Aqueous extraction of airborne particulate matter collected on Hi-Vol Teflon filters

An extraction method was developed for the quantitative recovery of fine particles collected on Hi-Vol Teflon filters and in a form suitable for assessment of the biological reactivity of atmospheric aerosols. Two major criteria identified for the selection of a procedure were maximum recovery and minimization of the introduction of chemicals into the extract solution. Experiments were conducted with different volumes of a pre-wetting agent (ethanol) and sonication times to select the appropriate conditions for the aqueous extraction of material from the hydrophobic Teflon surface. The developed procedure involved the pre-wetting of a filter (cut into 8 pieces) with 2 mL ethanol and sonication in 400 mL ultra pure water for 30 minutes. Results of gravimetric analyses indicated high mass recoveries (91+/-7%) of material from the Teflon filters. Analyses for polycyclic aromatic hydrocarbons (PAHs) were performed on organic extracts of portions of Teflon filters with particles and portions of the same filters subjected to aqueous extraction. Comparison of the results revealed high percentages (92+/-11%) of PAHs were transferred into the aqueous solution using the extraction method developed. Inorganic analyses performed on Teflon filters (loaded with particles) and freeze-dry residues of aqueous extracts of Teflon filters also suggested high transfer rates (84+/-33%) of inorganics into the aqueous extracts.