Neutron activation analysis of radiopharmaceuticals

In order to understand the chemical form of soluble technetium in paddy soil and its availability to a rice plant, soil incubation and uptake experiments have been carried out using^95mTc as a tracer. The chemical form of the soluble Tc was observed by gel chromatography and found not to be pertechnetate, but rather to be associated with soluble organic matter. An uptake experiment with rice seedlings using nutrient solution showed that this Tc-organic matter complex was less available than pertechnetate.     

Neutron activation analysis of soils

Résumé On décrit l'analyse de sols par activation neutronique au moyen de détecteur Ge(Li) à haute résolution pour la recherche de 31 éléments. Les éléments déterminés comprennent des métaux alcalins, des terres rares et des éléments de transition, la plupart d'entre eux sont utilisés, comme indices de différenciation géochimique et d'autres sont utilisés en tant que facteur de nutrition dans la physiologie des plantes. Quelques éléments comprenant Na, K, Rb, Cs, Ba, La, Ce, Sm, Eu, Th, Zr, Hf, Ta, Mn, Co, Fe, Sc, Cr, Sb, Ca, V, Al, Ti, Br et U ont été déterminés par spectrométrie gamma non-destructive, et d'autres Mo, W, Sr, Cu, Zn et Ga après une simple séparation radio chimique basée sur un échange d'ions et une extraction par solvant. On a employé l'activation dans les neutrons épithermique pour la recherche de l'U, utilisant des neutrons de réacteur. Les risques d'interférence dans les réactions et dans les spectres gamma, l'autoabsorption et les autres causes possibles d'erreur sont analysées et évaluées quand c'est possible. Les résultats sont donnés en temps que moyenne de plusieurs dosages. Dans tous les cas, on est parvenu à une grande précision.      

Neutron activation analysis of scandium

A neutron activation method is proposed for the determination of trace quantities of scandium, down to submicrogram level, in rocks, ores and meteorites. The sample and standard are irradiated intermittently for a total of 30 h, at a neutron flux of 5·10¹¹ n/cm²/sec; the radiochemical separation consists essentially of a one-step anion exchange. The induced γ-activity of ⁴⁰Sc, 85 days, isolated from the sample is measured and compared with that of a standard. The chemical yield averages 85% and there is a considerable saving of time in the radiochemical work. Results are quoted for the scandium contents of 2 standard rocks, cassiterite and several stony meteorites. Details of conflicting nuclear reactions are also given.     

Neutron activation analysis of semiconductor silicon

The determination of impurities in semiconductor silicon by nondestructive and destructive NAA is described. To improve the detection limit, a multiple beta—single gamma detector assembly is used. It is shown that²⁴Na is also produced from silicon by a (n, αp) reaction with reactor neutrons. The cross-section with fission neutrons is 1.8·10⁻⁹ barn.     

Neutron activation analysis of lithium niobate

A radiochemical neutron activation analysis procedure for the determination of Ta, W, Ir, Pt, Au, Cu, Cr, Co and Zn in lithium niobate has been developed. The method involves a one-step removal of radioactive nuclides of Nb, Ta and W representing the dominating radioactivity of the irradiated sample. After irradiation, the sample is fused with inactive carriers and Na₂O₂ in a nickel crucible. The fused cake is dissolved in HCl–H₂O₂ and Nb, Ta and W are homogeneously precipitated. The impurities are separated by combinations of precipitation and ion-exchange separations for precise -ray measurements with an overall chemical yield of 70% to 90%. The results are discussed.     

Neutron activation analysis of Cuban soils

Thirty elements were determined by INAA in Cuban soil samples collected in 17 zones from western regions of Cuba, which were affected by neuropathy epidemic in 1992. The presence of toxic elements was evaluated to provide data for the analysis of possible paths of intoxication through local agriculture product consumption. The results obtained for As, Th and U are compared with similar data reported on literature.     

Neutron activation analysis of urinary stones

Human vesical, urethral and renal stones were analyzed for the trace elements Co, Cu, Mn, Zn and Mo. Statistical correlations between the elements determined were sought which would be of possible interest in further research on the initial causes of urinary stone formation in the human body. This research project was funded by a grant from the National Research Council of the Philippines. Read at the 40th Annual Convention of the Philippine Medical Association held in Manila, May 9, 1947.     

Neutron activation analysis of Turkish clays

Neutron activation analysis was used in the determination of thirteen trace element concentrations in clays from various regions of Turkey. Comparison of results in terms of enrichment factors with those of lignite samples from the same regions revelaed no significant correlation between clay and lignite concentrations. Structural effects as well as local soil composition seem to affect the enrichment.Supported by the Turkish Atomic Energy Authority, and by IEAE-Vienna.     

Neutron activation analysis of Turkish coals

Neutron activation analysis of lignites taken from five different zones were carried out. It was observed that the elements which are selectively consumed by plants show relatively larger depositions in coals.     

Neutron activation analysis of Bawachi seeds

Seeds of (the plant) P. Corylifolia Linn (Bawachi) known for their therepeutic value in indigenous medicine have been analysed for Cu, As, Sb and Se by thermal neutron activation analysis involving substoichiometric extraction and precipitation technique. The amounts of Cu, As, Sb and Se per gram of seeds dried at 80°C are 16.0±1.1 μg, 0.90±0.4 μg, 12.1±0.6 μg and 4.0±0.2 μg respectively.     

Neutron activation analysis of arsenic species

Inorganic arsenic, MMA, DMA and arsenobetaine (As) were separated by the use of cation and anion exchange chromatography combined with neutron activation. Two complementary approaches were used: firstly, authentic, non-irradiated arsenic compounds, either singly or in mixtures, were separated and NAA of the fractions used as an element specific detection method. Secondly, the arsenic compounds were neutron irradiated under different conditions and for different times and the products separated and quantified. The⁷⁶As labeled species (mono-, di and trimethylated) were then additionally used to calibrate and improve the column separations. Using the separations developed, arsenic species in samples of shrimps and the standard reference material DORM-1 were determined, after an extraction step, using ion exchange chromatography followed by INAA of the fractions collected.     

Neutron activation analysis of semiconductor materials

Two examples of the use of neutron activation analysis for the characterization of semiconductor materials are given. 23 elements were determined in ASTM silicon intercomparison samples. Most elements are below the detection limits, which vary between 0.009–300 ng/g. CdS/CdTe thin films have been characterized by determining the Cd, Te, Cl, I and In concentrations of dissolved films. Parallel determinations in different samples of films prepared under identical conditions agreed within 0–53% (average deviation 21%) for Cl, Cd, In and I in CdS and 1.6–22% (average 8.7%) for Cd and Te in CdS/CdTe, respectively. It was determined both by NAA and resonance ionization spectrometry (RIS). The order of magnitude of the results was 1 ng/g and they agree within the range 7–64% (average difference 25%). The analytical procedures are described and discussed.     

Neutron activation analysis of refractory compounds

Instrumental neutron activation techniques for the determination of 26–36 impurities in MoSi₂, WSi₂, TiB₂, NbB₂, TiC, NbC and SiC with detection limit of 0.1–0.000001 ppm in the range of contents of 100–0.001 ppm have been developed. The determination of this large number of elements was achieved with using complex conditions of irradiation, including varying neutron energy and choosing optimal time parameters. The contents of short-lived radionuclides also have been determined. Self-shielding and disturbance of neutron flux, absorption of -rays were taken into account both with the help of literature data and preliminarily obtained experimental results.     

Neutron activation analysis of zeolite catalysts

A new method for the determination of aluminum and silicon has been developed for zeolite catalysts. In contrast to previous methods, thermal neutrons are used for the analysis of both elements, and cadmium absorbers are not needed. The silicon determination utilizes a one-hour irradiation to observe the³¹Si produced by the (n, ) reaction of³⁰Si. A 15-second irradiation is used for the²⁷Al(n, )²⁸Al reaction. The²⁸Al activity is corrected for the contribution from the²⁸Si(n,p)²⁸Al reaction by using the analyzed weight of silicon in the sample and the data for a silicon standard irradiated simultaneously with the zeolite and the aluminum standard. The quantitation limits are 0.012 g for silicon and 3.3×10^–5 g for aluminum. Sodium presents a significant interference, but this element can be removed by taking advantage of the ion exchange properties of these materials.     

Neutron activation analysis without multielement standards

A physical approach is described for instrumental multielement activation analysis with whole neutron spectrum (without Cd-cover) using the monostandard (single comparator) method. To test the capabiliteries of this method, 15 samples representing different Egyptian granite rocks were analyzed. As many as 21 trace elements beside Fe, K and Na were determined. Calculation of the experimental data has been done using the Gamma-Monostandard Analysis program with the Commodore Computer available at the Institute of Radiochemistry at Garching near München. The accuracy of the method for nondestructive multielement analysis agrees within 3% with the relative method using multielement standards.     

Neutron activation analysis without multi-element standards

The paper shows how, from the neutron irradiation of multi-element standards, one can derive neutron flux parameters for the irradiation position and, at the same time, greatly improve knowledge of nuclear data parameters, such as thermal cross sections, resonance integrals and gamma raz emission probabilities, for the nuclides concerned. It is then shown how the resulting neutron flux parameters and nuclear data parameters can be used to carry out neutron activation analysis without further irradiation of multi-element standards. The technique is applied to the analysis of Chinese geochemical reference material     

Neutron activation analysis without multielement standards

To carry out neutron activation analysis without using multielement standards requires knowledge of (i) the absolute photopeak efficiency as a function of energy of the gamma-ray detector, (ii) nuclear data for each reaction used, and (iii) neutron flux parameters for the irradiation position. The present paper discusses each of these topics and shows an example of the determination of flux parameters and improved nuclear data.     

Neutron activation analysis of CdxHg1-xTe

A procedure has been developed for the analysis of Cd_xHg_1-xTe samples; the elements to be determined /Na, K, Cr, Mn, Cu, Co, Zn, As, La/ are separated by chromatography after neutron activation. The detection limit varies between 1×10^–5% and 5×10^–8%. A comparison of the calculation and semiempirical methods of the screening effect determination has been made.