Novel selection of recycled PET surrogates based on non-targeted screening of non-intentionally added substances and chemometrics

Abstract

Waste PET is utilized to produce recycled PET (rPET) through bottle-to-bottle recycling in order to reduce environmental pollution. However, non-intentionally added substances (NIAS) may be generated during rPET production, potentially posing a threat to food safety. In this study, a non-target screening of 13 batches with a total of 39 rPET samples was performed using GC-QTOF-MS and 240 compounds were tentatively identified. It was worth noting that the detection of phthalate esters in rPET from China, such as bis(2-ethylhexyl) phthalate, exhibits a higher diversity (17 different types) and frequency (7.8 %–100 %) in comparison with related studies. Subsequently, based on the principles for selection of surrogates used in challenge test, seven molecular descriptors were selected as variables for compound characterization, followed by principal component analysis (PCA) for representation. Based on this analysis and referencing the EFSA and FDA surrogate suggestion lists, eight surrogates were proposed for China, namely chlorobenzene, toluene, benzophenone, bis(2-ethylhexyl) terephthalate, methyl salicylate, methyl stearate, 1-phenyldecane and phenylcyclohexane. High-throughput detection methods were developed for each surrogate with the regression correlation coefficients over 0.999, spiked recoveries ranging from 99.3-107.5 %, LODs of 0.003–2.192 ng/mL, LOQs of 0.009–7.306 ng/mL, RSD of 0.71–4.23 %, respectively. This research provides foundational data and methodological support for the evaluation of rPET challenge testing in China, offering technical support for subsequent safety assessments of rPET.