A method for characterization of low molecular weight organic acids in atmospheric aerosols using ICM
Lacey C. Brent
The structural composition of PM2.5 monitored in the atmosphere is usually divided by the analysis of organic carbon, black (elemental) carbon, and inorganic salts. The characterization of the chemical composition of aerosols represents a significant challenge to analysts and studies are frequently limited to determination of aerosol bulk properties. To better understand the potential health effects and combined interactions of components in aerosols, a variety of measurement techniques for individual analytes in PM2.5 need to be implemented. The method developed here for the measurement of organic acids achieves class separation of aliphatic monoacids, aliphatic diacids, aromatic acids, and polyacids. Additionally, baseline resolution of nitrite and nitrate from organic acids was obtained. Sulfate and phosphate were not chromatographically resolved from the organic species, but the selective ion monitoring capability of a triple quadropole mass analyzer was frequently capable of overcoming instances of incomplete separations. Standard Reference Material (SRM) 1649b Urban Dust was characterized; 34 organic acids were qualitatively identified and 6 inorganic salts plus 6 organic acids were quantified. In addition to SRM 1649b serving as a test material for method validation, the information provided here can benefit future analytical measurements.