Semi-Volatile Species in PM_2.5: Comparison of Integrated and Continuous Samplers for PM_2.5Research or Monitoring

ABSTRACT

Fine particles in urban atmospheres contain substantial quantities of semi-volatile material [e.g., NH₄NO₃ and semi-volatile organic compounds (SVOCs)] that are lost from particles during collection on a filter. Several diffusion denuder samplers have been developed for the determination of both NO₃ ^- and organic semi-volatile fine particulate components. The combination of technology used in the BOSS diffusion denuder sampler and the Harvard particle concentrator has resulted in the Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) for the 24-hr (or less) integrated collection of PM_2.5, including NH₄NO₃ and semi-volatile organic material. Modification of the BOSS sampler allows for the weekly determination of these same species. Combination of BOSS denuder and tapered element oscillating microbalance (TEOM) monitor technology has resulted in the real-time ambient mass sampler (RAMS) for the continuous measurement of PM_2.5, including the semi-volatile components. Comparison of the results obtained with the BOSS and with each of the newly developed modifications of the BOSS indicates that the modified versions can be used for the continuous, daily, or weekly monitoring of PM_2.5, including semi-volatile species, as appropriate to the design of each sampler.