Supercritical fluid extraction of nitrated polycyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons from diesel exhaust particulate matter

Abstract

Polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (nitro-PAHs) were extracted from diesel exhaust particulates and diesel soot using supercritical CHClF 2 (freon-22), CO 2, and CO 2 with added modifiers. Pure CO 2 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 CHClF 2 or 10% toluene in CO 2 as a modifier, whereas 10% mixtures of CHClF 2 or methanol in CO 2 yielded only moderate recoveries. Supercritical CHClF 2 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 CO 2 modified with CHClF 2 or toluene.