Comparison of Four Sampling Methods for Semi-volatile Organic Compounds in Gas Phase Diesel Engine Exhausts 2008-01-2435

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. The average percent breakthrough for all monitored SVOC's for X2, EM, HI, and CT methods are 8.5%, 7.0%, 19%, and 28%, respectively. The X2 and EM methods produced data with higher precision than HI and CT methods.