Collection and Characterization of Particulate and Gaseous-Phase Hydrocarbons in Diesel Exhaust Modified by Ceramic Particulate Traps

Protocols for sampling and analysis of particulate and gaseous-phase diesel emissions were developed to characterize the chemical and biological effects of using ceramic traps as particulate control devices. A stainless-steel sampler was designed, constructed, and tested with XAD-2 sorbent for the collection of volatile organic compounds (VOC). Raw exhaust levels of TPM and SOF and mutagenicity of the SOF and VOC were all reduced when the traps were used. Hydrocarbon mass balances indicated that some hydrocarbons were not collected by the sampling system and that the proportions of collected SOF and VOC were altered by the use of the traps. SOF hydrocarbons appeared to be derived mainly from engine lubricating oil; VOC hydrocarbons were apparently fuel-derived. There was no apparent effect on SOF mutagenicity due to either sampling time or reexposure of particulate to exhaust gases. The moderately-polar SOF and VOC subtractions were the most mutagenic, partly due to the presence of nitro-FAH. Twenty-eight PAH were identified, many of them common to both SOF and VOC subtractions.