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Newly designed Teflon® O-rings along with XAD-2 resin, stainless steel screens, lock rings, and glass cartridges were used to construct a new semi-volatile organic compounds (SVOC's) sampling device. This new sampling device allows direct and repeated sampling, extraction, and cleaning without ever having to be disassembled or reassembled. This new XAD-2 glass cartridge (X2) was compared with three other sampling methods namely Empore® membrane (EM), hexane impinger (HI), and “Cold Trap” (CT) for SVOC sampling efficiency on diesel engine exhaust emissions. The X2 method showed the highest overall SVOC collection efficiency, followed by the EM and HI methods. The X2 method has higher trapping efficiency for the oxygenates, polycyclic aromatic hydrocarbons (PAH's), alkyl cyclohexanes, and the alkyl aromatics than the other three SVOC sampling methods. The HI method has the highest trapping efficiency for the normal alkanes.

Regulated and unregulated exhaust emissions (individual hydrocarbons, aldehydes and ketones, polynuclear aromatic hydrocarbons (PAH), and nitro-polynuclear aromatic hydrocarbons (NPAH)) were characterized for the following alternate diesel combustion modes: premixed charge compression ignition (PCCI), and low-temperature combustion (LTC). PCCI and LTC were studied on a PSA light-duty high-speed diesel engine. Engine-out emissions of carbonyl compounds were significantly increased for all LTC modes and for PCCI-Lean conditions as compared to diesel operation; however, PCCI-Rich produced much lower carbonyl emissions than diesel operations. For PAH compounds, emissions were found to be substantially increased over baseline diesel operation for LTC-Lean, LTC-Rich, and PCCI-Lean conditions. PCCI-Rich operation, however, gave PAH emission rates comparable to baseline diesel operation.