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Bioassay-Directed Fractionation of Diesel and Biodiesel Emissions
Citation:
Mutlu, E., S. Warren, C. King, Bill Linak, D. Nash, Ian Gilmour, AND D. DeMarini. Bioassay-Directed Fractionation of Diesel and Biodiesel Emissions. Presented at Society of Toxicology, March 10 - 14, 2013.
Impact/Purpose:
Studies found that emissions from biodiesel were less mutagenic than those from petroleum diesel, and most of the activity is associated with PAHs.
Description:
Biofuels are being developed as alternatives to petroleum-derived products, but published research is contradictory regarding the mutagenic activity of such emissions relative to those from petroleum diesel. We performed bioassay-directed fractionation and analyzed the polycyclic aromatic hydrocarbon (PAH) levels of particles generated using petroleum diesel (B0) and those from soy-based biodiesel where the soy accounted for 20, 50 or 100% of the fuel (B20, B50, B100) from a Yanmar L70 diesel engine. We also evaluated a composite sample of diesel-exhaust particles (C-DEP) generated from petroleum diesel with a 30-kW 4-cylinder Deutz BF4M1008 diesel engine connected to an air compressor. The biodiesel and C-DEP particles were extracted with dichloromethane (DCM), and the percentage of extractable organic material of these complex environmental mixtures were determined. The extracts were then solvent exchanged into dimethyl sulfoxide and evaluated for mutagenicity in various Salmonella strains +/-S9. We calculated the mutagenic emission factors (revertants/megajoule, rev/MJ) from data from strain TA100 +S9, which responds to PAH-type mutagenicity. These mutagenic emission factors for the biodiesels were 3X less (B20), 6X less (B50), and 8X less (B100) than that of petroleum diesel (B0). The whole extract of C-DEP (petroleum diesel) was sequentially fractionated with solvents of increasing polarity, and >50% of the mass eluted in fraction 1; this fraction was not mutagenic. The 2nd fraction had 60% of the TA100+S9 activity, indicative of PAHs; the 3rd fraction contained 60% of the TA98-S9 activity, indicative of nitroarenes. We conclude that under these experimental conditions, emissions from biodiesel were less mutagenic than those from petroleum diesel, and based on the fractionation of the C-DEP, most of the activity is associated with PAHs. [Abstract does not reflect the views or policies of the U.S. EPA.]