Showing papers by "Bianhua Liu published in 1989"

Location of double bonds in fatty acids of fish oil and rat testis lipids. Gas chromatography-mass spectrometry of the oxazoline derivatives.

Abstract: A new approach to the derivatization and analysis of long chain polyunsaturated fatty acids is described. The method is based on the formation of 2-alkenyl-4,4-dimethyloxazolines by condensation of the starting material with 2-amino-2-methylpropanol. The derivatization method is rapid, efficient and specific with respect to the chain feature of the parent acids. Volatility, comparable with that of the corresponding simple esters, and improved gas chromatographic separation are achieved without difficulty. The derivatives exhibit clear and regular fragmentation patterns that allow easy discrimination of positional isomers and assignment of double bond location in the chain.

Location of triple bonds in the fatty-acids from the kernel oil of pyrularia-edulis by gc-ms of their 4,4-dimethyloxazoline derivatives

Abstract: Location of triple bond in long-chain fatty acids has been effected by mass spectrometry or gas chromatography-mass spectrometry of their 4,4-dimethyloxazoline (DMOX) derivatives. The position of acetylenic linkage, either isolated or conjugated with olefinic bond(s) is indicated by a clear separation of 10 atomic mass units between the highest peaks of two neighboring fragment clusters. The acetylenic acid components of the kernel oil ofPyrularia edulis were found to be 17:1(8a), 18:1(9a), 18:2(9a,11), 18:2(9a,17) and 18:3(9a,11,17).

The structures of cyclopentenyl fatty acids in the seed oils of flacourtiaceae species by GC-MS of their 4,4-dimethyloxazoline derivatives

Abstract: The structures of cyclopentenyl fatty acids in the seed oils ofHydnocarpus anthelmintica Pierre et Laness.,H. alphina Wight,H. hainanensis (Merr.) andTaraktogenos merrilliana C.Y. Wu, all belonging to the family Flacourtiaceae, have been identified by GC-MS of the mixed 2-substituted 4,4-dimethyloxazoline (DMOX) derivatives. These variations are characterized by the presence of key fragments at (M-43), (M-55) and (M-67), while the location of a double bond in the chain is indicated by a 12-mass interval between the highest peaks of two adjacent homologous ion clusters. The unique fragmentation pattern coupled with the good gas chromatographic qualities of these derivatives enable convenient structure determination of cyclopentenyl fatty acids in complex mixtures.