C-13 NUCLEAR MAGNETIC RESONANCE SPECTRAL CONFIRMATION OF DELTA-6- AND DELTA-7-TRANS-18/1 FATTY ACID METHYL ESTER POSITIONAL ISOMERS

摘要

Trans octadecenoic acid methyl ester isomers were obtained from a partially hydrognated soybean oil and isolated by silver-ion high-performance liquid chromatography. Recently, the double-bond positions for nine individual trans octadecenoic acid positional isomers (Delta 8 through Delta 16) were confirmed by gas chromatography-electron ionization mass spectrometry after derivatization to 2-alkenyl-4,4-dimethyloxazoline. In this communication, the presence of two additional trans-18:1 fatty acid methyl ester positional isomers (Delta 6 and Delta 7) in the same mixture is confirmed by C-13 nuclear magnetic resonance spectroscopy. The identity of the Delta 5-trans-18:1 far/acid methyl ester positional isomer is inferred. [References: 10]