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DEVELOPMENT OF A SAMPLING PROCEDURE FOR LARGE NITROGEN- AND SULFUR-BEARING AEROSOLS
Citation:
Randtke, S., D. Lane, AND T. Baxter. DEVELOPMENT OF A SAMPLING PROCEDURE FOR LARGE NITROGEN- AND SULFUR-BEARING AEROSOLS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-90/048.
Description:
A single-stage impactor was modified to utilize a removable TFE impaction surface mounted on the end of an annular denuder. hen used with a polycarbonate filter coated with silicone oil, its cut point was 2.5 um and bounce was <1% for 8-um particles. ignificant bounce occurred with uncoated or grease-coated surfaces. Bounce was about 2% using oil-saturated porous glass disks, but particle extraction was difficult. he best performance was achieved using a vertically mounted impactor with a bent-tube inlet to sample isoaxially. or 2.0-2.8 um particles, 4-8% of the mass sampled was found in the denuder and 10-17% on the spacer between the impactor and the denuder; internal losses for larger and smaller particles were negligible. everal oils and greases were compatible with ion chromatography. Polycarbonate filters, silicone oil, and Vaseline were free of anionic impurities and adsorbed little, if any, nitrate or sulfate when exposed to high concentrations of HN03 and SO2. NH4Cl and NH4N03 particles impacted on an uncoated filter did not volatilize. mpacted particles of varying composition were generally unreactive toward high concentrations of HN03 or 502. cidic NaHS03 particles impacted on a greased surface reacted to a limited extent (1.7-3.5%) with NH3. n a 24-hour field test employing four collocated sampling systems, the precision of the method for coarse-particle nitrate and sulfate was +/- 3.4% and +/- 3.3%, respectively.