Direct Determination of the Phase Distributions of Semi-VolatilePolycyclic Aromatic Hydrocarbons Using Annular Denuders

An annular denuder-based sampler, here called the integrated organic vapor/particle sampler (IOVPS), has been developed for direct determination of both gas and particulate semi-volatile organic species. The IOVPS uses a cyclone inlet for removal of particles greater than 2.5 micrometers from the airstream, followed by two or three sandblasted glass annular denuders coated with ground particles of an adsorbent resin. The denuders trap the gas phase species of interest before the airstream passes through a filter and a backup denuder. Extracts of the denuders and filters are analyzed for the semi-volatile species of interest. The IOVPS has been tested and validated for sampling semi-volatile polycyclic aromatic hydrocarbons (PAH) in indoor laboratory room air and environmental tobacco smoke (ETS). Ground XAD-4 was the adsorbent for these initial studies. Gas- and particulate-phase concentrations of semi-volatile PAH are presented for these two environments. The new sampler provides the means for directly determining phase distributions of PAH and other classes of semi-volatile organic species, rather than by difference or by techniques that are subject to large positive and negative artifacts. For example, the results obtained with the IOVPS indicate that the volatilization artifact ('blow-off') from particulate PAH collected in indoor laboratory room air with a conventional filter-sorbent bed sampler at face velocity of 33 cm sec-1 led to three-fold underestimation of the particulate fractions of phenanthrene, pyrene and chrysene. Phase distributions for PAH in ETS are also reported here