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1.
B. M. Uralbekov B. Smodis M. Burkitbayev 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):805-810
New data are presented on 238U concentrations in surface and ground waters sampled at selected uranium mining sites in Kazakhstan and Kyrgyzstan and in
water supplies of settlements located in the vicinity of these sites. Radiochemical neutron activation analysis (RNAA) was
used for 238U determination in all cases. In addition, for data accuracy assessments purposes, a sub-set of these samples was analysed
by high-resolution alpha spectrometry, following standard radiochemical separation and purification. Our data show that drinking
waters sampled at various settlements located close to the uranium mining sites are characterised by relatively low uranium
concentrations (1.9–35.9 μg L−1) compared to surface waters sampled within the same sites. The latter show high concentrations of total uranium, reflecting
the influence from the radioactive waste generated as a result of uranium ore production. 相似文献
2.
J. H. Zaidi M. Arif I. Fatima S. Ahmed I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(1):123-127
Rapid radiochemical neutron activation analysis (RNAA) procedures were developed and employed for the determination of 32
trace impurities in high purity aluminum thin foils. Anion exchange column chromatography was developed for the sequential
group chemical separation of various elements which helped in reducing the spectral interferences and improving the sensitivity
of the method. The procedure is simple and requires a very short time to separate the elements in three groups for radiometric
assay. To determine very low contents of uranium and thorium,239Np and233Pa as activation products were separated using anion exchange and coprecipitation methods. The impurity contents were found
to be low, therefore, their adverse effects on microelectronic devices would be negligible. Our data could partially be compared
with the data reported in literature. 相似文献
3.
I. P. Alimarin A. Z. Miklishanskii Yu. V. Yakovlev 《Journal of Radioanalytical and Nuclear Chemistry》1970,4(1):45-51
A method with a sensitivity of 2·10−7 to 1·10−10% has been developed for determining Yb, Ho, Dy, Gd, Eu, Sm and La impurities in metallic uranium by means of neutron activation.
The method is based on a preliminary chromatographic separation of the total amount of rare earth elements from uranium by
passing the solution in sulphuric acid through KU-2 cation exchange resin and eluting the traces of uranium retained by the
resin with a solution of ascorbic acid. The rare earth impurities are then eluted from the resin with 4–5N HCl, evaporated, and irradiated for 20 hours with a neutron flux of 1.2·1013 n·cm−2·sec−1. Subsequently the traces of the rare earth elements are co-precipitated with Fe(OH)3, dissolved in concentrated HCl and separated from the iron and other impurities by passing the solution through Dowex 1X8
anion exchange resin in the chloride form. The individual rare earth elements are then separated from each other using KU-2
cation exchange resin and a solution of ammonium α-hydroxyisobutyrate as the eluant. 相似文献
4.
R. K. Singhal J. Preetha Rupali Karpe P. Hema Ajay Kumar V. M. Joshi A. K. Ranade A. G. Hegde 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):301-306
During this work the determination of uranium in the range of μg·L−1 to tens of μg·L−1 was done by alpha-spectrometry after electroplating the aliquots of water sample using (NH4)2SO4 as an electrolyte. In general, the determination of uranium by alpha-spectrometry needs its separation from other transuranics
specially thorium. The process described here does not involve any sample digestion and radiochemical separation of uranium
from other transuranics. In this method an aliquot (1 to 3 mL) of the sample was dried and dissolve in (NH4)2SO4 and thereafter the sample was electroplated on a stainless steel (SS) planchet by using an electrochemical cell of special
design. The proposed techniques have a distinct advantage over the determination of uranium by adsorptive stripping voltammetry
(AdSV) in which uranium-chloranilic (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) acid complex was used for concentrating
the uranium from the solution. Since in the case of AdSv, the determination of uranium was not possible for samples having
dissolved organic carbon (DOC) more than 15 mg·L−1 and Cl− concentration is in the range of 40,000 μ·g−1. In the case of spike experiments with 232U the recovery was observed in the range of 90–95% in aqueous medium having higher concentration of Cl− and DOC as indicated above. 相似文献
5.
V. I. Malyshev M. B. Shiryaeva Z. A. Sokolova L. M. Lyubimova Yu. P. Salmin M. A. Tatarkin K. N. Ryumina A. M. Shelyakina 《Journal of Radioanalytical and Nuclear Chemistry》1980,57(2):287-297
Data on the applicability of neutron activation analysis to determine various rare and trace elements and the isotopic abundance
of some of them in natural samples are discussed as relevant to the solution of various geological and geochemical problems.
For the determination of minute amounts of elements from small weighed quantities of rocks and minerals a number of modifications
of neutron activation analysis are used: analysis with the radiochemical separation of individual elements—RNAA (tantalum,
tungsten, antimony, arsenic, molybdenum, rhenium, osmium, etc.) and analysis with semiconductor—Ge (Li)—gamma-spectrometry,
which is multi-element and non-destructuve—INAA (scandium, europium, tantalum, iron caesium, rubidium, cobalt, antimony, etc.)
or the combination of the latter with group radiochemical separation—IRNAA (alkaline, alkaline-earth, rare-earth elements,
etc.). First steps have been made towards developing techniques for the determination of the isotopic rations of some elements
by means of neutron activation method, e.g., the isotopic ratio of58Fe/54Fe. The accuracy of isotopic ratio determination is 1 to 3 relative per cent. 相似文献
6.
R. K. Singhal H. Basu M. K. T. Bassan M. V. Pimple V. Manisha D. K. Avhad P. K. Sharma A. V. R. Reddy 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):675-681
Direct determination of uranium in the concentration range of 8 μg L−1 to mg L−1 in water samples originating from different geochemical environments has been done using Inductively Coupled Plasma-Optical
Emission Spectroscopy (ICP-OES). Uranium detection with 2–3% RSD (relative standard deviation) has been achieved in water
samples by optimizing the plasma power, argon and sheath gas flow. These parameters were optimized for three different emission
lines of uranium at 385.958, 409.014 and 424.167 nm. Interference arising due to the variation in concentration of bicarbonate,
sodium chloride, calcium chloride, Fe and dissolved organic carbon (DOC) on the determination of uranium in water samples
was also cheeked as these are the elements which vary as per the prevailing geochemical environment in groundwater samples.
The concentration of NaHCO3, CaCl2 and NaCl in water was varied in the range 0.5–2.0%; whereas Fe ranged between 1 and 10 μg mL−1 and DOC between 0.1–1%. No marked interference in quantitative determination of uranium was observed due to elevated level
of NaHCO3, CaCl2 and NaCl and Fe and DOC in groundwater samples. Concentration of uranium was also determined by other techniques like adsorptive
striping voltametry (AdSv); laser fluorimetry and alpha spectrometry. Results indicate distinct advantage for uranium determination
by ICP-OES compare to other techniques. 相似文献
7.
Being aware of the importance to consider every step in the evaluation of the combined measurement uncertainty of the result,
the purpose of this work was to evaluate the contribution of the radial thermal neutron flux gradient to the uncertainty budget
for trace level uranium determination in biological materials by a radiochemical neutron activation analysis (RNAA). Determination
of uranium via the short-lived nuclide 239U was based on solvent extraction with TBP and measurement of the chemical yield from the gamma-ray spectrum of the isolated
fraction via 235U. It has been shown previously, that radial neutron flux gradient, could have a relevant effect on the final result obtained
by RNAA. In the present work, radial neutron flux gradient within the irradiation assembly generally accepted in our lab (standards
tapped beside the sample), varied between 93 and 108% around the mean value and contributes approximately 20% to the combined
measurement uncertainty of the result. 相似文献
8.
J. H. Augustson J. W. Haynes T. W. Sanders 《Journal of Radioanalytical and Nuclear Chemistry》1980,60(2):373-383
A method for the determination of uranium based on235U thermal neutron fission, has been developed and employed on samples of ashed fish tissue and seaweed. The method involves
a post-irradiation ion exchange separation of iodine isotopes. The 884 keV photopeak of134I is used for measurement. Uranium detection limits in the samples concerned have been estimated to be 1·10−8g in terms of natural uranium. The precision achieved in analysing several series of 3–5 samples was 4–10 per cent. The accuracy
of the method was tested by employing an independent neutron activation procedure based on239U measurement. The accuracy of both methods was checked by analysing NBS SRM 1571 ‘Orchard Leaves’. 相似文献
9.
C. Vandecasteele R. Kieffer J. Hoste 《Journal of Radioanalytical and Nuclear Chemistry》1977,37(1):255-265
Fast neutrons produced by irradiation of a thick beryllium target with 20–50 MeV deuterons are used for activation analysis.
The spatial neutron flux distribution around the target is measured. A rotating sample holder is used for the simultaneous
irradiation of samples and standards. Instrumental analysis can be applied for a number of elements. As an example, results
for calcium and strontium in some reference materials are given. The19F(n, 2n)18F reaction is used for the radiochemical determination of fluorine in rocks with a fluorine concentration ranging from 9 to
5400 μg·g−1
Aspirant of the N.F.W.O. 相似文献
10.
Eduardo H. Montoya Pablo A. Mendoza Patricia S. Bedregal Oscar R. Baltuano Isaac M. Cohen 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):175-178
A method that combines the use of non-destructive neutron activation analysis and high-resolution α spectrometry has been
developed for determination of the activities of 234U and 238U in geological samples of low uranium content. The 238U content is determined by k0-based neutron activation analysis, whereas the 234U/238U relationship is measured by α spectrometry after isolation and electrodeposition of the uranium extracted from a lixiviation
with 6 M HCl. The main advantage of the method is the simplicity of the chemical operations, including the fact that the steps
destined to assure similar chemical state for the tracer and the uranium species present in the sample are not necessary.
The method was applied to soil samples from sites of the North Peru Coast. Uranium concentration range 3–40 mg/kg and the
isotopic composition correspond to natural uranium, with about 10% uncertainty. 相似文献
11.
A. M. Golubenkov A. F. Malenchenko 《Journal of Radioanalytical and Nuclear Chemistry》1977,36(2):547-556
For the solution of most of the problems which are connected to the biological and physiological role of natural uranium in
plants and animal organisms about 10−14 g uranium should be determined. However most of the physico-chemical methods for the determination of natural uranium in
biomaterials are time-consuming and possess considerable error. On the basis of addition and inner standard methods a version
of Solid State Nuclear Track Detectors (SSNTD) method has been developed in order to determine the natural uranium in biospecimens.
According to the experimental data simple relations have been obtained for the calculation of uranium concentration in biomaterial
and minium uranium concentration in biosolution which can be measured by the detector used. Under irradiation of SSNTD at
a thermal neutron flux of (3–5)·1015n·cm−2 the detector sensitivity is 2.30·10−9 g U/ml for glass detectors; 9.60·10−10g U/ml for the detectors made from artificial mica. 相似文献
12.
Summary A new radiochemical neutron activation analysis (RNAA) method has been developed for low-level determination of Si in biological materials, which is based on the 30Si(n,γ)31Si nuclear reaction with thermal neutrons. The radiochemical separation consists of an alkaline-oxidative decomposition followed by distillation of SiF4. Nuclear interferences, namely that of the 31P(n,p)31Si with fast neutrons, have been examined and found negligible only when irradiation is carried out in an extremely well-thermalized neutron spectrum, such as available at the NIST reactor. The RNAA procedure yields excellent radiochemical purity of the separated fractions, which allows the measurement of the β--activity of the 31Si by liquid scintillation counting. Results for several reference materials, namely Bowen’s Kale, Bovine Liver (NIST SRM 1577b), Non-Fat Milk Powder (NIST SRM 1549) and several intercomparison samples, Pork Liver-1, Pork Liver-2 and Cellulose Avicel, are presented and compared with literature values. 相似文献
13.
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. 相似文献
14.
Rajmund S. Dybczyński Bo?ena Danko Halina Polkowska-Motrenko Zbigniew Samczyński 《Talanta》2007,71(2):529-536
The idea of highly accurate (definitive) methods by radiochemical neutron activation analysis (RNAA) is presented and illustrated with several examples of methods worked out in this Laboratory over the past several years. Definitive methods by RNAA are constructed by combining reactor neutron activation with very selective and quantitative post-irradiation separation of the indicator radionuclide by column chromatography followed by γ-ray spectrometric measurement. All conditions for the determination of the individual element are optimized and uncertainties associated with every step of the analytical procedure are minimized. Even after the method has been thoroughly elaborated and validated through the analysis of appropriate certified reference materials (CRMs), the results obtained in each series of measurements are acknowledged as obtained by definitive method only when a series of previously formulated criteria is simultaneously fulfilled. The examples of definitive methods for the determination of cadmium, cobalt and molybdenum, respectively, in biological materials are presented. Each of these methods has detection limit of the order of ng g−1 or better, and yields accurate and precise results. The expanded standard uncertainty is of the order of 2.6% for the case of single-element determination (Co) and 3.4-5.2% for the less favourable case (Mo) where there is necessity for simultaneous determination of uranium to correct for interference due to fission reaction. Definitive methods by RNAA may constitute an option or alternative with respect to ID-MS as methods of “guaranteed accuracy” being also a perspective solution in the case of monoisotopic elements, for which ID-MS cannot be used. 相似文献
15.
The uranium adsorption on activated carbon from dilute solutions was studied as a function of pH, uranium concentration and
ageing time. Optimum conditions for quantitative adsorption of uranium from water solutions were determined: uranium concentration
2.5.10−4 g/l or less; adsorption must be carried out in fresh prepared solutions with ageing time not more than one hour; pH 7.5–8.5;
time for achieving the adsorption equilibrium not less than 20 min. The instrumental neutron activation method was used for
the uranium analysis. 相似文献
16.
V. K. Bhargava V. K. Rao S. G. Marathe S. M. Sahakundu R. H. Iyer 《Journal of Radioanalytical and Nuclear Chemistry》1978,47(1-2):5-15
A radiochemical method is described for the separation of heavier rare earths from the fission of uranium. The method is particularly
suitable for the separation of low yield (10−5%–10−7%), highly asymmetric rare earth fission products viz.179,177Lu,175Yb,173Tm,172,171Er,167Ho and161,160Tb in the neutron induced fission of natural and depleted uranium targets. Additional separation steps have been incorporated
for decontamination from239Np (an activation product) and93-90Y (a high fission-yield product) which show similar chemical behaviour to rare earths. Separation of individual rare earths
is achieved by a cation exchange method performed at 80°C by elution with α-hydroxyisobutyric acid (α-HIBA). 相似文献
17.
M. Ebihara K. Tomura M. Masutani 《Journal of Radioanalytical and Nuclear Chemistry》1987,109(1):69-78
We determined uranium in silicate materials such as standard rocks and a meteorite by radiochemical neutron activation analysis. After activation with a cadmium cover, samples were subjected to radiochemical separation of uranium immediately. The gamma-ray intensity of239U was measured with a planar type pure germanium detector system. Our data are mostly consistent with the literature or reported values. Compared with a non-destructive method, the present method was found to improve the sensitivity by at least a factor of ten. Several errors which might be involved in our RNAA procedures were examined and their degrees were evaluated. 相似文献
18.
V. Martínez-Miranda S. Martínez-Gallegos M. V. Esteller S. Bulbulian 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(2):323-325
A method based on neutron activation analysis was developed for the determination of fractions of milligrams of 2,4-D (2,4-dichlorophenoxy
acetic acid) in aqueous solution in laboratory tests. The indirect determination of 2,4-D was based on the quantification
of chlorine,38Cl, produced by neutron activation. The range of application was 0.01–100 mg l−1. No loss of38Cl by chemical effects of the nuclear reaction was found. The advantages of the proposed method include high precision and
sensitivity of determination. Results were compared with those obtained by UV-Vis spectrophotometry, where concentrations
less than 1 mg·l−1 were not detected. 相似文献
19.
J. B. Luten H. A. Das C. L. De Ligny 《Journal of Radioanalytical and Nuclear Chemistry》1977,35(1):147-155
A routine-method for the determination of bromine and iodine in environmental water by neutron activation is presented. The
elements are isolated by isotope exchange between the irradiated sample and a solution of Br2 or I2 CCl4. The method is not sensitive to the chemical species in which the halogen is present. The lower limit of the determination
is 1.0 μg Br·1−1 and 0.1 μgI·1−1. 相似文献
20.
Silver in selected, predominantly biological, reference materials (NIST SRM 1515, 1547, 1549, 1566a, 1571, 1577b, 2704, CTA-OTL-1,
and Bowen’s Kale) was determined using neutron activation analysis (NAA) in two different analytical modes: instrumental NAA
with epithermal neutrons (ENAA), and NAA with radiochemical separation (RNAA). The ENAA mode was based on long-time 5-hour
irradiation of samples in a special Cd lined box with counting after 8-month decay. The RNAA procedure consisted in 20-hour
irradiation of samples, their decomposition/dissolution by alkaline-oxidative fusion, and precipitation of AgCl including
several purification steps. Both methods provided Ag contents in the analyzed reference materials consistent with certified
and/or literature values down to the ng·g−1 level. 相似文献