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TOPIC #7

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Molecular Marker Speciation of PM Collected with Personal Samplers

Philip M. Fine, Manisha Singh, Constantinos Sioutas
University of Southern California

Glynis C. Lough, Rebecca J. Sheesley, Mark Mieritz, James J. Schauer
University of Wisconsin - Madison

Michael P. Hannigan
University of Colorado, Boulder

Previously, organic speciation of PM has been conducted on samples collected with large, stationary sampling equipment. Recent evidence suggests that actual human exposure to PM may not be accurately represented by fixed site monitors. Several new commercially available personal PM samplers, designed to be worn by human subjects, have been developed and deployed in exposure assessment campaigns. Due to the generally low flow rates, samples from these devices have low mass loadings, and thus, organic speciation of molecular markers from such samples has not been attempted.
The current study deployed four of these devices to collect twenty-four hour particulate matter samples at the Southern California Supersite near downtown Los Angeles. A total of five twenty-four hour sampling periods were collocated with a conventional low-volume area sampler and a MOUDI impactor. The four personal samplers tested were: (1) a URG PM2.5 mini-cyclone with filter holders; (2) a BGI PM2.5 cyclone with filter holders; (3) an Aerosol Dynamics Incorporated (ADI) PM2.5 Personal Particle Speciation Sampler (PPSS); and (4) an SKC Sioutas Impactor (four size ranges below PM10). The samplers were placed outdoors at a fixed location, and thus were not worn by human subjects. However, the feasibility of organic speciation of samples collected with these devices could still be assessed and compared with traditional sampling methods.
Since flow rates of the personal samplers ranged from 2 to 9 lpm, the mass loadings were lower than typical samples used for organic speciation. In order to allow speciation of a wide range of molecular markers from these low mass samples, sample preparation and GC/MS methods were modified from previous organic speciation methods. Details of the method modifications, method detection limits, and an intercomparison of the speciation measurements from the different samplers will be presented.

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