Mercury Exposure from the Consumption of Dietary Supplements Containing Vegetable, Cod Liver, and Shark Liver Oils.

Vegetable and fish oils constitute a significant part of all dietary supplements. Due to increasing environmental pollution, the raw materials used for their production may be contaminated with toxic substances, including metals. The aim of the present study was to determine the mercury (Hg) content in vegetable oils, shark liver oils, and cod liver oils. The tests conducted were to help determine the level of mercury contamination of the tested preparations and the related potential threat to human health. The amount of Hg in the tested dietary supplements was compared, and the amount of the metal consumed at various times of use was determined. A total of 36 preparations of dietary supplements available on the Polish market were used for the study. The method of atomic absorption spectrometry using the amalgamation technique was used for the determinations (AMA 254, Altec, Czech Republic). Among the sample of all of the tested preparations, the Hg concentration ranged from 0.023 to 0.427 µg/kg, with an average of 0.165 µg/kg. Differences in Hg content in the various tested preparations (shark liver oil, cod liver oil, and vegetable oils) were statistically significant. The average concentration of Hg in the vegetable oils (0.218 µg/kg) was more than twice that of the cod liver oils (0.106 µg/kg) and shark liver oils (0.065 µg/kg). In none of the tested preparations did the amount of Hg exceed the acceptable standard for dietary supplements (0.10 mg/kg). The analysis showed that the Hg content in vegetable oils, shark liver oils, and fish oils from the Polish market is at a low level, guaranteeing the safety of their use, and as such, they do not pose a threat to health.

Evaluations of the Peroxidative Susceptibilities of Cod Liver Oils by a 1H NMR Analysis Strategy: Peroxidative Resistivity of a Natural Collagenous and Biogenic Amine-Rich Fermented Product.

High-resolution 1H nuclear magnetic resonance (NMR) analysis was employed to molecularly screen the lipid, lipid oxidation product (LOP), and antioxidant compositions of four natural (unrefined) cod liver oil (CLO) products. Products 1-3 were non-fermented CLOs, whilst Product 4 was isolated from pre-fermented cod livers. Supporting analytical data that were acquired included biogenic amine, flavanone, tannin, phenolic antioxidant, α-tocopherol, and oxygen radical absorbance capacity (ORAC) determinations by recommended HPLC, LC/MS/MS, or spectrophotometric methods. SDS-PAGE, HPLC, and 1H NMR analyses investigated and determined collagenous antioxidants and their molecular mass ranges. 1H NMR analysis of aldehydic LOPs was employed to explore the susceptibilities/resistivities of each CLO product to peroxidation that is induced by thermal stressing episodes (TSEs) at 180°C, or following prolonged (42 day) storage episodes at 4 and 23 °C. Product 4 displayed extremely high ORAC values, which were much greater than those of Products 1-3, and that were predominantly ascribable to significant levels of peroxidation-blocking and/or aldehyde-consuming collagenous polypeptides/peptides and ammoniacal agents therein. Significantly lower levels of toxic aldehydes were generated in the pre-fermented Product 4 during exposure to TSEs, or the above long-term storage episodes. These results confirmed the enhanced peroxidative resistivity of a fermented, antioxidant-fortified natural CLO product over those of non-fermented unrefined products. Product 4: Green Pasture Blue Ice™ Fermented Cod Liver Oil.

Determinations of the peroxidative susceptibilities of cod liver oils by a newly-developed 1H NMR-based method: resistance of an antioxidant-fortified product isolated from pre-fermented sources.

OBJECTIVE: To explore the molecular composition and antioxidant status of four natural (unrefined) cod liver oil (CLO) products, three of which (Products 1-3) were non-fermented, whilst one (Product 4) was isolated from pre-fermented cod livers, and hence was naturally antioxidant-fortified. Potential antioxidants and aldehyde-scavenging agents were determined by recommended and/or 1H NMR methods; peroxyl radical-specific oxygen radical absorbance capacity (ORAC) values were measured fluorimetrically. The activities of such antioxidants were also investigated by assessing the susceptibilities/resistivities of these CLOs to thermo-oxidation by 1H NMR analysis, which monitored the time-dependent evolution of aldehydic lipid oxidation products at 180 °C. RESULTS: Product 4 displayed much higher, albeit variable ORAC values (mean ± SEM 91.4 ± 19.5 mmol. trolox equivalents/kg) than those of Products 1-3, an observation arising from significant levels of peroxidation-blocking and/or aldehyde-consuming collagenous polypeptides/peptides, flavonones, biogenic amines, total phenolics, tannins, and ammoniacal agents therein. All of these agents were undetectable in Products 1-3. Quantitative considerations indicated that collagenous gel agents (present at ca. 1.5% (w/w)) were the most powerful Product 4 antioxidants. Significantly lower levels of aldehydes were generated in this product when exposed to thermal-stressing episodes. Results confirmed the enhanced peroxidative resistivity of a pre-fermented, antioxidant-rich natural CLO over those of corresponding non-fermented products. Product 4: Green Pasture Blue Ice™ fermented cod liver oil.

Chemometric tools for the authentication of cod liver oil based on nuclear magnetic resonance and infrared spectroscopy data.

Cod liver oil is a popular dietary supplement marketed as a rich source of omega-3 fatty acids as well as vitamins A and D. Due to its high market price, cod liver oil is vulnerable to adulteration with lower priced vegetable oils. In this study, 1H and 13C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gas chromatography (coupled to a flame ionization detector) were used in combination with multivariate statistics to determine cod liver oil adulteration with common vegetable oils (sunflower and canola oils). Artificial neural networks (ANN) were able to differentiate adulteration levels based on infrared spectra with a detection limit of 0.22% and a root mean square error of prediction (RMSEP) of 0.86%. ANN models using 1H NMR and 13C NMR data yielded detection limits of 3.0% and 1.8% and RMSEPs of 2.7% and 1.1%, respectively. In comparison, the ANN model based on fatty acid profiles determined by gas chromatography achieved a detection limit of 0.81% and an RMSEP of 1.1%. The approach of using spectroscopic techniques in combination with multivariate statistics can be regarded as a promising tool for the authentication of cod liver oil and may pave the way for a holistic quality assessment of fish oils. Graphical abstract.

Identification of arsenolipids and their degradation products in cod-liver oil.

Oils from marine samples are known to contain high concentrations of arsenolipids. However, their identification in lipid matrix poses a significant challenge especially when present in low concentrations. Here, we report the identification of sixteen arsenolipids in cod-liver oil. The fish oil was fractionated on a silica gel column and the fraction enriched with arsenic analysed using RP-HPLC online with ICP-MS and ES-Orbitrap-MS. Among the arsenolipids identified nine compounds have not been reported before. Structural assignment was achieved by arsenic signal from ICP-MS, retention time behaviour and accurate mass determination of fragment and molecular peaks. In addition, the unknown degradation products of arsenolipids eluting in the void volume were investigated using fraction collection, cation exchange chromatography and accurate mass determination, and were found to contain predominantly dimethylarsinic acid (DMA) with trace amounts of methylarsonic acid (MA), dimethylarsenopropanoic acid (DMAP) and dimethylarsenobutanoic acid (DMAB). This finding is essential in epidemiologic studies where urinary DMA and other arsenic metabolites have been used as biomarker in accessing human exposure to arsenic.

Long echo time proton magnetic resonance spectroscopy for estimating relative measures of lipid unsaturation at 3 T.

PURPOSE: To examine the behavior of lipid olefinic and diallylic resonances as a function of PRESS (point resolved spectroscopy) echo time (TE) to determine an optimal long TE value for their measurement at 3 T. MATERIALS AND METHODS: Experiments were conducted on nine oils (almond, canola, cod liver, corn, linseed, peanut, sesame, sunflower, and walnut oil) and on vertebral and tibial bone marrow in vivo at 3 T. The methylene (or methyl + methylene), diallylic, and olefinic resonances were measured with PRESS with multiple TEs. RESULTS: J-coupling evolution effects on the olefinic and diallylic peaks appeared to be minimized when TE = 200 msec. The TE = 200 msec olefinic/methylene and diallylic/methylene peak area ratios calculated for each oil correlated well with ratios deduced from oil compositions in the literature (R(2) = 0.92 and 0.98 for the olefinic and diallylic protons, respectively). In addition, the relative amounts of bone marrow unsaturation of vertebral and tibial bone marrow inferred from the TE = 200 msec olefinic/(methyl + methylene) peak area ratio agreed with values estimated from the literature. CONCLUSION: A PRESS sequence with a long TE value of 200 msec is suitable for determining relative amounts of lipid unsaturation at 3 T.

Quality of ready to serve tilapia fish curry with PUFA in retortable pouches.

UNLABELLED: Studies on the physical, chemical, and microbiological qualities of fresh tilapia meat revealed its suitability for the preparation of ready to eat fish curry packed in retort pouches. Studies on the fatty acid profile of tilapia meat suggest fortification with polyunsaturated fatty acid (PUFA) to increase the nutritional value. Based on the commercial sterility, sensory evaluation, color, and texture profile analysis F(0) value of 6.94 and cook value of 107.24, with a total process time of 50.24 min at 116 °C was satisfactory for the development of tilapia fish curry in retort pouches. Thermally processed ready to eat south Indian type tilapia fish curry fortified with PUFA was developed and its keeping quality studied at ambient temperature. During storage, a slight increase in the fat content of fish meat was observed, with no significant change in the contents of moisture, protein, and ash. The thiobarbituric acid (TBA) values of fish curry significantly increased during storage. Fish curry fortified with 1% cod liver oil and fish curry without fortification (control) did not show any significant difference in the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), during thermal processing and storage. Sensory analysis revealed that fortification of fish curry with cod liver oil had no impact on the quality. Tilapia fish curry processed at 116 °C and F(0) value of 7.0 (with or without fortification of cod liver oil) was fit for consumption, even after a period of 1-y storage in retort pouch. PRACTICAL APPLICATION: Tilapia is a lean variety of fish with white flesh and therefore an ideal choice as raw material for the development of ready to serve fish products such as fish curry in retort pouches for both domestic and international markets. Ready to eat thermal processed (116 °C and F(0) value of 7.0) south Indian type tilapia fish curry enriched with PUFA and packed in retort pouch was acceptable for consumption even after a storage period of 1 y at ambient temperature.

Fish oil and cod liver as safe and healthy food supplements.

OBJECTIVES: The aim of this study is to determine the content of mercury, methylmercury and persistent organic pollutants in the capsules filled with fish oil from marine fish and in the canned cod liver and find out, whether analyse products are safe and suitable for human consumption. METHODS: Total mercury was determined by cold vapour atomic absorption spectroscopy on an AMA-254 (Altec Ltd., Czech Republic) single-purpose mercury analyzer. Methylmercury in the cod liver in the form of chlorid methylmercury was determined by gas chromatography. Seven indicator congeners of PCB (PCB 28, 52, 101, 118, 138, 153, 180), HCH, HCB, DDT and its degradation products DDE and DDD, were determined by gas chromatography-mass spectrometry. RESULTS: In capsules filled with fish oil (n=19) total Hg levels were in the range of 0.013 to 2.03 ng/g. All the capsule oil samples analyzed for MeHg were below the detection limit. The highest concentration of total Hg was found in cod liver - can A (0.223 ng/g). The maximum percentage of MeHg in total Hg concentration was found in a liver sample - can B. The values of alpha-, beta-, gamma-, delta- HCH and of HCB were found below the detection limits in all the capsule samples analyzed. In eight capsules, the presence of highly lipophilic PCB congeners was demonstrated. DDT and its important DDE metabolite were found in ten samples. In canned cod liver the highest concentration of all PCB congeners was demonstrated in can D. The lowest congener concentrations, however, were found in smoked cod liver - can C. DDT with its main metabolite DDE was detected in can C. No additional DDT and DDD persistent pollutants were detected. CONCLUSIONS: The consumption of fish oil in capsules, and canned cod liver is safe and healthy and should be encouraged.

A matrix assisted laser desorption ionization time-of-flight mass spectrometry investigation to assess the composition of cod liver oil based products which displayed a different in vivo allergenic power.

Cod liver oil is a well-known "nutraceutical", which contains a wide range of substances, including triacylglycerols (TAGs), mono- and di-acylglycerols, free fatty acids, vitamins and n-3 polyunsaturated fatty acids. Topically applied, cod liver oil contributes to faster wound healing and improvement in skin quality. We recently reported a case of allergic contact dermatitis to cod liver oil contained in a topical ointment, in whom the patch test reaction with the ointment containing cod liver oil at a concentration of 40% was stronger than the reaction induced by a pure cod liver oil at the same concentration. We hypothesized that the different reactivity could be explained by differences in composition of the two products. In order to verify this hypothesis, we assessed the composition of those products using a matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The results obtained showed that the spectra of the ointment and of the cod liver oil samples were very similar, even if a major number of peaks were observable in the higher mass range of the spectra relevant to the analysis of the ointment sample, that have been assigned to higher molecular weight TAGs. Our results suggest that the different reactivity to the two products could be due to differences in the amount of contained TAGs. TAGs may favor the penetration of the allergen(s) or may be the direct culprit substances, taking into account that TAGs have been reported to have sensitizing properties.

Evaluation of use of a very short polar microbore column segment in high-speed gas chromatography analysis.

Very fast GC analyses are commonly carried out by using 10 m x 0.1 mm id capillaries. In order to achieve rapid elution times (1-3 min), the latter are operated under suboptimum conditions. The present research is focused on the evaluation of use of a 0.1 mm id polar column segment (2 m), operated under near-to-optimum conditions, in very fast GC analysis. The results attained are compared with those derived from using a 10 m microbore column in very fast GC experiments. Prior to method development, the effects of gas velocity, temperature program rate, and sample amounts on analytical performance were evaluated. Following these preliminary applications, a complex lipidic sample, cod liver oil, was subjected to rapid separation (approximately 2.1 min) on the 10 m capillary through the application of a 50 degrees C/min temperature rate and a 130 cm/s gas velocity. The same matrix was analyzed on the 2 m capillary using the same temperature program rate and range, but with a close-to-ideal linear velocity. The results observed were of interest, as the separation was achieved in less time (1.45 min) with improved peak resolution. Finally, both methods were validated in terms of retention time and peak area repeatability, LOQ, and linearity.

Hydroxytyrosol prevents oxidative deterioration in foodstuffs rich in fish lipids.

Hydroxytyrosol, a natural phenolic compound obtained from olive oil byproduct, was characterized as an antioxidant in three different foodstuffs rich in fish lipids: (a) bulk cod liver oil (40% of omega-3 PUFAs), (b) cod liver oil-in-water emulsions (4% of omega-3 PUFAs), and (c) frozen minced horse mackerel ( Trachurus trachurus) muscle. Hydroxytyrosol was evaluated at different concentration levels (10, 50, and 100 ppm), and its antioxidant capacity was compared against that of a synthetic phenolic, propyl gallate. Results proved the efficiency of hydroxytyrosol to inhibit the formation of lipid oxidation products in all tested food systems, although two different optimal antioxidant concentrations were observed. In bulk oil and oil-in-water emulsions, a higher oxidative stability was achieved by increasing the concentration of hydroxytyrosol, whereas an intermediate concentration (50 ppm) showed more efficiency, delaying lipid oxidation in frozen minced fish muscle. The endogenous depletion of alpha-tocopherol and omega-3 polyunsaturated fatty acids (omega-3 PUFAs) was also inhibited by supplementing hydroxytyrosol in minced muscle; however, the consumption of the endogenous total glutathione was not efficiently reduced by either hydroxytyrosol or propyl gallate. A concentration of 50 ppm of hydroxytyrosol was best to maintain a longer initial level of alpha-tocopherol (approximately 300 microg/g of fat), whereas both 50 and 100 ppm of hydroxytyrosol were able to preserve completely omega-3 PUFAs. Hydroxytyrosol and propyl gallate showed comparable antioxidant activities in emulsions and frozen fish muscle, and propyl gallate exhibited better antioxidant efficiency in bulk fish oil.

Comparison of GC and LC determinations of hexabromocyclododecane in biological samples - results from two interlaboratory comparison studies.

In order to assess the quality and comparability of results from determinations of 1,2,5,6,9,10-hexabromocyclododecane (HBCD) in biological samples, two interlaboratory comparison studies have been organized. Up to 13 laboratories determined either the total HBCD concentration, or concentrations of alpha-, beta- and gamma-HBCD, or both in cod liver oil, herring filet, salmon filet, butter and chicken meat. The laboratories were able to determine total HBCD concentrations in the marine samples with satisfying quality (RSD <35%). However, the analysis of samples with low HBCD contamination (

Enantioselective determination of anteiso fatty acids in food samples.

Anteiso fatty acids (aFAs)-long-chain carboxylic acids with a methyl branch on the (n - 2)-carbon-are among the most simple fatty acids that are chiral. The most frequently occurring aFAs in food are 12-methyltetradecanoic acid (a15:0) and 14-methylhexadecanoic acid (a17:0), structures where the asymmetric carbon is more than 10 carbons separated from the polar head group. Previously, only enantioseparation of 4-methyl-substituted carboxylic fatty acids has been reported by gas chromatography. Here we present the first direct partial enantioresolution of synthesized racemic a15:0-a17:0 on a capillary column coated with 50% heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-beta-cyclodextrin diluted in OV1701. Synthesized (S)-(+)-enantiomers were used to demonstrate that the elution order was (R)- prior to (S)-enantiomers. Using this system, food samples (butter, goat's milk fat, suet, human milk, seal oil, cod liver oil) known to contain aFAs were analyzed. Prior to the enantioselective gas chromatography, unsaturated fatty acids were preseparated by urea complexation, silver ion high performance liquid chromatography (Ag+-HPLC), or both from food samples. The fractions of the food samples enriched with methyl-branched fatty acids were then analyzed by GC/MS in the SIM mode. The measurements confirmed that the (S)-enantiomer of a15:0 (ee >96%), a16:0, and a17:0 (ee >90%, respectively) dominated in all samples. While the (R)-enantiomers could not be identified in samples from ruminants and human milk, their presence could be established in cod liver and seal oil (ee <86%).

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 (microL amounts) of a reagent and solvent, while the derived fatty acid methyl esters (FAMEs) were separated in 120 s on a 10 m x 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.

Polychlorinated biphenyls, hexachlorobenzene, hexachlorocyclohexane isomers, and pesticide organochlorine residues in cod-liver oil dietary supplements.

Levels of polychlorinated biphenyls (PCBs), hexachlorobenzene, hexachlorocyclohexane isomers (alpha, beta, gamma), and chlorinated pesticides (DDTs) in cod-liver oil used as a dietary supplement were determined. Total PCB and DDT concentrations varied from 25 to 201 ng g(-1) lipid weight basis and from 25 to 133 ng g(-1) lipid weight basis, respectively. Hexachlorobenzene contributed very little to the overall contaminant burden of dietary supplement oils, whereas hexachlorocyclohexane isomers were below the instrumental detection limits in all samples. The daily intake of PCBs and DDTs derived by the consumption of cod-liver oil at manufacturer-recommended doses varied from 0.004 to 2.01 microg/day and from 0.004 to 1.24 microg/day, respectively. Relative to some dioxin-like PCB congeners (mono-ortho PCB 105, 118, and 156; non-ortho PCB 77, 126, and 169), the intakes calculated varied from less than 0.001 to 0.74 pg of toxic equivalency values (TEQ) per kg of body weight per day. These values, although below the range of 1 to 4 pg of TEQ per kg of body weight per day set by the World Health Organization, emphasize the need for strict and continuous monitoring of fish oil contamination to reduce, as much as possible, the risks to human health.

Canned cod liver as a source of n-3 polyunsaturated fatty acids, with a reference to contamination.

Lipid composition (HPLC), fatty acid composition (GC/MS), lipid oxidation (peroxide value, anisidine value), UV-VIS and fluorescence spectra (Ex 365 nm), and susceptibility of lipids to oxidation (photooxidation test) as well as heavy metal, PCB, and DDT contents were determined in canned, raw, and thermally treated cod liver (separately in the released oil and in the solids). Canned products of three manufacturers were examined. Mean contents of n-3 polyunsaturated fatty acids (n-3 PUFAs) in the oil and solids were 31.91 +/- 1.83 and 16.59 +/- 7.48 g/100 g, respectively, the respective contents of docosahexaenoic acid (DHA) being 17.88 +/- 1.69 and 8.79 +/- 3.67 g/100 g. Lipid resistance to oxidation was found to decrease after thermal treatment of livers. However, the lipid oxidation level in canned liver stored for 3-8 months was not high and averaged, for the entire can content, 0.47 +/- 0.4 Meq O, the oil being more susceptible to oxidation that the solids. It is concluded that canned cod liver is a very good source of n-3 PUFA, particularly with respect to DHA. Heavy metal, DDT, and PCB contamination and the presence of lipid oxidation products in the canned products tested remain at a level producing no perceivable health hazard and could in no way interfere with consumption of recommended amounts of n-3 PUFAs.

Determination of non-ortho polychlorinated biphenyls in environmental Standard Reference Materials.

The concentrations of three non-ortho ("coplanar") polychlorinated biphenyls, 3,3',4,4'-tetrachlorobiphenyl (IUPAC PCB 77), 3,3',4,4',5-pentachlorobiphenyl (IUPAC PCB 126), and 3,3',4,4',5,5'-hexachlorobiphenyl (IUPAC PCB 169), were determined in five NIST Standard Reference Materials (SRMs) of environmental and biological interest. The measured levels were approximately between (0.2 to 1.3) ng/g in SRM 1588a (Organics in Cod Liver Oil), (0.3 to 9) ng/g in SRM 1944 (New York/New Jersey Waterway Sediment), (0.2 to 0.4) ng/g in SRM 1945 (Organics in Whale Blubber), (1 to 18) ng/g in SRM 2974 (Organics in Freeze-dried Mussel Tissue [Mytilus edulis]), and (0.1 to 0.4) ng/g in candidate SRM 1946 (Lake Superior Fish Tissue). PCB 169 was present at < 0.1 ng/g in SRMs 1944 and 2974.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of cod liver oil and the effect of analyte/matrix concentration on signal intensities.

Cod liver oil (CLO) is known to contain a complex mixture of triacylglycerols (TAGs) in which the component fatty acids include: myristic (C(14:0), M), C(14:1) (M(1)), palmitic (C(16:0), P), palmitoleic (C(16:1), P(1)), stearic (C(18:0), S), oleic (C(18:1), O), linoleic (C(18:2), L), arachidic (C(20:0), A), C(20:1) (A(1)), eicosapentaenoic (EPA, C(20:5), A(5)), docosanoic (C(22:0), D), docosaenoic (C(22:1), D(1)), and docosahexaenoic (DHA, C(22:6), D(6)). Because of the presence of EPA and DHA in cod liver oil, it has been used for several generations as a nutritional supplement, and recommended for the relief of various physiological ailments including arthritis, depression, and high blood pressure. Consequently, it was of interest to develop a sample preparation protocol that would enable rapid screening of such a chemically complex and nutritionally useful oil. Thus, we have analyzed two commercial brands of cod liver oil by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). There was no significant difference between the mass spectral profile of the two CLO brands. alpha-Cyano-4-hydroxycinnamic acid, dissolved in acetonitrile/tetrahydrofuran, was used as the matrix. MALDI-TOFMS produced only sodiated triacylyglycerol molecules [M + Na](+). Based on the sodiated TAGs, 64 TAG assignments were made, and these include MM(1)L, MML, MMO and MMS, M(1)P(1)L MP(1)L, P(1)P(1)P, PPP, P(1)P(1)Ln, P(1)PLn, PPL, PPO, P(1)LnLn, PLnLN, PLLn, PLL, POL, POO, P(1)A(6)Ln, P(1)A(5)Ln, P(1)A(5)L, PA(5)L PA(5)O, PP(1)D(6), OOL, OOO, SOO, SSS, P(1)LnD(6), PLnD(6), PLD(6), POD(6) (or P(1)A(5)A(1)), PA(5)A(1), OLA, OLA(1), SLA(1), SOA(1), SSA, LA(5)A(5) (or P(1)A(5)D(6)), OA(5)A(5) (or PA(5)D(6)), SA(5)A(5), LnA(1)A(5), OOD(6), SOD(6), SSD(6), LA(1)D(6), OA(1)D(6), OA(5)D(6), SA(5)D(6), SA(5)D(5), D(6)A(1)O, D(6)A(1)S, D(1)A(1)O, DA(1)O, D(1)D(6)O, and DD(6)O. The sample preparation method developed in this study could be used for the routine screening of oils that contain similar types of polyunsaturated TAGs.

Capillary gas chromatography combined with atomic emission detection for the analysis of DDT and metabolites.

Capillary gas chromatography with atomic emission detection (GC-AED) was evaluated for the determination of DDT and metabolites in biological samples. Utilizing chlorine-selective detection at 479 nm, DDT, DDE, and DDD were quantified down to the 20 ng/g (fat weight) level (S/N = 10) in cod liver oil, while the detection, limit was 6 ng/g (S/N = 3). With splitless injection performed in the pressure programmed mode, DDT and related compounds were quantified based on a single chlorine calibration curve (universal calibration). The quantitative data obtained by GC-AED were in excellent accordance with similar results from capillary gas chromatography with electron capture detection (GC-ECD), while the procedure for calibration was simplified with the former technique.