Migration of oligomers from Tritan™ copolyester: application of hydrolysis for overall oligomer determination.

Tritan™ (a kind of glycol-modified polycyclohexylene dimethylene terephthalate) is a novel copolyester mainly in use for the production of sports bottles and food storage containers. Oligomers in three food-grade Tritan™ samples were identified after dissolution-precipitation by high performance liquid chromatography with diode array detection and mass spectrometry and quantified after alkaline hydrolysis to the monomers. The obtained overall oligomer content <1000 Da determined by hydrolysis ranged from 7.2 to 10.6 mg/g material. Three consecutive migration experiments were performed according to the Commission Regulation (EU) No 10/2011. Oligomer migration values decreased from first to third migration during all simulations. Less than 25 µg/kg (third migrate) were detected in bottle migrates when tested under room temperature storage conditions (40 °C, 24 h) with simulants 3% acetic acid, 20 and 50% ethanol and during hot-fill testing (70 °C, 2 h) with simulants 3% acetic acid and 20% ethanol, respectively, while 170 µg/kg were determined in 50% ethanol after migration at 70 °C for 2 h. Food storage containers that were labelled as microwave-suitable by the supplier were tested according to the Joint Research Centre recommendations for microwave dishware. A strong deformation of the containers as well as a loss of transparency were observed during the tests (100 °C, 2 h with 10% ethanol and 3% acetic acid in an autoclave, 121 °C, 30 min with sunflower oil), questioning the suitability of the material for microwave applications. Maximum oligomer migration was 379 µg/kg during the third migration (sunflower oil at 121 °C for 30 min). Based on the migration data and an oligomer evaluation according to the threshold of toxicological concern concept, no exceedances of daily thresholds for oligomers are expected from a proper use of Tritan™ drinking bottles, even with hot drinks.