析等,确立结果判定的方法和程序。并通过对234份勾兑样品的检测,初步评估新建方法的准确性。结果精炼地沟油和正常植物原油相比,其拉曼光谱呈现出拉曼强度高(达到105数量级)、平滑包状的特点,而后者除玉米原油和初榨芝麻油外,拉曼强度较低(仅在104数量级),均无平滑包状的特点,且油脂固有成分对应的各种谱带清晰可见。精炼地沟油的一阶导数图谱中2 839 cm-1的峰高值均为负值,正常植物原油均为正值。确定的植物原油一阶导数图谱中2 944和2 839 cm-12峰强度比值的下限值最高为-0.851,最低为-3.015。运用新建方法对勾兑样品(5%、10%、20%地沟油勾兑植物原油)进行判定,10%勾兑样品的正确检出率达到了80%以上;20%勾兑浓度的地沟油勾兑样品检测的准确率达到了100%。结论地沟油拉曼光谱图与植物原油拉曼光谱图有显著不同,可作为鉴别地沟油的参考依据。

Objective To develop a simple,quick,and accurate detection method for distinguishing hogwash oil from raw vegetable. Methods Testing samples included 106 raw vegetable oils in 10 categories and 11 batches of refined hogwash oils. The Raman spectra were scanned to compare the morphology and acquire the first derivatives,including the lower limit value for each kind of raw vegetable oils to establish steps of the method. The accuracy was evaluated by detecting 234 mixture samples. Results There was morphology of smooth bulk peak in all refined hogwash oils,and the 2 839 cm^-1peak values were negative for the first derivatives. The ratios of peak 2 944 to 2 839 cm^-1were between-0. 851 and-3. 015.The accuracies for the mixtures with 10% and 20% hogwash oil were 80% and 100%,respectively. Conclusion Raman spectra of hogwash oil and raw plant oil were significantly different and can be used as reference for distinguishing between them.