高分辨质谱直接分析食用油中脂肪酸甘油酯

食用油中不饱和脂肪酸甘油酯的含量与人体健康密切相关,针对其建立快速有效的检测方法具有重要意义。本研究建立了一种可直接分析食用油中脂肪酸甘油酯的方法,采用大气压化学电离-高分辨质谱技术(APCI-HRMS)对食用油中脂肪酸甘油三酯及脂肪酸甘油二酯分子直接进样分析,在指纹区高分辨质谱数据的基础上,采用分解系数和平均不饱和度(DBE)对不同油品进行比较分析。结果表明,食用油与餐厨回收油及动物油具有明显差别,当分解系数大于10时,或DBE小于3时,可判断样品为餐厨回收油或动物油,利用这两个特征参数可成功地区分食用油与餐厨回收油样品。通过偏最小二乘法的分组验证,以及添加不同比例餐厨回收油的食用植物油样品分解系数和平均不饱和度的比较验证,表明该方法可便捷、准确地分析油品中脂肪酸甘油酯的含量变化,有望成为监测食用油品质的快速、有效的新型分析方法。

Direct Analysis of Fatty Glyceride in Edible Oil by High-Resolution Mass Spectrometry

The content of unsaturated fatty glyceride in edible oil is closely related with human health. Edible vegetable oil contains high content of unsaturated fatty glyceride, while animal oil has much saturated fatty glyceride. When the edible vegetable oil was used repeatedly, the content of unsaturated fatty glyceride will decrease and that of saturated fatty glyceride will increase, which will bring bad effect to human health, so it is of great importance and value to establish a rapid and effective method to measure the content change of the whole unsaturated fatty glyceride profile. In this study, a novel high-resolution mass spectrometry method in atmospheric pressure chemical ionization mode (APCI-HRMS) for direct analysis of fatty glyceride in edible oil was developed. The oil samples were simply diluted with trichloromethane-methanol solvent (2∶1, V/V), and then directly injected into mass spectrometer without any separation. So the analysis is able to be performed quite fast (1.5 min/per sample) in a high throughput. Intensity difference can be directly observed in fatty acid triglyceride and fatty acid diglyceride comparing edible oil with waste oil. To confirm the intensity difference, the decomposition ratio (intensity of fatty acid diglyceride/intensity of fatty acid triglyceride) and average degree of unsaturation (DBE, average DBE of all the detected fatty acid triglyceride and fatty acid diglyceride) were calculated in edible vegetable oil and waste oil. It was found that the decomposition ratio obviously increased, while average DBE sharply decreased in waste oil. It shows that waste oil has similar characters with those of animal oil. The result demonstrates that decomposition ratio and average DBE can be used as the indicators to differentiate edible oil and waste oil. Furthermore, data matrix of fatty acid triglyceride and fatty acid diglyceride were under an orthogonal partial least squares discriminant analysis (OPLS-DA). The analysis result shows that the edible oil and waste oil are well separated, the grouped result validates that the differentiation is convincing. By calculating the decomposition ratio and average DBE of samples adding different portion of waste oil into edible oil, the method was further validated. It demonstrates that the method can easily accurately and fast measure the content change of fatty glyceride in oil, and it has the potential to become a rapid and effective method to monitor the quality of edible oil.