added 109 research items
Prof. T.J. Simat, TU Dresden, Professur für Lebensmittelkunde und Bedarfsgegenstände, Bergstraße 66 D-01069 Dresden www.chm.tu-dresden.de/lc/simat.shtml Zusammenfassung Die Kombination verschiedener spektroskopischer und chromatographischer Methoden ermöglicht die Ermittlung eines Höchstmaßes an qualitativen und quantitativen Informationen über migrierfähige Substanzen aus Verbundfolien. Dafür werden die Gesamtmigrate einer ausgewählten Folie in den Ersatzsimulanzien nach RL 82/711/EWG, 95 % Ethanol und Iso-Octan, untersucht. Die 1 H-NMR bietet die Möglichkeit zum Screening der Migrate auf bestimmte Strukturmerkmale, die Additiven oder Monomeren zugeordnet werden können. Die qualitative Absicherung sowie quantitative Ermittlung der spezifischen Migranten wird anhand von RP-HPLC mit verschiedenen Detektoren (UVD, FLD, ELSD, CLND) sowie GC-MS/FID durchgeführt. Niedermolekulare Oligomere aus PE-Siegelschichten werden in Summe mittels 1 H-NMR quantifiziert. Mit Hilfe dieser unterschiedlichen Methoden können für die untersuchte Verbundfolie die nicht-flüchtigen organischen Substanzen im Gesamtmigrat aufgeklärt werden.
Apoptosis, also known as programmed cell death, is a physiological and irreversible process in tissue homeostasis that leads to DNA fragmentation of multiples of 180-200 bp. Because apoptosis can be initiated not only by physiological stimuli but also by various chemical substances, the present paper investigates the suitability of apoptosis as a biomarker for biological effect monitoring in the marine environment. Aquarium experiments with dab (Limanda limanda) were carried out to examine the effects of exposure to cadmium, PCB 118, and PCB 77 (each 1 mg/kg fish wt) on apoptosis in dab liver. Determination of apoptosis was carried out by DNA gel electrophoresis and quantification of DNA fragments smaller than 1500 bp. In addition, accumulated amounts of cadmium, PCB 118, and PCB 77 in dab liver were analyzed. Quantification of the three xenobiotics resulted in an accumulation of about factor 10(2)-10(4). Exposure to PCB 118 and cadmium resulted in an increase in apoptotic DNA fragmentation. Exposure to PCB 77 led mainly to cell death by necrosis.
The products of γ-irradiation of tripeptides (AWA, LWL, LWM) and lysozyme were determined by HPLC and UV/fluorescence detection. A fast and simple one-step hydrolysis with pronase E (30 – 60 min, 40°C) was developed to release the radiation products, without damage, from the peptide chain. N-Formylkynurenine (NFK), oxindolylalanine (OIA), 4-, 5-, 6- and 7-hydroxytryptophan were the main products of irradiation of peptides and lysozyme. It is possible that the nonphysiological hydroxytryptophan isomers 4-, 6- and 7-hydroxytryptophan could serve as marker substances for irradiated food with a high protein content.
Styrene-acrylonitrile-copolymer (SAN) and acrylonitrile-butadiene-styrene-copolymer (ABS) are gaining in importance as food contact materials. Oligomers and other non-intentionally added substances can migrate into foodstuffs. Five SAN and four ABS samples from the German market and manufacturers were extracted and the extractable oligomers were characterised by high performance liquid chromatography-mass spectrometry/ultraviolet detection/chemiluminescence nitrogen detection/fluorescence detection and gas chromatography-mass spectrometry. Trimers, formed from acrylonitrile and styrene units, were determined to be the dominating group of extractable oligomers in SAN and ABS in concentrations of about 4900–15800 mg/kg material. Furthermore, styrene-acrylonitrile dimers, styrene oligomers, styrene monomer and ethylbenzene were identified in the sample extracts. Migration testing with three consecutive migrations for multiple use articles was performed for two SAN articles. Migration of trimers into water, 3% acetic acid, 10% and 20% ethanol under hot-fill conditions (70°C, 2 h) was not detectable above 9 µg/dm², while 50% ethanol acting as a food simulant for milk (124 µg/dm² trimers during the third migration) was shown to overestimate the actual migration into milk (< 11 µg/dm² trimers at 70°C, 2 h). 2-Amino-3-methyl-1-naphthalenecarbonitrile (AMNC), an oligomer degradation product and a primary aromatic amine, was detected in all material sample extracts (0.3–17.1 mg/kg material) and was released into food simulants in low amounts (< 0.014 µg/dm² during the third migration into 50% ethanol at 70°C, 2 h).