Colin Crews

Headspace analysis of benzene in food contact materials and its migration into foods from plastics cookware

Concentrations of benzene of 29 and 64 mg/kg were found in two samples of thermoset polyester compounded for the manufacture of plastic cookware. In collaboration with the suppliers of the materials, it was established that the benzene originated from the use of t-butyl perbenzoate used as an initiator in the manufacture of the polymer. Samples of thermoset polyester made to the original formulations and thus contaminated with benzene showed migration levels of 1.9 and 5.6 mg/kg in olive oil after extraction for 1 hour at 175 degrees C. Migration levels into olive oil at 175 degrees C for samples produced with non-aromatic initiator were less than 0.1 mg/kg. Concentrations of benzene in thermoset polyester cookware purchased from retail outlets were 0.3 to 84.7 mg/kg. Low amounts of benzene (less than 0.01 to 0.09 mg/kg) were detected in foods when the articles were used for cooking in microwave or conventional ovens. Other plastics used for retail food packaging, such as polystyrene and PVC, which might utilise t-butyl perbenzoate catalyst, were also analysed for benzene. Levels were mostly below 0.1 mg/kg, with the highest amounts detected being from 0.2 to 1.7 mg/kg, predominantly in articles of expanded polystyrene.

Identification of a major new involatile N-nitroso compound in smoked bacon

Abstract The new N-nitroso compound identified in smoked bacon is 2-(hydroxymethyl)-3-nitrosothiazolidine-4-carboxylic acid. Identification was based on comparison of data from liquid chromatography, capillary gas chromatography and mass spectrometry with those for the authentic compound, the synthesis of which is described.

The migration of propylene glycol, mono-, di-, and triethylene glycols from regenerated cellulose film into food

ZusammenfassungPralinen, Fruchtbonbons, Caramelbonbons, Kuchen und Fleischpasteten wurden in Folien aus Regeneratcellulose (sowohl mit als auch ohne Beschichtung) verpackt, die verschiedene Mischungen von Glykolweichmachern enthielten und speziell für ihre Eignung bei besonderen Lebensmittelanwendungen hergestellt wurden. Nach Ablauf der normalen bzw. maximalen Haltbarkeitszeit der Lebensmittel und ebenso bei einigen dazwischenliegenden Zeitpunkten wurden die Proben ausgepackt und auf ihre Glykolkontamination überprüft. Die Analyse umfaßte die Homogenisierung der Lebensmittel in heißem Wasser, die Abtrennung von Fetten mittels Hexan, die Fällung der Zucker unter Verwendung von Calciumhydroxid und die Analyse der Glykole durch Capillar-Gaschromatographie mit Flammen-Ionisations-Detektion (GC/FID) nach der Trimethylsilyl(TMS)-Derivatisierung. Die Bestimmung von Triethylenglykol erfolgte mittels selektiver Ionenregistrierung-GC/Massenspektrometrie (GC/MS), da sich bei der GD/FID-Methode Probleme der Interferenz ergaben. Die Versuchsergebnisse zeigten bei Propylenglykol einen höheren Wanderungsgrad als bei Triethylenglykol, wobei das Vorhandensein einer Beschichtung in beiden Fällen die Wanderung der Weichmacher reduzierte. Mono- und Diethylenglykolgehalte der Lebensmittel waren im allgemeinen unter 10 mg/kg, jedoch enthielten manche Proben, die in Folien mit Polyethylenglykolweichmachern verpackt wurden, eine Glykolmenge die sich der zur Zeit vorgeschriebenen Höchstgrenze von 50 mg/kg nähert.SummaryChocolates, boiled sweets, toffees, cakes and meat pies were wrapped in regenerated cellulose films (with or without coatings) that contained various mixtures of glycol softeners and which had been specially formulated for particular food applications. Samples were unwrapped at intervals (up to the end of the usual maximum shelf-life for the food) and analysed for their glycol content. Analysis involved homogenization of the food in hot water, removal of fats with hexane, precipitation of sugars with calcium hydroxide and analysis of the glycols by capillary gas chromatography with flame ionization detection (GC/ FID) after trimethylsilyl (TMS) derivatization. Triethylene glycol was analysed by selected ion monitoring GC/mass spectrometry (GC/MS) as interference problems occurred with the GC/FID approach. The results of the study showed that higher levels of migration occurred for propylene glycol than for triethylene glycol and the presence of a coating reduced the migration of both softeners. Generally, mono- and diethylene glycol levels in the food samples were below 10 mg/kg, although some samples wrapped in polyethylene glycol-softened films contained levels approaching the current statutory limit of 50 mg/kg.

Automated headspace GC-MS analysis of ethylene dibromide fumigant residues in fresh fruits.

An automated headspace capillary column GC-MS method using selected ion monitoring was developed for the analysis of ethylene dibromide (EDB) residues in fresh fruits. The method was shown to be rapid, to give good agreement with more conventional methods involving distillative extraction, to be free from interferences and to have a limit of detection of 1 microgram/kg. A small survey of a range of fresh fruits including oranges, grapefruit, lemons and mangoes showed no detectable EDB residues in a total of 45 samples obtained from various retail outlets.

Structural studies of an oligomer (vinyl chloride tetramer) isolated from poly(vinyl chloride) resin used for food packaging applications

Abstract A presumptive single component previously isolated from PVC base resin and tentatively identified from GC-MS data as a vinyl chloride tetramer (mol. wt = 248) has been the subject of further studies. After hydrogenation, two isomeric compounds were separable by capillary GC. Mass spectra confirmed the earlier assignment of one double bond in the parent compounds. Further evidence for the presence of a pair of isomers in the apparently pure tetramer was obtained by epoxidation where two products giving identical mass spectra were produced. The MS fragmentation pattern suggested that the double bond position was allylic to chlorine; GC-MS analysis of the derived chlorohydrins supported this conclusion. Analysis of the tetramer by NMR gave complex overlapping signals, thought to be due to impurities, which hindered interpretation. Some supportive evidence for an allylic double bond was obtained. The structure of the tetramer thus remains only partially determined; the complexities of isomer purification and the difficulties of assigning chlorine substituent patterns make future unequivocal characterisation unlikely.