Ultrasonic-assisted Solvent Extraction Method for the Determination of Environmentally Persistent Free Radicals in PM2.5

Environmentally persistent free radicals (EPFRs) are a class of long-lived environmental risk substances that exist in air fine particulate matter (PM2.5). In the present study, different sample pre-treatment conditions were optimized. The developed method was successfully used to determine the contamination levels of EPFRs in PM2.5 collected from Zhengzhou in winter. The results will be useful for extensive research on the sources, concentrations, formation mechanisms, physical-chemical characteristics and biological toxicity of EPFRs in the atmosphere. Different sample pre-treatment conditions (extraction solvent, methods and temperatures) were optimized. A novel method of soaking ultrasonic-assisted solvent extraction with methanol as extraction solvent under low temperature followed by electron paramagnetic resonance detection for the determination of environmentally persistent free radicals (EPFRs) in PM2.5. The method will be useful for extensive research of EPFRs in the atmosphere.