Application of the INAA methods for KRISS infant formula CRM analysis: standardization of INAA at KRISS

We have established an instrumental neutron activation analysis (INAA) method, including k₀-based INAA, at the Korea Research Institute of Standards and Science (KRISS) for the certification of reference materials. As part of establishing INAA measurements, KRISS infant formula certified reference material was analysed for multiple elements at three different metrological institutes: KRISS and NIST for the standard comparator method, and JSI for the k₀-INAA method. The mass fraction of most elements was consistent within expanded uncertainty (k?=?2). In addition, the results were used to verify the validity of elemental analysis of Zn using the standard comparator INAA at KRISS, and spreadsheet-based INAA calculations were evaluated.

     

Trace elements in the water cycle of the Šalek valley,Slovenia, using INAA

Three watersheds were studied by sampling bulk precipitation deposition, seepage water at 50 cm soil depth and spring water. As the main analytical method for determination of trace elements and heavy metals in water samples, thek ₀-based method of INAA was used. The results showed an increased content and concentration range of trace elements in precipitation, soil water and spring water in the vicinity of the otanj Thermal Power Plant. We demonstrated that thek ₀-based method of INAA as a multielement nondestructive technique is a highly suitable approach to determining some toxic trace elements in environmental studies of the water cycle.     

Implementation of <Emphasis Type="Italic">k</Emphasis><Subscript>0</Subscript>-standardization method of the INAA at ETRR-2 research reactor

The k ₀-method of INAA standardization has been implemented using the irradiation facilities of the fast pneumatic rabbit and some selected manually loaded irradiation positions, which designated for short and long irradiation, respectively, at Egypt second research reactor. The neutron flux parameters (f and α) in each site have been determined using Zr–Au sets as neutron flux monitors. The reference materials coal NIST 1632c and IAEA-Soil 7 were analyzed for data validation and good agreement between the experimental values and the certified values was obtained.     

Comparison of the catalogues of thek 0-and thek Zn single comparator methods for standardization in INAA

The independently measured catalogues of two single comparator methods for standardization in INAA, i.e., thek _Zn-and thek ₀-method, were compared. Many reactions were listed only in thek _Zn-catalogue; in these cases other literature data were used to supplement thek ₀-catalogue. The agreement between thek _Zn-and thek ₀-catalogue was found to be much better than the agreement between thek _Zn-catalogue and other literature data. It is therefore suggested to use the convertedk _Zn-catalogue as a supplement of the previously publishedk ₀-catalogue.     

INAA and PIXE for the determination of the contents of extractable sediment

The three-stage BCR sequential step reference extraction procedure was applied to the reference material BCR CRM 601, especially developed for fractionation studies. Extracted fractions were analyzed for Cr, Ni, Zn, Cd, and Pb, by k ₀-standardized instrumental neutron activation (k ₀ INAA) and proton induced X-ray emission (PIXE), and flame atomic absorption spectrometry (FAAS). Sample preparation procedures were developed for both k ₀ INAA and PIXE techniques, related to the evaporation of the solutions in order to get solid samples for neutron and proton irradiation. Quality control was assessed by intercomparison of the analytical results obtained by the applied techniques, which included results for a few certified reference materials. In the extracted fractions, chromium concentration was not determined accurately by both nuclear techniques. Concerning Cd, Ni, Pb, and Zn, the results were in general in good agreement with the certified values and FAAS. Some incomplete separation of the residue might have occurred.     

Element profiles of onion producing districts in Japan, as determined using INAA and PGA

We carried out instrumental neutron activation analysis (INAA) as well as k ₀-based prompt gamma-ray analysis (k ₀-PGA) to measure the amount of the elements in onions and studied whether the onions collected from different sites can be categorized based on the elemental concentration profile. Six elements (Na, Mg, Cl, K, Ca, Mn) and 3 elements (B, S, Cl) were measured by INAA and PGA in the onions grown in two districts, Hokkaido and Saga, in Japan, respectively. After principal component analysis, it was found that Cl was an important element to feature the producing districts of onions.     

Determination of trace elements in cigarette tobacco with the <Emphasis Type="Italic">k</Emphasis><Subscript>0</Subscript>-based NAA method using Es-Salam research reactor

The k ₀-standardization method of NAA is known as one of the most remarkable progress of NAA with its many advantages. Recently, our laboratory is highly involved in various areas of application of k ₀-NAA. This paper focuses on the application of the k ₀-NAA method in Nutritional and Health-Related Environmental field. Tobacco holds a leading position among different commodities of human consumption. The adverse health effects of toxic and trace elements in tobacco smoke on smokers and non-smokers are a special concern. In the present study, the concentration of 24 trace elements in cigarette tobacco of five different brands of Algerian and American cigarettes have been determined by k ₀-based INAA method. The results were compared with those obtained for samples from Iranian, Turkish, Brazilian and Mexican cigarettes tobacco. To evaluate the accurate of the results the SRM IAEA-140/TM was executed. The analytical results showed that the relative error of most of the elements was less than 10%.     

Establishing a basis for nuclear archaeometry in Australia using the 20 MW OPAL research reactor

The k ₀-method of standardisation for instrumental neutron activation analysis (INAA) has been used at the OPAL research reactor to determine the elemental composition of three certified reference materials: coal fly ash (SRM 1633b), brick clay (SRM 679) and Montana soil (SRM 2711). Of the 41 certified elements in the three materials, 88 percent were within five percent of the certified values and all determinations were within 15 percent of the certified values. The average difference between the measured and certified values was 0.1 percent, with a standard deviation of 4.1 percent. Since these reference materials are widely used as standards in the analysis of archaeological ceramics by INAA, it has been concluded that the INAA facility in Australia is particularly well-suited for nuclear archaeometry.     

Multielement Analysis of Iliac Crest Bone by Neutron Activation

The k ₁-method for standardization in INAA specifically tackles the problem of the interpretation of gamma-ray spectra as obtained with highly efficient detectors, as opposed to the k ₀-method. In this paper, results obtained from three NIST reference materials, measured after neutron activation with a gold-lined well-type detector, are presented. It is concluded that the accuracy of the method is better than 1%.     

Instrumental neutron activation analysis of large samples: A pilot experiment

A large sample INAA (LS-INAA) was conducted based on available experimental conditions. Four different materials, e.g., a quartz-sand and three wastes from an incineration plant were analyzed on sample size of 1 kg. The neutron flux spatial distribution was determined by irradiation of flux monitors in the sample. The gamma-ray apparent counting efficiency was evaluated based on the effective-solid angle concept, using linear attenuation coefficients calculated from an iteration process. The k ₀- and the modified monostandard methods were modified for the LS-INAA. To check the LS-INAA performance, a conventional small sample INAA was carried out for the quartz sand and a waste. All detected elements in the LS-INAA are presented and the discussion is conducted to explore the sources of errors in the LS-INAA. As a pilot experiment, the information from this work will be used in constructing irradiation and counting devices for the new FRM-II neutron source in Garching, Germany.     

Development and implementation of thek 0-standardization and other parametric methods of INAA in Cuba. Part II

The main results obtained during the characterization of the Triga Mark III reactor at NNRI, Salazar, Mexico, the development of the nonconventional multimonitor HAV-1, the use of Certified Reference Material (CRM) as multimonitor fork ₀-factors experimental determination, and to study the reactor power and slowing-down thickness dependencies of the reactor flux parameters and its influence ink ₀-INAA are presented. The experience of thek ₀-INAA group at ISCTN, in the application of this analytical technique for different purposes is resumed.     

The 1993 ISO Guide to the Expression of Uncertainty in Measurement Applied to NAA

Principles of the expression of uncertainty in measurements are briefly reviewed and special aspects of the uncertainty quantification in NAA are discussed in detail regarding the relative and k ₀-standardization in both modes of the technique, i.e., INAA and RNAA. A survey of uncertainty sources is presented and calculation of the combined uncertainty is demonstrated by an example of manganese determination in biological material by RNAA.     

Comparison of routine INAA procedures based on k0 and kZn standardizations

Performance characteristics (especially accuracy) of a routine INAA with k₀ standardization were verified and compared with those of INAA with a classical single comparator. For this purpose, samples of three certified reference materials of environmental origin (Fly Ash, Orchard Leaves and Buffalo River Sediment—all supplied by NIST) were irradiated with both kinds of comparators (Au–Zr for k₀ and Zn for classical k method) in one irradiation rabbit. Also the following steps of INAA procedure were practically the same for both standardization methods used (counting, spectral processing, etc.). The results have shown that the k₀ method gives sufficiently accurate results comparable with those of the well established and routinely used single comparator (Zn) method, provided proper neutron flux monitoring, efficiency calibration and also coincidence summing corrections are applied. This work shows that modern k₀ standardization method in INAA can be sucessfully used in routine practice and applied with an advantage in INAA laboratories subject to changes of neutron spectra or counting conditions.     

Marine gradients of halogens in moss studies by epithermal neutron activation analysis

INAA is known to be a powerful technique for the simultaneous determination of chlorine, bromine and iodine. In this paper INAA using epithermal neutrons is shown to be particularly useful to elucidate marine gradients of these elements. Examples are from a transect study in northern Norway where samples of the feather moss Hylocomium splendens were collected at distances of 0-300 km from the coastline. All three elements decrease exponentially as a function of distance from the ocean in the moss samples, strongly indicating that the atmospheric supply from the marine environment is the predominant source of these elements to the terrestrial ecosystem. It is suggested that environmental studies of halogens in general and iodine in particular is a promising future area of application for INAA, when employing epithermal neutrons. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thek 0 calibration of the IRI system for INAA of samples in the kg range

The feasibility of the INAA of samples in the kg range has been demonstrated in 1994 byOverwater et al. In his studies, however, he demonstrated only the agreement between the corrected -ray spectrum of large samples and that of small samples of the same material. In this paper, thek ₀-calibration of the IRI facilities for large samples is described, and some ofOverwater's results for homogeneous materials are presented again, this time in tems of (trace) element concentrations. It is concluded that large sample INAA can be as accurate as ordinary INAA.     

True coincidence correction for k0-method in INAA of plant materials with well-type detectors

Summary The k₀-method in INAA has been used at CENA/USP Brazil for analyzing geological and biological materials. With the acquisition of a well-type detector, it was realized that the true-coincidence effects, originally corrected by semi-empirical procedures with the in-house k₀-software (Quantu-INAA), would affect the accuracy of results. Thus, new coincidence correction algorithms were developed, based on a theoretical equation for obtaining the correction factors. Validation of the algorithms was performed by analysis of plant certified reference materials.     

Use of solvent isotope effect to identify an intermediate carbanion in the β-elimination reactions from N-[2-(4-pyridyl)ethyl]quinuclidinium and N-[2-(2-pyridyl)ethyl]quinuclidinium induced by acetohydroxamate/acetohydroxamic acid buffers

Solvent isotope effect is a useful technique for identifing and characterizing an intermediate carbanion in the base-induced -elimination reaction from N-[2-(4-pyridyl)ethyl]quinuclidinium, 1, and N-[2-(2-pyridyl)ethyl]quinuclidinium, 2. While at high [buffer]k _obs(D₂O) > k _obs(H₂O) due to the presence of a primary kinetic solvent isotope effect on the reprotonation of the intermediate carbanion by BD, at low [buffer] no solvent isotope effect is observed, and k _obs(D₂O) k _obs(H₂O). The data are in agreement with a reversible E1cb mechanism in which carbon deprotonation occurs from NH⁺, the substrate protonated at the nitrogen atom of the pyridine ring. In the absence of solvent isotope effect at low [buffer], and with the similarity of the results obtained with the two isomers, 1 and 2, the significance of an intramolecular proton transfer in the intermediate carbanion can be excluded in these processes.     

Comparison of relative INAA and k 0-INAA using soil and sediment reference materials

The objective of this work was to compare the results obtained by the relative INAA and k ₀-INAA methods for the same input parameters (sample mass, nuclear data, net peak area for the same gamma line and the same measurement and same cooling and measurement times). In total eight environmental soil and sediment reference materials (RM) or certified reference materials (CRM) from different producers were analysed. In this work only the recommended or certified values were considered, allowing comparison of the two methods for 30 elements. The results point out that k ₀-INAA possesses superior qualities compared to relative INAA, being insensitive to flux gradients, and independent of recommended/certified values in RMs/CRMs, often used as standards in relative INAA.     

Einfluß der Polarität und Viskosität des Lösungsmittels auf die Deaktivierung des S1-Zustandes von Donator-Akzeptor-substituiertentrans-Stilbenen

The dependence of the fluorescence constantsk _f ⁿ and the adiabatic twisting constantsk _tpof the S₁-State upon the solvent polarity, the capacity of hydrogen-bonding, as well as the solvent viscosity, were investigated for donor-acceptor substitutedtrans-stilbenes [4-dimethylamino-4-cyano-stilbene (1 g), 4-dimethylamino-4-diphenylphosphinyl-stilbene (1 b), 4-dimethylamino-4-brom-stilbene (1 h) and 4-dimethylamino-4-methoxistilbene (1 k)] by using the multiparameter model. An increase of the solvent polarity results in the decrease of the fluorescence ratek _f ⁿ for all these compounds. The specific interaction between the strongly polar stilbenes such as1 g and1 b and a solvent leads to additional decrease ink _f ⁿ but in the case of a relatively weak polar compound1 k to its growth. The linear combination of universal and specific solvent-solute interactions yields distinct relations fork _tp. Both interactions have an influence onk _tpfor1 g,1 b, and1 k to an equal degree. The twisting observed for1 g and1 b due to the interaction with solvent is hindered, however it is being supported for1 k. The influence of the investigated small range of viscosity onk _tpat simultaneous variable solvent polarity (pure solvent) is only visible for the weak polar1 k. In the other cases the effect of solvent-polarity is predominant.The viscosity dependence ofk _tpwas also experimentally proved for1 g,1 b and1 k by applying the obtained different dimethylformamid-acetonitril mixtures. According previous results the radiationless deactivation process is caused by twisting around ethyl-bonding, thereforek _tpevidently decreases with an increase of viscosity.

     

Application of neutron activation analysis to bone samples

Summary Neutron activation analysis technique, using Au as flux monitor, was applied to determine element concentrations of Ca, K, Na, Mg, Mn and Sr in certified reference material (NIST 1400 Bone Ash). The results were compared with those using comparative INAA and they were compatible. The same results were obtained using the recommended k₀ factors, in order to obtain the activation cross section as input in concentration for the same reference material. Some applications in the health area aiming clinical evaluation in bone samples of medium and small-sized animals were performed and the viability of using this methodology was discussed.