Particulate Nitrate Measurement Using Nylon Filters

Abstract

Nylon filters are a popular medium to collect atmospheric fine particles in different aerosol monitoring networks, including those operated by the U.S. Environmental Protection Agency and the Interagency Monitoring of Protected Visual Environments (IMPROVE) program. Extraction of the filters by deionized water or by a basic aqueous solution (typically a mixture of sodium carbonate and sodium bicarbonate) is often performed to permit measurement of the inorganic ion content of the collected particles. Whereas previous studies have demonstrated the importance of using a basic solution to efficiently extract gaseous nitric acid collected using nylon filters, there has been a recent movement to the use of deionized water for extraction of particles collected on nylon filters to eliminate interference from sodium ion (Na ϩ ) during ion chromatographic analysis of inorganic aerosol cations. Results are reported here from a study designed to investigate the efficiency of deionized water extraction of aerosol nitrate (NO 3 Ϫ ) and sulfate from nylon filters. Data were obtained through the conduct of five field experiments at selected IMPROVE sites. Results indicate that the nylon filters provide superior retention of collected fine particle NO 3 Ϫ , relative to Teflon filters, and that deionized water extraction (with ultrasonication) of collected NO 3 Ϫ and sulfate is as efficient, for the situations studied, as extraction using a basic solution of 1.7 mM sodium bicarbonate and 1.8 mM sodium carbonate.

Atmospheric ammonia and particulate inorganic nitrogen over the United States

“…Several field experiments were designed and conducted to investigate the chemical composition of PM 2.5 aerosol and the concentrations of trace gases (HNO 3 , NH 3 and SO 2 ) at monitoring locations for the IMPROVE program from the late 1990's through 2010 ( Aerosol composition measured at these sites has previously been reported (Yu et al, 2005b(Yu et al, , 2006Lee et al, 2004Lee et al, , 2008a. In addition, a series of yearlong intensive measurements were made in Rocky Mountain National Park (November 2008-October 2009, daily), Boulder, WY (December 2006-December 2010, 3 and 4-day average), and Brush and Loveland, CO (December 2008-November 2009.…”

Uncertainties in PM2.5 Gravimetric and Speciation Measurements and What We Can Learn from Them

“…[41][42][43][44][45][46][47][48][49][50][51][52][53] Turpin and Lim 41 concluded that a factor of about 1.6 would be appropriate for an urban organic aerosol, whereas a factor of 2.1 may be more appropriate for an aged, nonurban aerosol.…”

Intercomparison of Real Time Ammonium Measurements at Urban and Rural Locations in New York

“…Collection of the aerosol usually occurs onto low cost and flexible filter packs; or using an impactor; but the time resolution and sometimes the sensitivity can be relatively poor (Huang et al 2004). In addition, the filters are not expected to retain all of the semi-volatile compounds such as ammonium nitrate (Yu et al 2005(Yu et al , 2006. The positive artifact of ammonium resulting from the adsorption and absorption of ammonia gas onto the filter or collected aerosol can not be neglected on the filter based-samples (Andersen and Hovmand 1994;Harrison and Kitto 1990;Pathak and Chan 2005).…”