AN IMPROVED FRACTIONATION PROCEDURE FOR THE BIOASSAY-DIRECTED CHEMICAL-ANALYSIS OF AMBIENT AIR PARTICULATE EXTRACTS

Methodologies have been developed for the efficient extraction and fractionation of organic components present in ambient air particulate matter. A protocol of ultrasonic solvent extraction, solvent exchange, and solid-phase extraction (SPE) results in five organic fractions which account for more than 95% of the mass of the dichloromethane (DCM) extractable organic components. These fractionated samples are amenable to subsequent bioassay studies and identification of potentially toxic compounds. A National Institute of Standards and Technology (NIST) ambient "Air Particles" sample (SRM 1649) was used to help validate this procedure. The unoxidized lubricating oil, polymeric components (MwBAR/MnBAR=4700/1300) and hydrated inorganic salts were effectively separated from the polar organic compound fractions. The recovery of mutagenic activity for the fractionation procedure was 72 and 78% (with and without S9 activation enzymes) using a TA98 Salmonella typhimurium microsuspension bioassay. Further analysis shows that the chemical integrity of the extract is maintained using this fractionation procedure.