Determination of polybrominated biphenyls in industrial ash and flue gas by GC-MS/MS: Method development, validation,...

Polybrominated biphenyls (PBBs) are legacy brominated flame retardants formerly utilized in plastics, electronics, and textiles. Currently, the simultaneous determination of mono- to deca-brominated PBBs in complex industrial matrices remains challenging due to wide bromination range and matrix interference. In this study, an isotope dilution gas chromatography‑triple quadrupole mass spectrometry method was established for the determination of 23 PBB congeners. Samples were Soxhlet-extracted and purified on acid silica gel, multilayer silica gel and activated carbon columns. To overcome the difficulties associated with the wide boiling point range, a dual-column strategy (30 m for mono- to hepta-BBs; 15 m for octa- to deca-BBs) mitigated on-column degradation and enhanced response for highly brominated targets. The method exhibited excellent linearity (R² > 0.999), low method detection limits (0.01-0.04 ng g^-1 for ash and 0.03-0.20 ng m^-3 for flue gas), satisfactory accuracy (62.3%-122.9%), and relative standard deviations < 18.6% for solid and gas matrices. The validated method was successfully applied to 88 real samples from e-waste co‑processed in copper smelting, cement kiln co‑processing hexabromocyclododecane-containing waste, and municipal solid waste incineration. PBB concentrations in copper smelting ranged from 0.5 to 26.4 ng m^-3 in flue gas and 0.3 to 16.5 ng g^-1 in ash, while cement kiln co-processing yielded levels of 0.1-15.6 ng g^-1 in ash. The field investigations indicated that co-processing of bromine-containing wastes could lead to the unintentional formation of PBBs. This work presents a robust tool for the trace analysis of full-spectrum PBBs, facilitating the investigation of unintentional formation of brominated pollutants in industrial thermal processes.