An improved preparation method based on solid phase extraction (SPE) for determination of epoxy fatty acids derived from oleic acid in frying oils was developed. A three-step separation of fatty acid methyl esters (FAMEs) by SPE on a silica gel column was proposed, and quantification by gas chromatograph with a fiame ionization detector (GC-FID) was performed. The limits of detection (LODs) of trans- and cis-epoxy stearic acid (ESA) were 6.32 and 13.09 μg/mL, respectively. And the limits of quantification (LOQs) ranged from 20.87 to 43.19 μg/mL with recoveries ranging from 89.32% to 107.08%. Good reproducibility was observed, with an intraday relative standard deviations of 0.93–2.35%, and an interday relative standard deviations of 2.44–11.68%. Results showed total levels of ESAs in different oil samples were in the range of 235.65–5916.05 mg/kg, and the contents of ESAs increased with the increase of frying time. Thus, combining the improved sample preparation method for ESAs analysis with the separation on a fused-silica capillary column using GC is highly useful for determination of ESAs in frying oils.

提出了一种改进的基于固相萃取的制备方法，用于测定煎炸油中油酸衍生的环氧脂肪酸。提出了在硅胶柱上通过SPE对脂肪酸甲酯（FAME）进行三步分离的方法，并通过气相色谱仪和火焰离子化检测器（GC-FID）进行了定量。检测限的（检测限）反式-和顺-环氧硬脂酸（ESA）分别为6.32和13.09μg/ mL。定量限（LOQs）在20.87至43.19μg/ mL之间，回收率在89.32％至107.08％之间。观察到良好的重现性，日内相对标准偏差为0.93–2.35％，日间相对标准偏差为2.44–11.68％。结果表明，不同油样中ESA的总含量在235.65–5916.05 mg / kg范围内，并且ESSA的含量随煎炸时间的增加而增加。因此，将改进的用于ESA分析的样品制备方法与使用GC在熔融石英毛细管柱上的分离相结合，对于测定煎炸油中的ESA非常有用。