Analysis of Cyclic Fatty Acid Monomer 2-Alkenyl-4,4-dimethyloxazoline Derivatives by Gas Chromatography−Matrix Isolation−Fourier Transform Infrared Spectroscopy

Abstract

Recently, cyclic fatty acid monomers (CFAMs) were isolated from heated flaxseed (linseed) oil and analyzed as methyl ester (ME) derivatives by capillary gas chromatography−matrix isolation−Fourier transform infrared spectroscopy (GC−MI−FTIR) and as 2-alkenyl-4,4-dimethyloxazoline (DMOX) derivatives by GC−electron ionization mass spectrometry (EIMS). The latter produced fragmentation patterns that were used to determine ring and double-bond positions along the hydrocarbon chain. However, for four CFAM ME derivatives, the FTIR spectra were consistent with CFAM structures having either a cyclohexenyl or a cyclohexadienyl ring, whereas those found by EIMS for the corresponding CFAM DMOX derivatives were consistent with both ring structures. In the present study, the FTIR spectra observed for the DMOX derivatives of this CFAM mixture were consistent with the earlier FTIR results obtained for the corresponding ME derivatives. Mass spectral data observed for deuterated analogues are also reported. Keywords: Cyclic fatty acid monomers; infrared