NMR-based differentiation of conventionally from organically produced chicken eggs in Germany

Both the German and European organic food markets are growing fast, and there is also a rising demand for organic chicken eggs. Consumers are willing to pay higher prices for organic eggs produced in an animal-appropriate environment considering animal welfare. Strict labelling requirements do not prevent chicken eggs from being a subject of food fraud. Conventionally produced (barn/free-range) eggs can easily be mislabeled as organic eggs. Especially because the demand for organically produced chicken eggs is likely to exceed supply in the future, mislabeling appears to be a realistic scenario. Therefore, there is a need for analytical methods that are suitable to classify eggs as being either conventionally or organically produced. Nuclear magnetic resonance (NMR) spectroscopy in combination with multivariate data analysis is a suitable tool to screen eggs according to the different systems of husbandry. Sample preparation is based on a fat extraction method, which was optimised for application to freeze-dried egg yolk. Samples were analysed using typical q-NMR parameters. A nontargeted approach was used for the analysis of the ¹H NMR data. Principal component analysis (PCA) was applied followed by a linear discriminant analysis (PCA-LDA) and Monte Carlo cross-validation. In total, 344 chicken eggs (214 barn/free-range eggs and 130 eggs from organic farms), most of them originating from Germany, were used to build and validate the prediction model. The results showed that the prediction model allowed for the correct classification of about 93% of the organic eggs.     

Comparative crystal-chemical analysis of simple sulfites and selenites and binary compounds

With the use of the TOPOS structural topological program package, comparative crystal-chemical analysis has been performed for anhydrous inorganic salts with pyramidal anions, namely, for 12 simple sulfites and 23 simple selenites. Comparative topological analysis has been carried out for simple sulfites and selenites and 1417 representatives of the topological types of binary compounds. This analysis shows that six sulfites and selenites are topologically similar to NaCl, NiAs, TiO₂ (rutile), and ZnTe. The topology and uniformity of the ionic matrices in all the structures are surveyed: in 10 of the 35 salts under consideration, at least one of the matrices has close packing topology.     

Enhanced levels of dioxins in eggs from free range hens; a fast evaluation approach

As a consequence of an initiative of the local authorities of the city of Antwerp (Belgium), dioxin levels were determined in eggs from free range hens owned by private owners in the Northern districts of Antwerp. The reasons for this survey stem from some fears that free range eggs could be contaminated by local environmental sources (e.g. soil, grass, earthworms) as a result of the presence in this area of intensive industrial and domestic activities. The analyses revealed high levels of PCDD/F in the home-produced eggs (average = 9.9 pg WHO-TEQ per g of fat; n = 15). An evaluation of the available results has been carried out by the Scientific Committee of the Belgian Federal Agency for the Safety of the Food Chain. From this evaluation, it appeared that the analysis of congener profiles was of limited use because all profiles were dominated by the OCDD congener, independently of the level of contamination. There were not enough indications allowing a causal link to be established between high dioxin levels in eggs and soil contamination and, on the other hand, it was assumed that other factors such as feeding habits, physiological state and egg laying rhythm of the hens could not be ruled out as potential causes of aggravation. A quick risk assessment led to the conclusion that the impact of this contamination is highly relevant for the consumer’s health due to the important contribution of such home-produced eggs in the estimations of total body burden.     

Comparative thermal analysis (CTA) of thermally-stable polymers and model compounds. Polyimides and model compounds

The method of comparative thermal analysis has been used to determine the thermal stability of polyimides and their model compounds. The extent of defects in the investigated polyimides was determined by gas chromatography. The dependence of the extent of the defects on the chemical structure of the initial components and the supermolecular structure of the polyimides was established.

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Zusammenfassung Die Methode der vergleichenden Thermoanalyse wurde zur Bestimmung der Hitzestabilität von Polyimiden und ihren Modellverbindungen eingesetzt. Das Ausmass der Defekte in den untersuchten Polyimiden wurde gaschromatographisch bestimmt. Die Abhängigkeit des Umfangs der Defekte von der chemischen Struktur der Ausgangskomponenten und der supermolekularen Struktur der Polyimide wurde festgestellt.

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Résumé La méthode d'analyse thermique comparée (CTA) a été utilisée pour étudier la stabilité thermique des polyimides et de leurs composés modèles. On a déterminé par chromatographie en phase gazeuse l'étendue des défauts dans les polyimides étudiés. On a établie de même les rapports qui existent entre l'étendue des défauts dans la structure chimique des composants initiaux et la structure supermoléculaire des polyimides.

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Limits of rapid log P determination methods for highly lipophilic and flexible compounds

Lipophilicity is of crucial importance in many fields including pharmaceutical, environmental, cosmetic and food industries. Whereas different experimental strategies have been developed for rapid lipophilicity determination of new chemical entities, log P determination of highly lipophilic compounds is always challenging. In this study, three published chromatographic methods have been compared on a series of phenylalkanoic acids including the pro-perfume Haloscent^®D (HD-C12). Different log P values were obtained depending on the chromatographic method used for log P estimation. Molecular modelling suggested that log P variations may be due to the chromatographic conditions applied (isocratic or gradient mode, ratio methanol/water in the mobile phase), responsible of specific conformations of the molecule in solution. Thus, for flexible compounds, published methods have to be used with caution and considered as a good tool to estimate a log P range, depending on the molecular conformational state.     

Comparative crystal-chemical analysis of d-metal sulfides, selenides, and tellurides and binary compounds

The structures of d-metal sulfides, selenides, and tellurides containing a tetrahedral complex anion have been compared to 1573 representatives of the topological types of binary compounds with the use of the TOPOS structural topological program package. The cases of similarity between these classes of compounds are found and discussed. Based on the results of topological analysis of ionic matrices, the rules are formulated that allow one to predict specific features of the structures of salts with complex chalcogen-containing anions.     

Evaluation of antioxidant activity of hydrophilic and lipophilic compounds in edible oils by a novel fluorimetric method

A novel fluorimetric method is described for the evaluation of the antioxidant activity of hydrophilic and lipophilic compounds and complex natural products such as edible oils. The method is based on the measurement of fluorescence emission intensity of N-methylacridone produced during the reaction of lucigenin with hydrogen peroxide. The presence of antioxidants in the sample inhibits the concentration of N-methylacridone and reduces the fluorescence intensity. The method was fully validated and applied to a variety of hydrophilic and lipophilic compounds as well as to various types of edible oils and their corresponding hydrophilic and lipophilic extracts. Results were compared to those derived from a lucigenin based chemiluminescent method and the Folin-Ciocalteau method for total phenols. The differences in total antioxidant activity of edible oils of various origins and the effect of heating on total antioxidant activity was further studied and discussed.     

Proton-ionizable crown compounds. 13. Synthesis and structural studies of crown compounds containing the triazole subcyclic unit and lipophilic substituents

Eight new macrocyclic polyether ligands containing the proton-ionizable triazole subcyclic unit have been prepared. Most of these compounds contain octyl, benzo or cyclohexano lipophilic groups. The unsubstituted triazolo-18-crown-6 ( 5 ) formed an unusual complex with silver ion. The crystal structure of this silver complex showed one crown complexed with one silver cation and two associated silver nitrate molecules. The new lipophilic triazolo-crowns are being tested as cation carriers for alkali and other metal cations in a bulk liquid membrane system.     

Comparative molecular field analysis (CoMFA) of new herbicidal sulfonylurea compounds

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Analysis of hydrophilic and lipophilic choline compounds in radioresistant and radiosensitive glioblastoma cell lines by HILIC-ESI-MS/MS

A new method based on hydrophilic interaction chromatography-electrospray ionisation–tandem mass spectrometry (HILIC-ESI-MS/MS) coupled to the use of a stable isotope labelled substrate was developed to study the metabolism of choline (Cho) compounds in two human glioblastoma multiform (GBM) cell lines with different responses to ionising radiation. Analysis was performed in the positive ion mode using multiple reaction monitoring. This fast, sensitive and selective method enabled the profiling of both hydrophilic and lipophilic Cho-containing compounds, to analyse specifically different phosphatidylcholine (PtdCho) molecular species, and to measure simultaneously native and labelled Cho metabolites. Radioresistant (SF763) and radiosensitive (SF767) cells were incubated for 8 h with d ₉-Cho. Higher native Cho and phosphocholine (PCho) concentrations and higher uptake of d ₉-Cho and formation of d ₉-PCho were found in the radioresistant cell line. The similar low concentrations of native cytidine 5′-diphosphocholine (CDP-Cho) and d ₉-CDP-Cho in both cell lines show that CDP-Cho is the limiting metabolite in the two models. The turnovers (percentage of each d ₉-Cho compound in its respective pool, i.e. native + labelled) were lower in radioresistant cells for all Cho compounds, suggesting a global PtdCho metabolism more active in radiosensitive cells that could be related to their higher proliferation rate.     

Comparative Analysis of the Distribution of Copper in Green and Brown Brazilian Propolis Extracts

We proposed here a novel analytical procedure for copper speciation in green and brown propolis extracts using SEC—HPLC—GFAAS with 0.5% m v^?1 SDS in 2.5 m mol L^?1 Tris–HCl (pH 7.4) as the mobile phase buffer solution. Both basic (0.05 mol L^?1 NaOH) and acid (0.05 mol L^?1 HCl) conditions were evaluated for sample extraction. Depending on the extraction procedure, differences in copper distribution were identified. Copper was mainly associated with high-molecular-weight (HMW) fractions in green propolis extract when extracted with basic solution, whereas with acid extraction solution, only low-molecular-weight (LMW) fractions were obtained in both samples. Furthermore, combined analysis of results obtained using SEC-UV and GF AAS confirmed the association of copper with LMW and HMW species.     

Differentiation of organically and conventionally produced milk by stable isotope and fatty acid analysis

Increasing sales of organic milk mean intensified tests for authenticity are required. In addition to comprehensive documentation, analytical methods to identify organic milk, and thus to differentiate it from conventional milk, are needed for consumer protection. Because the composition of milk is fundamentally dependent on the feeding of the cows, thirty-five samples from both production systems in Germany, including farm and retail milk, were collected within 12 months, to reflect seasonal variation, and appropriate properties were analysed. Fatty acid analysis enabled organic and conventional milk to be completely distinguished, because of the higher α-linolenic acid (C18:3ω3) and eicosapentaenoic acid (C20:5ω3) content of the former. Organic milk fat contained at least 0.56% C18:3ω3 whereas the maximum in conventional milk was 0.53%. Because of the parallel seasonal course of the C18:3ω3 content of organic and conventional retail samples, however, time-resolved comparison at the five sampling dates resulted in a clearer difference of 0.34 ± 0.06% on average. Analysis of stable carbon isotopes (δ¹³C) also enabled complete distinction of both types of milk; this can be explained by the different amounts of maize in the feed. For conventional milk fat δ¹³C values were −26.6‰ or higher whereas for organic milk fat values were always lower, with a maximum of −28.0‰. The time-resolved average difference was 4.5 ± 1.0‰. A strong negative correlation (r = −0.92) was found between C18:3ω3 and δ¹³C. Analysis of a larger number of samples is required to check the preliminary variation ranges obtained in this pilot study and, probably, to adjust the limits. Stable isotopes of nitrogen (δ¹⁵N) or sulfur (δ³⁴S) did not enable assignment of the origin of the milk; in cases of ambiguity, however, some trends observed might be useful in combination with other properties. Figure Correlation (r = −0.92) between δ¹³C value and C18:3ω3 content of milk fat from different production systems     

High performance liquid chromatography-tandem mass spectrometry of phospholipid molecular species in eggs from hens fed diets enriched in seal blubber oil

The total lipid fraction of eggs from hens fed diets enriched in seal blubber oil (1.25-5.0% SBO) was directly analysed with normal-phase high performance liquid chromatography coupled on-line with electrospray ionization ion-trap tandem mass spectrometry (HPLC-ESI-MS-MS) for the identification of the molecular species of phospholipids (PLs). The species of phosphatidylethanolamine (PE) and phosphatidylinositol (PI) were all detected as the [M-H](-) ions. The phosphatidylcholine (PC), sphingomyelin (Sph) and lysophosphatidylcholine (LPC) classes, were detected as formate adducts [M+HCOO](-). Tandem MS of PE and PI showed the loss of the carboxylate anions, and, for PI, also the loss of water and inositol. Product ion spectrum of PC, LPC and Sph contained only the [M-CH(3)](-) ion fragment. Feeding different levels of SBO for 5 weeks resulted in a significant increase of PE, PC and PI molecular species carrying eicosapentaenoic acid (C(20:5 omega3), EPA), docosapentaenoic acid (C(22:5 omega3), DPA) and docosahexaenoic acid (C(22:6 omega3), DHA), but not Sph nor LPC. The highest increase of the omega3/omega6 ratio occurred for PE and PC. On the contrary, PI was less affected by the increase of SBO in the diet.     

Comparative thermal analysis of thermally stable polymers and model compounds: II. Aromatic DI-and Polyketones

Thermooxidative degradation in oxygen of aromatic diketones,crosslinked polyketones and model compounds has been investigated. It was found that 1,1'-di-(4'-phenoxybenzophenonyl ether exhibits the highest thermal stability among diketones. This is presumably due to the alternation of electron accepting and electron donating groups in the chain of this compound.On the basis of data on the oxidation kinetics of cross-linked polyketones and model compounds, it was established that the thermal stability of the latter is much higher. This is due to the fact that the polymer contains unsaturated structures and residual acetyl groups because the curing process of diacetylaromatic compounds is incomplete.It was shown that comparative thermal analysis (CTA) may be used to evaluate the extent of completeness of curing of di- and polyfunctional monomers.