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.
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).
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).
Values Assigned for Elements:
SRM 1640 Natural Water
SRM 2694a Simulated Water
SRM 1648a Air Particulate Matter
SRM 2783 Air Particulate Matter on Filter Media
SRMs 2583 and 2584 House Dust
SRM 1566b Oyster Tissue
SRM 2976 Mussel Tissue
SRMs 1946 and 1947 Fish Tissue
SRM 1577c Bovine Liver
SRMs 2586, 2587, 2701, 2709a, 2710a, and 2711a Soils
SRMs 1646a, 1944, 2702, and 2703; RM 8704 Sediments
SRMs 2781 and 2782 Sludges
SRM 1515 Apple Leaves
SRM 1547 Peach Leaves
SRM 1570a Spinach Leaves
SRM 1573a Tomato Leaves
SRM 1575a Pine Needles
Values Assigned for Organic Contaminants:
SRM 1649b Air Particulate Matter
SRM 2585 House Dust
SRM 1650b Diesel Particulate Matter
SRMs 1974b and 2977 Mussel Tissue
SRMs 1946 and 1947 Fish Tissue
SRM 1588b Cod Liver Oil
SRM 1945 Whale Blubber
SRMs 1941b and 1944 Marine Sediment
SRM 1939a River Sediment