Identification and quantification of (brominated) flame retardants during mechanical recycling of polystyrene from WEEE by means of pyrolysis-GC-MS

With the increasing electronification of societies, the generation of Waste Electrical and Electronic Equipment (WEEE) continues to rise, while formal recycling rates are lagging behind at around 25 wt%. Apart from low collection rates, the presence of potentially hazardous brominated flame retardants (BFRs) in WEEE plastics further complicates recycling. As a result, restrictions have been implemented for flame retardants (FRs) classified as persistent organic pollutants (POPs). As regulatory thresholds tighten and more substances are added to restriction lists, effective analysis of these compounds in complex waste matrices becomes increasingly important. This study explores pyrolysis-GC-MS (Py-GC-MS) for the simultaneous identification and quantification of five flame retardants: HBCD, TBBPA, DBDPE, TPHP, and PolyFR. The main novelty of the work lies in the systematic development of the Py-GC-MS method, including the complementary capabilities of TGA and the optimal use of multi-shot analysis. In addition, the proposed analytical methodology has been applied to different plastic waste samples, collected from a mechanical recycling plant processing WEEE. Results confirm that most halogenated plastics can be isolated effectively via density-based sorting, with total bromine content reaching up to 2755 ± 430 mg kg⁻¹. This study highlights the release of significant bromine levels (i.e., up to 300 kg⁻¹) during extrusion, suggesting that brominated degradation products might escape from the extrusion lines in WEEE plastic reprocessing facilities. Among the investigated flame retardants, TBBPA was the most abundant (i.e., up to 1534 ± 244 mg kg⁻¹). The study demonstrates that accurate quantification of multiple FRs simultaneously in complex waste samples by Py-GC-MS is feasible, though challenges remain due to potential interferences of reaction products.