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Cyclic monomer and oligomers are the major migrating substances from polyamide (PA) food contact materials. An increase of caprolactam (+44%) and cyclic oligomer content (+27%, incl. caprolactam) in PA6 was observed by thermal treatment, here by extrusion of a PA6 film from a granulate. Migration experiments with a PA6 and a PA66 packaging film were carried out into food simulants according to directives 85/572/EEC and 82/711/EEC. Contact conditions (2 h/100°C) were chosen for a heat treatment of the food in the packaging, in this case production of scalded sausage. Aqueous and ethanolic food simulants clearly revealed to be the worst case for migration of cyclic PA6 and PA66 monomer and oligomers. Migration of cyclic oligomers into oil was one order of magnitude lower. No migration could be observed into isooctane (<8 µg dm−2). The substitutes for oil, 95% ethanol and isooctane, were inapplicable for simulating migration of cyclic oligomers into oil. Caprolactam showed different migration behaviour compared with cyclic oligomers, migrating into oil and water to the same extent depending on contact conditions. Fifty percent of the extractable caprolactam migrated from a PA6 sausage casing into scalded sausage (4.2 mg kg−1), residual 41% apparently were extracted by the boiling medium or during pretreatment (soaking) of the casing. Potential migration of caprolactam and cyclic oligomers from a PA6 tea bag was found to be 18% of the specific migration limit for caprolactam and 36% of the overall migration limit. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A rapid, reproducible, and sensitive ion-exchange chromatography (IEC) method combined with graphite-furnace atomic absorption spectrometry (GF-AAS) was developed to separate and quantify basal amounts of both metallothionein (MT) isoforms in dab (Limanda limanda) liver samples. Dab liver homogenates were saturated with Cd, and obtained cytosols were purified by a two-step acetone precipitation prior to chromatographic analysis. Metallothionein isoforms were separated by IEC and were subsequently quantified indirectly by GF-AAS via their Cd contents. The amount of Cd needed for saturation was optimized. The efficiency of Cd saturation and acetone precipitation was proven by gel permeation chromatography (GPC) and metal distribution analysis. Based on the method of standard addition, a recovery for MT was 98% after acetone precipitation and 68% after IEC. The repeated determination ofMT isoforms in a dab liver homogenate resulted in coefficients of variation of approximately 12% for both isoforms. Based on the detection limit for GF-AAS, the calculated detection limit for MT isoforms is2 ng/mg protein. Therefore, this method is suitable for monitoring purposes. The implications of isoform-specific measurement for biomarker monitoring are discussed. [ABSTRACT FROM AUTHOR]