Dual-platform targeted workflow for multi-residue determination of 625 organic contaminants in atmospheric fine particulate matter

Myriads of organic contaminants in atmospheric fine particulate matter (PM_2.5) have been documented to pose appreciable health risks. Meanwhile, the quantities of analytes monitored by most established approaches have remained modest, hindering systematic elucidations of PM_2.5-bound pollution. Therefore, this study developed a high-throughput and efficient methodology for targeted determination of 625 trace-level chemicals, which covered both emerging and conventional contaminants, as well as their transformation products. Additionally to notorious pollutants, like legacy brominated flame retardants (LBFRs), polycyclic aromatic hydrocarbons, organochlorine pesticides, and phthalate esters (PAEs), our analyte list also encompassed multiple classes of contaminants of emerging concern, including alternative BFRs, synthetic antioxidants, organophosphate esters (OPEs), liquid crystal monomers, and PAE replacements (PAEAs). The optimized protocol demonstrated satisfactory recoveries and negligible matrix effects for over 96% of the target compounds. The resulting method detection limits, ranging from 0.011 to 5.47 pg/m³, could rival the values reported for counterpart protocols quantitating even less contaminant categories. Following the final analytical procedures, we confirmed the measurable levels of 337 analytes in Chinese urban PM_2.5 samples, with total concentrations spanning from 15.5 to 76.0 ng/m³. It is noteworthy that compound groups of the greatest abundances were PAEAs and OPEs, both introduced as alternative plasticizers and/or flame retardants, indicating recent market shifts of industrial additives in China. Moreover, outstanding residues were also observed for tire-derived chemicals, suggestive of their urban signatures. The broad-spectrum surveillance approach we built can facilitate data acquisitions for comprehensive regulation of atmospheric pollution.