NMR Laboratory, Department of Chemistry, University of Crete, PO Box 2208, Voutes Campus, 710 03 Heraklion, Crete, Greece.
Talanta. 2010 Mar 15;80(5):2165-71. doi: 10.1016/j.talanta.2009.11.024. Epub 2009 Nov 12.
NMR spectroscopy was employed for the detection of adulteration of refined olive oil with refined hazelnut oil. Fatty acids and iodine number were determined by (1)H NMR, whereas (31)P NMR was used for the quantification of minor compounds including phenolic compounds, diacylglycerols, sterols, and free fatty acids (free acidity). Classification of the refined oils based on their fatty acids content and the concentration of their minor compounds was achieved by using the forward stepwise canonical discriminant analysis (CDA) and the classification binary trees (CBTs). Both methods provided good discrimination between the refined hazelnut and olive oils. Different admixtures of refined olive oils with refined hazelnut oils were prepared and analyzed by (1)H NMR and (31)P NMR spectroscopy. Subsequent application of CDA to the NMR data allowed the detection of the presence of refined hazelnut oils in refined olive oils at percentages higher than 5%. Application of the non-linear classification method of the binary trees offered better possibilities of measuring adulteration of the refined olive oils at a lower limit of detection than that obtained by the CDA method.
NMR 光谱法被用于检测精制橄榄油中是否掺有精制榛子油。通过（1）H NMR 测定脂肪酸和碘值，而（31）P NMR 则用于定量分析包括酚类化合物、二酰基甘油、甾醇和游离脂肪酸（游离酸度）在内的微量化合物。通过正向逐步典型判别分析（CDA）和分类二叉树（CBT），基于脂肪酸含量和微量化合物浓度对精制油进行分类。这两种方法都能很好地区分精制榛子油和橄榄油。通过（1）H NMR 和（31）P NMR 光谱法对不同比例的精制橄榄油和榛子油混合物进行分析。随后，将 CDA 应用于 NMR 数据，能够在精制橄榄油中检测到精制榛子油的存在，其含量高于 5%。与 CDA 方法相比，二叉树的非线性分类方法能够更好地检测到精制橄榄油的掺假情况，检测下限更低。
