Fine particles in urban environments contain substantial quantities of material that canb e lost from the partiles during sample collection on a filter. This materials include ammonium nitrate and semovilatile organic compounds. Methods for the accurate determination of these species in integrated samples have been developed using diffusion denuder samplers. However, it is often desirable to determine fine particlulate mattr on a continous basis. The real-time ambient mass sampler (RAMS), a containous monitor using diffusion denuder and tapered element oscilating microbalance 9TEOM) technologies, has been evaluate by monitoring fine particulate species in Riverside, CA during August and Sepember, 1997, and in Bakersfield, CA during February and March, 1998. The results are compared to measurements made in 1 h integrated samples in Riverside and in 2 h integrated samples in Bakersfield with a diffusion denuder sampeler, the particle concentrator-Brigham young Univerity organic smapling system (PC-BOSS). An average of 5 of the Riverside fine particulate matter was present as semivolatile ammonium nitrate and 33 as semivolatile orgnaic matrial that was lost from a PC-BOSS filter during sampling. In Bakersfield the fraction of PM_(2.5) lost from a PC-BOSS filter averaged 3 as semivolatile ammonium nitrate and 15 as semivolatile organic material. These species were correctly determined by the RAMS. However, the usefulness of the RAMS as a continuous monitor is limite by the black variability witht he design presented here.
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