Certification of a new NIST fly ash standard reference material

In June 1993 the National Institute of Standards and Technology (NIST) released the third version of Constituent Elements in Coal Fly Ash Standard Reference Material (SRM 1633b). This material is intended for quality assurance purposes in evaluating the analytical methods used for the determination of constituent elements in coal fly ash or in materials with similar matrices. It has been certified for 23 major, minor and trace elements using ten different analytical techniques. For an element to be certified in a NIST SRM, its concentration is usually determined by at least two independent analytical techniques. The concentrations of additional 24 elements are provided for information only purposes in the new fly ash. Current plans are to certify the concentrations of a number of rare earths upon completion of additional analytical work now in progress. Homogeneity testing was accomplished using instrumental neutron activation analysis and X-ray fluorescence. This presentation summarizes the preparation of this new material and the analytical results used for certification.     

The determination of trace elements in new food grain SRM's using neutron activation analysis

Potentially toxic metals in the food chain that can lead to deleterious effects on human health have been well documented. Because of the toxicity of some metals, levels of 1 ppm or less must be routinely monitored in foods to ensure human safety. To ensure the accuracy of measurement, NBS in a cooperative interagency agreement with the Food and Drug Administration is involved in developing and certifying selected elements in food grain as a part of the Standard Reference Material program. Both instrumental and radiochemical neutron activation analysis were used to analyze two food grain standard reference materials (Rice and Wheat Flours) for trace element certification.     

Role of neutron activation analysis in the evaluation of sampling,storage, and analysis of samples for the national environmental banking system

Some problems inherent to the sampling, storage and analysis of whole organs or tissue biopsies were studied. The method used to evaluate the proper conditions of these, was neutron activation analysis. This work was supported in part through Interagency Agreement Number EPA-1AG-D5-0568 with the Environmental Protection Agency.     

Recent developments in NIST botanical SRMs

The National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards (NBS)) issued the first botanical reference material certified for elemental content in January 1971, as Standard Reference Material (SRM) 1571, Orchard Leaves. In the following years a total of nine additional botanical certified reference materials have been issued by NIST. Each of these materials was certified for major, minor and trace elements except for SRM 2695, certified for fluorine only. Botanical SRMs issued since 1991 are significantly improved over previous materials in a number of ways. Probably the most significant change is the use of a jet-milling process to grind them to extremely fine particles. This has resulted in botanical SRMs with significantly improved homogeneity. These NIST reference materials are described with information on homogeneity, drying techniques and grit content.