The chemical homogeneity of 10 mg samples of the (U. S.) National Bureau of Standards standard reference material 1633a (coal flyash) was determined for several elements by instrumental neutron activation analysis. The homogeneity was tested for the purpose of using small samples of the flyash as a multielement comparator standard. For small sample masses the flyash may be unacceptably heterogeneous for Fe, Co, Ba, and perhaps As and Sb. Homogeneity is improved by grinding the flyash. For comparison, homogeneity data for USGS GSP-1 is also presented.
The (U. S.) National Bureau of Standards standard reference material 1633a (coal flyash) was standardized for the concentrations of 29 elements against chemical standards by instrumental neutron activation analysis. United States Geological Survey basalt standard BCR-1 was analyzed concurrently as a check. SRM 1633a is a good multielement comparator standard for geochemical analysis for 25 of the elements analyzed and is a better standard than rock-powder SRMs commonly used. Analytical data for USGS DTS-1, PCC-1, GSP-1, BIR-1, DNC-1, and W-2; NBS SRMs 278 and 688; and GIT-IWG (French) anorthosite AN-G are also presented.
Described is a series of INAA data reduction programs collectively known as TEABAGS (Trace Element Analysis By Automated Gamma-ray
Spectrometry). The programs are written in FORTRAN and run on a Nuclear Data ND-6620 computer system, but should be adaptable
to any medium-sized minicomputer. They are designed to monitor the status of all spectra obtained from samples and comparison
standards irradiated together and to do all pending calculations without operator intervention. Major emphasis is placed on
finding all peaks in the spectrum, properly identifying all nuclides present and all contributors to each peak, determining
accurate estimates of the background continua under peaks, and producing realistic uncertainties on peak areas and final abundances.
Authors:J. Jacobs, R. Korotev, D. Blanchard, and L. Haskin
Procedures for instrumental neutron activation analysis (INAA) have been developed and used on more than a thousand small
samples of terrestrial and lunar silicate rocks and minerals for determination of Co, Cr, Fe, Hf, Na, Ni, Sc, Ta, Th, and
the rare earths La, Ce, Sm, Eu, Tb, Yb, and Lu. Precision has been determined by repeated analysis of Knippa basalt and DTS-1
to be better than ±5 percent for all elements except Ni, Yb, Lu, and Hf. Mean values and estimates of accuracy are given for
Knippa basalt and USGS standards AGV-1, G-2, GSP-1, and W-1. Important features of the method are its precision and ease of