基于固相微萃取技术的地沟油快速检测方法的研究

Illegal cooking oil events happened everywhere around China in recent years, which is harmful for human health. However, there were no effective detection methods to determine illegal cooking oil accurately at home or abroad. As a result, an effective, fast, simple and sensitive detection method is urgent to be developed. This study is intended to establish a comprehensive rapid detection method for illegal cooking oil using the methods of SPME-GC/MS and electrical conductivity. The detail study contents are as followed. 1) The extraction fibers will be optimal selected to be suitable for the detection of illegal cooking oil. 2) The influence of the absorption efficiency of the components to be determined by electrosorption-enhanced SPME and circulating cooling SPME will be studied. 3) The equipments of electrosorption will be improved to gratify the detection of electrical conductivity while sampling. 4) The disciplines of characteristic products produced in each kind of edible oils with the raise of temperature will be studied. And then component data bases of gas phase and liquid phase of the oil will be set up to select the characteristic components as the analytes in the illegal cooking oil. 5) It will be researched that he best qualitative and quantitative analytical conditions of SPME-GC/MS for characteristic components in illegal cooking oil. The work curve of this method will be established and evaluated. The lowest additive amount of illegal cooking oil will also be studied, and finally a comprehensive rapid detection method for illegal cooking oil will be established.

近年地沟油事件频发，极大地危害人们的身体健康，而国内外均无有效的检测方法准确判定地沟油。因此，亟待开发有效、快速、简便、灵敏的检测方法。本研究拟以固相微萃取技术与GC/MS联用法和电导率法建立综合的地沟油快速检测方法。具体研究内容包括：1）优选适合用于地沟油检测的固相微萃取纤维；2）研究固相微萃取技术的电吸附增强法和循环-冷凝萃取法对特征检测成分吸附效果的影响；3）在固相微萃取采样的同时检测被测样的相对电导率； 4）研究单一成品食用油随温度上升其特征反应物质的产生规律，建立不同种类成品油 的GC/MS 气相物质的"组分库"和液相物质的"组分库"，筛选出特征检测成分以确定地沟油的分析对象；5）探讨SPME-GC/MS法定性、定量分析地沟油特征检测成分的最佳条件，建立工作曲线并对方法进行评估，探索地沟油最低检测掺入量，最终得到一种综合的地沟油快速检测方法。

地沟油回流餐桌事件引起了社会的广泛关注。固相微萃取（SPME）作为集采样、富集和解析于一体的新型技术，具有高灵敏度、强选择性和稳定性的优点。本项目提出了基于固相微萃取与GC-MS联用的技术，对地沟油和食用油中挥发性和半挥发性成分吸附测定。经过实验条件对比，项目选择活性炭纤维（ACF）作 为SPME的萃取纤维，通过预实验和萃取条件的优化选择，得到了ACF-SPME检测地沟油的最佳萃取条件：取0.0250g样品，加入0.0050g Na2SO4，在120℃下萃取50min，色谱解析1min，萃取过程不搅拌。在最佳条件下，分别测定不同来源的地沟油和不同种类的食用油，对比这些油脂的挥发性组分发现：地沟油中丙位十二内酯、7-癸烯-2-酮等物质在葵花籽油、花生油和大豆油中均不存在，将其归为外源性污染物；而1,2-环氧十四烷、2-十四环酮等物质为食用油经过高温加热后新生成物质，在地沟油中也可检测到，称之为内源性污染物。外源性和内源性污染物构成了地沟油特征组分库。.实验进一步发现，地沟油与食用油中部分物质的峰面积或峰高有较大的差别。利用这些差别拟合出M值、A值和T值计算式，用数值方法反映出不同油脂间的差别。其中：.M值表示不同油脂中2-十九烷酮含量的差异。结果表明：不同品牌植物油的M值均低于40，而地沟油远高于40，可达到339.07。分析原因，地沟油中M值较高是因为在使用过程中不断有猪油等动物油脂积累所致。因此，M值测定适用于泔水油的判定。.A值表示食用油经过不同次数的高温加热后挥发性物质发生的变化。结果表明:随着加热次数的增加，A值不断增大，且地沟油、煎炸老油的A值远高于食用油。因此，该方法不仅适用于区分地沟油与食用油，还适用于煎炸老油的判定。.T值反映了地沟油与食用油按照不同掺杂的混合油中挥发性物质发生的变化。结果表明，地沟油的T值远大于植物油，该方法可用于判定掺有地沟油的植物油。