Semi-volatile species in PM2.5: Comparison of integrated and continuous samplers for PM2.5 research or monitoring

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 diffu sion 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 part icle concentrator has resulted in the Particle Concentrator-Brigham Young U niversity Organic Sampling System (PC-BOSS) for the 24-hr (or less) integra ted collection of PM2.5, including NH4NO3 and semi-volatile organic materia l. Modification of the BOSS sampler allows for the weekly determination of these same species. Combination of BOSS denuder and tapered element oscilla ting microbalance (TEOM) monitor technology has resulted in the real-time a mbient mass sampler (RAMS) for the continuous measurement of PM2.5, includi ng the semi-volatile components. Comparison of the results obtained with th e BOSS and with each of the newly developed modifications of the BOSS indic ates that the modified versions can be used for the continuous, daily, or w eekly monitoring of PM2.5, including semi-volatile species, as appropriate to the design of each sampler.