GAS-CHROMATOGRAPHY MASS-SPECTROMETRY OF THE PICOLINYL ESTER DERIVATIVES OF DEUTERATED ACETYLENIC FATTY-ACIDS

Deuteration (with Wilkinson's catalyst) of methyl 12:1(3a), 14:1(5a), 15:1(6a), 16:1(7a), 18:1(9a), 18:2(9a, 11a), 17:2(10a. 12a) and 18:2(5a, 10c) gave the corresponding deuterium-labelled saturated fatty esters. The mass spectral analysis of their picolinyl esters gave predictable diagnostic ion fragments for most isomers. In the case of 12:1(3a) and 14:1(5a) isomers, hydrogen-deuterium scrambling occurred during electron impact to give unique fragmentation patterns. This method allows the accurate determination of the positions of the unsaturated centres in the alkyl chain of the fatty esters.