Serum aluminum determination by instrumental neutron activation analysis in long-term haemodialysis patients

Serum aluminum levels were determined by instrumental neutron activation analysis in 31 patients undergoing long-term haemodialysis. Aluminum-28 1.778 MeV (T _1/2=2.24 min) γ-rays produced by the thermal neutron reaction²⁷Al(n,γ)²⁸Al were detected. Successive irradiation of the samples at epithermal neutron fluence was performed to correct for the interference from the fast neutron reaction³¹P(n,α)²⁸Al. Serum aluminum level in this group of subjects was adequately represented by a lognormal distribution with a mean and variance of 16.5 μg/l and 16.8 μg/l, respectively. The results obtained were found to be in agreement with serum aluminum determination performed by electrothermal atomic absorption spectrophotometry (r ²=0.97). Instrumental neutron activation can provide a rapid technique to routinely monitor long-term haemodialysis patients in order to identify individuals at greater risk to develop aluminum toxicity.     

Distribution of aluminum species in normal urine as determined by chemical neutron activation analysis

A procedure developed for separating and quantifying non protein and protein fractions of aluminum species in urine was applied to four consecutive 24 hr collections of five healthy subjects. The total Al content of urine was determined by a chemical neutron activation analysis technique reported elsewhere. Results from the analysis of all subjects indicate that the majority of aluminum is bound to protein (>88%) with minor fractions as citrate complexes. These data are comparable with other speciation experiments with blood plasma indicating 90% of the aluminum was bound to plasma proteins.     

Design of a permanent Cd-shielded epithermal neutron irradiation site in the Syrian Miniature Neutron Source Reactor

A Cd-shield (cylindrical shell 1 mm in thickness, 34 mm in diameter and 180 mm in length) was used to design a permanent epithermal neutron irradiation site for epithermal neutron activation analysis (ENAA) in the Syrian Miniature Neutron Source Reactor (MNSR). This site was achieved by shielding the surface of the aluminum tube of one of the outer irradiation sites. The calculated depression ratio of thermal neutron flux was 1/10. Homogeneity of the neutron flux in the first outer irradiation site has been found numerically using the WIMSD4 and CITATION codes and experimentally by irradiating five short copper wires using the outer irradiation capsule. Good agreement was obtained between the calculated and the measured results of the neutron flux distributions.     

Arsenic distribution in rats fed a Hijiki diet

Very large doses of sodium arsenate (Na₂HAsO₄), 14 mg As kg^?1 of body weight, were administered to Sprague-Dawley male rats (body weight 300 g) fed a 5% Hijiki diet by stomach tube twice within two days. After 24 h, the rats were sacrificed and various organs were dried for subsequent neutron activation analysis. The distribution of arsenic (As) in selected organs was determined by neutron activation analysis. The highest concentration of As was found in blood cells with a rather high concentration in the liver and heart. As the control, rats which were fed on a 5% cellulose diet were used. Control rats which were administered arsenate showed that the arsenic distribution and the concentration in their organs were similar to those on the 5% Hijiki diet. Even the blood cells of the controls without any arsenic administration were found to contain a small amount of arsenic.     

Prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals

The design, calibration, dosimetry and performance evaluation of a prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals (i.e. rats or rabbits) is discussed. The system design was guided by Monte Carlo transport calculations using MCNP-4C code. A system was built and performance evaluation was made using a 185-GBq Pu-Be neutron source. Prompt-gamma rays produced by neutron capture reactions were detected by a combination of a NaI(Tl) scintillation and a HPGe semiconductor detectors. Nitrogen and chlorine were quantified by analysis of the 10.83-MeV and 6.11-MeV peaks, respectively. Appropriate corrections for the animal body size were determined. The facility described allows the in vivo determination of protein and extracellular space in sets of experimental animals.     

Determination of human and Sprague-Dawley rat trimethylselenonium ion and total selenium urine concentrations from endogenous body selenium pool by neutron activation analysis

This study determined trimethylselenonium ion [TMSe, (CH₃)₃Se⁺] and total organic selenium cationic species urinary excretion values for healthy human subjects and Sprague-Dawley rats fed regular diets. The only source of TMSe was from the endogenous selenium body pool. Total selenium concentration, in urine was determined by instrumental neutron activation analysis. TMSe and total selenium cationic species concentrations and percent of total selenium urine excretion were determined by chemical neutron activation analysis and coupled anion-cation exchange chromatography and anion-exchange chromatography, respectively. Within experimental error, mean values for TMSe and cationic species as percent selenium were comparable for both human subjects and Sprague-Dawley rats. This study suggested that TMSe excreted in urine by healthy human subjects and Sprague-Dawley rats fed a normal diet is not a minor but a general metabolite of selenium ingested in a normal diet.     

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.     

Characterization of a new external neutron beam facility at the Ohio State University

A thermal neutron beam facility has been designed and implemented at the Ohio State University Research Reactor. A project is underway to construct a large vacuum chamber such that the facility could have neutron depth profiling and neutron radiography capabilities as intended. The neutron beam is extracted from the reactor through a neutron collimator emplaced in Beam Port #2. The neutron spectrum entering the neutron collimator was unfolded from foil activation analysis results and also simulated with a full reactor core model in the MCNP Monte Carlo code. The neutron collimator uses polycrystalline bismuth as a gamma ray filter and single-crystal sapphire as a fast neutron filter. The beam is defined by multiple 3.0 cm diameter apertures made of borated aluminum. Characterization of the beam was performed using foil activation to find the flux and a low-budget neutron imaging apparatus to see the beam profile. The modulation transfer function was calculated to offer insight into the resolution of the imaging system and the collimation of the beam. The neutron collimator delivers the filtered thermal neutron beam with a ~4 cm diameter and a thermal equivalent flux of (1.27 ± 0.03) × 10⁷ n/(cm²s) at 450 kW power at the end of the collimator.     

Trace aluminum determination and sampling problems of archeological bone employing destructive neutron activation analysis

A destructive neutron activation analysis procedure was developed for determining trace aluminum content in bone. It was found that soil contamination can influence the aluninum bone levels in prehistoric bone specimens. These maximum aluninum content values for prehistoric bone are larger than those of modern bone and comparable to aluminum levels present in bone from renal patients.     

In vivo monitoring of skeletal aluminum burden in patients with renal failure

In vivo neutron activation analysis was used to examine the total body and partial body (hand) aluminum levels in patients with end-stage renal failure. Patients maintained on chronic hemodialysis had higher mean body burdens of aluminum than, did those clinically managed without dialysis. Approximately 70% of the patients examined indicated elevated levels of body or skeletal aluminum. A significant correlation was observed between the in vivo aluminum/calcium ratio obtained for the hand measurement and the increase in serum aluminum levels following a disferroxamine infusion test. The direct in vivo monitoring of hand Al/Ca values in patients may provide an alternate choice to bone biopsy for the detection of aluminum intoxication.     

Contents and uptake rates of Mn, Fe, Co, Zn, and Se in Se-deficient rat liver cell fractions.

The contents of manganese (Mn), iron (Fe), cobalt (Co), zinc (Zn), and selenium (Se) in nuclear (NU), mitochondrial (MT), microsomal (MC), and cytosolic (CS) fractions of liver homogenates of normal and selenium-deficient (SeD) rats were determined by instrumental neutron activation analysis (INAA). The uptake rates of these elements in the liver cell fractions of both groups of rats were determined by multitracer analysis (MTA). The results indicated that Se-deficiency caused a significant increase in the content of Fe in the MC fractions. The MTA showed that the uptake rate of Fe was highest in the MC fraction, and that the uptake rate in the fraction was similar between the SeD and normal rats.     

Instrumental neutron absorption activation analysis

We present and discuss a modification of instrumental neutron activation analysis (INAA) that is sensitive for nuclides that do not yield (suitable) activation products but have high cross sections for neutron absorption. Their presence in a sample may thwart INAA by neutron flux suppression inside the sample, but they remain undetected and thus unnoticed by the analyst. In particular, this refers to Li, B, Cd and Gd. The proposed method—instrumental neutron absorption activation analysis (INAAA)—takes advantage of the flux depression inside the sample caused by the neutron absorbers. It is made visible by addition of an activatable nuclide (indicator). The concentration of the neutron absorber (analyte) causes a decrease in activity of the indicator. The activity difference between a mixed sample (sample plus indicator) and the pure indicator carries the analytical information. The calibration curve hence follows a reciprocal exponential function. In a proof-of-principle experiment, the applicability for the quantification of boron was exemplified. In presence of only one neutron absorber (whose nature is known), INAAA can be applied easily for quantification of the analyte in powdered or liquid samples. Although INAAA is no trace sensitive method, it has the potential to increase the reliability of INAA analyses by fast and straightforward quality control (even in presence of two or more neutron absorbing nuclides). It is especially suited for research reactors that do not operate a prompt gamma neutron activation analysis (PGNAA) station.     

Monitoring of neutron flux changes in short-lived neutron activation analysis

It is well known variations in neutron fluxes can adversely affect the final result in neutron activation analysis. The monitoring of neutron flux changes are usually described for medium and long-lived NAA using foils of cobalt, gold, zirconium, etc. However, for short-lived neutron activation analysis there appears to be no systematic study of the variations of the neutron flux. With our new automatic pneumatic system, where irradiation timing, decay and counting and position are very reproducible, we have performed a series of experiments using thermal and epithermal neutrons using aluminum wire as a monitor to monitor the neutron fluxes. Our experiments confirm that neutron flux fluctuations in the worst case can be up to ±12 % with a SD of 2–3 %. This effect can be seen regardless of the irradiation time and must be taken into consideration to achieve the best result.     

Rapid analysis of biological reference materials by instrumental neutron activation

Summary Instrumental neutron activation analysis (INAA) was applied to the rapid determination of cadmium and other elements in the IAEA biological reference material horse-kidney (H-8). Nuclear reactor neutrons and epithermal neutrons were used as neutron sources. Cadmium, bromide, iodine and phosphorus were determined by epithermal neutron activation analysis. Aluminum was determined by reactor neutron activation analysis taking into account the contribution of phosphorus to the ²⁸Al activity.     

Dynamics of structural transformations in the reduction of copper aluminate

The dynamics of structural transformations during copper aluminate reduction in the temperature range used for catalyst activation was studied by high-temperature X-ray analysis under controlled conditions (hydrogen, 2O–4OO‡C). The techniques of neutron diffraction analysis, IR spectroscopy, chemical phase analysis, and electron microscopy were also used at particular stages. In the course of reduction, copper metal is deposited onto the surface of spinel crystals from the bulk. Spinel becomes cation-deficient with respect to copper. An analysis of powder diffraction patterns demonstrated that copper is reduced and released from tetrahedral positions of the spinel structure at temperatures below ~300‡C and from octahedral positions only at temperatures above 300‡C. In this case, a redistribution of aluminum ions was observed simultaneously. It is likely that the electrical neutrality is attained by the formation of OH groups, the appearance of which in reduced samples was detected by IR spectroscopy and confirmed by neutron diffraction analysis. At a reduction temperature of 400‡C, the oxygen framework was partially disintegrated. The structures of reduced copper aluminates and chromites were compared.     

Performance of NAA Methods in an International Interlaboratory Reference Material Characterization Campaign

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.     

A study of environmental analysis of urban river sediments using activation analysis

Sediments of the Kitajukkengawa River (Sumida-ku, Tokyo, Japan) were analyzed by activation analyses. Concentrations of 36 elements for each sample were determined by instrumental neutron activation analysis (INAA) and neutron induced prompt gamma-ray analysis (PGA). Based on the correlation matrix between the elements in vertical distribution, principal component analysis (PCA) was performed. The degree of chemical weathering of silicate minerals was highest in the middle layer of the Kitajukkengawa River sediment and that adsorbed amount of trace metals such as Cd and Cr was increased along with chemical weathering.     

Vanadium determination in rat tissues and biological reference materials by neutron activation analysis

Vanadium was determined in adrenal gland, brain, ileum, kidney, liver, lung, muscle, myocard, skin, spleen, gonads, thyroid, and tibia of rats fed with normal diet and exposed to high vanadium doses in drinking water. Both radiochemical neutron activation analysis (RNAA) and instrumental neutron activation analysis (INAA) were employed. The RNAA procedure consisted in dry ashing samples prior to irradiation and vanadium separation from the irradiated samples by extraction with N-benzoyl-N-phenylhydroxylamine (BPHA) in toluene from 5 mol·l^–1 HCl. Vanadium accumulation as a function of a type of the tissue, exposure time, sex of rats, and administration of V(IV) or V(V) was studied. For quality assurance purposes, the biological (standard) reference materials NBS SRM 1571 Orchard Leaves, NBS SRM 1577a Bovine Liver, IAEA H-4 Animal muscle, and Bowen's Kale were analyzed.Presented at the 2nd Balkan Conference on Activation Analysis and Nuclear-Related Analytical Techniques, Bled, 4–6 October, 1989.     

Determination of vanadium in serum by pre-irradiation and post-irradiation chemistry and neutron activation analysis

Vanadium in serum was investigated by pre-irradiation chemistry neutron activation analysis employing anion exchange chromatography and post-irradiation neutron activation employing solvent extraction techniques. From a comparison of these techniques it is concluded that vanadium is present in human serum in the sub-ppb range.     

Prompt gamma activation analysis and time of flight neutron diffraction on ‘black boxes’ in the ‘Ancient Charm’ project

The aim of the ‘Ancient Charm’ project is combining neutron tomography, prompt gamma activation analysis, time of flight neutron diffraction and neutron resonance transmission to generate elemental, and phase compositions of complex museum objects in 3D. To develop a protocol for such investigations, complex test samples were constructed and then analyzed by each method. The ‘black boxes’ are sealed iron and aluminum walled cubes, containing 2D or 3D arrangements of materials relevant for the compositions of archaeological samples. The experimental results obtained from bulk PGAA at BNC and TOF-ND at ISIS on two selected boxes are reported.