Black spruce /Picea mariana/ twigs and needles have been collected from a uraniferous area of northern Saskatchewan and characterized for their content of some radionuclides and trace elements in an interlaboratory program. These materials, rich in uranium, are available as reference materials, for estimating accuracy in the analysis of vegetation, from the Canadian Certified Reference Materials Project in Ottawa, Canada.
The nature of summary reports now being prepared for issuance, summarizing the results of detailed INAA Advance Prediction Computer Program (APCP) calculations for many widely used reference materials, is discussed and illustrated. For each material, the best photopeak %
rel value (where it is10%) is shown for each of the 12 condition sets (ti/td/tc) calculated from the input elemental composition. These summary reports will be very useful to groups that use various reference materials as multi-element standards.
Authors:C. Erasmus, H. Fesq, E. Kable, S. Rasmussen, and J. Sellschop
The NIMROC reference materials NIM-D, NIM-G, NIM-L, NIM-N, NIM-P, and NIM-S and the precious metal ore PTO-1 have been analysed
using thermal and epithermal methods of instrumental neutron activation. The abundances of 40 major, minor and trace elements
are reported. The usefulness of the NIMROC reference materials is assessed in terms of the requirements of neutron activation
techniques. Of the seven reference materials, NIM-L is the most useful geochemical material for activation analysis. It contains
suitably high concentrations of most elements that can be determined. Inhomogeneity problems encountered in PTO-1 for some
elements give emphasis to the difficulty of selecting suitable geological material for ultra-trace elements where small quantities
of sample are used.
Authors:M. Carmo Freitas, L. Moens, P. De Paepe, and J. Seabra E Barros
A 7 kg stone of a Carrara marble was reduced to grains smaller than 100 m, mixed and homogeneized in order to prepare a marble reference material. The homogeneity was tested for 16 elements by instrumental neutron activation analysis (INAA). Through a one-way analysis of variance based on several analyses of each of 15 bottles and within the same bottle, it was concluded that the inter-bottle heterogeneity is not greater than the intra-bottle heterogeneity. Results on the concentration of major and trace elements in the marble reference material, obtained by different laboratories and different techniques, are given. The limestone certified reference material KALKSTEIN KH was used to evaluate measurement accuracy, to intercalibrate laboratories, and to provide compatibility of measurement data.
Non-destructive neutron activation analysis was employed to determine zinc in ten biological standard reference materials from the National Bureau of Standards and the National Research Council of Canada. The use of a 4 h. irradiation at a medium neutron flux allows excellent accuracies, precision and sensitivities to be attained for all the samples analyzed. It is suggested that neutron activation analysis be one of the benchmark methods for the determination of zinc in biological reference materials for concentrations as low as the one part per million level.
Authors:E. Moreira, M. Vasconcellos, M. Catharino, V. Maihara, and M. Saiki
Instrumental neutron activation analysis was used at a 2-month long isochronous short term stability test performed on a Perna perna mussel candidate reference material. The assessment of the analysis of variance test, as well as, the normalized results
to the control temperature showed no systematic changes in the concentration of Ag, As, Br, Co, Cr, Cs, Fe, Eu, La, Na, Rb,
Se, Sc, Th and Zn during the test period. The result showed that the candidate reference material may be transported under
normal transport conditions without significant changes in composition for the determined elements.
Authors:Songsheng Jiang, Zhiyuan Chang, Min Zhao, Yonggang Zhao, X. L. Zhao, and W. E. Kieser
Under an IAEA project for upgrading of reference materials, a new determination of the 129I concentration in the IAEA-375 reference material was performed. A chemical procedure was set up for the preparation of the AgI samples. Measurement of 129I was carried out using the IsoTrace Tandetron AMS facility at University of Toronto. To ensure the accuracy of the calibration, the tuning of the AMS system was iterated using not only the QC (quality control) samples but also all unknown samples. To minimize any possible current-dependent effects between 129I and 127I ions in the injection magnet, low Cs+ sputtering beam intensity (10 μA) was used. The reproducibility in determining the 129I/127I ratio in the IAEA-375 AgI samples was less than 1%. The activity concentration (CA) of 129I in the IAEA-375 reference material was determined to be 1.59±0.08 mBq . kg-1 at 95% confidence level. The present value is about 7% lower than the IAEA recommended value (1.7 mBq . kg-1) listed in 2000 or 20% lower than the recommended value (2 mBq . kg-1) listed in the IAEA AQCS Reference Material Catalogue (2002-2003). Since the IAEA recommended values for IAEA-375 materials was issued about 10 years ago and error range of the recommended values were large, the results we obtained might be useful in upgrading the recommended value.
Three standard reference materials were analyzed by a method of absolute INAA. Two different light water pool-type reactors
were used to produce equivalent analytical results even though the epithermal to thermal flux ratio in one reactor was higher
than that in the other by a factor of two.
Authors:A. Bleise, B. Smodiš, D. Glavic-Cindro, and R. Parr
The International Atomic Energy Agency (IAEA) maintains a database of biological and environmental reference materials of natural origin (human and animal tissues, foods, plants, soils, sediments, etc.) for trace elements, radionuclides, stable isotopes, organic contaminants and other related measurands. The purpose is to help analysts to select reference materials for quality assurance purposes that match as closely as possible (i.e., with respect to matrix type and concentrations of the measurands of interest) the real samples that are to be analyzed. Former versions of this database were prepared in co-operation with the United Nations Environment Programme (UNEP), and provided as hardcopies free of charge. The latest version was from 1995. More recently the database has been updated by the IAEA so that it now contains more than 22,500 values (mass fraction or concentration) for 660 different measurands and 1,705 reference materials developed by 56 producers from 22 countries. This paper gives an overview of the structure and content of the database and of the two ways it may be browsed. Emphasis is given to reference materials that are intended to verifying analysis for radioanalytical measurements. The database is soon accessible on-line, cost-free, via the internet.