Abstract: A gas Chromatography-electron impact mass spectrometric method was developed for analyzing the compositionof the fatty acids form purslane 2-amino-2-methylpropanol was used as chemical modifying reagent to the fatty acids. Modifyingcarboxyl group into nitrogen-contaning heterocycle effectively suppressed the migration of double bonds in the fatty acid chainunder the electron impact source and led to regular informative mass spectra regarding the position of the olefinic bonds in thechain. The position of double bonds of the fatty acids form purslane was located by analyzing electron impact mass spectra of2-amino-2-methylpropanol derivatives of the fatty acids. 10 fatty acids were identified according to the analysis of GC-EIMS.Purslane consisted of the fatty adids of C16～C22 and 70.64% of them were polyunsaturated fatty acids. The main componentof the polyunsaturated fatty acids was 9,12,15-linolenic acid whose relative content was 50.08. Besides, 5,8,11,14,17-eicosapentaenoic acid(EPA)and 4,710,13,16,19-docosahexenoic acid(DHA)which existed rarely in other plants were identified.

Key words: gas chromatography-electron impact mass spectrometry, Purslane, fatty acids, chemical modification, 2-amino-2-methylpropanol