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Measurements and Standards for Contaminants in Environmental Samples

Summary

For the past 40 years NIST has developed SRMs for the determination of inorganic and organic contaminants in environmental matrices such as sediments/soils, marine and animal tissues, air particulate, and botanical materials. These natural environmental-matrix SRMs for contaminants are used worldwide as the basis for validating accuracy and comparability within the environmental measurement community. For inorganic analysis, the natural matrix SRMs typically have concentration values assigned for toxic metals and other elements of interest. Typical organic contaminants with values assigned in these natural matrix SRMs include polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and persistent chlorinated pesticides.

Description

In 1971 NIST issued the first natural environmental matrix SRM for contaminants, SRM 1571 Orchard Leaves, with certified concentrations for trace elements. The development of SRM 1571 Orchard Leaves formalized the approach of combining results from "two or more independent and reliable analytical methods" to assign certified values as applied to natural environmental matrix SRMs for trace element content. During the 1970s, additional natural matrix SRMs for trace element content were developed using this approach including bovine liver, fly ash, spinach, pine needles, water, river and estuarine sediment, air particulate matter, and oyster tissue. A decade later the first environmental matrix SRM for organic contaminants was issued, SRM 1649 Urban Dust/Organics, with certified concentrations for a limited number of polycyclic aromatic hydrocarbons (PAHs). SRM 1649 and subsequent natural matrix materials issued during the next decade (coal tar, diesel particulate matter, marine sediment, and mussel tissue) established the multiple methods approach for organic contaminants in environmental matrices for PAHs, polychlorinated biphenyls, and chlorinated pesticides. During the past four decades, NIST has issued over 60 natural environmental matrix SRMs with certified values for inorganic and/or organic contaminants.

Many of these SRMs have been developed specifically to address the regulations and needs of the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA). For example the first air particulate SRMs were developed with support from EPA as well as the house dust materials for trace elements primarily for lead measurements. NOAA was the primary driver for the development of the first marine sediment and mussel tissue SRMs for organic contaminants to support marine monitoring programs initiated in the late 1980s.

For the SRMs intended for inorganic analysis, values are typically provided for 15 to 25 elements with emphasis on the heavy metal contaminants. Recent efforts have focused on the development of materials for speciated metals (e.g., hexavalent chromium in soil) and methylmercury in marine tissues) and providing values at lower concentration levels. The development of natural-matrix SRMs for the determination of organic environmental contaminants has focused primarily on persistent organic pollutants including PAHs, PCBs, and chlorinated pesticides. Recent activities have focused on expanding the number of PAHs and PCB congeners with values assigned and on assigning values for new classes of compounds. Recent environmental matrix SRMs typically have values assigned as appropriate for 30 to 50 PAHs, 40 to 50 PCB congeners, and 10 to 15 chlorinated pesticides. New classes of organic contaminants now included on some matrix SRMs include nitro-substituted PAHs, polycyclic aromatic sulfur heterocycles (PASH), toxaphene, and emerging contaminants such as brominated flame retardants, e.g., polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HCBD).

ASSOCIATED PUBLICATIONS

Zeisler, R., Murphy K.E., Becker D.A., Davis, W.C., Kelly, W.R., Long, S.E., and Seiber, J.R., Standard Reference Materials (SRMs) for Measurement of Inorganic Environmental Contaminants, Anal. Bioanal. Chem.386, 1137-1151 (2006).

Created February 5, 2009, Updated May 22, 2018