Hydrophobic filter sampling for simultaneous determination of airborne plasticizers and microplastics in indoor air by Py-GC/MS.

Airborne microplastics, an emerging environmental concern, have attracted global attention due to their ubiquitous occurrence in indoor environments. In this work, a method for the simultaneous determination of airborne microplastics and phthalate esters (PAEs) in indoor air was developed by double-shot pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) combined with filter sampling. The commercial glass fiber filters were modified via reaction with silylation reagent. The modified filters had significantly high enrichment factors for PAE additives, ranging from 6,921 to 150,260. Subsequently, the modified filters were employed to enrich airborne PP and PE, as well as 10 PAE additives from indoor air. A quantitative method based on selected ions was established and validated. Both PAEs and microplastics exhibited good linearity over their respective linearity ranges with correlation coefficients more than 0.98. LOQs were 0.03-1.0 ng/m3 for 10 PAEs and 0.6-1.7 ng/m3 for microplastics. This proposed approach was applied to quantify PP and PE microplastics and their associated PAE additives in real indoor air samples. The obtained results showed that various trace-level airborne PAEs existed in indoor air. Of all the measured PAEs, di(2-ethylhexyl) phthalate (>33.3 ng/m3), dibutyl phthalate (>7.89 ng/m3) and diisobutyl phthalate (0.98-10.42 ng/m3) were the predominant congeners, and the concentrations of the remaining PAEs were below 1.82 ng/m³. The detected concentrations in indoor air samples ranged from 2.78 to 5.00 ng/m³ for PP and 88.10 to 184.67 ng/m³ for PE, respectively. This approach provides a practical reference for the monitoring of trace-level pollutants in indoor air.