Recycled plastics and reuse of food contact materials: outcomes from analytical characterization and performance evaluation

The new Regulation on Packaging and Packaging Waste encourages the diffusion of reused and recycled plastic items to replace single-use plastics. The conformity of materials for repeated use is checked according to the EU Regulation 10/2011 based on three consecutive migrations, considering that contaminant amount decreases with increasing number of uses. It is generally accounted that migrant amount is proportional to its initial concentration, according to the law of diffusion based on coefficients constant over time1. However, it is not taken into account that aged materials exhibit a different behaviour respect to new items, since washing procedures before reuse, and recycling processes, result in mechanical, thermal and chemical stress affecting additives amount, and leading to the potential formation of non-intentionally added substances (NIAS) from degradation reactions2. Therefore, there is a need for deeper analytical controls, and for performance evaluation of the material during ageing and after repeated industrial processing. Within a collaboration with some companies, a series of experiments was performed on food contact articles for repeated use, and on virgin and industrial processed PET. To determine the identity of potential contaminants, solvent extraction was carried out before performing migration in simulants. The effect of the use of different solvents has been investigated, and showed a variable patterns of extracted analytes. Additives and NIAS have been identified by chromatographic techniques coupled to mass spectrometry, and quantification was then performed on simulants for the substances whose standards were available. A different trend depending on the substance was observed: a decrease with ageing was shown for colorants in reused items, whereas compounds deriving from material degradation increased. As for recycled plastics, the effects of industrial processing and recycling procedures were investigated to explore if could lead to additives degradation and formation of NIAS. Preliminary results showed differences in the profile of analytes in PET virgin granules compared to processed material. Aged and recycled bottles were also investigated.