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 chemical analysis of organics extracted from  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.  The particles were extracted with dichloromethane (DCM), and the percentage of extractable organics (%EOM) determined. Extracts were 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.  The %EOM was 25, 20, 30, and 60% for B0-B100.  The mutagenic emission factors for the whole extracts in TA100+S9, which detects PAHs preferentially, were 0.3, 0.1, 0.05, and 0.04 rev/MJ for B0-B100.  These mutagenic emission factors for the biodiesel emissions were 3X less (B20), 6X less (B50), and 8X less (B100) than that of petroleum diesel (B0).  The whole extracts of the diesel and biodiesel organics were sequentially fractionated with solvents of increasing polarity.  More than 50% of the mass for all the whole extracts of B0-B100 eluted in fraction 1 (hexane), and this fraction was not mutagenic.  Most of the PAH-type mutagenicity (TA100+S9) eluted in fraction 2 (hexane/DCM), whereas most of the nitroarene activity (TA98-S9) eluted in fraction 3 (DCM). Fraction 4 (methanol) contained polar compounds.  Sub-fractionation of the 4 fractions by HPLC confirmed these activity/chemical class distributions.  We conclude that under these experimental conditions, emissions from biodiesel were less mutagenic than those from petroleum diesel, and most of the activity is associated with PAHs.  [Abstract does not necessarily reflect the views or policies of the U.S. EPA.]

Mutagenicity and bioassay-directed fractionation of diesel and biodiesel emissions

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.