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The amount of evaporation residue was investigated as an index of total amount of non-volatile substances that migrated from plastic kitchen utensils into four food-simulating solvents (water, 4% acetic acid, 20% ethanol and heptane). The samples were 71 products made of 12 types of plastics for food contact use. The amount was determined in accordance with the Japanese testing method. The quantitation limit was 5 µg/mL. In the cases of polyethylene, polypropylene, polystyrene, acrylonitrile styrene resin, acrylonitrile butadiene styrene resin, polyvinyl chloride, polyvinylidene chloride, polymethylpentene, polymethylmethacrylate and polyethylene terephthalate samples, the amount was highest for heptane and very low for the other solvents. On the other hand, in the cases of melamine resin and polyamide samples, the amount was highest for 4% acetic acid or 20% ethanol and lowest for heptane. These results enabled the selection of the most suitable solvent, and the rapid and efficient determination of evaporation residue.

Formaldehyde (FA), acetaldehyde (AA) and oligomers in recycled polyethylene terephthalate (PET) were analyzed by HPLC. All of the physically recycled PET contained detectable levels of FA, AA and oligomers, and the levels were almost the same as in used bottles. Most superclean-like and chemically recycled PET contained lower levels than new pellets. These compounds showed no decrease upon physical recycling, but showed a marked decrease upon superclean-like recycling. In PET sheets made using physically recycled PET, FA was decreased, though AA was increased by the sheeting process as same as new one. FA, AA and oligomers originated from PET resin and their levels in recycled products were almost equivalent to those in new products. It was concluded that there is no particular safety concern about their presence in recycled PET.

Metals in recycled polyethylene terephthalate (PET) were analyzed by ICP-MS following microwave digestion with nitric acid. Physically and superclean-like recycled PET contained both Ge and Sb, and sometimes contained Co, P or Si. In contrast, the chemically recycled PET contained only Ge or Sb, and some samples contained Co. The recycled PETs did not contain Pb or Cd. Ge and Sb were catalysts of the polymerization, and the other metals also originated from the PET resin as additives. It was concluded that there is no safety concern about metals in recycled PET. It became clear that the presence of both Ge and Sb could identify products formed using physically or superclean-like recycled PET. According to this discrimination method, about half of the sheet molding products used recycled PET.

The residual volatiles in recycled polyethylene terephthalate (PET) were analyzed using headspace/GC/MS. Recycled PET samples were made from PET bottles used for beverages, alcohol and soy sauce, and they were recycled in physical recycling plants, chemical recycling plants and superclean-like recycling trials. The physically recycled PET flakes contained small amounts of volatiles such as ethanol, limonene, 2-methyl-1,3-dioxolane, acetone, octanal and nonanal. Most of them originated from foods packed in bottles, and only 2-methyl-1,3-dioxolane was derived from polymer impurities. In contrast, the superclean-like or chemically recycled PET contained no detectable volatiles, like new PET pellets. The PET sheets shaped from physically recycled PET had no detectable volatiles. Not only the chemically and superclean-like recycled PET, but also the physically recycled PET contained no hazardous volatiles. It was concluded that there is no safety concern about volatiles in recycled PET, for the present use.

A simple and rapid test has been developed to quantitatively measure the migration of antimony (Sb) and germanium (Ge) from polyethylene terephthalate (PET) products. The PET product was soaked in 4% acetic acid (2 mL/cm2) for 30 min at 60 degrees C and 95 degrees C. The test solution was analyzed by ICP-MS. Recoveries of spiked Sb (0.025 microg/mL) and Ge (0.05 microg/mL) were 101% and 100%, respectively, with relative standard deviations (RSDs) of 2.3% and 1.7%. In ten successive analyses, Sb and Ge in the 4% acetic acid solution were analyzed with RSDs of 1.7% and 2.2%. Sb and Ge were not subject to interference from other elements simultaneously present in the 4% acetic acid solution. This method is simple, rapid and safe, requiring no pretreatment or use of the hazardous solvent carbon tetrachloride. Therefore, this test is a useful method to analyze Sb and Ge migration from PET products.

The containers of mineral water and the foreign plastic substances which were found in the mineral water were investigated. Most of plastic bottles were made of polyethylene terephthalate (PET) and the caps were made of polypropylene (PP), polyethylene (PE) or aluminum. PE liners were attached to some caps. Most of the foreign plastic substances were PET while others were PE, PP, Teflon and rubber. Some bottles had a scratch on the top inside. The origin of most PET fragments was presumed to be scraped off the bottles by the lowering of the injection nozzle during the water filling process. The sources of the other substances were also determined.