Impact of extraction methods on ambient PM2.5 components and cytotoxicity

Obtaining PM2.5 samples that are consistent with the natural composition of PM2.5 is crucial for toxicological research. However, current extraction methods inevitably alter the physicochemical properties of PM2.5. Based on variations in processing procedures: extraction solvent (Water, Ethanol or dimethyl sulfoxide [DMSO]), sonication and filtration steps (coarse filtration with 40 μm filters and fine filtration with10 μm filters), five PM2.5 extraction methods were developed, designated as WSF10, ESF10, DSF10, DCF10, and DCSF10, respectively. A mathematical model was developed to evaluate the similarity of PM2.5 samples and the result showed that PM2.5 extracted by DCF10 method (Coarse filtration, Fine filtration, dissolved in DMSO) were closest to that of natural PM2.5, with the highest overall similarity value of 0.70 (0.70 ± 0.01). The cytotoxicity of DCF10-extracted PM2.5 were significantly higher than other groups, inhibiting BEAS-2B cell viability by up to 60% after 9 days exposure, which aligned best with the similarity results. The outcomes highlight that improper extraction methods may underestimate the actual toxicity of PM2.5. Therefore, optimizing and refining PM2.5 extraction protocols is critical for accurately evaluating its toxicity and providing valid evidence for health risk assessment.