The Speciation of Organics for Apportionment of PM-2.5 in the New York City Area (SOAP) project was conducted from May 2002 to May 2003. It operated at four sites: Queens, NYC (high density urban residential); Elizabeth, NJ (adjacent to the NJ Turnpike); Westport, CT (downwind NYC); and a regional background site in Chester, NJ (upwind NYC). Its chief objectives were to expand the chemical characterization of organic compounds and to estimate the source contributions of carbonaceous fine particles at urban and background monitoring sites. Prior to network operation, a detailed QA/QC evaluation was performed on all aspects of sample collection and chemical analysis of organic molecular tracers with ambient fine particle mass concentrations of 0.02 to 10 ng m-3. Molecular level quality control of SOAP blanks and ambient samples was performed for 39 marker compounds by gas chromatography/mass spectrometry analysis (GCMS) and for common organic background contaminants.

A major goal of SOAP was to collect high quality fine PM samples that would provide air quality managers with detailed information on the atmospheric abundance and seasonal patterns of organic fine PM components. Such distributions broadly describe the contribution of primary organics (neutral, unoxidized compounds) and secondary organics (acidic, polar compounds) to the fine particle mass. Seasonal and spatial trends of neutral and acidic organic fractions are measured for the SOAP samples. Ambient concentrations were determined for important molecular tracers within the neutral and acidic fractions. Examples of neutral organic compounds are n-alkane homologs (C25-C32), hopane homologs (C27-C32), and PAHs (benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[e]pyrene, indeno[1,2,3-cd]pyrene, indeno[1,2,3-cd]fluoranthene, retene). Examples of acidic organic compounds are n-alkanoic acid homologs (C10-C30), dicarboxylic acids (C3-C9), and aromatic carboxylic acids (phathalic and isophathalic acids). These neutral and acidic tracers are necessary input for source receptor models. They also describe the chemical nature of the organic complex mixture of fine airborne particles (PM2.5) regulated by the National Ambient Air Quality Standards (NAAQS).

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