title: Quantification of the ratio of positional isomer dilinoleoyl-oleoyl glycerols in vegetable oils.
abstract: The distribution of fatty acids in a triacylglycerol is of great importance from nutritional, biochemical, quality and technological points of view. The ratio of triacylglycerol positional isomers containing two linoleic acid (18:2) and one oleic acid (18:1) moieties--namely, 1(3),2-dilinoleoyl-3(1)-oleoyl glycerol (LLO) and 1,3-dilinoleoyl-2-oleoyl glycerol (LOL)--were quantified in grape seed, olive, pumpkin seed, soybean, sunflower and wheat germ oils by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI-MS) in selected ion monitoring (SIM) mode. Relative LOL contents (LOL/(LLO+LOL)) of the oils were calculated from the mass abundances of the [LL]+ and [LO]+ diacylglycerol fragment ions ([M+H-RCOOH]+) using a calibration curve. The calibration curve of the relative diacylglycerol mass abundances was measured in SIM mode. The relative LOL contents were found to be relatively consistent for each oil variety. The relative LOL content in grape seed, sunflower, pumpkin seed, soybean and wheat germ oils accounted for 44.2 +/- 2.6, 26.8 +/- 3.2, 16.7 +/- 4.6, 15.9 +/- 2.9 and 13.9 +/- 4.3%, respectively. Only olive oils contained practically 100% of the LLO isomer. These results indicate that the unsaturated fatty acids such as linoleic and oleic acids have 'non-random' distribution patterns in various oils.
authors.affiliation: Group of Separation Science, Research Laboratory of Materials and Environmental Chemistry, Chemical Research Center, Hungarian Academy of Sciences, P.O. Box 17, H-1525 Hungary. janna@chemres.hu
authors.forename: A
authors.initials: A
authors.lastname: Jakab
authors.forename: I
authors.initials: I
authors.lastname: Jablonkai
authors.forename: E
authors.initials: E
authors.lastname: Forgács
mesh_terms: D028464:Cucurbita / Q000737:chemistry; D005990:Glycerol / Q000031:analogs & derivatives / Q000032:analysis* / Q000737:chemistry*; D007536:Isomerism; D013058:Mass Spectrometry; D019906:Nuclear Magnetic Resonance, Biomolecular; D019301:Oleic Acid; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry*; D012015:Reference Standards; D012639:Seeds / Q000737:chemistry; D013024:Soybean Oil / Q000737:chemistry; D000074242:Sunflower Oil; D027843:Vitis / Q000737:chemistry
chemical_list: D000069463:Olive Oil; D010938:Plant Oils; D000074242:Sunflower Oil; C050055:wheat germ oil; D019301:Oleic Acid; D013024:Soybean Oil; D005990:Glycerol