Neutron Activation Analysis Method Research Articles

Determination of uranium in ores using instrumental neutron activation analysis

An instrumental neutron activation analysis method based on the measurement of239Np has been developed for the determination of uranium in ores. The samples after 5 sec irradiation were cooled for 3 days and the gamma-ray spectra were measured with a 30 cm3 Ge(Li) detector. The precision and accuracy of the proposed method were determined by analysing IAEA Standard Uranium Ore samples.

Relative chromium response as an indicator of chromium status

Twenty-seven women ages 40 to 75 were divided into normal (n = 15) and hyperglycemic (n = 12) groups on the basis of 3-hr glucose tolerance tests. Each subject received 5 g of brewer's yeast extract containing 4 µg of chromium daily for 3 months. Glucose, insulin, and chromium levels were analyzed by oxidase, radioimmunoassay, and radiochemical neutron activation analysis methods, respectively. The fasting and 1-hr serum chromium levels (ng/ml) changed from 1.67 and 1.43 to 1.46 and 1.86 in the normal group, and from 1.89 and 1.03 to 0.94 and 1.03 in the hyperglycemic group. Considerable changes occurred in the relative chromium response (RCR) at the 1-hr point. RCR is defined as (1-hr serum chromium level/fasting serum chromium level) × 100. Among the normal subjects, 73% showed an improved RCR after the supplementation: mean RCR was 107% before and 140% after. Among the hyperglycemic subjects, 75% showed an improved RCR: mean RCR was 81% before and 149% after the supplementation. The increased RCR was associated with decreased serum insulin and glucose levels. This is interpreted as reflecting an improved chromium status for the majority of individuals in both groups after the supplementation. The observations suggest that: 1) in response to a glucose load, serum chromium levels drop in subjects with presumably inadequate chromium storage; 2) a low value of relative chromium response at the 1-hr point indicates a suboptimal chromium nutritional status.

Two types of island arc tholeiite in Japan

Abundances of fourteen trace elements were determined for ten representative tholeiitic basalts from the Northeast Japan arc by instrumental neutron activation analysis and fission track methods. Comparison of geochemical features of the tholeiitic basalts from the Kurile, Northeast Japan and Izu-Bonin arcs suggests that island arc tholeiites in Japan can be further classified into at least two types: Izu-Bonin type and Northeast Japan type. The latter type island arc tholeiites have relatively higher La/Yb and Th/U ratios than the former.

Low level mercury analysis by neutron activation analysis

During the years 1974–77 about 200 low level mercury analyses on samples with less than 1000 ng Hg/kg were made at the Danish Isotope Centre. This paper describes our method of neutron activation analysis for low level mercury analysis. The accuracy of the mercury analyses is shown by the results of the determinations on NBS standard, SRM 1642, and on intercalibration analyses. The accuracy found is better than 10% for samples with about 100–300 ng Hg/kg and better than 10 ng Hg/kg for samples with less than 100 ng Hg/kg. The limit of detection for the analyses is about 1–5 ng Hg/kg, depending on the sample and the exact method of analysis. The lowest standard deviations on duplicate analyses are about 1 ng Hg/kg. The general level found in sea water is about 10 ng Hg/kg, in ground water about 50 ng Hg/kg, and in rain water about 100 ng Hg/kg.

Retrospective trend analysis of the content of U.K. air particulate material 1957–1974

Particulate air samples have been collected on a daily basis in a high volume air sampler at Chilton (Oxfordshire U.K.) a semi-rural site in southern England from 1957 to 1974. Although the samples collected on esparto grass filters were intended to measure debris from nuclear weapons, they have proved susceptible to analysis for a variety of inorganic elements and ions. The concentration of twenty-seven elements and ions have been determined by instrumental neutron activation analysis and other methods. Measurements were performed on three-monthly groups of samples over seventeen years. Comparison with another series of current measurements over the latter part of the period indicate that the results are probably valid and thus, may represent the longest period for which continuous data of this nature are available. The detailed results are presented here. There are marked fluctuations in the levels displayed which can be categorised in three ways. There are seasonal changes. Winter levels, due either to increased emission rates or to meteorological phenomena, are greater than summer. The largest seasonal differences occur with chalcophilic (volatile) elements. Medium term fluctuations, in which excursions continue over extended periods, occur in similar ways with most constituents. A difference between the behaviour of anthropogenic and marine components indicate a meteorological mechanism for these changes. The most interesting changes are those showing long term trends. Many elements exhibit initial high levels with a rapid decline to 1961 and thereafter fall more slowly. The similarity of this behaviour with that of local “black smoke” indicates a component in the inorganic aerosol at Chilton from coal burning or industrial sources. The behavior of some lithophilic elements suggests an additional natural source. The behaviour of lead is consistent with a rise in emissions from petrol although there appears to be a residual component from other anthropogenic sources. A rise in bromine levels too, might be similarly explained. Vanadium appears to arise from the combustion of fuel oil now in increasing use. Concentrations of ammonium sulphate rise during the summers of the survey. It is likely that a photochemical mechanism for the production of sulphur dioxide oxidants from automobile exhaust is responsible. Similar photochemical processes and other reactions may cause the rises of ammonium nitrate although these display less seasonal bias. This survey at a single site demonstrates the value of data gathered over a long period, and emphasises the need to conduct controlled measurements for similar times at a variety of differing environmental and geographical locations.

Dietary intake of 25 elements by man estimated by neutron activation analysis

The trace element content of the total daily diet (food and beverages) of each of 4 adult males was determined over a period of one week. A method of radiochemical neutron activation analysis is briefly described which enables the determination of up to 31 elements in biological samples. Of the 25 elements determined in the diet 12 are essential elements (Ca, Cl, Co, Cr, Cu, Fe, K, Mn, Mo, Na, Se, Zn) while 6 (As, Ba, Br, Cd, Hg, Sb) are classified as toxic. The average concentrations of the toxic trace elements As, Cd and Hg of the diet are below the provisional tolerable dietary intakes recommended by WHO/FAO. The contents of Cl, Cu, Fe, K, Mn, Na and Zn are adequate to the proposed nutritional requirements.

Determination of heavy metals in sewage-based fertilizer using short-lived isotopes

A fully instrumental method for the neutron activation analysis of heavy metals in sewage sludges has been developed, based on short-lived isotopes, and restricting the total experiment time to 1 hour per sample. The irradiation scheme consists of a cyclic and conventional part, the period of the cyclic irradiation being optimised for the determination of lead, using207mPb (T=0.8 s). Gamma ray spectra from Ge(Li) detectors are stored on magnetic tape and analysed using the SAMPO programme. An IDENTIFY subroutine enables absolute determinations to be made eliminating the need for standards. Sensitivities and detection limits for 21 heavy metals have been determined and the results for several sludges are presented.

Scalp hair as a monitor of population exposure to environmental pollutants

Concentrations of As, Cd, Hg, Pb, Sb and Zn have been measured in hair from population groups with varied types of environmental exposure. Rural and urban controls have exhibited low levels of most toxic elements, whereas people residing near urban lead refineries, rural gold refinery and other industries have shown high elemental concentrations in their hair. A combination of instrumental as well as radiochemical neutron and photon activation analysis methods have been used to determine the concentrations of the above elements. The precision and accuracy of these methods have been evaluated.

Optimal use of instrumental neutron and photon activation analyses for multielement determinations in sewage sludges

A combination of instrumental neutron activation analysis (INAA) and instrumental photon activation analysis (IPAA) methods has been developed for multielement determinations in a variety of sludges and fertilizers. The precision and accuracy of both the methods have been evaluated by analyzing replicate samples, NBS standard reference materials, and an interlaboratory intercomparison sewage sludge sample. The concentration rages of up to 50 elements in raw and chemical sludges, sludge-based fertilizers, and other organic and inorganic fertilizers are reported here. The advantages and limitations of the INAA and IPAA methods are also discussed here.

Neutron activation analysis of high purity noble metals (palladium, platinum, rhodium, gold and silver)

Methods of neutron activation analysis of high purity noble metals have been developed based on the selective extraction procedures for matrix activities separation. These procedures are shown to provide purification coefficients from matrix of about 106–108. High-resolution gamma-spectrometry makes possible the determination of 25–30 elements simultaneously in aqueous phases remained after matrix separation. Complex standard for NA analysis of pure materials has been described.

Determination of molybdenum and cobalt in hydrodesulfurization catalysts using a computerized radioisotope x-ray fluorescence system

A rapid, non-destructive method is presented for the determination molybdenum and cobalt in hydrodesulfurization catalysts employing a PDP-11/05 computer-base radioisotope x-ray fluorescence technique. Precision for molybdenum and cobalt better than 2.5% and 4.0%, respectively, are achieved in 100 sec of fluorescent time. The values obtained by this method are in agreement with values from atomic absorption and neutron activation methods. Besides being nondestructive, only about 50 mg of sample is needed, and no time-consuming acid dissolution is required as in atomic absorption and colorimetric methods. The results for six different commercial catalysts are compared with determinations by atomic absorption, neutron activation analysis methods as well as an x-ray fluorescence system with manual calculations of the percentage of molybdenum and cobalt.

Survey of trace elements in coals and coal-related materials by neutron activation analysis

Utilizing primarily instrumental neutron activation analysis (INAA) and other analytical methods as many as 61 elements were quantitatively surveyed in 170 U.S. whole coals, 70 washed coals, and 40 bench samples. Data on areal and vertical distributions in various regions were obtained along with extensive information on the mode of occurrence of various elements in the coal matrix itself.

A very rapid instrumental neutron activation analysis method for the forensic comparasion of bullet-lead specimens

Since speed of attainment of results is often essential in actual case work in crime investigation, a new and much faster instrumental neutron activation analysis method has been developed for the intercomparison of bullet-lead specimens. It utilizes the 93-sec124m 1Sb, 24.4-sec110Ag, and 5.10-min66Cu induced activities, and requires only about three minutes per sample. The method has already been employed in a number of criminal cases.

The determination of ko factors and their application to the neutron activation analysis of pure zirconium metal by the single-comparator method

The procedures followed for the determination of standardization factors and their use in the single-comparator method for multi-element reactor neutron activation analysis are described. The method is applied to the determination of Cr, Mn, Fe, Ni and Mo in pure zirconium metal. The matrix could serve as the single comparator and as a bi-isotopic thermal-to-epithermal neutron flux ratio monitor.

Determination of cobalt, molybdenum, and nickel in hydrodesulfurization catalysts by neutron capture .gamma.-ray spectrometry and neutron activation analysis

Neutron capture ..gamma..-ray spectrometry has been applied to analyze 12 hydrodesulfurization catalysts. A collimated neutron beam has been constructed allowing the nondestructive determination of Co and Mo in 10 min. If Ni is present, an additional 30 min per sample was required. Titanium oxide is used as internal standard and the metal/titanium counts ratio is linear with respect to the corresponding mass ratio. The method is independent of flux inhomogeneities and sample geometry effects. Standard deviations of 5% were typical for concentration ranges of 2 to 15%. Unavailability of a standard reference catalyst led to the development of a neutron activation analysis method. The two methods differed from 0 to 13% for 11 samples.

Trace Element Contamination of Intravenous Solutions

The trace element content of various intravenous solutions was investigated, using atomic absorption and neutron activation analysis methods. The variable content of zinc, calcium, and magnesium led us to seek a source of contamination. Quantities of zinc ranging from 10.75 mug to 132 mug were leached from the rubber stoppers when placed in 0.1N nitric acid for a period of 96 hours. Calcium and magnesium were also leached from the stoppers, but in lesser amounts.

Concentration and distribution pattern studies of some admixtures in boron and its compounds and the investigation of the conductivity mechanism in β-rhombohedral boron

In this work, the quantitative determination of admixtures of Na, Mg, Al, Cl, V, Mn, Fe, Cu, Br, Mo, Ta, W, Ca, Ti, Co, Ag, Pt, Au, Pd and Ir in boron, B 2O 3, H 3BO 3, and B 4C, has been carried out using combined instrumental and autoradiographical methods of neutron activation analysis. The results of distribution-pattern determinations in zone-melted β-rhombohedral boron samples are given for technologically-occurring impurities such as manganese, iron, molybdenum, tungsten, and tantalum. In the course of the analysis, corrections were made for the self-shielding effect due to the large value of the boron thermal-neutron capture cross-section. Experimental trace-determination sensitivity ranged from 10 −4 to 10 −10 g for sample weights of not more than 0.3 g, and the root mean square error was in the range 10–20%.

Neutron activation analysis method for the determination of neptunium in sub-microgram quantities in process solutions

A neutron activation analysis method, for the estimation of sub-microgram level237Np present in process solutions of a fuel reprocessing plant is described.

Determination of selenium in steel by neutron activation and Ge(Li)γ-spectrometry

Two methods of instrumental neutron activation analysis for the determination of selenium in steels, based on respectively77mSe (t1/2= 17.5 s) and75Se (t1/2 = 120 d) are presented. Good agreement is obtained by application of both methods on a series of steels containing selenium at the 0.1% level. Interferences and advantages associated with either method are discussed.

Bromide residues in lettuce after soil fumigation with methyl bromide, and some factors involved

High bromide residue levels in agricultural crops have been determined by several authors; however, different residue tolerances are proposed by different countries and organisations. It was therefore our aim to study a few of the factors affecting the bromide content of plants after soil fumigation with methyl bromide. For this purpose, lettuce plants were chosen as test material for experiments with regard to the problematic accumulation of bromide in this species. Some soil conditions that are optimal for effective fumigation are also favorable for a low bromide content in the plant, while others are not. The effects of several factors are discussed. Bromide content was measured colorimetrically and on one occasion the results were checked by means of the instrumental neutron activation analysis method.