Certification of Three NIST Renewal Soil Standard Reference Materials® for Element Content: SRM 2709a San Joaquin Soil, SRM 2710a Montana Soil I, and SRM 2711a Montana Soil II
Elizabeth A. Mackey, Christopher S. Johnson, Richard M. Lindstrom, Stephen E. Long, Anthony F. Marlow, Karen E. Murphy, Rick L. Paul, Rachel S. Popelka-Filcoff, Savelas A. Rabb, John R. Sieber, Rabia Oflaz, Bryan E. Tomlin, Laura J. Wood, James H. Yen, Lee L. Yu, Rolf L. Zeisler, S. A. Wilson, M. G. Adams, Z. A. Brown, P. L. Lamothe, J. E. Taggart, C. Jones, J. Nebelsick
For the past 20 y, the National Institute of Standards and Technology has provided three soil Standard Reference Materials certified for element content: SRM 2709 San Joaquin Soil (Baseline Trace Element Concentrations); SRM 2710 Montana Soil I (Highly Elevated Trace Element Concentrations); and SRM 2711 Montana Soil II (Moderately Elevated Trace Element Concentrations). These materials have been used worldwide for quality assurance by a variety of laboratories involved in the determination of major, minor, and trace element content of soils and similar materials. Stocks of these original SRMs were depleted by 2008, and replacement SRMs were produced which became available in 2009. This paper describes, in detail, the process for the renewal of these three soil SRMs including soil collection and preparation methods, homogeneity assessment, experimental design, and the element analysis and data evaluation methods used to provide certified, reference, and information mass fraction values for 44 to 48 major, minor, and trace element constituents. For each SRM, the acid-extractable content of selected elements was determined by participants in the US Environmental Protection Agencys Contract Laboratory Program, and summaries of those method-specific results are included as addenda to the certificates of analysis.