GAS-LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY OF THE 4,4-DIMETHYLOXAZOLINE DERIVATIVES OF DELTA-5-UNSATURATED POLYMETHYLENE-INTERRUPTED FATTY-ACIDS FROM CONIFER SEED OILS

The fatty acids from the seed oils of three Conifer species lone Pinac eae, Pinus pinaster, and two Cupressaceae, Chamaecyparis lawsoniana an d Biota orientalis) have been analyzed as their 4,4-dimethyloxazoline (DMOX) derivatives by gas-liquid chromatography coupled with mass spec trometry. The structures of six Delta 5-unsaturated polymethylene-inte rrupted fatty acids (Delta 5-UPIFA) were established, confirming previ ous studies in which they were identified by their equivalent chain-le ngths (ECL) and by comparison with related authentic standards. These acids were: cis-5,cis-9 18:2, cis-5,cis-9,cis-12 18:3 (P. pinaster), c is-5,cis-9,cis-12,cis-15 18:4 (C. lawsoniana), cis-5,cis-11 20:2, cis- 5,cis-11,cis-14 20:3 (all species), cis-5,cis-11,cis-14,cis-17 20:4 (B . orientalis) acids. In addition, cis-9 18:1, cis-9,cis-12 18:2 (all s pecies) and cis-9,cis-12,cis-15 18:3 (Cupressaceae) acids, together wi th their elongation products [cis-11 20:1, cis-11,cis-14 20:2 (all spe cies) and cis-11,cis-14,cis-17 20:3 (B. orientalis) acids] were also i dentified. In the mass spectra, DMOX derivatives of all Delta 5-UPIFA showed an intense peak at m/z 153, which is a diagnostic ion of fatty acid derivatives with a Delta 5-ethylenic bond. Other double bonds wer e localized by ion pairs that differed by 12 atomic mass units. The pr esent study fully justifies the use of ECL to identify Delta 5-UPIFA i n Conifer seed oils, in which they are ordinary components.