An extensive database of analytical results from a recent biological matrix Reference Material Characterization Campaign permitted an intercomparison of the performances of various methods among each other and with "true" best estimate concentration values established for these materials. Six different variants of neutron activation analysis (NAA) methods were employed including: instrumental neutron activation analysis, instrumental neutron activation analysis with acid digestion, neutron activation analysis with radiochemical separation, neutron capture prompt gamma activation analysis, epithermal instrumental neutron activation analysis, and neutron activation analysis with preconcentration. The precision and accuracy performance of NAA-based analytical methods are compared with three other major techniques, atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) and mass spectrometry (MS) for 28 elements in 10 natural matrix materials.
Authors:S. Jonah, U. Sadiq, I. Okunade, and I. Funtua
The k0-IAEA program developed for implementation of the single comparator instrumental neutron activation analysis method (k0-INAA) has been used for elemental analysis with NIRR-1 irradiation and counting facilities. The existing experimental protocols
for routine analysis based on the relative method were used to test the capability and reliability of the program for the
analyses of geological and biological samples. The Synthetic Multi-element Standards (SMELS) types I, II and III recommended
by the international k0 user community for the validation of k0-NAA method in NAA laboratories, furthermore, the following standard reference materials: NIST-1633b (Coal Fly Ash) and IAEA-336
(Lichen) were analyzed. Results obtained with the version 3.12 of the k0-IAEA program were found to be in good agreement with the data obtained with the established relative method using WINSPAN-2004
software. Detection limits for elemental analysis of geological and biological samples with NIRR-1 facilities are provided.
Authors:J. Moon, M. Ebihara, B. Ni, B. Arporn, P. Setyo, R. Theresia, B. Wee, N. Salim, and P. Pabroa
Since 2000, collaborative studies for applying NAA have been performed through the Forum for Nuclear Cooperation in Asia (FNCA)
sponsored by the Japanese Government. White rice is a main food for Asians and thus was selected as a common target sample
for a collaborative study in 2008. Seven Asian countries including China, Indonesia, Japan, Korea, Malaysia, Philippines and
Thailand, are greatly concerned about the composition of arsenic, heavy metals, and essential trace elements and took part
in this study. Rice samples were purchased and prepared by following a protocol that had been proposed for this study. Samples
were analyzed by their own NAA systems. In each country, more than 10 elements were examined and the results were compared.
These data will be very useful in the monitoring of the levels of food contamination and to evaluate the nutritional status
for people living in Asia.
A neutron-induced prompt -ray analysis (PGA) has become widely utilized due to the improved analytical sensitivities and detection limits especially by using low energy guided neutron beams. Current studies on the low energy neutron guided beam PGA are reviewed. Historical backgrounds, current analysis systems, advantages when compared with conventional NAA, standardization for elemental determination and analytical applications in JAERI of the guided beam PGA are described.
Authors:H. Arriola S., F. Monroy G, and M. Cruz M.
A study was carried out using NAA to measure the concentration of Al and Fe leached from kitchen ware into some popular Mexican
sauces and juices. These elements were measured in red and green hot sauces cooked in Fe, Al and clay pans compared to a stainless
steel pan. Similarly Al was measured in organe and grapefruit juices obtained using an Al extractor compared to a plastic
Principles of the expression of uncertainty in measurements are briefly reviewed and special aspects of the uncertainty quantification in NAA are discussed in detail regarding the relative and k0-standardization in both modes of the technique, i.e., INAA and RNAA. A survey of uncertainty sources is presented and calculation of the combined uncertainty is demonstrated by an example of manganese determination in biological material by RNAA.
The position of pre-irradiation separations in neutron activation analysis is shortly discussed. Special attention is given
to separations for purification and/or concentration of analyte elements, either complexed or uncomplexed, via sorption on
activated carbon. It was shown for a number of trace elements that the blank value introduced due to the use of activated
carbon is small or mostly even negligible. The NAA determination via pre-separations based on activated carbon is highlighted
for selenium, cobalt and iodine.
Authors:Kil-Yong Lee, Sang-Kwan Shim, Yoon-Yeol Yoon, Yong-Sam Chung, and Gae-Ho Lee
Neutron activation analysis (NAA) has been studied to improve the accuracy and sensitivity of the analysis of trace and ultratrace
metallic impurities in plastic materials. There are two main problems in the analysis of plastics by NAA. First the contamination
during sample preparation, especially sample crushing procedure is very serious for ultratrace analysis. Another problem is
the destruction of the sample capsule due to the pressure build-up by the gases formed during neutron irradiation. A simple
preparation technique of the sample crushing method using liquid nitrogen and reducing the capsule pressure by a pin hole
was developed to solve the above problems. Two different irradiation and seven cooling conditions were also investigated to
optimize the experimental conditions. A SRM from NIST (1632b coal) has been used to investigate the accuracy of the analysis.
More than thirty elements could be analyzed in the range of sub-ppb to percent. Samples analyzed in this work were polyethylene
and polypropylene which were made by different manufacturing procedure, and pigments. Two kinds of plastic products used for
food and drug containers were also analyzed. It was found that NAA could be a powerful technique for the analysis of metallic
impurities in plastics even though their concentrations were at ultratrace levels.
An analytical expression has been developed to calculate the neutron self-shielding in a cylindrical sample using the elemental
thermal neutron absorption cross sections, σabs, and the newly-defined epithermal neutron absorption cross-sections, σabs,ep. The σabs,ep were measured experimentally for 13 nuclides and calculated from resonance parameters for 76 nuclides. Agreement between
the two was good to about 20% in most cases. A spreadsheet program was written to use these nuclear parameters to perform
iterative self-shielding corrections of concentrations measured by NAA. In cases with up to 30% self-shielding, the correction
factors had uncertainties varying from 2% to 3%.
Authors:T. Bučar, B. Smodiš, P. Pelicon, J. Simčič, and R. Jaćimović
Cellulose cylinders and circular filter papers spiked with known amounts of standard element solutions were prepared for studying
some aspects of assessing measurement uncertainty of NAA and the elemental distribution measured by micro-PIXE analysis. Results
for the cylinders showed strongly non-homogeneous distribution of the elements, both in radial and vertical directions, dominantly
caused by osmosis driven transport of added liquid solution from the centre to the edges. Results for the thin cellulose filter
paper disks exhibited weaker peaking of the standard element concentrations at the edges in comparison with the thick cylinders.