Contaminants and levels of occurrence in washed and shredded poly(ethylene terephthalate) from curbside collection. II: Validation of extraction procedures, particle size sampling and crystallinity

Occurrence of volatile contaminants in recycled poly(ethylene terephthalate) by HS-SPME-GC×GC-QTOF-MS combined with chemometrics for authenticity assessment of geographical recycling regions

A comparison was performed on various methods detecting the volatile contaminants (VCs) in recycled poly(ethylene terephthalate) (rPET) flakes, the results demonstrated that head-space solid phase micro-extraction combined with comprehensive two-dimensional gas chromatograph-tandem quadrupole-time-of-flight mass spectrometry (HS-SPME-GC×GC-QTOF-MS) was a sensitive, effective, accurate method, and successfully applied to analyze 57 rPET flakes collected from different recycling plants in China. A total of 212 VCs were tentatively identified, and the possible source were associated with plastic, food, and cosmetics. 45 VCs are classified as high-priority compounds with toxicity level IV or V and may pose a risk to human health. Combined chemometrics for further analysis revealed that significant differences among these three geographical recycling regions. 6, 7, and 6 volatile markers were chosen based on VIP values and S-plot among plant1 plant 2 and plant 3, respectively. The markers differed significantly between recycled rPET samples in three geographical recycling regions based on chemometrics analysis. The initial classification rate and cross-validation accuracy were 100% on the identified VCs. These significant differences demonstrate that a systematic study is needed to obtain a comprehensive data on the contamination of rPET for food contact applications in China.

Polímeros reciclados para contato com alimentos

Os resíduos sólidos urbanos (RSUs) são atualmente um dos maiores problemas ambientais, por serem gerados em grande quantidade e ocuparem extensos espaços por um longo período, resultando na diminuição do tempo de vida útil dos aterros sanitários. Os polímeros constituem um grande percentual da composição do RSUs, sendo que as embalagens plásticas contribuem com maior volume e massa. Apesar da reciclagem de polímeros estarem se consolidando no Brasil, graças ao seu mercado ascendente e promissor, existem ainda restrições quanto a sua utilização em contato com alimentos devido aos eventuais processos de migração de contaminantes que podem ocorrer da resina reciclada para o alimento. Por outro lado, dados recentes do setor indicam que a maior parte do consumo de resina virgem é destinada, justamente, para o mercado de embalagens alimentícias. Assim, o desenvolvimento e o gerenciamento de tecnologias que possibilitem o retorno destes materiais a sua aplicação original é de grande importância para sociedade contemporânea. Em um panorama geral, este trabalho aborda as exigências e limitações do uso de polímeros reciclados para contato com alimentos.

Identification of chemicals, possibly originating from misuse of refillable PET bottles, responsible for consumer complaints about off-odours in water and soft drinks

Mineral water and soft drinks with a perceptible off-odour were analysed to identify contaminants originating from previous misuse of the refillable polyethylene terephthalate (PET) bottle. Consumers detected the off-odour after opening the bottle and duly returned it with the remaining content to the producers. The contaminants in question had thus been undetected by the in-line detection devices (so-called 'sniffers') that are supposed to reject misused bottles. GC-MS analysis was carried out on the headspace of 31 returned products and their corresponding reference products, and chromatograms were compared to find the possible off-odour compounds. Substances believed to be responsible for the organoleptic change were 2-methoxynaphthalene (10 bottles), dimethyl disulfide (4), anethole (3), petroleum products (4), ethanol with isoamyl alcohol (1) and a series of ethers (1). The mouldy/musty odour (5 bottles) was caused by trichloroanisole in one instance. In some cases, the origins of the off-odours are believed to be previous consumer misuse of food products (liquorice-flavoured alcohol, home-made alcohol containing fusel oil) or non-food products (cleaning products, petroleum products, oral moist snuff and others). The results also apply to 1.5-litre recyclable PET bottles, since the nature and extent of consumer misuse can be expected to be similar for the two bottle types.