乳中C18：1反式脂肪酸的色谱保留时间规律与质谱特征研究

Gas chromatographic retention time rule and mass spectrometric fragmentation rule of trans C_(18∶1) fatty acids in milk

用高速离心提取乳中脂肪,经两步甲酯化后,采用100m长CP-Sil88 FAME毛细管柱、程序升温,GC/MS法测定。研究了反式C18∶1长链脂肪酸的反式异构体气相色谱出峰顺序,得到其保留时间规律;研究了C18∶1反式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。本方法分离效果好,操作简便、快速,结果可靠,适用于测定乳中反式C18∶1脂肪酸异构体含量。

The fat in milk samples was extracted using high speed centrifugal effect, and in vial derivatived to their corresponding methyl ester using two steps and subsequently analyzed by GC/MS. Sufficient separation for the homologous and isomers of methyl esters of fatty acids was obtained with CP-Sil 88 capillary column. The gas chromatographic retention time rule and mass spectrometric fragmentation rule of homologues and isomers of trans C18：1 fatty acids methyl esters were studied. A novel method that could ascertain carbon atom number and double bond number in fatty acids using 3 characteristic ions, as well could confirm trans isomers and double bond positional isomers based on retention time rule was established. The method was accurate, reliable and convenient. It was applied to the determination of the content of trans fatty acid in milk samples.