For simplicity and unification of the comparator methods it is proposed to obtain a calibrating function of changing relative efficiency of registrating -radiation for any geometry of measurement (for any detector) from -spectrum comparator isotopes directly. In determining elements by their short- and medium-lived radionuclides the comparators52V and24Na were used. Biisotope comparator (65Zn,122Eu or182Ta) was used for long-lived radionuclides. The developed universal comparator method significantly simplifies the procedures for determining relative registration efficiencies of analytical lines of interesting radionuclides, thus reducing the labor and time requirements of analysis; this is very important in the case of a large scale NAA.
IAEA standard reference material SOIL-7 has been analyzed by both instrumental NAA and radiochemical NAA using epithermal
neutron activation. These analyses confirm the NAA value of Ag in the intercomparison SOIL-7 which disagrees with some AAS
values. Further geostandards were included and compared with literature data.
A derivative form of NAA is proposed which is based on the use of an endogenous internal standard of already known concentration in the sample. If a comparator with a known ratio of the determinand and endogenous standard are co-irradiated with the sample, the determinand concentration is derived in terms of the endogenous standard concentration and the activity ratios of the two induced nuclides in the sample and comparator. As well as eliminating the sample mass and greatly reducing errors caused by pulse pile-up and geometrical differences, it was shown that in the radiochemical mode, if the endogenous standard is chosen so that the induced activity is radioisotopic with that from the determinand, the radiochemical yield is also eliminated and the risk of non-achievement of isotopic exchange greatly reduced. The method is demonstrated with good results on reference materials for the determination of I, Mn and Ni. The advantages and disadvantages of this approach are discussed. It is suggested that it may be of application in quality control and in extending the range of certified elements in reference materials.
One of the missions of our Institute is the promotion of basic nuclear teaching for students as well as professional teaching
for workers in nuclear industry and research. For nuclear chemistry education, we present here a one day teaching course on
radioactive decay and nuclear reactions, and a two or three days course based on reactor irradiation of uranium oxide, instrumental
and radiochemical analysis of fission products. In the first experiment, the neutron capture is presented as an example of
nuclear reaction; the neutron activation of a silver coin with a Am-Be neutron source, followed by γ-ray spectrometry, is
used to identify three radionuclides of silver and to calculate their half-lives. In the second experiment, our teaching reactor
is used as a neutron source with a flux about 1010 n·cm−2·s−1 at a low thermal power (10 kW). This low flux allows us to irradiate a small uranium sample which is usable for spectrometry
after a short cooling time of about two hours. The first day is reserved for instrumental analysis of the fission products
and a second day for the radiochemical separation of a fission radionuclides. With these experimental results, the students
have to calculate the number of fissions in the irradiated sample. On optional third day for postgraduate students is devoted
to the presentation of NAA and some applications as uranium determination by the fission product spectrometry.
Authors:C. Zamboni, M. Suzuki, S. Metairon, M. Carvalho, and O. Sant’Anna
The Br (0.0022 ± 0.0006 gL−1), Ca (0.113 ± 0.012 gL−1), Cl (3.07 ± 0.36 gL−1), K (2.63 ± 0.14 gL−1), Mg (0.045 ± 0.002 gL−1) and Na (2.09 ± 0.10 gL−1) concentrations were determined in whole blood of SJL/J mice using the Neutron Activation Analysis (NAA) technique. Eleven
whole blood samples were analyzed in the IEA-R1 nuclear reactor at IPEN (São Paulo, Brazil). These data contribute for applications
in veterinary medicine related to biochemistry analyses using whole blood. Moreover, the correlation with human blood estimation
allows to checking the similarities for studying muscular dystrophy using this model animal.
Taking advantages of nuclear analytical techniques (NATs) with non-destruction, multielement capability, small and estimable
uncertainties over a wide range of sample sizes, the sampling behavior of multielements for a home-made natural matrix material
was studied with sample sizes ranging from several hundred mg down to tenths ng, namely nine orders of magnitude, by a combination
of three NATs, neutron activation analysis (NAA), proton induced X-ray emission (PIXE) and synchrotron radiation X-ray flurescence
(SR-XRF), in an effort to explore a procedure for the development of certified reference materials (CRMs) suitable for quality
control of microanalysis. For accurately weighable sample sizes (>1 mg), sampling uncertainties for 13 elements were found
to be less than 1% by INAA. For sample sizes unable to be accurately weighed (<1 mg), PIXE and SR-XRF were used, respectively.
Sampling uncertainties were found to be less than 1% at sample sizes of tenth mg level for seven elements, and less than 10%
on ng levels for three elements. Considering these three elements have satisfied homogeneity (sampling uncertainty less than
10%) at ng sample size level, any one of them can be served as a “relative balance” in sampling behavior characterization
of multielements on sample size levels larger than ng (e.g., μg level). On this basis, sampling uncertainties for nine elements
were found to be less than 10% on μg sample size level by INAA. The results indicate that the matrix is eligible as a candidate
of CRMs suitable for quality control of solid sampling microanalysis.
Authors:Cibele Zamboni, Laura Oliveira, Luciana Kovacs, and Sabrina Metairon
In this study the neutron activation analysis (NAA) technique was applied to determine Ca and Mg in whole blood from inhabitants
of Brazil for the purpose of establishing concentration ranges indicative of sex and age. The initiative to perform these
measurements is related to the increase in heart disease. According to recent statistics from WHO, the average is one death
due to heart attack in Brazil, every five minutes. The measures were performed considering lifestyle factors (non-smokers,
non-drinkers and no history of toxicological exposure) of Brazilian inhabitants. A healthy group constituted of male (n = 94) and female (n = 84) blood donors, ages between 18 and 70 years and above 50 kg, was selected from the blood banks and hematological laboratories
of Brazil. The influence of sex was also investigated considering several age ranges (18–29, 30–40, 41–50, >50 years). The
results show significant differences when a comparison is made by sex and age and may be useful to identify or prevent clinical
diseases. These results emphasize the need to perform periodic evaluation of Ca and Mg in blood.
NAA and ICP-MS are both highly sensitive methods for multi-element trace-and ultra-trace element determination. A comparison between analytical figures of merit of both methods is made. Both methods have specific advantages that put them beyond competition for certain applications. It is concluded that ICP-MS can replace NAA for many routine analyses. NAA remains essential as a highly reliable and accurate reference method.
45 elements have been determined by NAA in an IAEA Lake Sediment RM SL-3 Multitechniques were used to fully tap the potential of NAA in terms of the number of the determinable elements and the accuracy of each data.
Results of several IAEA intercomparison runs organized over the last 8 years are analyzed from the point of view of contribution
and performance of NAA as compared to other techniques. It is shown that NAA is the method of good accuracy and precision
providing on average greater share of results than any other single analytical technique. The prominent position of NAA among
other methods used in trace analyses seems to be firmly established and there are no signs that there might be any change
of the trend in the nearest future.