Determination of aluminum levels in serum and red blood cells from long-term haemodialysis patients using instrumental neutron activation analysis

Aluminum levels of serum and red blood cell (RBC) were determined by instrumental neutron activation analysis (INAA) in 15 patients undergoing long-term haemodialysis. In the sample, aluminum was bombarded with thermal neutrons due to ²⁷Al(n,γ)²⁸Al and was determined by measuring 1779 keV gamma-ray of ²⁸Al (T _1/2 = 2.24 min) with a HPGe detector. Phosphorus, causing an important interference by the fast neutron reaction, ³¹P(n,α)²⁸Al, was determined by the photometric method to correct the net-area under the ²⁸Al gamma-peak. The one-sample Kolmogorov-Smirnov test was used to control the normality distribution of the aluminum levels in serum and RBC. The results obtained were found to be in agreement with the serum aluminum determination performed by electrothermal atomic absorption spectrophotometry. The statistical results show a correlation between the aluminum levels of serum and RBC. This revised version was published online in July 2006 with corrections to the Cover Date.     

Non-destructive bone aluminum assay by neutron activation analysis

A non-destructive method based on instrumental neutron activation analysis (INAA) for the assay of aluminum in bone samples is described. The²⁸Al signal obtained upon neutron irradiation includes contributions from both the reaction²⁷Al(n,)²⁸Al and³¹P(n,)²⁸Al. The first reaction is with the thermal neutrons and the second one is with the fast neutrons. The contribution from the³¹P reaction is calculated from the fact that Ca/P ratio in bone mineral is constant and the amount of calcium can be measured from the thermal reaction⁴⁸Ca(n, )⁴⁹Ca. The aluminum values obtained by the INAA procedure agreed within 10% of those obtained by atomic absorption spectrophotometry. With this assay the levels of aluminum in normal bones (<70 g g^–1 apatite) cannot be determined reliably but higher aluminum levles in bone biopsies associated with Al toxicity, e.g. some patients with renal osteodystrophy, can be determined with a precision of ±10%.     

Method for determination of silicon in plant materials by neutron activation analysis

Silicon has been found to be an essential element for the growth and development of many ecomomically important plants such as sugarcane, rice, oats, and wheat. A method is described for the quantitative determination of silicon in plant samples. Measurements were made with two Ge(Li) detectors matched with a multiplexing unit to provide a single amplified signal to a computerized analyzer system. For those materials containing greater than 0.5 weight percent silicon, the reaction²⁹Si(n, p)²⁹Al (1273 keV) provides a direct measurement of the quantity of silicon provided the irradiation is done in a special boron nitride capsule to reduce interferences from thermal neutron reactions and a correction is made for the single escape line from²⁸Al (1268 keV). For lesser quantities of silicon, a technique which utilizes the fast neutron reaction²⁸Si(n, p)²⁸Al is preferred. Corrections for the interference produced by the presence of phosphorus³¹P(n, α)²⁸Al are made by determining the phosphorus content following the instrumental analysis using a unique application of neutron activation analysis, i. e., measurement of tungsten in tungstomolybdophosphoric acid produced when molybdate and tungstate ions are added to dissolved samples of the plant material containing phosphorus. Aluminum, which may also produce an interference by thermal neutron reaction²⁷Al(n, γ)²⁸Al, is determined directly from the original activation data after subtracting out the effect of the phosphorus. Thus, three irradiations in the pneumatic sample irradiator are necessary; one short irradiation (1 min) without thermal neutron shielding, a longer irradiation (6 min) in the boron capsule, and a final irradiation of the tungstomolybdophosphoric acid provide all data required to accurately determine silicon in plant materials. A computer program has been developed that provides rapid reduction of the data in final report format. Elements such as sodium, chlorine, calcium, manganese, potassium, and magnesium extrinsic to the analysis for silicon are also determined by this method. The method has been tested on a large number of samples and reliable results are obtained with less than 0.2 g of sample. This work was supported by Grant 533 from the Michigan Memorial—Phoenix Project.     

A system for the determination of silicon in the human lung using neutrons from A 2MV Van de Graaff generator

Neutron activation analysis, using inelastic scattering, provides a quantitative, non-invasive technique of studying silica burdens and is potentially useful as a screening procedure for occupationally exposed workers. In this method, silicon is measured using the fast neutron inelastic scattering reaction²⁸Si(n,n )²⁸Si which emits 1779 keV -rays. The method requires a source of fast neutrons (> 2MeV). A 2MV Van de Graaff generator has been developed to produce a pulsed beam of 5.2 MeV neutrons. The pulsed beam has the advantage of improving measurement sensitivity by separating in Bone the inelastic scattering -rays from those due to thermal-neutron capture reactions. The incident neutron energy was chosen to maximise the silicon -ray count rate, while keeping the signal from the competing reaction³¹P(n,)²⁸Al negligible.     

Measurements of the thermal neutron cross-sections and resonance integrals for 186W (n,γ) 187W and 98Mo (n,γ) 99Mo reactions

The thermal neutron cross-sections and resonance integrals of the ¹⁸⁶W (n,γ) ¹⁸⁷W and ⁹⁸Mo (n,γ) ⁹⁹Mo reactions in the thermal and 1/E regions, respectively, of a thermal reactor neutron spectrum have been experimentally determined by the activation method using ¹⁹⁷Au (n,γ) ¹⁹⁸Au reaction as a single comparator. The high purity natural W, Mo, and Zr foils; and Au wire diluted in aluminum, were irradiated without Cd shield in two neutron irradiation sites, characterized with different values for the thermal-to-epithermal flux ratios, f at the Second Egyptian Research Reactor (ETRR-2). The induced activities in the samples were measured by high-resolution γ-ray spectrometry with a calibrated germanium detector. Thermal neutron cross-sections for 2200 m/s neutrons and resonance integrals for the ¹⁸⁶W (n,γ) ¹⁸⁷W and ⁹⁸Mo (n,γ) ⁹⁹Mo reactions have been obtained relative to the reference values, σ₀ = 98.65 ± 0.09 b and I ₀ = 1500 ± 28 b for the ¹⁹⁷Au (n,γ) ¹⁹⁸Au reaction. The necessary correction factors for thermal neutron and resonance neutron self-shielding effects, and the epithermal flux index (α) were taken into account in the determinations. The results obtained were: σ₀ = 38.43 ± 0.4 b and I ₀ = 502 ± 65 b for ¹⁸⁶W (n,γ) ¹⁸⁷W, and σ₀ = 0.137 ± 0.014 band I ₀ = 6.47 ± 0.8 for ⁹⁸Mo (n,γ) ⁹⁹Mo. These results are discussed and compared with previous measurements and evaluated data in literature. The traditional method of determining thermal cross-sections and resonance integrals via neutron irradiation with and without Cd shield in one irradiation position was avoided in this work by neutron irradiation without Cd shield in at least two different neutron irradiation positions. This method provides alternative way for determining thermal cross-sections and resonance integrals simultaneously.     

Application of fast solvent extraction processes to studies of exotic nuclides

The nucleus²³Na has been investigated by studying the primary γ-rays emitted from 53 keV neutron capture in it using a high resolution and high efficiency (100%) HPGe detector and NaI(T1) detector for anti-Compton. 24 primary γ-rays were placed in the²⁴Na, in which 3 primary γ-rays were new ones from a (n, γ) reaction, and reported for the first time. In order to obtain an exact energy calibration within 7 MeV,⁵⁶Fe(n,γ)⁵⁷Fe reaction was used at thermal neutron energy. Intensity calibration was obtained from the²⁷Al(p,γ)²⁸Si reaction atE _p=2046 keV. The neutron binding energy of²⁴Na was determined to be 6959.75 keV.     

The preparation of carrier-free102Rh and102m Rh

Long-lived rhodium radionuclides were produced by the following reactions:¹⁰³Rh(n, 2n)^102(m)Rh;¹⁰³Rh(γ,xn)¹⁰⁰Rh,¹⁰¹Rh,^102(m)Rh;¹⁰⁴Pd(d, α)^102(m)Rh; Ru(d, n)⁹⁹Rh,^101(m)Rh,^102(m)Rh; and . The average cross-section of the¹⁰³Rh(n, 2n)¹⁰²Rh reaction in a fission neutron spectrum is about 0.75 mb. Irradiation of rhodium in the bremsstrahlung spectrum of 50 MeV electrons yielded a¹⁰²Rh activity of 0.11 μCi/g after 3 days at a power of 2 kW. The thick target yield of the reaction¹⁰⁴Pd(d, α)¹⁰²Rh was 0.002 μCi/μAh for 12 MeV deuterons. The thick target yield of the reaction Ru(d,xn)¹⁰²Rh was 0.05 μCi/μAh for 12 MeV deuterons and 4.8 μCi/μAh for 18 MeV deuterons. The best yield was obtained by deuteron bombardment of ruthenium. The chemical separation of carrier-free Rh radionuclides from deuteron-irradiated ruthenium is described, with a chemical yield better than 90%. The same procedure has also been applied for the isolation of¹⁰⁵Rh from neutron-irradiated ruthenium. γ-Ray spectra of⁹⁹Rh,^101(m)Rh and^102(m)Rh from deuteron-irradiated ruthenium and of¹⁰⁵Rh from neutron-irradiated ruthenium, taken with a Ge(Li) detector, are shown; a number of γ-rays, not reported in the literature, were observed. The γ-ray energies were determined with a precision of ca. 0.3–0.4 keV.     

Determination of silicon dioxide in iron and steel-making slags and fluorspars by 14 MeV neutron activation and high-resolution gamma-ray spectrometry

Silicon as silicon dioxide in iron and steel-making slags and fluorspars was analyzed by 14 MeV neutron activation high-resolution γ-ray spectrometry. Silicon was detected by measuring the 1.78 MeV γ-ray of²⁸Al, the product of the²⁸Si(n, p) reaction, using a 30 cm³ coaxial Ge(Li) detector. A modified TPA method was used for the calculation.²⁸Al is also produced from phosphorus by the³¹P(n,α) reaction, and from aluminium by the²⁷Al(n,γ) reaction. The contribution from the former reaction could be corrected experimentally when the P₂O₅ content of the sample was known, while the latter reaction could be neglected in this neutron energy region. The experimental correction coefficient for phosphorus agreed well with the theoretical value calculated from the nuclear properties of silicon and phosphorus. Yields of²⁸Al from SiO₂, P₂O₅ and Al₂O₃ of the same weight percentages were calculated as 1, 0.426 (experimentally 0.44) and 0.0022, respectively. The results of this method agreed well with the results of the usual chemical methods. The limit of detection of SiO₂ in iron and steel-making slags and fluorspars was calculated as 0.07%. The coefficient of variation of repeated experiments was compared with the statistical one.     

Reactor neutron activation analysis by a triple comparator method

The single comparator method has been extended to a triple comparator method, using⁶⁰Co,^114m In and¹⁹⁸Au. In this technique, thek-ratios of the elements to be analyzed, now determined against the three comparators, are corrected for each new ratio of thermal to epithermal reactor neutron flux. These flux ratios are calculated from the absolute activities of the three comparators. The thermal neutron activation cross-section and the resonance integral for the reaction¹¹³In(n,γ)^114m In have been determined.     

Measurement of bromide ion used as a solute-transport monitor via epithermal neutron activation analysis

In soil science (ca. 1970), bromide ion (Br⁻) in various forms (e.g., KBr, NaBr, SrBr₂) was introduced as a non-reactive stable tracer in solute transport studies normally moving freely with the flux of water without substantial chemical or physical interactions with the soil. Typically, Br⁻ is extracted from soil and quantified using either a bromide selective electrode (sensitivity is ≈10μg/ml) or by high-performance liquid chromatography (sensitivity is ≈0.010 μg/ml). Where the sensitivity is adequate, the selective conductivity method, which is simple, affordable and fast, is preferred. More recently (ca. 1990), workers have reported that 20% of Br⁻ tracers, at low groundwater pH, may be adsorbed by iron oxides and kaolinite when present in the alluvial aquifer. We investigated the use of Epithermal Neutron Activation Analysis (ENAA) as a means of measuring Br⁻ directly in soil samples without an extraction. ENAA was chosen because of its high theoretical advantage factor over aluminum (i.e. ≈20), the principal interfering soil constituent, calculated for the⁷⁹Br(n,γ)⁸⁰Br reaction compared to²⁷Al(n, γ)²⁸Al. Br⁻ was measured (sensitivity is ≈0.050 μg/g) in one gram soil samples from a 5 s irradiation (φ_epi=2.5·10¹² n·cm^-2·s^-1) using a BN capsule.     

Instrumental neutron activation analysis of phosphorus in rocks

The possibilities are discussed of the instrumental activation analysis of phosphorus in rocks by the reaction³¹P(n, γ)³²P (T=14.2 d). Results are given for six standard rocks of the U.S. Geological Survey.     

Non-destructive determination of aluminum in biological reference samples using neutron activation analysis

The non-destructive methods of thermal and epithermal neutron activation analysis have been employed to determine the aluminum concentration of seven National Institute of Standards and Technology certified biological reference materials. Through the judicious use of both thermal and epithermal neutron activation analysis using bare and boron-lined irradiation carriers, the major and minor contributions of the³¹P/n, /²⁸Al and of the²⁸Si/n, p/²⁸Al reactions, respectively, to the²⁷Al/n, /²⁸Al reaction could be corrected for explicitly. Based on replicate determinations precision of the analysis ranged from 2.5% for citrus leaves determined at the 75 ppm level to 18% for bovine liver measured at the 1 ppm level. Accuracy was demonstrated whenever possible by comparison to existing published data.     

Die Bestimmung von53Mn,Welches in Meteoritischem Material Durch Kosmische Strahlung Erzeugt Wurde,mit Hilfe der Neutronenaktivierung

Among a number of stable and unstable nuclides formed in material exposed to cosmic radiation the spallation nuclide⁵³Mn (T=2·10⁶ a) is investigated in meteoritic manganese by combined techniques of neutron activation and advanced γ-spectrometry. The need for an economic use of precious meteorites is so ensured best. Intense neutron bombardment transforms the long-livedK-emitter⁵³Mn into⁵⁴Mn, which is detected by its 0.84 MeV γ-rays. Using the (n,γ) cross section—recently derived byMillard—⁵³Mn-values in the range of 60–600 dpm/kg (10⁻¹¹ g/g) are found in a larger number of iron meteorite samples, which are only 1–3 g in weight. The determination is very specific and under appropriate conditions unaffected by side reactions. The attempt to use the⁴⁴Ti (n,γ)⁴⁵Ti reactions for the analysis of spallogenic titanium failed, because the σ_therm of⁴⁴Ti was found to be unexpectedly low (10 barns). Additionally,⁴⁵Sc was determined after (n,γ) reaction by the⁴⁶Sc γ,γ-cascades.      

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.     

Measurement of reaction cross-sections for 64Ni(n, γ) 65Ni at E n = 0.025 eV and 58Ni(n, p) 58Co at E n = 3.7 MeV

The reaction cross-sections for ⁶⁴Ni(n, γ) ⁶⁵Ni at E _n  = 0.025 eV and ⁵⁸Ni (n, p) ⁵⁸Co at E _n  = 3.7 MeV have been experimentally determined using activation and off-line γ-ray spectrometric technique. The thermal neutron flux used is from the thermal Column of the reactor APSARA at BARC, Mumbai, whereas the neutron energy of 3.7 MeV is from the ⁷Li(p, n) reaction at Pelletron facility, TIFR, Mumbai. The ⁶⁴Ni(n, γ) ⁶⁵Ni and ⁵⁸Ni(n, p) ⁵⁸Co reactions cross-sections from present work are compared with the available literature data and found to be in good agreement. The ⁵⁸Ni(n, p) ⁵⁸Co reaction as a function of neutron energy is also calculated theoretically using TALYS computer code version 1.2 and found to be higher than the experimental data.     

Determination of silicon in aluminium by 14 MeV neutron activation analysis

A method has been developed for determining silicon in aluminium by fast neutron activation. It is based on the separation of two gamma lines by a Ge(Li) detector: the 1.73 MeV line from the product of²⁷Al(n, α)²⁴Na and the 1.78 MeV line from the²⁸Si(n, p)²⁸Al reaction. In the case of aluminium-silicon alloys 100 μg silicon can be determined, with an error of 10% in an aluminium sample of 1 g. This work was supported in part by the International Atomic Energy Agency.     

Determination of aluminium in lutetium by instrumental neutron activation analysis

In lutetium metal 45 ppm aluminium have been determined by instrumental neutron activation analysis. Interference from the very intensive γ-radiation of^176mLu was eliminated by application of lead filters. The determination limit of the method was estimated to be 0.7 μg or 3 ppm Al.     

Determination of carbon impurities in epitaxial layers from semiconductor silicon by means of charged particles

The energy-dependent range of charged particles in activation analysis according to the reaction¹²C(d,n)¹³N permits the method to be applied to carbon determination in model epitaxial layers of sufficient thickness. We investigated 100 μm epitaxial layers of the n-type and undoped 50 μ layers as to p⁻ Czochralski substrates. Deuterons were slowed down with Cu and Ta foils having a limiting energy of 13.5 MeV, to 4.2 MeV and 2.9 MeV, respectively. In the resulting activation depths of 52 and 102 μm, the sensitivity of the method, which is 3·10¹⁴ at ·cm⁻³C at E_d=10 MeV in silicon, is reduced to 25% and 10%, respectively. An optimal flux of 0.9 μA·cm⁻² was maintained. After irradiation, 20 or 10 μm were etched off. The sample was inductively fused at 1500 K in a Pb₃O₄/B₂O₃ mixture.¹³N was passed with He as carrier gas into an absorption vessel kept at 77 K, and its activity was measured in γ, γ-coincidence.     

Neutron activation analysis of uranium in human bone,drinking water and daily diet

Uranium in human bone, drinking water and daily diet has been determined by neutron activation analysis using the²³⁸U(n, γ)²³⁹U reaction. An improved scheme for the separation of the²³⁹U is proposed; with this scheme, after neutron irradiation in a 100 kW TRIGA reactor, a uranium content as low as 5·10⁻¹¹ g can be determined reliably, rapidly and easily. A wide range of uranium concentrations, from about 0.1 ppb up to about 10 ppb has been found in the bones of normal Japanese. Water from several Japanese city water services, and the daily diet taken in two Japanese cities, have been found to contain an average 9·10⁻⁹ g/l and 1.5 μg per person-day uranium, respectively.     

Simultaneous determination of silicon and phosphorus in cast iron by 14 MeV neutron activation analysis

A fast (10 min), non-destructive simultaneous determination of silicon and phosphorus in cast iron and steel by 14 MeV neutron activation was developed. The 1.78 MeV²⁸Al activity (T=2.24 min) induced by the reaction²⁸Si(n, p)²⁸Al is counted on a NaI(Tl) detector. Two measurements are made to correct for the 1.81 MeV⁵⁶Mn activity (T=2.58 hr) from the iron matrix. However,²⁸Al is also produced via³¹P(n, α)²⁸Al. By (n, 2n) reaction, phosphorus yields also³⁰P (T=2.6 min), the 0.511 MeV annihilation radiation of which is counted by two opposite NaI(Tl) detectors in coincidence. Again, two successive coincidence measurements are carried out in order to take into account the⁵³Fe activity (β⁺; T=8.9 min) from⁵⁴Fe(n, 2n)⁵³Fe. The²⁸Al measurement is appropriately corrected via the computed phosphorus content. An oxygen flux monitor was used to normalize to the same flux. Nuclear interferences have been examined. Special attention has been paid to the presence of copper. The standard deviation for phosphorus being as high as ca. 0.09% P for a single determination, this technique can only be practical as an independent phosphorus analysis for high phosphorus cast irons. The precision on the²⁸Al measurement is 5% relative for 0.2% Si and 2.5% above 1% Si. Aspirant of the N.F.W.O.