Efficient collection of atmospheric aerosols with a particle concentratorelectrostatic precipitator sampler

A novel particle sampling methodology developed recently by our group (Han et al. 2008) has been extended in this article to collect atmospheric particles in electrostatic precipitators (ESPs) for chemical and biological-toxicological analysis. Particles are grown to super-micron droplets via condensation of ultrapure deionized water, and concentrated by virtual impaction in the versatile aerosol concentration enrichment system (VACES). The grown droplets are charged in a carbon fiber charger with negligible ozone generation, and diffusion-dried to their original particle size, while preserving their acquired charges. The charged particles are subsequently collected on suitable substrates in two different ESP prototypes, which can then be used for further chemical (e.g., Inductively Coupled Plasma Mass Spectrometry, Ion Chromatography, organic analysis by means of either gas chromatography-mass spectroscopy (GC-MS) or high performance liquid chromatography (HPLC)), as well as toxicological analyses using cellular or non-cellular assays. To minimize possible chemical reactions between sampled particles and ions generated in the corona region, the previously developed carbon fiber charger was modified, by separating the charging zone from the ionization zone. By combining this novel charger with the VACES, we achieved a higher number of elementary charges per particle (i.e., more than 50) and high particle removal efficiency (i.e., more than 90%) in the ESP, while preserving the chemical composition of the sampled atmospheric aerosols. Uniform particle deposition, which is an essential feature for cell exposures to particulate matter (PM), was accomplished on the ESP substrate designed for biological PM analysis.