气相色谱-质谱联用法测定食用油脂中的缩水甘油酯

Determination of Glycidyl Esters in Edible Oils by GC-MS

采用甲醇钠/甲醇酯转化-苯基硼酸（PBA）衍生化-气相色谱质谱（GC-MS）联用技术,优化建立了有关食用油脂中缩水甘油酯（GEs）的分析检测方法。GC-MS的分析方法为：TG-5MS色谱柱（0.25 mm×30 m×0.25μm）,梯度升温程序,进样口和传输线温度为280℃,脉冲不分流进样,载气流速为1.18 m L/min;MS条件：EI离子源,EI电离能量为70 e V,接口温度为280℃,溶剂延迟时间为8 min,选择离子模式（SIM）定量。本方法的检出限（LOD）为0.01 mg/kg,加标回收率为87.64%~98.99%,相对标准偏差（RSD）为2.16%~5.87%。利用本方法对几种常见食用油脂中GEs的含量进行了检测,同时还研究了菜籽油在精炼过程中GEs含量的变化。结果表明：该分析方法定性定量准确,灵敏度高,重复性好,能满足食用油脂中GEs分析检测的要求,在所测的植物油脂中,棕榈油中GEs含量相对较高,另外,在植物油的精炼工序中,脱臭工序是产生GEs的一个关键环节。

An improved method for the determination of glycidyl esters（GEs） in edible oils is described here. Gas Chromatography-Mass Spectrometry（GC-MS） reveled that, after being derivatized with phenylboronic acid, 3-MCPD was successfully released by transesterification with sodium methoxide. For GC-MS analysis, a TG-5MS capillary column（0.25 mm × 30 m × 0.25 μm） was used with a gradient temperature program. The injection and transfer line temperature was 280 ℃ using pulsed splitless mode,and ultrapure grade helium with a flow of 1.18 m L/min as the carrier gas. Electron impact ionization mode was used with an ionization energy of 70 e V. The interface temperature was 280 ℃,with an 8 min solvent delay. The MS was operated in elected ion mode. The limit of detection was 0.010 mg/kg and the recovery rate was 87.64~98.99% with a relative standard deviation of 2.16~5.87%. The content of GEs in several edible vegetable oils was detected to verify this method. Additionally, the effects of oil and fat refining processes on GEs have been studied. The results showed that this method of analysis is both qualitatively and quantitatively accurate,with high sensitivity and good reproducibility. Therefore, this method can meet the demands of the detection and analysis of GEs in edible oils. Among edible vegetable oils, palm oil had a relative high content of GEs. Additionally, analysis of the oil refining process revealed that deodorization was the key process in which GEs were generated.