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., NH 4 NO 3 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 NO 3 -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 NH 4 NO 3 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 IMPLICATIONS Fine particles in urban environments contain significant amounts of semi-volatile organic material and NH 4 NO 3 that can be lost from collected particles during sampling. Diffusion denuder techniques have been commonly used for the determination of semi-volatile NH 4 NO 3 . However, these techniques generally have not been applied to the determination of semi-volatile particulate organic material. Brigham Young University has developed both continuous (RAMS) and integrated (PC-BOSS) sampling systems for the determination of total PM 2.5 , including both semivolatile NO 3 -and organic material. Measurements reported in this paper show that the two very different approaches both indicate that urban fine PM contains significant amounts of semi-volatile organic material that is not sampled by conventional methods. This PM material can be determined using the two newly developed samplers. These should prove to be useful tools for PM research.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.

Particulate Nitrate Measurement Using Nylon Filters

“…[11][12][13][14][15][16][17][18][19][20][21] Positive NO 3 Ϫ measurement artifacts, for example, can be caused by collection of gaseous HNO 3 and/or other nitrogen oxides with subsequent reaction on filter media. The use of diffusion denuders upstream of particle sampling filters can effectively remove HNO 3 (and perhaps other species depending on denuder coating), thereby minimizing this artifact.…”

New York State Urban and Rural Measurements of Continuous PM2.5 Mass by FDMS, TEOM, and BAM

“…There are both positive and negative artifacts associated with this method, and a number of papers have addressed these issues and the issues of comparability of this method with the FRM. 2,7,8,22,23 The TEOM monitor has been designated an "automated equivalent method" for the measurement of PM 10 by EPA. 24 …”

The Regional Nature of PM2.5 Episodes in the Upper Ohio River Valley

“…[13][14][15][16] The samples for the determination of PM 2.5 chemical composition were all collected from 12:00 p.m. Eastern standard time on each sampling day to 12:00 p.m. the next day from November 1999 through September 2000. 5,15 PM 2.5 elemental content (proton-induced X-ray emission [PIXE] analysis) was determined from samples collected on a polycarbonate filter (47-mm, 0.4-m pore, Gelman) taken from a side-flow stream sampled before the PC-BOSS particle concentrator and denuder.…”