Temperature Dependence of Gas–Particle Partitioning of Primary Organic Aerosol Emissions from a Small Diesel Engine

A new experimental technique has been developed to study the gas–particle partitioning behavior of primary organic aerosol (POA) emissions from combustion sources at atmospherically relevant concentrations. The technique involves slowly filling a Teflon chamber with a constant emission source. As aerosol concentrations increase inside the chamber, the gas–particle partitioning of semivolatile organics shifts to the particle phase, thus increasing the fuel-based POA emission factor. The technique allows characterization of partitioning under isothermal conditions and atmospherically relevant concentrations. The technique was evaluated using emissions from a small diesel engine; the measured changes in gas–particle partitioning agreed well with previously published data for this engine measured with a dilution sampler. The temperature dependence of the gas–particle partitioning was investigated by conducting experiments at three different temperatures (15°C, 26°C, and 33°C). Increasing organic aerosol conce...