An innovative ultrasound assisted extraction micro-scale cell combined with gas chromatography/mass spectrometry in negative chemical ionization to determine persistent organic pollutants in air particulate matter

New clean technologies are needed to determine concentration of organic pollutants without generating more pollution. A method to extract Persistent Organic Pollutants (POPs) from airborne particulate matter was developed using a novel technology recently patented called ultrasound assisted extraction micro-scale cell (UAE-MSC). This technology extracts, filters, collects the sample, and evaporates the solvent, on-line. No sample transfer is needed.The cell minimizes sample manipulation, solvent consumption, waste generation, time, and energy; fulfilling most of the analytical green chemistry protocol. The methodology was optimized applying a centred 2(3) factorial experimental design. Optimum conditions were used to validate and determine concentration of 16 organochlorine pesticides (OCIs) and 6 polybrominated diphenyl ethers (PBDEs). The best conditions achieved were 2 extractions with 5 mL (each) of dichloromethane over 5 min (each) at 60 degrees C and 80% ultrasound potency. POPs were determined by gas chromatography/mass spectrometry in negative chemical ionization (GC/MS-NCI). Analytical method validation was carried out on airborne particles spiked with POPs at seven concentration levels between 0.5 and 26.9 pg m(-3). This procedure was done by triplicate (N = 21). Recovery, ranged between 65.5 +/- 2.3% and 107.5 +/- 3.0% for OCIs and between 79.1 +/- 6.5% and 105.2 +/- 3.8% for PBDEs. Linearity (r(2)) was >= 0.94 for all compounds. Method detection limits, ranged from 0.5 to 2.7 pg m(-3), while limits of quantification (LOQ), ranged from 1.7 to 9.0 pg m(-3). A Bias from -18.6% to 9% for PBDEs was observed in the Standard Reference Material (SRM) 2787. SRM 2787 did not contain OCIs. OCIs recoveries were equivalent by UAE-MSC and Soxhlet methods UAE-MSC optimized extraction conditions reduced 30 times less solvent and decreased the extraction time from several hours to ten minutes, respect to Soxhlet. UAE-MSC was applied to 15 samples of particles less than 2.5 mu m (PM2.5) from three seasons (warm dry, rainy, and cold dry) collected in five sites around Mexico City. OCIs (4,4'-DDE and endrin aldehyde) concentrations ranged from