Citation:

SCHANTZ, M., S. WISE, S. R. MCDOW, AND J. JUNGERS. REFERENCE MATERIALS AND QUALITY ASSURANCE FOR THE CHARACTERIZATION OF ORGANIC COMPOUNDS IN PARTICULATE MATTER. Presented at American Association of Aerosol Research 2005, Atlanta, GA, February 07 - 11, 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:

One of the first environmental matrix Standard Reference Materials (SRMs) developed by the National Institute of Standards and Technology (NIST) for determination of organic species was SRM 1649 Urban Dust, ambient total suspended particulate matter (PM) collected in Washington DC in the late 1970's. Since SRM 1649 was issued in 1981, it has found widespread use in the PM measurement community, and NIST has assigned values for over 100 organic species in this material. However, there is a growing need for additional SRMs to support organic speciation in PM, particularly for the fine PM fraction and representative of contemporary combustion sources. NIST is collaborating with the U.S. Environmental Protection Agency (EPA) to develop SRMs and to provide interlaboratory comparison exercises to improve the accuracy and comparability of organic speciation measurements in PM.

As part of the NIST/EPA collaboration, the Organic Speciation Working Group was formed in 2000 to assist in this effort by participating in interlaboratory comparison studies and to provide input for the development of SRMs to support these measurements. This group has participated in three interlaboratory comparison studies for the determination of polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs, alkanes (including hopanes and cholestanes), sterols, carbonyl compounds (ketones and aldehydes), acids (alkanoic and resin), phenols, and sugars in PM-related samples. Because these interlaboratory comparison studies are performance-based, participating laboratories are encouraged to use the analytical methods that they routinely use in their laboratories to analyze PM samples. The results from the participating laboratories, following outlier testing, are used to assign a consensus concentration for each analyte in the unknown PM samples. Results are used in the consensus value assignment for the unknown PM sample only if the laboratory's results for analysis of SRM 1649a Urban Dust, which is provided as a control material, 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. The third NIST/EPA interlaboratory study was recently completed, and the results will be presented.

Based on the results of these studies, the list of target analytes has been refined and priorities for the development of SRMs have been identified. Calibration solution SRMs are currently under development for: polycyclic aromatic hydrocarbons (PAHs) (two redesigned solutions with an expanded list of 53 PAHs and alkyl-substituted PAHs), aliphatic hydrocarbons, nitro-substituted PAHs (redesigned with an expanded list of 27 compounds), hopanes/steranes, and 13C-labeled and deuterium-labeled levoglucosan (for use as internal standards). The status of the development of these organic solution SRMs and the priorities for future SRM development will be discussed.

This work has been funded in part by the U.S. Environmental Protection Agency. It has been subjected to Agency review and approved for publication.

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