Optimization of a novel method for the organic chemical characterization of atmospheric aerosols based on microwave-assisted extraction combined with stir bar sorptive extraction.

A practical analytical methodology based on coupling microwave-assisted extraction-stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry (MAE-SBSE-TD-GC-MS) was developed and validated for the characterization of several SVOC in atmospheric particulate matter (PM). The high enrichment capacity of SBSE makes it a powerful tool for improving detection limits and MAE has been useful for overcoming the long extraction times and high volumes of extraction solvent used in traditional methodologies. Relative to Soxhlet extraction followed by GC-MS analysis (EPA Methods 3540 and 8270C), the MAE-SBSE-TD-GC-MS methodology resulted with approximately 10(4) times better detection limits. Detection limits ranged from 0.3 to 8.3 pg m(-3) for pp'-DDD and decachlorobyphenyl, respectively in PM2.5, 24 m3 air sample. The performance of the optimized methodology gave good precisions, with R.S.D. less than 30% for most of the standards, and linearity within the range tested of 0.1-15 microg L(-1). Analysis of real PM samples resulted in the identification of compounds in the ng L(-1) range.