Precision and Accuracy in the Determination of Sulfur Oxides, Fluoride, and Spherical Aluminosilicate Fly Ash Particles in Project MOHAVE

• Published in: Journal of the Air & Waste Management Association (1995) 1997-04, Vol.47 (4), p.455-467
• Main Authors: Eatough, Norman L., Eatough, Michele, Joseph, Jyothi M., Caka, Fern M., Lewis, Laura, Eatough, Delbert J.
• Format: Article
• Language: English
• Subjects: Analysis methods; Applied sciences; Atmospheric pollution; Exact sciences and technology; Pollution
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10473289.1997.10464414

The precision and accuracy of the determination of particulate sulfate and fluoride, and gas phase S0 2 and HF are estimated from the results obtained from collocated replicate samples and from collocated comparison samples for highland low-volume filter pack and annular diffusion denuder samplers. The results of replicate analysis of collocated samples and replicate analyses of a given sample for the determination of spherical aluminosilicate fly ash particles have also been compared. Each of these species is being used in the chemical mass balance source apportionment of sulfur oxides in the Grand Canyon region as part of Project MOHAVE, and the precision and accuracy analyses given in this paper provide input to that analysis. The precision of the various measurements reported here is ±1.8 nmol/m 3 and ±2.5 nmol/m 3 for the determination of S0 2 and sulfate, respectively, with an annular denuder. The precision is ±0.5 nmol/m 3 and ±2.0 nmol/m 3 for the determination of the same species with a high-volume or low-volume filter pack. The precision for the determination of the sum of HF(g) and fine particulate fluoride is +0.3 nmol/m 3 . The precision for the determination of aluminosilicate fly ash particles is ±100 particles/m 3 . At high concentrations of the various species, reproducibility of the various measurements is ±10% to ±14% of the measured concentration. The concentrations of sulfate determined using filter pack samplers are frequently higher than those determined using diffusion denuder sampling systems. The magnitude of the difference (e.g., 2-10 nmol sulfate/m 3 ) is small, but important relative to the precision of the data and the concentrations of particulate sulfate present (typically 5-20 nmol sulfate/m 3 ). The concentrations of S0 2 (g) determined using a high-volume cascade impactor filter pack sampler are correspondingly lower than those obtained with diffusion denuder samplers. The concentrations of SO x (SO z (g) plus particulate sulfate) determined using the two samplers during Project MOHAVE at the Spirit Mountain, NV, and Hopi Point, AZ, sampling sites were in agreement. However, for samples collected at Painted Desert, AZ, and Meadview, AZ, the concentrations of SO x and S0 2 (g) determined with a high-volume cascade impactor filter pack sampler were frequently lower than those determined using a diffusion denuder sampling system. These two sites had very low ambient relative humidity, an average of 25%. Possible causes of ob