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DICARBOXYLIC ACID CONCENTRATION TRENDS AND SAMPLING ARTIFACTS
Citation:
RAY, J. AND S. R. MCDOW. DICARBOXYLIC ACID CONCENTRATION TRENDS AND SAMPLING ARTIFACTS. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 39(40):7906-7919, (2005).
Impact/Purpose:
1) Develop a TOA protocol that meets the basic assumptions of the method and peer review of the method, 2) understand the role of sampling, analysis, and blank subtraction on the differences between the IMPROVE and STN OC and EC results 3) Evaluate the use of light absorbance methods to estimate EC on human exposure samples, 4) develop a sensitive analytical method suitable for analysis of STN and micro-environmental samples for organic molecular markers, and 5) develop an optimum list of organic molecular markers for source apportionment of particulate matter.
Description:
Dicarboxylic acids associated with airborne particulate matter were measured during a summer period in Philadelphia that included multiple air pollution episodes. Samples were collected for two ten hour periods each day using a high volume sampler with two quartz fiber filters in series and analyzed by gas chromatography-mass spectrometry (GCMS) with diazomethane derivatization. Among the dicarboxylic acids investigated, phthalic acid and adipic acid exhibited the greatest diurnal variations and the strongest linear relationship with maximum daily ozone concentration. Dicarboxylic acids and ozone concentration exhibited a poor linear relationship with organic to elemental carbon ratio. All species investigated were affected by significant sampling artifact errors at low concentrations, but sampling errors were negligible at high concentrations observed during ozone episodes.