毛细管气相色谱法测定食用油中15种反式脂肪酸的含量

Determination of 15 Trans Fatty Acids in Edible Oil by Capillary Gas Chromatography

提出了毛细管气相色谱法测定橄榄油、芝麻油和花生油中的15种反式脂肪酸。样品用异辛烷溶解,与2mol·L-1氢氧化钾的甲醇溶液进行酯化反应,生成的脂肪酸甲酯经强极性聚二氰丙基硅氧烷毛细管气相色谱柱SP-2560分离,用氢火焰离子化检测器检定。在优化的试验条件下,15种反式脂肪酸甲酯的质量浓度在一定范围内与其峰面积呈线性关系,方法的检出限(3S/N)和测定下限(10S/N)分别为0.012%(以脂肪计)和0.024%(以脂肪计)。对空白样品进行加标回收试验,回收率在86.6%~109%之间,测定值的相对标准偏差(n=10)在2.0%~4.2%之间。方法用于分析市售橄榄油、芝麻油和花生油中的15种反式脂肪酸,结果与标准方法的测定值相符。

A method of capillary gas chromatography was proposed for simultaneous determination of 15 kinds of trans fatty acids in olive oil,sesame oil,peanut oil,and sunflower oil.The sample was dissolved in isooctane,and reacted with 2mol·L-1 KOH-methanol solution to form fatty acid methyl esters(FAMEs),which were then separated on the highly polar Poly(bis cyanopropyl siloxane)capillary chromatographic column(SP-2560)and detected by FID.Under optimized conditions,the linear relationships between the peak area and the mass concentration of the 15 trans fatty acid methyl esters were in a certain range,with detection limits(3S/N)of0.012% and limits of quantification(10S/N)of 0.024%.Recovery measured by standard addition method was in the range of 86.6%-109%,with RSD(n=10)in the range of 2.0%-4.2%.The method was used for the analysis of olive oil,sesame oil,peanut oil,and sunflower oil,giving results consistent with those obtained by the standard method.