Dioxins, dioxin-like PCBs and non-dioxin-like PCBs in dairy products on the German market and the temporal tendency in Schleswig-Holstein

140 Milcherzeugnisse aus verschiedenen Regionen Deutschlands wurden 2006 auf Dioxine, dioxin?hnliche PCB und nicht dioxin?hnliche PCB untersucht. Insgesamt wurden 66 K?se-, 23 Butter- und 51 Quark- bzw. Joghurterzeugnisse analysiert. Die Probenahme erfolgte in Superm?rkten und Einzelhandelsgesch?ften auf der Basis der Produktionsmengen in den einzelnen Bundesl?ndern der Bundesrepublik Deutschland. Die Dioxinkonzentrationen und die Summe der WHO-TEQ blieben weit unter den EU-Grenzwerten von 3 pg WHO-PCDD/F-TEQ/g Fett und 6 pg WHO-PCDD/F-PCB-TEQ/g Fett. Die Dioxingehalte lagen bei niedrigen 0,07–0,53 pg WHO-PCDD/F-TEQ/g Fett mit einem arithmetischen Mittelwert von 0,19 pg WHO-PCDD/F-TEQ/kg Fett. Die WHO-PCDD/F-PCB-TEQ Gehalte lagen zwischen 0,21 und 2,1 pg WHO-TEQ/g Fett, mit einem mittleren Gehalt von 0,76 pg WHO-TEQ/g Fett. Regionale Abh?ngigkeiten und Unterschiede zwischen den einzelnen Produktgruppen konnten nicht festgestellt werden. Langj?hrige Messungen der Dioxingehalte in Butter und K?se aus Schleswig-Holstein zeigen über den Zeitraum von 13 Jahren eine deutliche Abnahme der Gehalte von 0,43 auf 0,19 pg WHO-PCDD/F-TEQ/g Fett.     

Interkristalline Spannungsrißkorrosion bei niedriglegierten Stählen

Vergleichende Zugversuche in Laugen an Kesselstählen und Feinkornstählen. Ermittlung der zur Auslösung von Spannungsrißkorrosion nötigen Mindestspannungen. Einfluß des Gefüges, der Carbidausscheidungen und des Gehaltes an Kohlenstoff und Stickstoff sowie der Bindung des Stickstoffs an Aluminium und Vanadin auf das Verhalten gegenüber interkristalliner Spannungsrißkorrosion.     

Non-targeted analysis of tea by hydrophilic interaction liquid chromatography and high resolution mass spectrometry

Tea is the second most consumed beverage in the world and its consumption has been associated with numerous potential health benefits. Factors such as fermentation methods, geographical origin and season can affect the primary and secondary metabolite composition of tea. In this study, a hydrophilic interaction liquid chromatography (HILIC) method coupled to high resolution mass spectrometry in both positive and negative ionisation modes was developed and optimised. The method when combined with principal component analysis to analyse three different types of tea, successfully distinguished samples into different categories, and provided evidence of the metabolites which differed between them. The accurate mass and high resolution attributes of the mass spectrometric data were utilised and relative quantification data were extracted post-data acquisition on 18 amino acids, showing significant differences in amino acid concentrations between tea types and countries. This study highlights the potential of HILIC chromatography combined with non-targeted mass spectrometric methods to provide a comprehensive understanding of polar metabolites in plant extracts.     

Mycotoxin exposure and human cancer risk: A systematic review of epidemiological studies

In recent years, there has been an increasing interest in investigating the carcinogenicity of mycotoxins in humans. This systematic review aims to provide an overview of data linking exposure to different mycotoxins with human cancer risk. Publications (2019 and earlier) of case–control or longitudinal cohort studies were identified in PubMed and EMBASE. These articles were then screened by independent reviewers and their quality was assessed according to the Newcastle–Ottawa scale. Animal, cross‐sectional, and molecular studies satisfied criteria for exclusion. In total, 14 articles were included: 13 case–control studies and 1 longitudinal cohort study. Included articles focused on associations of mycotoxin exposure with primary liver, breast, and cervical cancer. Overall, a positive association between the consumption of aflatoxin‐contaminated foods and primary liver cancer risk was verified. Two case–control studies in Africa investigated the relationship between zearalenone and its metabolites and breast cancer risk, though conflicting results were reported. Two case–control studies investigated the association between hepatocellular carcinoma and fumonisin B1 exposure, but no significant associations were observed. This systematic review incorporates several clear observations of dose‐dependent associations between aflatoxins and liver cancer risk, in keeping with IARC Monograph conclusions. Only few human epidemiological studies investigated the associations between mycotoxin exposures and cancer risk. To close this gap, more in‐depth research is needed to unravel evidence for other common mycotoxins, such as deoxynivalenol and ochratoxin A. The link between mycotoxin exposures and cancer risk has mainly been established in experimental studies, and needs to be confirmed in human epidemiological studies to support the evidence‐based public health strategies.     

Validation of the performance of a GMO multiplex screening assay based on microarray detection

A new screening method for the detection and identification of GMO, based on the use of multiplex PCR followed by microarray, has been developed and is presented. The technology is based on the identification of quite ubiquitous GMO genetic target elements first amplified by PCR, followed by direct hybridisation of the amplicons on a predefined microarray (DualChip^® GMO, Eppendorf, Germany). The validation was performed within the framework of a European project (Co-Extra, contract no 007158) and in collaboration with 12 laboratories specialised in GMO detection. The present study reports the strategy and the results of an ISO complying validation of the method carried out through an inter-laboratory study. Sets of blind samples were provided consisting of DNA reference materials covering all the elements detectable by specific probes present on the array. The GMO concentrations varied from 1% down to 0.045%. In addition, a mixture of two GMO events (0.1% RRS diluted in 100% TOPAS19/2) was incorporated in the study to test the robustness of the assay in extreme conditions. Data were processed according to ISO 5725 standard. The method was evaluated with predefined performance criteria with respect to the EC CRL method acceptance criteria. The overall method performance met the acceptance criteria; in particular, the results showed that the method is suitable for the detection of the different target elements at 0.1% concentration of GMO with a 95% accuracy rate. This collaborative trial showed that the method can be considered as fit for the purpose of screening with respect to its intra- and inter-laboratory accuracy. The results demonstrated the validity of combining multiplex PCR with array detection as provided by the DualChip^® GMO (Eppendorf, Germany) for the screening of GMO. The results showed that the technology is robust, practical and suitable as a screening tool.     

Composition and quality attributes of conventionally and organically farmed Pangasius fillets (Pangasius hypophthalmus) on the German market

A range of conventionally and organically farmed Pangasius or sutchi catfish fillets available on the German market were analysed to compare both composition and quality. Differentiation of Pangasius hypophthalmus from Pangasius bocourti was achieved by RFLP-SSCP analysis. The protein content of conventionally farmed fillets ranged between 13.3 and 15.7%, whereas organically produced fillets had significantly higher protein contents of between 17.0 and 17.4%. No difference in the fat content between farming methods was observed, which varied between 1.4 and 3.2%. Polyunsaturated fatty acids represented about 24% of the total fatty acids with a high level of linoleic acid. The comparison of the proximate composition indicated that water was added to most of the conventionally farmed products, in different amounts, as well as water-binding capacity enhancing additives. Differential scanning calorimetry was used to demonstrate the presence of polyphosphate on muscle proteins. Differences in texture, water-binding capacity and colour are discussed.     

Effect of UV irradiation on organic matter extracted from treated Ohio River water studied through the use of electrospray mass spectrometry

Ohio River water was treated by settling, sand filtration, and granular activated carbon filtration. It was then irradiated by low-pressure (monochromatic) and medium-pressure (polychromatic) UV lamps to investigate the effects of UV irradiation on the extracted organic matter (EOM). When the EOM, collected by solid phase extraction cartridges, was analyzed by conventional UV spectroscopy and size exclusion chromatography (SEC), no significant changes in the EOM were revealed for various UV doses. Positive and negative electrospray ionization mass spectrometry (ESI-MS) of the EOM produced mass spectra that vary significantly with UV dose. The UV dosage conditions also appear to affect the reactivity of the EOM to subsequent chlorination. The magnitude of the spectral changes is generally greater for medium-pressure lamps than for low pressure and increases with UV exposure. Based on the observed MS peaks, the changes may be due to the presence of lignin, resulting perhaps from photooxidation and/or photo rearrangement of macromolecules in the sample. When chlorination is used for secondary disinfection, these results suggest that it may be important to consider the effects of UV irradiation on the organic matter in the water before applying UV disinfection technology to a particular source water.