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 f or quality assurance purposes in evaluating the analytical methods use d for the determination of constituent elements in coal fly ash or in materials with similar matrices. It has been certified for 23 major, m inor and trace elements using ten different analytical techniques. For an element to be certified in a NIST SRM, its concentration is usuall y determined by at least two independent analytical techniques. The co ncentrations of additional 24 elements are provided for ''information only'' purposes in the new fly ash. Current plans are to certify the c oncentrations 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 an d the analytical results used for certification.