As part of a Cooperative Agreement with DOE-NETL, the University of North Dakota Energy and Environmental Research Center (EERC) is developing advanced sampling and analysis methodologies for particulate matter that can be used for source apportionment and to assist in health studies. These techniques will be used to determine sources of fine particulate matter in rural states such as North Dakota.

One of the primary activities of this effort is the development of a procedure using subcritical water to fractionate organics in air particulates, and test the toxicity of the fractionated organics using various tests. In contrast to inorganic aerosols, which are often well characterized, only ca. 15%–50% of the organic carbonaceous (OC) particulate mass has been characterized. The characterized compounds are almost exclusively nonpolar. The limited knowledge on OC fractions is due to the use of organic solvents which are able to extract only nonpolar or slightly polar organics. Subcritical water has not previously been used to fractionate OC from air particulates, but should have the ability to extract a broad range of polar to low-polarity OC, as well as to provide extracts in a solvent (water) which is directly useful for biological tests. Earlier studies have shown that compounds of different polarities, such as phenols, PAHs, and alkanes, can be sequentially extracted from a petroleum waste sludge by increases in subcritical water temperature.

The method fractionating two common carbonaceous aerosols, diesel exhaust particulate (relatively nonpolar matrix) and wood smoke particulate (polar matrix), was developed. Both particulate samples were sequentially extracted using a range of subcritical water temperatures from ca. 25° to 300°C. The individual fractions were characterized gravimetrically and with a CHN analyzer. Moreover, samples were analyzed using gas chromatography with flame ionization and mass spectrometric detectors. The quantitative and qualitative data were compared to results obtained with the toxicity test Polytox. The method development of another toxicity test SOS chromotest was started.