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.     

BEAMGAA: A chance for high precision analysis of big samples

Summary In activation analysis of traces in small samples, the non-equivalence of the activating radiation doses of sample and calibration material gives rise to sometimes tolerable systematic errors. Conversely, analysis of major components usually demands high trueness and precision. To meet this, beam geometry activation analysis (BEAMGAA) procedures have been developed for instrumental photon (IPAA) and neutron activation analysis (INAA) in which the activating neutron/photon beam exhibits broad, flat-topped characteristics. This results in a very low lateral activating flux gradient compared to known radiation facilities, however, at significantly lower flux density. The axial flux gradient can be accounted for by a monitor-sample-monitor assembly. As a first approach, major components were determined in high purity substances as well as selenium in a cattle fodder additive.     

Application of epithermal neutron activation in multielement analysis of silicate rocks employing both coaxial Ge(Li) and low energy photon detector systems

The instrumental activation analysis of silicate rocks using epithermal neutrons has been studied using both high resolution coaxial Ge(Li) detectors and low energy photon detectors, and applied to the determination of 23 elements in eight new U.S.G.S. standard rocks. The analytical use X-ray peaks associated with electron capture or internal conversion processes has been evaluated. Of 28 elements which can be considered to be determinable by instrumental means, the epithermal activation approach is capable of giving improved sensitivity and precision in 16 cases, over the normal INAA procedure. In eleven cases the use of the low energy photon detector is thought to show advantages over convertional coaxial Ge(Li) spectroscopy.     

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.     

Application of the single comparator method to instrumental photon activation analysis

Journal of Radioanalytical and Nuclear Chemistry - Instrumental photon activation analysis (IPAA) is nondestructive and multi-elemental analysis method like instrumental neutron activation...     

Activation analysis of trace metals in several kinds of tissues of even-toed ungulates

The normal concentration levels of trace metals in several kinds of tissues of even-toed ungulates have been determined by instrumental neutron activation analysis, photon activation analysis, and flame atomic absorption spectrometry. In the present work the concentrations of 13 elements (Ag, Br, Ca, Co, Cu, Fe, Mg, Mn, Mo, Na, Rb, Se, and Zn) were analyzed.     

Use of low energy photon spectroscopy in activation analysis of noble metals with high-energy bremsstrahlung

Noble metals have been analyzed in high purity copper and a platinum ore to be certified as reference materials. Analyses were performed by photon activation analyses using both conventional gamma and low energy photon spectroscopy. Our values agree very well with those of other laboratories using various analysis methods. Low energy photon spectroscopy is more advantageous than gamma spectroscopy from various points of view.     

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.     

Quantitative evaluation of interference reactions in photon activation analysis

Interferences of different types (competing reactions, overlapping photons emission energies etc.) occur more frequently during activation analysis with high energy exciting radiation that in conventional thermal neutron activation. Three main types of interference in high energy photon activation analysis (PAA) have been determined quantitatively, using experimentally obtained data exclusively. Based on the results presented, it is possible in many critical cases to improve significantly the accuracy of analysis results obtained by PAA.     

NAA of Platinum Group Elements and Gold in Reference Materials: A Comparison of Two Methods

Two methods have been developed for the determination of platinum group elements (PGEs) and gold in four geological reference materials: one using radiochemical neutron activation analysis and the other using nickel sulphide fire assay, followed by instrumental neutron activation analysis. The results from ten multiplicate measurements have been discussed in terms of precision and accuracy. The average precision for both methods is about 5%. Comparing the reported data with existing values in the literature, the accuracy of the proposed methods is good agreement in most cases. Detection limits in the range 0.001–0.015 ng have been derived for both methods under the operational conditions.     

Different methodologies in neutron activation to approach the full analysis of environmental and nutritional samples

Different methodologies of neutron activation analysis (NAA) are now available at the Technological and Nuclear Institute (Sacavém, Portugal), namely Compton suppression, epithermal activation, replicate and cyclic activation, and low energy photon measurement. Prompt gamma activation analysis (PGAA) will be implemented soon. Results by instrumental NAA and PGAA on environmental and nutritional samples are discussed herein, showing that PGAA — carried out at the Institute of Isotope Research (Budapest, Hungary) — brings about an effective input to assessing relevant elements. Sensitivity enhancement in NAA by Compton suppression is also illustrated. Through a judicious combination of methodologies, practically all elements of interest in pollution and nutrition terms can be determined.     

The determination of pd,pt, au,ag and ir in copper by neutron activation analysis

The determination of palladium, platinum and gold in copper metal by neutron activation analysis is described. The matrix activity was separated from the noble metals by cation-exchange adsorption. Gold was extracted; palladium and platinum were precipitated. The precipitates were counted with a low-energy photon detector. The gold results were checked by instrumental neutron activation analysis. Silver, iridium, selenium, antimony and arsenic were also determined simultaneously.     

How Effectively is the Photon Activation Analysis Applied to Meteorite Samples?

Chondritic meteorite samples were analyzed nondestructively by photon activation analysis. Powdered samples weighing about 50 mg each were irradiated with photons (-rays) converted from electrons accelerated by a linear electron accelerator at 20 and 30 MeV. With 30-minute and 6-hour irradiations, 11 and 12 elements with duplication of 6 elements could be determined, respectively. Considering that several major elements including Mg, Si and Fe can be determined in addition to Ti, Rb, Sr, Y and Zr, which cannot or hardly be determined by instrumental neutron activation analysis (INAA) with rather high sensitivity, instrumental photon activation analysis is as effective as INAA.     

Geochemical characterization of impact glasses from the Zhamanshin crater by various modes of activation analysis. Remarks on genesis of irghizites

A large set of impact glasses from the Zhamanshin crater in Kazakhstan was analyzed by various modes of instrumental neutron activation analysis, supplemented by instrumental photon activation analysis and prompt gamma-ray activation analysis. Results of the determination of more than forty major and trace elements have shown that the analyzed set of homogeneous, tektite-like impact glasses with size of several centimeters and of various forms could be divided into two geochemically different groups. The lustrous, silica rich (acidic) glasses with high Ni content have been classified conventionally as irghizites. The dull, silica poor (basic) glasses with very low Ni content should not be confused with the large, heterogeneous impactite forms??zhamanshinites, but considered as a separate type of impact glass. Within both primary groups, further division has been suggested based on lower contents of Ni in an irghizite subgroup, and evidence of mixing of source materials for both primary groups in a part of the basic glasses. Based on the contents of Ni, Cr, Mn, Fe and Co, an ordinary chondrite impactor has been suggested with its contribution to the irghizite matter ranging between 4 and 21%. Possible source materials and impact processes leading to irghizite formation have been outlined.     

Application of an Apple IIe microprocessor for data acquisition and analysis in instrumental neutron activation analysis with a low energy photon detector

The determination of thirteen elements, eleven rare-earth elements (La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Tm, Tb and Lu), thorium and uranium were performed by instrumental neutron activation analysis for four geological reference materials (G-2, AGV-1, GSP-1 and SY-2) as well as our laboratory rare-earth standard. The analyses were performed using a low energy photon detector coupled to an Apple IIe microprocessor employed as a multichannel analyzer not only to collect the data but also for data analysis. Finally, based on this work we have proposed a simple, rapid routine method for the determination of eleven rare-earth elements, thorium and uranium in geological materials employing IVIC's RV-1 nuclear reactor.     

A comparison of neutron activation and alpha spectroscopy analyses of thorium in crystalline rocks

The concentrations of Th in samples of crystalline rock from three drillcore sections were analysed independently by instrumental neutron activation analysis and by chemical separation and alpha spectroscopy. The two methods show good general agreement over an approximate concentration range of 1 to 100 ppm Th. Variations in results between the two methods are not of a systematic nature and probably arise from sample heterogeneity. The results confirm the reliability of both methods and provide a useful comparison of the standards and reference materials used. The study indicates that, in cases where Th isotopic information is not required, the simpler and more rapid neutron activation analysis provides a satisfactory method.     

The problem of large samples: An activation analysis study of electronic waste material

Large-volume instrumental photon activation analysis (IPAA) was used for the investigation of shredded electronic waste material. Sample masses from 1 to 150 grams were analyzed to obtain an estimate of the minimum sample size to be taken to achieve a representativeness of the results which is satisfactory for a defined investigation task. Furthermore, the influence of irradiation and measurement parameters upon the quality of the analytical results were studied. Finally, the analytical data obtained from IPAA and instrumental neutron activation analysis (INAA), both carried out in a large-volume mode, were compared. Only parts of the values were found in satisfactory agreement.     

Application of different activation analysis techniques for determination of trace elements in human blood

One of the requirements of stable isotope tracer technique is detection of two isotopes of same element. It is preferable to use instrumental techniques in order not to contaminate the samples. Different instrumental nuclear techniques namely neutron activation analysis (NAA), photon activation analysis (IPAA), and prompt gamma ray activation analysis (PGAA) were tried on human blood samples. The techniques were found to be complementary to each other, NAA being the most sensitive of the three. Zinc is choosen for validation work among the three feasible elements (Zn, Cr, Se) for stable isotope tracer technique. As NAA was not sufficient to detect two isotopes of Zn, a radiochemical separation scheme was developed later.     

Development of a combined method to carry out a multielement analysis for environment preser vation

The paper discusses the possibilities of energy dispersive X-ray fluorescence spectroscopy and instrumental neutron activation analysis in the investigation of environmental pollutions. The X-ray fluorescence spectroscopy of samples was performed using the MECA-1044A analyzer (XR-500, LINC SYSTEMS, Great Britain) with a pulsed X-ray tube with a silver target as a source of excitation. Neutron activation analysis was carried out on the basis of two reactors: IBR-2 LNP JINR, Dubna, and TWR ITEP, Moscow. The optimal regimes of measurement for both methods as well as the detection limits corresponding to these regimes are given. To illustrate the perspectives of the methods, the ecological problem of the consequences of introducing into soil of the now available meliorator CaSO₄·2H₂O is solved in the paper. Data on absorption of trace elements in a wide range including rare-earth elements by agricultural plants are presented. This paper may be of interest for specialists in analytical chemistry and ecology.