DETERMINATION OF DOUBLE-BOND POSITION IN TRIAENOIC TO HEXAENOIC FATTY-ACIDS BY MASS-SPECTROMETRY

Methylesters of polyenoic fatty acids (FAE) with up to six double bonds can be transformed to polyhydroxy derivatives by treatment with OsO4. Under low energy electron impact the trimethylsilyloxy (O-TMS) derivatives of these polyenoic fatty acids exhibit mass spectrometric fragmentation patterns that are straightforward due to the almost exclusive cleavage of CC bonds in between vicinal O-TMS groups. Thus it is possible to localise original double bond positions and also to predict fragmentation patterns of hitherto unknown fatty acid species. The method is applicable to polyenoic compounds with isolated as well as conjugated double bonds. © 1979.