Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2012
Publication Date: 5/30/2012
Citation: Lin, J.T., Chen, G.Q. 2012. Ratios of regioisomers of minor acylglycerols less polar than triricinolein in castor oil estimated by mass spectrometry. Journal of the American Oil Chemists' Society. dx.doi.org/10.1007/s11746-012-2083-1.
Interpretive Summary: Castor oil has been used in industry such as the manufacture of biodegradable plastics, nylon, plasticizers, lubricants, cosmetics and paints. We have recently identified 34 molecular species of acylglycerols containing various hydroxy fatty acids in castor oil. The hydroxy fatty acids on the different locations of the glycerol backbone affect the physical property of the oil for industrial uses, such as viscosity, pour point and melting point. The ratios of isomers of each molecular species of acylglycerols were estimated for the location of fatty acids on the glycerol backbone. This will help to characterize the oil for industrial uses.
Technical Abstract: We have recently reported the identification of forty new minor molecular species of acylglycerols containing hydroxy fatty acids less polar than triricinolein by electrospray ionization mass spectrometry of the lithium adducts. The ratios of regioisomers of triacylglycerols (ABC and AAB types) and tetraacylglycerols (AAAB type) identified were estimated by the relative abundances of the fragment ions from the neutral losses of fatty acids as a,ß-unsaturated fatty acids at the sn-2 position. The order of the contents of regioisomers of triacylglycerols with the fatty acids at the sn-2 position are: nonhydroxy fatty acids > monohydroxy fatty acids > dihydroxy fatty acids > trihydroxy fatty acids. For tetraacylglycerols (AAAB type) such as ricinoleoylricinoleoyl-ricinoleoyl-oleoyl-glycerol (RRRO), ricinoleoylricinoleoyl chain was predominately at the sn-2 position, while ricinoleate was not detected at the sn-2 position.