气相色谱-质谱法分析北大西洋瓜参脑苷脂中2-羟基脂肪酸

Analysis of 2-Hydroxy Fatty Acids of Cerebroside from Cucumaria frondosa by Gas Chromatography-Mass Spectrometry

通过酸甲酯化衍生、羟基乙酰化保护和二甲基二硫衍生方法对北大西洋瓜参脑苷脂中的2-羟基脂肪酸进行衍生,采用气相色谱-质谱技术分析其2-羟基脂肪酸组成。通过衍生处理和色谱优化,取得理想的色谱分析效果。根据质谱断裂规律,采用特征离子可对北大西洋瓜参脑苷脂中2-羟基脂肪酸上的羟基和双键位置进行准确判断,其中2-羟基饱和脂肪酸甲酯的特征离子为m/z 57(基峰离子),90,[M-59]+,[M-18]+和M+;2-羟基单烯脂肪酸甲酯的特征离子为m/z 55(基峰离子),90,[M-59]+,[M-18]+和M+。2-羟基单烯脂肪酸DMDS衍生物的特征离子为A+(m/z 75+14n)和B+(m/z 191+14m),根据这两个碎片离子即可快速准确推断2-羟基单烯脂肪酸中双键所处碳链位置。通过气相色谱-质谱分析,从北大西洋瓜参脑苷脂中共鉴定出9种2-羟基脂肪酸,以2-OH C24:1n-9(70.84%)、2-OH C23:1n-9(7.74%)和2-OH C20:0(6.82%)为主。

The 2-hydroxy fatty acid composition of cerebroside from Cucumaria frondosa was analyzed by gas chromatography-mass spectrometry in this paper, after the acid-catalyzed esterification, hydroxy group acetylation and dimethyl disulfide derivatization in turn. The great effects of chromatographic analysis were obtained by derivatization treatments and chromatographic optimization. Meanwhile, the accurate judgments on the hydroxy group and double-bond positions of hydroxy fatty acids could be rapidly made by characteristic ions, according to the fragmentation rules and mass spectrometry characteristics. Furthermore, the characteristic ions of 2-hydroxy saturated fatty acid methyl esters were m/z 57（base-peak ion）, 90, [M-59]＋, [M-18]＋and M＋; while 2-hydroxy monounsaturated fatty acid methyl esters were m/z 55（base-peak ion）, 90, [M-59]＋, [M-18]＋and M＋. The characteristic ions of dimethyl disulfide adduct of 2-hydroxy monounsaturated fatty acids were A＋（m/z 75＋14 n） and B＋（m/z 191＋14 m）, and the double-bond positions could be precisely judged on the basis of those two characteristic ions. Nine kinds of 2-hydroxy fatty acids were identified from cerebroside of Cucumaria frondosa, and were chiefly consisted of 2-OH C24：1 n-9（70.84%）, 2-OH C23：1 n-9（7.74%） and 2-OH C20：0（6.82%）.