脂肪酸的色谱保留时间规律与质谱特征研究及其在食品分析中的应用

用石油醚提取食品中的脂肪,经甲酯化反应后,采用HP-88(100m×0.25mm,0.33μm)弹性石英毛细管柱分离脂肪酸甲酯的同系物及异构体,GC/MS法测定。研究了不同链长脂肪酸的同系物及异构体的气相色谱出峰顺序,得到其保留时间规律;研究了不同脂肪酸的质谱断裂规律,选择3个特征离子来鉴定脂肪酸成分。建立了3个特征离子确定脂肪酸碳数及双键数目,色谱保留时间规律确定脂肪酸顺反异构体及双键位置异构体的方法。本法无需标准品即可快速测定脂肪酸同系物及异构体的含量,适用于脂肪酸组成的研究;及油脂、食品中脂肪酸,特别是反式脂肪酸的测定。

Gas Chromatographic Retention Time Rule and Mass Spectrometric Fragmentation Rule of Fatty Acids and Their Application in Food Analysis

The fat in food samples was extracted using Soxhlet technique, and in-vial derivatised to their corresponding methyl ester and subsequently analysed by GC/MS. Sufficient separation for the homologous and isomers of methyl esters of fatty acids was obtained with HP-88 capillary column. The gas chromatographic retention time rule and mass spectrometric fragmentation rule of homologues and isomers of fatty acids methyl esters were studied. A novel method that can ascertain carbon atom number and double bond number in fatty acids using 3 characteristic ions, as well can confirm cis-trans isomers and double-bond positional isomers based on retention time rule was established. Using this method, contents of homologues and different kinds of isomers of fatty acids can be determined without standards. This method can be applied to the investigation of the compositions of fatty acids, especially trans-fatty acid, and the determination of fatty acids in lipid and food samples. The method is accurate, reliable and convenient. It has been applied to the quantitative determination of the content of trans-fatty acid in food samples.