Evaluation of particle growth systems for sampling and analysis of atmospheric fine particles

Three types of water-based condensational growth systems,which can enable particles to grow in size to facilitate sampling and subsequent chemical analysis,were evaluated.The first one is a mixing type growth system where aerosols are mixed with saturated water vapor,the second one is a thermal diffusive growth system where warm flow enters cold-walled tube,and the third one is a laminar flow type where cold flow enters a warm wet-wall tube.Hygroscopic sodium chloride (NaCl),ammonium sulfate ((NH4)2SO4) and ammonium nitrate (NH4NO3),and non-hygroscopic polystyrene latex (PSL) particles,in the size range of 50-400 nm,were used to determine their growth factors through the growth systems.Our data showed that the third-type growth system could enable particles to grow most efficiently regardless of their hygroscopic property.Collection efficiency of particles in the size range of 0.05-2.5 μm,in a continuous aerosol sampler after they passed through the third-type growth system was about 100％,suggesting that the third-type growth system would be the most useful among the tested growth systems for sampling and subsequent chemical analysis of fine and ultrafine particles.