针对国家标准方法GB 5009.191-2016《食品安全国家标准 食品中氯丙醇及其脂肪酸酯含量的测定》第三法中存在的目标物响应偏低、净化过程复杂等问题,优化了酯键断裂反应条件、净化方式及衍生条件,提出了气相色谱-串联质谱法测定食用植物油中2-氯-1,3-丙二醇酯、3-氯-1,2-丙二醇酯及缩水甘油酯的方法。改进的试验条件如下:使用含0.5 mol·L^-1甲醇钠的甲醇溶液在室温下反应6 min,将氯丙醇酯水解为相应的氯丙醇;以体积比8∶2的甲基叔丁基醚-乙酸乙酯混合液为提取剂,并对样品提取2次;以300 μL含4%(体积分数)七氟丁酰基咪唑的正己烷溶液为衍生剂,于70 ℃反应20 min,完成对氯丙醇的衍生。在改进的方法中,2-氯-1,3-丙二醇和3-氯-1,2-丙二醇标准曲线的线性范围均为30~200 μg·kg^-1(低浓度水平)和300~3 200 μg·kg^-1(高浓度水平),检出限均为10 μg·kg^-1。按照标准方法进行回收试验,回收率为82.3%~109%,相对标准偏差(n=6)均小于9.0%。方法用于分析5种食用植物油样品,结果显示5种食用植物油中3-氯-1,2-丙二醇酯均有检出,质量分数为209.2~783.4 mg·kg^-1,其中杏仁油中3-氯-1,2-丙二醇酯的含量水平偏高,存在一定潜在风险。

To solve the problems of low target response and complex purification process in the third method of the national standard method GB 5009.191-2016 National Food Safety Standard the Determination of Chloropropanols and Its Fatty Esters in Food, the ester bond cleavage reaction conditions, purification methods, and derivative conditions were optimized, and the method for the determination of 2-chloro-1,3-propanediol esters, 3-chloro-1,2-propanediol esters and glycidyl esters in edible vegetable oil by gas chromatography tandem mass spectrometry was proposed. The improved experimental conditions were as follows. Chloropropanol esters were hydrolyzed into corresponding chloropropanols at room temperature for 6 min with methanol solution containing 0.5 mol·L^-1 sodium methoxide. The sample was extracted twice with a mixture of methyl tert-butyl ether and ethyl acetate at a volume ratio of 8∶2 as the extraction agent. Chloropropanols were completely derivatized at 70 ℃ for 20 min with 300 μL of n-hexane solution containing 4% (volume fraction) heptafluorobutyrylimidazole as the derivative. In the improved method, the same linear ranges of the standard curves for 2-chloro-1,3-propanediol and 3-chloro-1,2-propanediol were 30-200 μg·kg^-1 (at low concentration level) and 300-3 200 μg·kg^-1 (at high concentration level), with the same detection limits of 10 μg·kg^-1. Test for recovery was made by the standard addition method, giving results in the range of 82.3%-109%, with RSDs (n=6) of the determined values less than 9.0%. This method was applied to analysis of 5 edible vegetable oil samples, and it was shown that 3-chloro-1,2-propanediol esters were detected in all 5 edible vegetable oil, with mass fraction of 209.2-783.4 mg·kg^-1. Among them, the content level of 3-chloro-1,2-propanediol esters in almond oil was relatively higher, which was a certain potential risk.