Speciated Organic Composition of Atmospheric Aerosols: A New In-Situ Instrument

70753B02-II Energy production and the combustion of fossil fuels are sources of organic aerosols that have been linked to environmental degradation, human health problems, and changes in the radiative transfer properties of earth¿s atmosphere. New techniques are needed for the time-resolved in-situ characterization of the organic composition of atmospheric aerosols in order to understand their sources, sinks, and transformations. This project will develop a new, automated in-situ instrument for the routine identification and quantification of organic compounds in atmospheric aerosols. An integrated collection and analysis approach will utilize the impaction and direct thermal desorption of particulate samples, along with gas chromatographic separation and mass spectrometry detection. Phase I demonstrated the efficient transfer of samples to a collection and thermal desorption cell, as well as the efficient collection of particles within the cell. Reproducibility (CV=12%) was demonstrated for collocated sampling and analysis. Phase II will incorporate the collection and thermal desorption cell into a fully automated aerosol GC/MS instrument; design, construct, and validate an on-line aerosol calibration system to provide both internal and external standards; evaluate system integrity with laboratory standards; compare the analyses to filter-based measurements, and validate the instrument through field deployment with a suite of collocated measurements. Commercial Applications and Other Benefits as described by awardee: A commercially viable instrument for routine, hourly monitoring of the organic composition of atmospheric aerosols should substantially lower the cost per sample and increase the time resolution compared to current methods of filter collection, solvent extraction, and analysis.