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PubMed1996

Applicability of neutron activation analysis (NAA) in quantitative determination of some essential and toxic trace elements in food articles.

Accurate and reliable data on microgram and nanogram quantities of some essential and toxic elements in most food articles are very scarce. Neutron activation analysis (NAA), with its essentially blankfree advantage, is a valuable approach in the field of determination of trace elements in different foodstuffs and diets. Accordingly, various radiochemical (RNAA) and instrumental (INAA) approaches have been developed in our laboratory for the element As, Cd, Co, Cu, Hg, I, Mo, Ni, Sb, Se, Sn, Th, U, V, and others, and verified by the analysis of compositionally appropriate certified reference materials.

Animals↗
PubMed1982

Interferences in in vivo neutron activation analysis.

Significant errors can occur in the measurement of the total amounts of N, P, Cl, Na, Ca and K in the human body by in vivo neutron activation analysis because of the presence of interfering activity in the gamma-ray energy spectrum. The interfering activity may be present for two reasons: firstly, patients may have received an administered radioisotope in an unrelated investigation; secondly, activation of elements not normally present in the body in large quantities may have occurred. The size and duration of these errors have been examined for two administered radioisotopes, 67Ga and 47Ca. The interferences due to activated iron and chromium from stainless steel prostheses have been examined, as well as those due to activated iodine and barium in radiographic contrast media. A description of the method by which we correct for those interferences is given. The effects of the shape of the standard spectra used in least squares analysis of the results have been examined.

Activation Analysis↗
PubMedDate not supplied

Sr/Ca mass ratio determination in bones using fast neutron activation analysis.

The Sr/Ca mass ratio in human bones reveals information regarding the diet which is of interest in archaeology. By using fast neutron activation analysis this ratio can be measured in a non-destructive manner, which is important when bones are considered too precious to allow for destructive analysis. Simulations and measurements showed that the nuclear reactions 88Sr(n, 2n)87mSr and 44Ca(n, p)44K are highly useful for the purpose.

Archaeology↗
PubMed1998

The application of preirradiation combustion and neutron activation analysis technique for the determination of iodine in food and environmental reference materials.

The pre-irradiation combustion (PC) of samples to liberate iodine, followed by trapping the iodine on charcoal and quantifying the element by neutron activation analysis (NAA), has been used at the National Institute of Standards and Technology for the determination of iodine in biological materials. The applicability of this technique to numerous environmental and dietary matrices is illustrated by analysis of a range of certified reference materials (CRMs) and a powdered grass material that was prepared as an in-house reference material (RM). Because of the combustion step involved, samples with low or no fat content (e.g., cereal products, selected botanical specimens, and nonfat milk powder) and inorganic materials (e.g., coal fly ash and dried sediments) are more suited for analysis by this method. In general, the results for several types of samples obtained by this method agreed with those obtained by a second radiochemical (R) NAA, as well as by a third method using inductively coupled plasma mass spectrometry (ICP-MS). PC-NAA is a useful technique for determining iodine in biological and environmental samples, especially for verification of iodine results obtained from other methods.

Environmental Pollutants↗
PubMedDate not supplied

Mineral content of vertebral trabecular bone: accuracy of dual energy quantitative computed tomography evaluated against neutron activation analysis and flame atomic absorption spectrometry.

The goal of this study was to evaluate the accuracy of preprocessing dual energy quantitative computed tomography (QCT) for assessment of trabecular bone mineral content (BMC) in lumbar vertebrae. The BMC of 49 lumbar vertebrae taken from 16 cadavers was measured using dual energy QCT with advanced software and hardware capabilities, including an automated definition of the trabecular region of interest (ROI). The midvertebral part of each vertebral body was embedded in a polyester resin and, subsequently, an experimental ROI was cut out using a scanjet image transmission procedure and a computer-assisted milling machine in order to mimic the ROI defined on QCT. After low temperature ashing, the experimental ROIs reduced to a bone powder were submitted to either nondestructive neutron activation analysis (n = 49) or to flame atomic absorption spectrometry (n = 45). BMC obtained with neutron activation analysis was closely related (r = 0.896) to that derived from atomic absorption spectrometry, taken as the gold standard, with, however, a slight overestimation. BMC values measured by QCT were highly correlated with those assessed using the two reference methods, all correlation coefficients being > 0.841. The standard errors of the estimate ranged 47.4-58.9 mg calcium hydroxyapatite in the regressions of BMC obtained with reference methods against BMC assessed by single energy QCT, 47.1-51.9 in the regressions involving dual energy QCT. We conclude that the trabecular BMC of lumbar vertebrae can be accurately measured by QCT and that the superiority in accuracy of dual energy is moderate, which is possible a characteristic of the preprocessing method.

Aged↗
PubMed1978

Adhesive bonding of various materials to hard tooth tissues. XV. Neutron activation analysis of dentin sorption of mordant salts.

Five metallic chlorides were compared simultaneously, with regard to their interaction with dentin surfaces. Neutron activation analysis was used to measure the quantities absorbed. Each metal was bound by dentin to some extent during a 60-second exposure, and was not removed during a 20-second rinse with distilled water. Quantitatively, the gram-atom amounts of ions sorbed increased in the order Co less than Al less than Zn approximately Cu less than Fe. These mordant salts warrant further study as a possible means of improving adhesive bonding between dental resins (via polyfunctional surface-active comonomers) and dentin.

Adhesiveness↗
PubMedDate not supplied

Benchmarking the MCNP code for Monte Carlo modelling of an in vivo neutron activation analysis system.

The Monte Carlo computer code MCNP (version 4A) has been used to develop a personal computer-based model of the Swansea in vivo neutron activation analysis (IVNAA) system. The model included specification of the neutron source (252Cf), collimators, reflectors and shielding. The MCNP model was 'benchmarked' against fast neutron and thermal neutron fluence data obtained experimentally from the IVNAA system. The Swansea system allows two irradiation geometries using 'short' and 'long' collimators, which provide alternative dose rates for IVNAA. The data presented here relate to the short collimator, although results of similar accuracy were obtained using the long collimator. The fast neutron fluence was measured in air at a series of depths inside the collimator. The measurements agreed with the MCNP simulation within the statistical uncertainty (5-10%) of the calculations. The thermal neutron fluence was measured and calculated inside the cuboidal water phantom. The depth of maximum thermal fluence was 3.2 cm (measured) and 3.0 cm (calculated). The width of the 50% thermal fluence level across the phantom at its mid-depth was found to be the same by both MCNP and experiment. This benchmarking exercise has given us a high degree of confidence in MCNP as a tool for the design of IVNAA systems.

Body Composition↗
PubMed1994

Iron-58 and neutron activation analysis: a non-radioactive method for tracing hemoglobin iron.

To develop a non-radioisotopic alternative to radioactive Fe-59 as a hemoglobin iron tracer, we evaluated Fe-58 and neutron activation analysis (NAA). Upon irradiation with thermal neutrons, stable isotope Fe-58 is converted to radioactive Fe-59 through (n,gamma) neutron reaction; its radioactivity measured by a gamma counter is proportional to the original Fe-58 present. Organ samples from rats infused with Hb or saline were analyzed along with a 10 mg Hb as a standard (105 nanograms of Fe-58). The measured values of Fe-58 in tissues were compared with those derived from the literature tissue iron contents. The amount of Fe-58 in normal tissue is extremely low yet detectable by NAA demonstrating high sensitivity. Measured values of Fe-58 from tissues were generally correlated well with literature derived values (e.g., brain: 0.19 and 0.15 ng/mg tissue; kidney: 0.6 and 0.7 ng/mg tissue, respectively). The results indicate that Fe-58 can be used as a non-radioactive tracer for absorption, distribution, metabolism, and distribution studies of hemoglobin-based oxygen carriers.

Animals↗
PubMed1978

Determination of molybdenum in human serum by neutron activation analysis.

Several investigators have reported serum molybdenum determinations in healthy humans. However, their results diverge quite widely. We determined the element by neutron activation analysis in 30 individuals. We found a mean value of 0.58 ng/ml, a standard deviation of 0.21 ng/ml and a range of 0.28--1.17 ng/ml.

Adolescent↗
PubMed1975

A high sensitivity dual-detector shadow-shield whole-body counter with an 'invariant' response for total body in vivo neutron activation analysis.

The development of a dual-detector shadow-shield whole-body counting system of high sensitivity is described. The sensitivity and performance of the counter are analysed, with specific references to total body in vivo neutron activation analysis, and shown to be at least comparable with those of many conventional shielded-room counters.

Activation Analysis↗
PubMed1968

Neutron activation analysis ofr copper in biological material applied to Wilson's disease.

A method for the neutron activation analysis of copper in biological material is described and applied to the diagnosis and management of four cases of Wilson's disease. Results obtained for serum and urine are in agreement with values obtained by established colorimetric techniques. The method described can estimate 10(-9) g. copper to within 10% and this sensitivity has allowed the determination of copper from biopsy material such as liver, spleen, hair, and nail.

Activation Analysis↗
PubMed1996

A neutron activation analysis facility for in vivo measurement of nitrogen and chlorine in children.

The construction, calibration and evaluation of a prompt- gamma in vivo neutron activation analysis (IVNAA) facility for the simultaneous measurement of total body nitrogen (TBN) and chlorine (TBCl) in children is described. Subjects are irradiated unilaterally by a 0.2 GBq 252Cf neutron source from shoulder to mid thigh in both supine and prone positions. Prompt gamma-ray spectra are measured with two pairs of NaI(TI) crystals (each crystal: 10 cm x 10 cm x 15 cm) positioned on both sides of the subject. TBN and TBCl are estimated from the ratios of nitrogen-to-hydrogen (Nc/Hc) and chlorine-to-hydrogen (Clc/Hc) counts as determined from the measurement of 10.83 MeV, 8.57 MeV and 2.22 MeV prompt gamma-rays from the respective reactions 14N(n, gamma)15N, 36Cl(n, gamma)35Cl, and 1H(n, gamma)D. Nc/Hc and Clc/Hc are corrected for the effect of body width and thickness on background and gamma-ray attenuation. Total body hydrogen (TBH) is used as an internal standard which is independently determined using a four compartment model of body weight defined as the sum of total body water (TBW) measured by the D2O dilution technique, total body protein (TBPr) (i.e. 6.25 x TBN) measured by IVNAA, total body bone mineral (TBBM) measured by dual energy x-ray absorptiometry and total body fat (TBF) estimated as body weight less the sum of TBW, TBPr and TBBM. The effective dose equivalent to a small child is 0.25 mSv (Q = 20) per measurement scan. Repeated measurements of a child-size bottle phantom containing tissue-equivalent concentrations of nitrogen and chlorine yield respective intra- and inter-assay precision values of 2.8% (CV) and 2.3% for TBN measurements, and 7.9% and 10.0% for TBCl measurements. Similarly, intra- and inter-assay accuracy is determined to be respectively +0.1% +/- 1.0% (mean, 95% confidence interval) and +1.4% +/- 1.4% for TBN measurements, and +2.3% +/- 4.3% and +3.9% +/- 6.0% for TBCl measurements.

Adult↗
PubMed2003

Development of an internal monostandard instrumental neutron activation analysis method based on in situ detection efficiency for analysis of large and nonstandard geometry samples.

A k0-based internal monostandard instrumental neutron activation analysis method for determination of relative elemental concentration in samples of large size and irregular geometry has been developed. In this method, one of the elements present in the sample is used as comparator. A priori knowledge of the concentration of one of the constituents is required to convert the relative concentration into absolute values. The problems of gamma-ray self-attenuation and geometrical effects that arise in the assay of large and nonstandard geometry samples were overcome by an in situ relative detection efficiency calibration procedure, which requires one or more activation products emitting gamma-rays over a wide range of the spectrum. To minimize the problem of neutron flux perturbations that may arise in large samples, irradiations were carried out using a thermal column with thermal neutron component of more than 99.9%. The method has been standardized with samples of silica (approximately 0.5 kg) and water (0.5 L) spiked with known amounts of different elements and has been advantageously applied to some alloy and metal samples of irregular geometry, where complete compositional characterization was carried out using mass balance. This approach is highly valuable for analysis of large, irregularly shaped samples if not too high demands are set to the degree of accuracy.

Journal Article↗
PubMed1984

Whole-body elemental composition in patients with renal failure and after transplantation studied using total-body neutron-activation analysis.

Whole body elemental composition in seventy-five patients with either renal failure or a kidney transplant was measured by neutron-activation analysis and whole-body counting. Comparison was made with expected normal values and with a control group; between undialysed, dialysed and transplanted patients; and between those receiving dialysis treatment for various periods. A frequent finding was low body calcium, reflecting the prevalence of renal osteodystrophy. Sodium and chlorine were increased in undialysed patients, a consequence of their renal disease. Patients with transplanted kidneys had reduced amounts of most elements, indicating decreased lean body mass, but increased body weight, probably due to excess fat.

Body Composition↗
PubMed1980

Determination of manganese in tissues by neutron activation analysis using an antimony pentoxide column.

A rapid and accurate method is presented for the determination of manganese in biological samples, using neutron activation analysis. Biological samples were irradiated at 5000 kW for 30 min. The samples were ashed on a hot plate with 14 mol/l HNO3 and 6 mol/l HClO4, and resolved in 1 mol/l HClO4. 24Na and 24K were removed by passing each sample through in antimony pentoxide column. 54Mn was added as a tracer to calculate the ratio of manganese recovered by the separation procedure. Recovery was over 90%. This method was applied in order to determine manganese in various tissues. In the cervical spinal cord of the controls, the mean manganese concentrations in the anterior horn, the lateral and the posterior columns were 1.14, 1.06 and 0.90 ng/mg of dried tissue, respectively. In two cases if amyotrophic lateral sclerosis the manganese concentrations in the cervical spinal cord were elevated, particularly in the anterior horn and the lateral column.

Amyotrophic Lateral Sclerosis↗
PubMed2001

Preconcentration and preseparation procedure for platinum determination at trace levels by neutron activation analysis.

A procedure that simultaneously allows both preconcentration and preseparation of platinum for its determination by neutron activation analysis at trace levels (<0.1 microg x g(-1)) in environmental related matrixes is developed. The method is mainly based on a two-step chemical procedure: (i) a preirradiation concentration/separation based on a column chromatography separation where the platinum is previously retained and subsequently separated from Au, Ca, Na, Br, and P; (ii) a postirradiation separation/purification of the 199Au at 158.4 keV used for the platinum determination via [198Pt (n,gamma)-->199Pt (beta-)-->199Au]. The method eliminates the following radionuclides with the gamma lines in the region of 158 keV: 47Sc (daughter of Ca) at 159.3 keV; 199Au (produced by double neutron capture onto the natural 197Au) at 158.4 keV; 123m Te at 158.8 keV. In addition, the background activity deriving from 24Na, 32p, and 82Br is drastically reduced. The method was tested by the analysis of certified rock material and then applied for platinum determination in airborne particulate matter.

Journal Article↗
PubMed1985

Deranged Ca, Al and Mg content in the tissues of patients with chronic renal failure, as measured by non-destructive neutron activation analysis.

Ca, Al and Mg content in the bone, aorta, skin and hair of 55 persons was measured by non-destructive neutron activation analysis. The Ca content in the bone of nondialyzed and dialyzed patients was found to decrease. Al and Mg were relatively higher than Ca in the patients compared to the controls. The present study suggests that fluctuation in the content of Al and Mg may have some relation to renal osteodystrophy such as osteomalacia as well as similar and related disorders. Al and Mg content in the aorta, and that of Ca in the hair of uremic patients, were higher than the controls. The mean Ca content in the skin of the patients was 25% higher than the controls. These findings indicate 1) that Al and Mg are possibly related to the advance of osteodystrophy, and 2) that Ca, Al and Mg deposits in the organs of uremic patients are a reflection of metabolic disorders in chronic renal failure.

Adolescent↗