Multi-element analysis of japanese tea leaves by neutron activation analysis and the single comparator method

The reliability of the single comparator method in neutron activation analysis has been studied by comparing the calculated and experimental k values and by determining the concentration of trace elements in iron. The method has been applied to the analysis of tea leaves for thirteen elements; their concentrations varied over five orders of magnitude.     

The instrumental analysis of inactive tracers by photon activation

Because of incresing problems due to the general non-acceptance of the application of open radioactivity in modern industrial research an investigation was made concerning the possibility of replacing radiotracers by inactive substances activated by photons after sampling. As an example, investigations in the glass-processing industry was selected. The results were confirmed by the radiotracer experiment performed in parallel. The data obtained were in good agreement.     

Broad band application of combined instrumental photon and neutron activation analysis

The use of INAA and IPAA is illustrated by several applications (Zn-traces in Cu, neutron doping of Zn in copper, implanted Sb in silicon, trace elements in sediment material and polyethylene). The two methods are used to complement or to cross-check each other. Validation by IDA-TIMS was performed in the case of neutron doping and turned out to be a valuable support. Even developed routines of activation analysis need improvement. Two technical solutions, the high energy photon screen (HEPS) and a twin detector assembly, are dealt with in detail.     

Determination of nitrogen in boron carbide by instrumental photon activation analysis

Boron carbide is widely used as industrial material, because of its extreme hardness, and as a neutron absorber. As part of a round-robin exercise leading to certification of a new reference material (ERM-ED102) which was demanded by the industry we analysed nitrogen in boron carbide by inert gas fusion analysis (GFA) and instrumental photon activation analysis (IPAA) using the ¹⁴N(γ,n)¹³N nuclear reaction. The latter approach is the only non-destructive method among all the methods applied. By using photons with energy below the threshold of the ¹²C(γ,n)¹¹C reaction, we hindered activation of matrix and other impurities. A recently installed beam with a very low lateral activating flux gradient enabled us to homogeneously activate sample masses of approximately 1 g. Taking extra precautions, i.e. self-absorption correction and deconvolution of the complex decay curves, we calculated a nitrogen concentration of 2260 ± 100 μg g⁻¹, which is in good agreement with our GFA value of 2303 ± 64 μg g⁻¹. The values are the second and third highest of a rather atypical (non-S-shape) distribution of data of 14 round-robin participants. It is of utmost importance for the certification process that our IPAA value is the only one not produced by inert gas fusion analysis and, therefore, the only one which is not affected by a possible incomplete release of nitrogen from high-melting boron carbide. Figure Twin-Detector system for analyzing spatially extended samples     

Multi-elemental epithermal neutron activation analysis using an internal single comparator

Epithermal neutron activation analysis using an internal single comparator has been used for the analysis of Saudi Arabian iron ores. The concentration of thorium, barium, terbium, tantalum, cobalt, lanthanum and antimony was determined using iron in the ore as an internal comparator for all the elements. In case of antimony there was an agreement between this method and the conventional method indicating that the given method is accurate.     

Reactor neutron activation analysis by a triple comparator method

The single comparator method has been extended to a triple comparator method, using⁶⁰Co,^114m In and¹⁹⁸Au. In this technique, thek-ratios of the elements to be analyzed, now determined against the three comparators, are corrected for each new ratio of thermal to epithermal reactor neutron flux. These flux ratios are calculated from the absolute activities of the three comparators. The thermal neutron activation cross-section and the resonance integral for the reaction¹¹³In(n,γ)^114m In have been determined.     

The determination of some elements in rocks by instrumental photon activation analysis

This text describes the instrumental determination of some elements in silicate samples of ≃1 g by photon activation. The following elements can be determined: In acidic rocks: Mg, Ca, Ti, Mn, Sr, Zr and Nb, in ultramafic rocks: Mg, Cr, Ni, and Mn. The relative standard deviation is a few percent.     

Multi-element determinations of trace elements in glass by instrumental photon activation analysis

An instrumental photon activation method is reported for multi-element determinations in glass. The concentrations of 17 elements in NBS standard glass can be determined by irradiation with 30-MeV bremsstrahlung and measurement of the resulting γ-rays with a Ge(Li) detector. The average of all relative standard deviations is 2.7%; the relative deviations from the NBS certified values range from 1.4 to 3.4%.     

Nitrogen assay in winter wheat by short-time instrumental photon activation analysis and its comparison with the Kjeldahl method

The nitrogen content in winter wheat from various crops grown organically or conventionally was determined by instrumental photon activation analysis. The method utilizes measurement of the annihilation gamma line at 511 keV from the short-lived photoactivation product ¹³N, corrected for interference contributions from other positron emitting nuclides. Results compared well to those obtained by the Kjeldahl method. A positive impact of conventional agriculture on higher crude protein content in grain was found. Analysis of whole kernels and their germination and growth after irradiation were also tested.

     

Application of instrumental neutron activation analysis to ceramic solid electrolytes

Beta" alumina isomorphs with different conducting cations were produced by ion exchange in molten salts. The concentration of the main component (Al), of conducting ions (Na⁺, Sr⁺⁺, Ba⁺⁺) and of chlorides from residues of the melt inside the exchanged material was determined by instrumental neutron activation analysis (INAA).Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Multi-element analysis of soil from the north-western region of India by neutron activation analysis using the single comparator method with special reference to selenium toxicity

The single comparator (k₀) instrumental neutron activation analysis (INAA) was employed to determine the elemental composition of soil from the north-western region of India. The radiometric assay was carried out using high resolution gamma-ray spectrometry. Seventeen elements were detected including selenium whose concentration was found to be in the range of 1.02 to 6.79 mg/g.     

Application of anti-Compton counting in instrumental neutron activation analysis

The inherent advantage of anti-coincidence counting of low-level radioactivity is defined in terms of changes in the limits of decision, detection and determination. It appears that the advantage factor can be expressed in the experimentally observed reductions of peak area, compton continuum and natural background. For an array equipped with a sample changer the advantage factor for interference by the compton continuum is4, while that for interference by the natural background amounts to 3. By sacrificing the sample changer and closing its gap with a Nal-plug, additional factors of 1.5 and 2 can be obtained for compton and natural background respectively.     

Analysis of high-purity material—A comparison of photon activation analysis with other instrumental methods

Photon activation analysis (PAA) has been a well-established analytical method for about two decades. In this paper, its particular features are outlined in comparison with other modern instrumental techniques, especially radioanalytical methods, e.g. activation analysis with thermal or fast neutrons (NAA) or charged particles (CPA). Emphasis is placed upon the determination of trace components of high-purity material; iron, copper and lead matrix were selected as examples. In PAA, both instrumental and radiochemical procedures were applied. The results are presented in comparison with those obtained by other laboratories using a large variety of different techniques.     

Precise determination of macro contents of nitrogen in titanium carbonitride by instrumental photon activation analysis

SYNTH, a Windows^TM based software package developed for generating synthetic gamma-ray spectra, has been updated and extended to include the ability to generate gamma-ray spectra resulting from neutron activation. Along with a new gamma-ray library (based on the NNDC PCNuDat compilation), and the best available neutron cross-sections, it is now possible to simply, and quickly predict the interference effects of different bulk and trace element compositions by generating a synthetic gamma-ray spectrum that will be representative of a specific set of input parameters. The parameters include, but are not limited to: elemental composition (bulk, and trace) of the sample; irradiation, decay, and count times; thermal, and resonance neutron flux; sample to detector distance; detector specifications; and electronics configuration. Using existing data reduction codes, it is then possible to generate Minimum Detectable Activities (MDA's) for other trace elements that you may wish to detect in this type of matrix.     

Application of the internal standard method coupled with the standard addition method in photon activation analysis to trace characterization of environmental materials

The internal standard method coupled with the standard addition method has been applied to the analysis of environmental materials, such as urban particulate matter, vehicle exhaust particulates and coal fly ash by photon activation. High-resolution gamma-ray spectrometry makes possible to use multi-internal standard gamma-rays, in order to crosscheck the analytical results obtained from each internal standard. It was ascertained that this method can provide not only accurate analytical results but also the information of homogeneity of samples, correlation of elements in the sample, loss or contamination in the preparation process.     

Application of prompt gamma-ray analysis and instrumental neutron activation analysis to identify the beef production distinct

We present chemometric study to identify the provenance of agricultural product, beef. Combination of instrumental neutron activation analysis (INAA) and prompt gamma-ray analysis (k ₀-PGA) were performed to determine 10 elements, C, H, N, S, Sm, Br, Mg, Na, K, Cl, nondestructively. We measured elemental profiles in beef samples produced from different districts in Japan, Australia and USA. In the case of PGA, k ₀-method was employed to determine the elemental concentrations. There was a difference in elemental profiles between Japanese black cattle beef and that produced in USA through principal component analysis (PCA). However, Holstein beef of Japan and that of Australia was not sufficiently grouped by the PCA modeling with the elemental data set. This is the first study to identify the provenance of beef through elemental analysis.     

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.     

Error estimation of the single comparator method due to uncertainties of literature data for thermal and epithermal neutron activation cross-sections

The reliability of the single comparator method depends mainly on the accuracy of k factors. This paper describes error in theoretical k factors, especially that due to the scattering in literature data for thermal and epithermal neutron activation cross-sections. Error calculations were performed for thirteen elements using comparator sets of⁶⁰Co−¹⁹⁸Au and⁹⁵Zr−⁹⁷Zr to evaluate the accuracy of this method.     

Application of X-ray spectroscopy in nondestructive photon activation analysis

A survey is given on the use of X-ray spectroscopy for the qualitative and quantitative analysis of samples activated by 30 MeV bremsstrahlung from an electron linear accelerator. Detection limits are calculated from the measured X-ray spectra and compared with those for γ-ray spectroscopy. The advantages and limitations of the method are discussed. Some practical applications of X-ray spectroscopy in nondestructive multielement analysis are quoted.