Cod Liver Oil Fatty Acids Research Articles

Generation of Improved Gas Linear Velocities in a Comprehensive Two-Dimensional Gas Chromatography System

A comprehensive two-dimensional gas chromatography (GC x GC) system (for convenience defined as "split flow" GC x GC), which may be operated at improved gas linear velocities in both dimensions, has been developed. The setup is formed of an apolar 30 m x 0.25 mm i.d. column connected, by means of a Y press fit, to a detector-linked 1 m x 0.1 mm i.d. polar analytical column, which passes through the (cryogenic) modulator, and to a 0.3 m x 0.1 mm i.d. retention gap, which is connected to a manually operated split valve. The latter enables the regulation of gas flows through the second analytical column [e.g., 60:40 (FID) ratio, 50:50 ratio, 40:60 (FID) ratio, etc.], in order to generate the most appropriate gas linear velocity, which is related to each specific analysis. In the pre-sent investigation, two sets of traditional and split flow GC x GC analyses were carried out on a cod liver oil fatty acid methyl ester sample by using the same temperature programs [180-250 degrees C at (a) 3 degrees C/min and at (b) 1.3 degrees C/min] and at an average first-dimension linear velocity of approximately 35.0 cm/s; thus, primary column retention times (and therefore elution temperatures) were essentially maintained. The second-dimension linear velocity was calculated to be approximately 333 cm/s in the traditional applications, while it was split valve-regulated until the most appropriate values [(a) approximately 213 cm/s; (b) approximately 264 cm/s] were attained in the alternative applications. Substantial improvements were observed and measured in the chromatography along the y-axis, while the contour plot chemical class structure was maintained.

Rapid, micro-scale preparation and very fast gas chromatographic separation of cod liver oil fatty acid methyl esters

The present research is focussed on the optimization of a fast and economically convenient method for the sample preparation and gas chromatographic separation of fatty acids contained in lipidic samples. This, as part of a wider project that has, as ultimate goal, the automation of this specific analytical procedure. The developed approach was applied to the analysis of cod liver oil, a highly complex lipid characterized by a wide nutritional interest. Derivatization was carried out by using low quantities (μL amounts) of a reagent and solvent, while the derived fatty acid methyl esters (FAMEs) were separated in 120 s on a 10 m × 0.1 mm i.d. polar micro-bore column. The total analysis time required for six samples was approximately 45 min (7.5 min/sample), considering a simultaneous process of methylation and GC separation of previously prepared samples. The results obtained were compared to those derived from conventional applications on the same sample. With regard to the validation of the rapid method, peak area/retention time repeatability, linear range, limit of detection (LOD) and quantitation (LOQ) were determined. Peak assignment was carried out by exploiting bidimensional group-type mapping information obtained in a comprehensive gas chromatographic application.

Concentration and purification of stearidonic, eicosapentaenoic, and docosahexaenoic acids from cod liver oil and the marine microalgaIsochrysis galbana

n‐3 Polyunsaturated fatty acids (n‐3 PUFA) from the marine microalgaIsochrysis galbana were concentrated and purified by a two‐step process—formation of urea inclusion compounds followed by preparative high‐performance liquid chromatography. These methods had been developed previously with fatty acids from cod liver oil. By the urea inclusion compounds method, a mixture that contained 94% (w/w) stearidonic (SA), eicosapentaenoic (EPA), plus docosahexaenoic (DHA) acids (4:1 urea/fatty acid ratio and 4°C crystallization final temperature) was obtained from cod liver oil fatty acids. Further purification of SA, EPA, and DHA was achieved with reverse‐phase C18 columns. These isolations were scaled up to a semi‐preparative column. A PUFA concentrate was isolated fromI. galbana with methanol/water (80:20, w/w) or ethanol/water (70:30, w/w). With methanol/water, a 96% EPA fraction with 100% yield was obtained, as well as a 94% pure DHA fraction with a 94% yield. With ethanol/water as the mobile phase, EPA and DHA fractions obtained were 92% pure with yields of 84 and 88%, respectively.

Effect of Dietary Lipids on Growth, Tissue Composition and Metabolism of the Oyster (Crassostrea virginica)

Hatchery reared oysters (Crassostrea virginica) were fed six different diets for 30 weeks. The diets contained cod liver oil (CLO), corn oil (CO), corn oil and cod liver oil (1:2) (CO + CLO), hyrogenated coconut oil (HCO), ethyl esters of cod liver oil fatty acids (SF) or cod liver oil ethyl esters supplemented with cholesterol (CH). Data on growth and tissue composition imply that oysters have an essential fatty acid (EFA) requirement for both linolenic or omega 3 and linoleic or omega 6 series fatty acids, with the former playing a more significant role. The feeding study supported by a 14C-acetate metabolism experiment suggests that these oysters were unable to synthesize sterols and excessively high dietary sterol (1% of the dry weight of the diet) inhibited growth.

Fractionation of fish oil fatty acid methyl esters by means of argentation and reversed-phase high-performance liquid chromatography, and its utility in total fatty acid analysis

The utility of reversed-phase and argentation high-performance liquid chromatography (HPLC) as pre-fractionation methods in fatty acid analysis is discussed. Both HPLC modes were applied to cod liver oil fatty acid methyl esters. Apart from positional isomers, the fractions obtained by reversed-phase HPLC were analysed by gas-liquid chromatography and appear to be free of the usually occurring “critical pairs”. The mechanism of retention of the fatty acid methyl esters on low-loaded silver nitrate-impregnated silicas is discussed. It is shown that argentation HPLC is a rapid semi-preparative pre-fractionation method for highly unsaturated fatty esters with 3–6 double bonds.

Nonenzymic browning XIII. Effect of an antioxidant on the discoloration of lipid-protein mixtures.

Higher concentrations of butylated hydroxyanisole inhibited the autoxidation of mixtures of unsaturated cod liver oil fatty acid esters with model proteins. The rate of discoloration was far less efficiently affected by the antioxidant because the antoixidant did not prevent the further transformation into brown pigments of colourless precursors, mainly carbonyl lipid oxidation products, already present in the lipid fraction before the addition of antioxidant. The antioxidant also did not influence the pigments already formed.

COD LIVER OIL FATTY ACIDS AS SECONDARY REFERENCE STANDARDS IN THE GLC OF POLYUNSATURATED FATTY ACIDS OF ANIMAL ORIGIN: ANALYSIS OF A DERMAL OIL OF THE ATLANTIC LEATHERBACK TURTLE.

AbstractThe use of the esters of whole cod liver oil fatty acids as secondary standards in the GLC identification of animal polyunsaturated fatty acids is feasible. This technique is exemplified by an analysis on several polyester substrates of the component fatty acids of a somewhat unusual marine‐type oil from the Atlantic Leatherback turtleDermochelys coriacea coriacea (Linnȳ), with provisional identifications of minor components through the linear log plot and separation factor procedures.

On the antioxidant activities of the tocopherols II.—Influence of substrate, temperature and level of oxidation

AbstractThe antioxidant activities of the tocopherols have been compared at 60° and at 37° in distilled methyl esters of cottonseed, linseed and cod liver oil fatty acids containing small additions of oxidised ester as “starter”.In the linoleate (cottonseed) system the γ‐ and δ‐compounds were the most and the α‐, ζ‐ and ϵ‐compounds the least effective in extending the induction period. In the polyunsaturated (linseed and cod liver oil) systems the γ‐ was still good, but the δ‐ was at the bottom of the series and the α‐ and ζ‐compounds near the top.Factors, in addition to the presence of polyunsaturated fatty esters in the substrate, which tended to favour a relatively high activity of the α‐compound were (a) comparison of activities at a low peroxide value, still within the induction period and (b) a not too high temperature of oxidation. Under suitable conditions α‐tocopherol could be shown to exert the highest and δ‐ the lowest in vitro antioxidant activity, in agreement with their known in vivo vitamin‐E potencies.The antioxidant activities of the tocopherols are considered in relation to their structure.

Antioxidants in dry fat systems: Influence of the fatty acid composition of the substrate

AbstractThe activities of a number of antioxidants have been compared at 37° and 50° in purified distilled methyl esters of cottonseed, linseed and cod liver oil fatty acids, to which a small quantity of the pre‐oxidised ester had been added as ‘starter’. Relative activities were found to vary considerably with the fatty acid composition of the substrate and with the temperature and level of oxidation at which the measurements were made.