Improved methods for the isolation and study of the C18, C20 and C22 monoethylenic fatty acid isomers of biological samples: Hg adducts,HPLC, AgNO3-TLC/FID,and ozonolysis

The monoethylenic isomers of C₁₈, C₂₀ and C₂₂ chain lengths of the depot fat of a nonhominid primate (cynomolgus monkeys,Macaca fascicularis), fed a partially hydrogenated herring oil (IV=76.0) for 30 months, were examined by 2 different approaches. The first isolation method involved preparative gas liquid chromatography and argentation thin layer chromatography (TLC). The second sequence involved a chain-length fractionation system based on the TLC of the methoxy-bromomercuri quence involved a chain-length fractionation system based on the TLC of the methoxy-bromomercuri adducts of the total methyl esters to isolate groups of acids of common degrees of unsaturation, and then high performance liquid chromatography on a reverse-phase column. In both cases, the monoethylenic isomer distribution was determined by ozonolysis in BF₃/MeOH. Comparable results were obtained with the 2 methods. The second approach is recommended for small biological samples, especially for those containing a relatively high proportion of di- and other polyethylenic isomers which might interfere. Presented in part at the AOCS annual meeting, New Orleans, May 1981.     

Determination of selenium,arsenic, iodine and bromine in fish,plant and mammalian oils by cyclic instrumental neutron activation analysis

The concentrations of arsenic, selenium, iodine and bromine in a series of fish, plant and mammalian oils have been determined by cyclic instrumental neutron activation analysis (CINAA). Crude fish oils contain between 0.047 and 0.151 μg Se g⁻¹, 2.36–14.5 μg As g⁻¹, 2.36–9.63 μg Br g⁻¹ and 0.97–4.76 μgI g⁻¹. Seal oil contains the same four elements, but at levels below the lower end of the fish oil ranges. Iodine, bromine and arsenic were not detected in rape-seed or soybean oils and the concentration of selenium varied from < 0.010 to 0.042 μg g⁻¹. The levels of selenium, iodine and bromine are reduced markedly by hydrogenation of the menhaden oils. The CINAA method yielded results which were in agreement with pub-lished values obtained by other methods. The technique was rapid, requiring minimal sample manipulation, and was essentially free from interferences.     

Structural correlation of unsaturated fatty acid esters through graphical comparison of gas-liquid chromatographic retention times on a polyester substrate

The correlation of structures of esters of certain unsaturated fatty acids is possible through a linear relation when logarithms of retention time on polyester substrates are plotted against the number of carbon atoms in the fatty acid chain. This correlation is independent of any relation to the retention times of the esters of the saturated fatty acids, and depends solely on the fatty acid chain length, the number of double bonds, and the length of the end carbon chain. It appears to depend on the influence of the latter on vapor pressure. A sound basis is thus provided for advocating a modified equivalent chain length system, virtually independent of temperature effects, and based on certain commonly occurring monounsaturated acids rather than on the saturated acids.     

Determination of sulfur contents of vegetable and marine oils by ion chromatography and indirect ultraviolet photometry of their combustion products

A simple method for the determination of total sulfur content in vegetable and marine oils is described. The method involves combustion of the oil sample in an oxygen bomb to convert all forms of sulfur to sulfate ions with subsequent determination of the sulfate by ion chromatography and indirect ultraviolet detection. The ultraviolet system described is more sensitive than conductivity detection and enables the method to be applied more widely. Application of the method to a variety of vegetable and marine oils showed the general occurrence of sulfur in fats and oils, albeit often at a low level. Among the samples examined, crude Canola oil had the highest sulfur content (25.0 mg/kg) followed by the marine oils (5.8-15.2 mg/kg) and the non-Cruciferae vegetable oils (2.0-6.1 mg/kg). To whom correspondence should be addressed.     

An analysis of separation factors applicable in the gas-liquid chromatography of unsaturated fatty acid methyl esters on a polyester substrate

The employment of gas-liquid chromatography (GLC) separation factors between methyl esters of unsaturated fatty acids is feasible as a means of tentative identification, either between acids of one chain length and differing numbers of double bonds, or between acids of one chain length and the same number of double bonds in differing positions, provided the acid structures are appropriately grouped by end carbon chain. The modification of separation factors by temperature, chain length, number of double bonds, or position of double bonds is apparent from examination of a larger number of examples than was hitherto available. Examples of the usefulness of separation factors in identifying unknowns or predicting retention times are given.     

Molecular species of wax esters in jaw fat of atlantic bottlenose dolphin,Tursiops truncatus

The jaw fat of the Atlantic bottlenose dolphin (Tursiops truncatus) contains unusual wax esters which can be separated into short chain (<C₂₄) and long chain (>C₂₄) fractions by thin layer chromatography. The short chain wax esters (28 wt. %) have been characterized as a 72∶24∶4 mixture of isovaleroyl, isobutoryl, and 2-methylbutyrol, esters of C₁₄–C₁₈ n- and iso-alcohols. The intact <C₂₄ esters have been resolved into individual molecular species by gas liquid chromatography on open-tubular polyester columns. The long chain wax esters (12 wt. %) contain C₁₀–C₂₂ n- and iso-acids esterified to the same C₁₄–C₁₈ n- and iso-alcohols. Gas liquid chromatography of the intact, hydrogenated >C₂₄ esters on a short JXR column has characterized them according to carbon number and the number of methyl branches they contain.     

Removal of organochlorine pesticides and polychlorinated biphenyls from marine oils during refining and hydrogenation for edible use

Raw marine oils containing from 2–8 ppm DDT group pesticides, 0.00–0.03 ppm dieldrin, and 3–13 ppm polychlorinated biphenyls (as Aroclor 1254) were subjected to pilot plant refining, hydrogenation, and deodorization for margarine stock production. Residues of all 3 groups were reduced to below detectable limits (0.06 ppm, 0.01 ppm, and 0.5 ppm for ΣDDT, dieldrin, and polychlorinated biphenyls [determined as decachlorobiphenyl], respectively) as a result of processing.     

Serum lipid abnormalities in a chemical/viral mouse model for Reye's syndrome

Neonatal mice given nontoxic dermal applications of an industrial surfactant, Toximul MP8 (Tox), and subsequently infected with sublethal doses of mouse-adapted human Influenza B (Lee) virus (FluB) develop many of the biochemical features of Reye's Syndrome (RS). To determine whether these also include abnormal circulating lipid, we examined serum lipid profiles in the mouse model throughout the treatment course using Iatroscan-TH10. Following 10 days of exposure to surfactant, serum phospholipid and cholesterol levels were significantly reduced relative to control animals. These reductions were transient; however, four days following virus administration, significant differences in serum lipid were again evident. These abnormalities coincided and correlated with increased animal mortality. Animals that received combined Tox + virus treatment had significant decreases in serum total lipids relative to control animals, a reflection of a reduction in all lipid classes, including phospholipid, cholesterol, neutral glycerides (triglycerides plus diglycerides) and free fatty acids. Phospholipid (specifically phosphatidylcholine and lysophosphatidylcholine) and free fatty acid levels in the Tox + virus group were also significantly lower than those in animals that received virus alone. This study has demonstrated that suckling mice given chemical/viral treatment have the serum hypopanlipidemia but not the freefattyacidemia that are characteristic of RS.