内标法测定甘油酯上的十一烷酸和13-甲基十四烷酸及其在非正常油脂掺伪识别中的应用

Determination of undecanoic acid and 13-methyl-tetradecanoic acid connected to the glyceride with internal standard method and its application to the identification of adulteration of illegal cooking oil

结合非正常油脂(地沟油)的来源(加热植物油和动物油)及反映其不同来源的重要特征指示物,即连接在甘油酯上的十一烷酸和13-甲基十四烷酸,建立了内标法测定油脂中甘油酯上十一烷酸和13-甲基十四烷酸的方法。多维气相色谱-质谱采用不分流进样和选择性切割可以实现在线净化和富集,提高分析的灵敏度和分离度。十一烷酸和13-甲基十四烷酸的方法检出限分别达到0.070、0.006 mg/kg。此外,研究发现绝大多数正常植物油中十一烷酸和13-甲基十四烷酸的含量比非正常油脂中二者的含量低。通过待测油脂中十一烷酸和13-甲基十四烷酸的含量可以在一定程度上推断食用植物油的品质。

On the basis of the source of illegal cooking oil（heated vegetable oil and animal oil） and the important referents reflecting their sources,namely,undecanoic acid and 13-methyl-tetradecanoic acid connected to the glyceride,their corresponding ramifications in edible oil were detected with internal standard method.The sensitivity and selectivity of this method were improved by the on-line cleanup and preconcentration.The detection limits of the method were 0.070 mg/kg for undecanoic acid and 0.006 mg/kg for 13-methyl-tetradecanoic acid.Additionally,most of the normal vegetable oils have lower levels of both fatty acids than illegal cooking oils.It was suggested to evaluate the quality of edible oils to some extent on the basis of the contents of undecanoic acid and 13-methyl-tetradecanoic acid.