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INTERLABORATORY COMPARISON STUDIES FOR CHARACTERIZATION OF ORGANIC COMPOUNDS IN PARTICULATE MATTER
Citation:
Schantz, M. M., S. A. Wise, AND J Lewtas. INTERLABORATORY COMPARISON STUDIES FOR CHARACTERIZATION OF ORGANIC COMPOUNDS IN PARTICULATE MATTER. Presented at 2003 AAAR PM Meeting, Pittsburgh, PA, March 3-April 4, 2003.
Impact/Purpose:
The objective of this task is to develop and evaluate personal exposure and biomarker methods for toxic components associated with PM2.5 and SVOC in population exposures. Specific sub-objectives include the following:
1) Identification and quantification of either toxic or tracer organic chemicals associated with PM2.5 and associated SVOC.
2) Measurement of personal airborne exposure of selected toxic/tracer organic species in population based human exposure studies.
3) Development and application of urinary metabolite and other biomarker methods for these toxic/tracer organic species in human exposure studies.
4) Evaluation of multivariant receptor models for apportioning personal exposure using biomarker data.
Description:
A working group of investigators, who are characterizing and quantifying the organic compounds in particulate matter (PM) as part of the US EPA's PM 2.5 research program and related studies, was established three years ago to advance the quality and comparability of data on the organic composition of PM. This group has just completed their second interlaboratory comparison study. The first study used a subset of SRM 1649a (Urban Dust, sieved to <123 micrometer) that had been sieved to <63 micrometer (Air Particulate I) as an unknown PM sample. In addition to Air Particulate I, the participants received a dichloromethane extract of Air Particulate I as a second unknown sample and a sample of SRM 1649a for use as a control material. For the second study, initiated in March 2002, the participants received a sample of PM2.5 collected recently in Baltimore, MD along with a sample of SRM 1649a. It is a requirement that all participants return data on Air Particulate I and SRM 1649a prior to receiving the Baltimore PM2.5 material, so at this point there are participants at different stages of the two studies. The target analytes, organic source tracers and toxic species, include polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs, alkanes (including hopanes and cholestanes), sterols, carbonyl compounds (ketones and aldehydes), acids (alkanoic and resin), phenols, and sugars. Because this is a performance-based study, laboratories are encouraged to use the methods that they are routinely using in their laboratories to analyze similar samples. Laboratories are requested to return data from three analyses (subsamples) of each sample provided along with a summary of the methods used. The data received from the participating laboratories, following outlier testing, are then used to assign a consensus value to each analyte in the unknown samples. Results are used in the consensus value assignment for the unknown PM sample only if the laboratory's results for SRM 1649a are within 30% of the uncertainty limits of the certified values. The consensus values, accuracy and precision assessments, and the methods used by each laboratory are summarized in a report provided to the participants. In this report, laboratories are numerically identified with only the laboratory and the study coordinators knowing this numerical identification. The results from the two interlaboratory studies will be presented along with plans for future interlaboratory trials, standard reference materials, and calibration standards.
This work has been funded by the U S Environmental Protection Agency. It has been subjected to Agency review and approved for publication.