Abstract: A gas chromatography-electron impact mass specrometric method was developed for analyzing the compositions of the fatty acids in sea cucumber, whereas 2-amino-2-methylpropanol was used as the pre-column chemical modifying reagent for assaying the fatty acids. The functional group modilication effectively suppresses the migration of double bonds in the fatty acid chain and leads to regular informative mass spectra regarding to the position of the olefinic bonds in the chain. The position of double bonds of the fatty acids in sea cucumber were located by analyzing electron impact mass spectra of 2-alkenyl-4,4- dimethyloxazolines with a hidden carboxy1 as derivative of the fatty acids.According to the analysis of GC-EIMS, 16 fatty acids were identified. Sea cucumber consists of the fatty acids of C14～C24 and 33.49% of them are polyunsaturated fatty acids. The main components of the polyunsaturated fatty acids are 5,8,11,14,17-eicosapentaenoic acid and 4,7,10,13,16,19-docosahexenoic acid whose relative contents are 18.26% and 6.65% respectively. Besides, 14-tricosenoic acid (relative content 3.31%) with odd- numbered was identified.

Key words: sea cucumber, fatty acids, gas chromatography-elcctron impact mass spectrometry, chemical modification