Evaluation of the Performance of Annular Denuder Samplers

Abstract

Two annular denuder samplers were evaluated for the determination of atmospheric nitric acid, SO 2 , and fine particulate sulfate and nitrate. One, the University Research Glassware (URG) sampler, used an elutriator-impactor to remove coarse particles prior to sampling the aerosol through the denuder sections for the removal of acid gases. The second, the Rupprecht and Patashnick (R&P) ChemSpec, removes the acid gases in diffusion denuder sections and then removes coarse particles prior to the collection of fine particles. Possible sampling artifacts examined included the removal of HNO 3 (g) by the inlet of the URG sampler before the collection of this gas-phase species by the diffusion denuder, resulting in the underestimation of HNO 3 (g) and the deposition of some coarse particles in the R&P denuders prior to the removal of these larger particles, and the collection of fine particles on a filter, resulting in the overestimation of HNO 3 (g) and SO 2 (g). Samples were collected in Riverside, CA, Bakers...