SUPERCRITICAL FLUID EXTRACTION OF NITRATED POLYCYCLIC AROMATIC-HYDROCARBONS AND POLYCYCLIC AROMATIC-HYDROCARBONS FROM DIESEL EXHAUST PARTICULATE MATTER

Polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (nitro-PAHs) were extracted from diesel exhaust particulates and diesel soot using supercritical CHClF2 (freon-22), CO2, and CO2 with added modifiers. Pure CO2 was able to extract 1-nitropyrene spiked on air sampling filters, but did not yield quantitative extractions from diesel exhaust particulates [standard reference material (SRM) 1650 of the National Institute of Standards and Technology (Gaithersburg, MD, USA)]. 1-Nitropyrene could be quantitatively extracted in 45 min using either pure CHClF2 or 10% toluene in CO2 as a modifier, whereas 10% mixtures of CHClF2 or methanol in CO2 yielded only moderate recoveries. Supercritical CHClF2 also yielded quantitative extraction of PAHs from SRM 1650. Various nitro-PAHs could be determined in soot collected from the exhaust pipe of a bus after extraction with CO2 modified with CHClF2 or toluene.