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PubMed1980

[Neutron activation analysis of selenium using a coincidence counting method (author's transl)].

Neutron activation analysis of selenium using 75Se has been investigated by means of a coincidence counting of gamma-rays in the cascade decay series by a NaI(TI) detector and a Ge(Li) detector. Using this method, the background around the photopeak of 75Se-265 keV could be reduced to one twentieth, and thus the detection limit of selenium could be improved four times higher than the usual method. For examining the accuracy of this measuring method, selenium contained in Bovine Liver (NBS) was determined and the content of selenium was found to be 1.02 micrograms/g (the certified value is 1.1 +/- 0.01 micrograms/g). Selenium content in Orchard Leaves (NBS) was determined to be 0.081 +/- 0.006 micrograms/g (the certified value is 0.08 +/- 0.01 micrograms/g), though its non-destructive determination was difficult because of its very low content. The results obtained here indicate that the accuracy, the precision and the reproducibility for selenium determination are thought to be adequate. As an example of a sample containing many interference nuclides, selenium in a soot was determined on the basis of these results.

Activation Analysis↗
PubMed1999

An evaluation of thermal and epithermal neutron activation analysis compton suppression methods for biological reference materials.

For neutron activation analysis (NAA), the usual matrix problems of sodium, chlorine, and bromine are well known to give rise to high backgrounds that inhibit the determination of several trace elements for short-lived or medium-lived NAA. For long counting times in long-lived NAA, very low backgrounds are required to achieve good sensitivities. We have investigated the use of thermal and epithermal NAA in conjunction with Compton suppression to determine several elements such as arsenic, antimony, cadmium, and mercury, at the level of a few nanograms. The values of these techniques are discussed in contrast to the standard radiochemical methods.

Biological Assay↗
PubMed1994

A survey of trace elements in fresh-water fish and rice along the Han River by neutron activation analysis.

For a case study of environmental pollution, radiochemical neutron activation analysis (RNAA) was applied to the crucian and rice collected along the Han River. The crucian was analyzed for three times in 1973, 1987, and 1990. Sixteen trace elements (Hg, Cd, As, Br, Cu, Na, K, Se, Cr, Hf, Rb, Fe, Zn, Co, La, and Cs) were determined by RNAA using distillation and diethyldithiocarbamate extraction methods. Contents of Na, K, Se, Hf, Fe, Zn, and Co were almost constant regardless of the sampling place and year. The contents of the other elements showed increasing trends down river, especially in the first investigation. At the lower part of the river, the contents showed decreasing trends with the time of sampling, especially during the first two investigations. These trends were typical for Hg and Cd. Rice was analyzed by the same method for 12 elements, and the results showed no regional trends, but have decreased after 1973.

Animals↗
PubMed1989

Salts as a source of metals in dialysis fluids: an assessment study by means of neutron activation analysis.

Thirty-nine trace metals were determined by neutron activation analysis (NAA) in nine salts (glucose, NaCl, KCl, CaCl2, MgCl2, Na-lactate, Na-acetate, NaHCO3 and NaOH), from different European producers, used in the preparation of dialysis fluids. Metal concentrations vary widely from less than 1 ng g-1 to several micrograms per gram. The data are used to assess the potential metal contribution of the salts to a hypothetical dialysis fluid. A comparison of these calculations with NAA of commercial haemodialysis solutions, and water used for their preparation, suggests that salts are the main source of metal contamination of the dialysate. Despite this, the chemical purity of the salts analyzed is considered to be good and it would be unrealistic to expect a clearly better chemical quality on a commercial scale. In order to protect the health of dialysis patients against abnormal metal exposure, toxicological research directed towards the estimation of the effective daily metal exposure and the determination of possible metal overloads in dialysis patients is necessary. A standardization of the dialysis systems actually used is also an important aspect if uncontrolled metal contamination of the dialysis fluid is to be avoided.

Humans↗
PubMed1988

Determination of U in human tissues by delayed neutron activation analysis.

A rapid, sensitive and highly selective technique using Delayed Neutron Activation Analysis (DNAA) has been used to determine U concentrations in human tissues. Two different sample preparation techniques were compared: one involves total matrix destruction to a dry ash while the other is a nondestructive preparation of the wet sample. The data obtained from the analyses of the same sample by DNAA of wet tissues, DNAA of ashed tissues and from radiochemical analyses using alpha spectroscopy (a standard method of U determination) were statistically equivalent on the basis of variance analysis at the p = 0.05 level.

Activation Analysis↗
PubMed1990

Calibration of a prompt neutron activation analysis facility for the measurement of total body protein.

Prompt neutron activation analysis with 252Cf has been used to measure total body protein. Since simultaneous irradiation and detection generated a high count rate at the detectors the nucleonic system was optimised to reduce distortions in the gamma ray energy spectrum. Tissue-equivalent phantoms were used to calibrate the apparatus. A total of 53 studies was performed on 39 normal subjects. Ratios of total body protein to fat-free mass agreed well with those from other centres and with cadaver studies. Duplicate measurements of 14 subjects gave a coefficient of variation of +/- 2.9% for a measurement of total body protein, which is close to that calculated from the known errors of the technique of +/- 2.7%. The whole body dose equivalent was 0.17 mSv.

Activation Analysis↗
PubMed2002

Instrumental neutron activation analysis of archaeological ceramics: scale and interpretation.

Instrumental neutron activation analysis has become a standard technique for the study of the production and distributional patterns of archaeological pottery. Questions once framed within the context of long distance exchange are now focused on issues of subregional and even intrasite levels. The increasing specificity at which these questions are poised requires a high level of analytical precision as we seek to observe statistically and archaeologically significant differences among groups of pottery produced from geographically closely spaced resources or the compositional differences that arise from production behaviors of the producers of the pottery.

Journal Article↗
PubMed1980

Redox substoichiometry in neutron activation analysis. Determination of antimony in metallic tin.

Redox substoichiometry in neutron activation analysis has been applied to the determination of antimony content in metallic tin of chemical grade. The substoichiometric separation is based on the extraction of unreacted antimony(III) with an excess of N-benzoyl-N-phenylhydroxylamine (BPHA) after the substoichiometric oxidation of antimony(III) with potassium bromate, such as arsenic(III), could be prevented by the addition of large amounts of antimony(III) carrier before substoichiometric oxidation. Only about one hour is required for the antimony analysis of metallic tin, excluding the irradiation period of sample. The antimony content of 1.22 +/- 0.14 microgram tin (10 mg) was determined without separation of the matrix element.

Antimony↗
PubMed2006

Epithermal neutron activation analysis of Cr(VI)-reducer basalt-inhabiting bacteria.

Epithermal neutron activation analysis (ENAA) has been applied to study elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance, demonstrating that the bacteria differ in their rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(V) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 microg/g of dry weight) indicate bacterial adaptation to the environmental conditions typical of the basalts. The concentrations of at least 12-19 different elements were determined in each type of bacteria simultaneously starting with the major to ultratrace elements. The range of concentrations spans over 8 orders of magnitude.

Arthrobacter↗
PubMed1981

Instrumental neutron activation analysis of brain aluminum in Alzheimer disease and aging.

Instrumental neutron activation analysis procedures were used to determine the aluminum content of various brain regions in histologically verified Alzheimer disease (AD) and in controls. The grand mean aluminum level for 74 AD specimens was 0.372 +/- 0.058 microgram/gm and for 137 adult controls, 0.467 +/- 0.033 microgram/gm, both on a wet weight basis. No difference was found at the bulk sample level between AD and adult controls, corrected for age and sex, or when frontal, temporal, and hippocampal specimens were compared. Control specimens (infancy to 85 years) showed an increase in brain aluminum concentration with age. Comparison of freeze-dried to wet weight ratios of AD and controls revealed a small increase in water content in AD brains.

Adolescent↗
PubMed2001

The feasibility of accelerator-based in vivo neutron activation analysis of nitrogen.

The feasibility of accelerator-based in vivo neutron activation analysis of nitrogen has been investigated. It was found that a moderated neutron flux from approximately 10 microA of 2.5 MeV protons on a 9Be target performed as well as, and possibly slightly better than the existing isotope-based approach in terms of net counts per unit subject dose. Such a system may be an attractive alternative to the widespread use of (238,239)Pu/Be or 252Cf neutron sources, since there is more flexibility in the energy spectrum generated by accelerator-based neutron sources. From a radiation safety standpoint, accelerators have the advantage in that they only produce radiation when in operation. Furthermore, an accelerator beam can be pulsed, to reduce background detected in the prompt-gamma measurement, and such a device has a wide range of additional biological and medical applications.

Body Composition↗