Characterization of Mutagenic Subfractions of Diesel Exhaust Modified by Ceramic Particulate Traps

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Protocols were developed for collection and characterization of heavy-duty diesel exhaust hydrocarbons. Dichloromethane extracts of particulate and gaseous-phase samples were partitioned between hexane and methanol, and the highly mutagenic (Ames TA98) methanolic fractions were further separated with reverse-phase HPLC. Twenty-eight polycyclic aromatic hydrocarbons (PAH), including 4 nitro- and 13 oxy-PAH derivatives, were tentatively identified in the active (moderately polar) HPLC fractions with GC/MS. In terms of raw exhaust emissions (milligrams per cubic meter), the use of the ceramic traps caused reduced levels of particulate and associated organic compounds. Total mutagenic activity also decreased with the traps, but to a lesser extent than the decrease in particulate. Many of the identified PAH were common to both the particulate and gaseous-phase samples collected under the same conditions. Calculated hydrocarbon balances showed that more hydrocarbons passed through the samplers when the ceramic traps were used. © 1987, American Chemical Society. All rights reserved.

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Environmental Science and Technology