Multielement standards for instrumental neutron activation analysis of biological materials

Standards for instrumental neutron activation analysis (INAA) of biological materials are proposed. The standards are multielement solid solutions in phenol-formaldehyde resole resin (PFR) moulded as pellets weighing 30 to 50 mg. The concentrations of trace elements in the standards are selected so that, firstly, they are commensurable with their concentrations in the biological materials and, secondly, that the analytical lines of each of the elements incorporated in PFR are resolved with the aid of modern equipment. The principal standard contains 21 trace elements from among those of greatest interest for INAA of biological materials. This standard is recommended for work on high-resolution equipment. At the same time, standards of simpler trace element composition have been prepared and studied which can be used in work on simpler equipment or in solving particular problems in determination of certain groups of chemical elements.     

Application of k0-based internal mono standard instrumental neutron activation analysis method method for composition analysis of stainless steel clad sample

The k₀-based internal mono standard instrumental neutron activation analysis (INAA) method was used for the composition analysis of some irregular shape stainless steel (SS) samples of type SS 316M, which is used as fuel cladding in Indian fast breeder test reactor (FBTR). The method utilizes in situ relative detection efficiency using γ-rays of the activation products present in the sample for overcoming γ-ray self-attenuation. Samples were neutron activated using the thermal column as well as the core position of the reactor and the assay of radioactivity was carried out by high-resolution gamma ray spectrometry. The elements determined were Fe, Cr, Ni, Mo, Mn, Co, Cu, As and W. Since all the major elements (Fe, Cr, Ni, Mo and Mn) were amenable to NAA, the relative elemental concentrations with respect to Fe, obtained by this method, were converted to their absolute values by mass balance. The results were compared with specified compositions and found to be satisfactory. In order to validate these results obtained by the standard-less approach, sub samples of SS 316M in solution forms were analyzed by prevalent relative and k₀ methods of INAA, and results were found to be in good agreement. The accuracy of the internal mono standard INAA method has been evaluated by analyzing an alloy steel certified reference material, CRM 225/1 of British Chemical Standards (BCS).     

Comparison of instrumental neutron activation analysis of geological materials with other multielement techniques

Results obtained for 12 elements in approximately 1600 rocks by instrumental neutron activation analysis (INAA) are compared with those obtained by ICP emission spectrometry (ICP-ES), XRF, and atomic-absorption spectrometry (AAS). Sample duplicates and two controls are used to evaluate the precison of the methods investigated. Application of a method (Maximum Likelihood Functional Relationship) to determine and quantify rotational and translational bias is demonstrated. The elements Na, Fe, Ba, Co, Cr, La, Ni and Rb can be determined in rocks by INAA with sufficient sensitivity and precision, whereas the determination of Ag, Yb, Zn and Zr suffers from inadequate sensitivity. Good agreement is seen in the results for Na (by INAA, ICP-ES and XRF) and AG (INAA and AAS). A significant positive bias (13% or less) is evident in the comparison of results by INAA and ICP-ES or XRF for Cr, Ba, Ni and Fe over a wide range of concentration. A similar trend, though less significant, is observed for the elements Yb, Rb, La and Co; the upper limit of concentration for satisfactory determination is within a decade of the highest detection limit for these elements. Rotational and translational bias is evident for Zn in the comparison of data obtained by INAA and ICP-ES, the results by INAA being appreciably lower above about 400 ppm Zn.     

Use of neutron activation analysis for the characterization of single-wall carbon nanotube materials

Instrumental neutron activation analysis (INAA) and prompt gamma neutron activation analysis (PGAA) were used to characterize a variety of single-wall carbon nanotube (SWCNT) materials from different principal production processes, as well as a material containing SWCNTs together with other carbon species, catalyst residues, and trace element contaminants to be issued by the National Institute of Standards and Technology for characterization and distribution as Standard Reference Material SRM 2483 Carbon Nanotube Soot. INAA proved to be well suited for the direct determination of catalyst and contaminant trace elements requiring only minimal sample preparation. PGAA complemented the INAA data in particular with determinations of the light elements. Carbon and hydrogen results provided information on the materials purity and storage properties. Strategies for the quality assurance of the measurements in these new materials were developed. INAA and PGAA data were provided for the value assignment of mass fractions of catalyst and trace elements in the candidate SRM and a systematic overview was obtained of the catalyst and trace element contaminants associated with each of the major production routes.     

Determination of rare earth and other trace element abundances in human kidney stones and brain tissue by instrumental neutron activation analysis

We have used INAA to analyze more than 30 minor and trace elements in 10 human kidney stones (phosphate and oxalate types). In addition we also analyzed human brain tissue samples for trace elements by INAA to determine the limitations of the method. Samples were taken from the temporal and frontal cortex of the brain of a patient that suffered from dialysis encephalopathy (where an increased Al content is expected), as well as a number of control samples. Trace elements were analyzed to study possible compositional differences other than the Al content. The analyses were done using large volume HPGe detectors; because of the low abundances, accuracy and precision vary between 3–80% for individual elements. We found a difference between the rare earth element (REE) patterns for apatite and oxalate kidney stones, and a fractionation compared to typical REE contents in plants. For the brain samples there is evidence for differences between the dialysis patient and the control samples not only for Al, but also for some other elements including the REEs, but most differences are minimal, and may not be significant.     

A contribution to the certification of some elements in eight vegetal reference materials by using instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) has been applied to the determination of 21 elements in 8 different vegetal samples, to be used as reference materials in 35 European laboratories (CII). Many of these elements hitherto have not been evaluated; they can be useful markers in many environmental problems. The INAA values are compared with CII non-nuclear analytical techniques results. Some rare earths elements (REE) have been also determined and their chondritic ratio versus atomic radius is reported.     

Combined application of INAA and PIXE for studying the regional aerosol composition in Southern Africa

As part of the SAFARI-92 biomass buming experiment, aerosol collections were carried out with several size-fractionating sampling devices at a number of sites in Southern Africa. One of the samplers used at all ground-based sites was a stacked filter unit (SFU). The SFU samples were analyzed by both INAA and PIXE analysis. The present paper gives an intercomparison of the analytical results obtained in order to assess the accuracy and to check the quality assurance of the analytical procedures. Twenty-one common elements were determined by both INAA and PIXE. Concentrations of 13 elements (i.e., Na, Mg, Al, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Zn and Br) were generally measured with sufficient precision in both techniques for performing the intercomparison. The INAA and PIXE data were compared in terms of PIXE/INAA concentration ratios on a sample by sample basis for the coarse and fine size fraction separately. the atmospheric concentrations for K, Mn and Fe agreed within 5–10%, the agreement between the data for the other common elements was typically better than 15%. Possible explanations for lower than 1.0 ratios for Cl, Br and Na are presented. The common elements were classified into groups according to their detectability and sensitivity in each technique.     

An innovative Compton suppression spectrometer and its capability of evaluation in multi-elemental neutron activation analysis

A new Compton suppression system was established. A low energy HPGe detector (LO-AX) is used as the analyzing detector. It is completely shielded by a 50%n-type HPGe and two NaI(TI) detectors. Experiments show that a substantial Compton suppression effect is also achieved in the low energy region down to 15 keV. The capability of applying this system in INAA was evaluated for 13 elements (As, Cd, Co, Cr, Hg, Mo, Ni, Sb, Se, Sr, Th, U and Zn) in biological and environmental samples. The benefits and problems of using this Compton suppression spectrometer in INAA are examined for each element.     

The use of Big Sample INAA for inhomogeneous materials: Homogenizations no longer needed?

Two samples of one litre each of mercury contaminated soil were analyzed by Big Sample INAA. Using this method, sample preparation procedures can be omitted and the number of sample size reduction steps are decreased. Therefore, the representativity of the sample is improved. Afterwards, Big Sample INAA is compared to standard INAA by analyzing ten subsamples taken from each one litre sample. It is concluded that multi-element analysis results of Big Sample INAA are valid even for inhomogeneous large samples. This paper presents the first concentrations measured with BSINAA.     

Multielement analysis by sequential instrumental and radiochemical neutron activation

We measured 37 elements in six USGS geological camples and one NBS biological orchard leaf (OL) sample, using sequential INAA and radiochemical group separation coupled with high resolution, high efficiency Ge(Li), and a Ge(Li) with anticoincidence shields. The elemental concentrations in these samples vary over three orders of magnitude. Our results agree very well with the reported values. The rare earth values in PCC-1 are 2–4 times lower than the reported values. Precise REE patterns are defined in USGS samples, which are characteristic of the total rock types. The REE pattern in OL is identical to the mineral apatite. In addition to the possibility that OL may be contaminated by local soil, it is also possible that the uptake of REE trace elements by plants from soil is perhaps dominated by accessory mineral such as apatite, or plants take up the REE from bulk soil in a preferential manner as a smooth function of the REE ionic radii.     

Characterization of the rhyolitic rocks from the Lela ore body using neutron activation analysis

Instrumental neutron activation analysis (INAA) is a well-known analytical method for nondestructive, sensitive and accurate determination of elemental composition of geological samples. In the present work twenty-two elements were determined by INAA in nine rhyolitic geological samples from a wolframium ore body Lela, located in the territory of Isla de la Juventud, Cuba. The obtained results are important for the preliminary geochemical evaluation of the studied rocks.     

Sequential multielement analysis of a single aerosol filter by different instrumental and wet-chemical methods

Summary The direct instrumental methods X-ray fluorescence spectrometry (XRFS) and instrumental neutron activation analysis (INAA), and, after digestion of the sample, inductively coupled plasma mass spectrometry (ICP-MS) were applied in sequence to analyse small single aerosol filters. XRFS detected up to 19, INAA up to 22, and ICP-MS up to 33 elements. In total, up to 45 elements were determined, and, for a number of additional elements limits of detection could be given. For many elements, the data quality could be checked by cross-comparison of the results of two or all three methods. These methods very meaningfully complement each other and, in the manner used, allow the determination of all elements of interest in a small aerosol filter sample.     

Chemical characterization of graphite by instrumental neutron activation analysis

Nuclear and commercial grade graphite samples were analysed by instrumental neutron activation analysis (INAA) using high flux reactor neutrons. Eleven elements (Na, K, As, Sc, Fe, Cr, Co, Zn, La, Ce, and Sm) were determined in eight samples of graphite (two nuclear grade and six commercial grade) by irradiating at a neutron flux of 3?×?10¹³ cm^?2 s^?1 in CIRUS reactor and assaying the activity by high-resolution gamma ray spectrometry using 40% relative efficiency HPGe detector coupled to an MCA. Concentrations of elements were determined by relative method of INAA. Results of both types of graphites as well as detection limits achieved by INAA method are discussed in the paper.     

Environmental assessment of coastal sediments by the elemental ratioing technique

The distribution of heavy and trace elements in coastal sediments was obtained by elemental analysis techniques such as INAA and GFAAS. The elemental concentrations were expressed in terms of enrichment factors derived by the elemental ratioing method, and evaluation was done by comparison to those found in SRMs. The associated sources of polluting elements were traced from their distribution patterns and, where applicable, related to the surrounding activities. Sample to sample variation was also taken into account to establish any correlative factors.     

Characterization of protein-bound metal species by bioanalytical and neutron activation techniques

Several bioanalytical techniques have been employed in conjunction with instrumental neutron activation analysis (INAA) to study metalloproteins and protein-bound trace elements in bovine kidneys. The accuracy of the INAA method developed has been evaluated by analyzing certified reference materials. Up to 29 elements can be reliably determined in biological tissue samples by INAA. Dialysis of the bovine kidney homogenate shows that more than 90% of Ca, Cd, Cu, Fe, Mg, Mn, Mo, Se, V and Zn, and about 20% of Br are bound to macromolecules, mainly proteins. A combination of gel filtration and ion exchange chromatography, chromatofocusing, electrofocusing, ammonium sulphate precipitation and INAA of the bovine kidney microsomecytosol subcellular fraction further indicates that much of the copper is associated with a single protein of an isoelectric point around 5 and a molecular weight of about 30 000 daltons. Some results on manganese proteins are also reported.     

Use of low-background instrumental neutron activation analysis to measure contaminants in silicon and biological samples

Instrumental Neutron Activation Analysis (INAA) is a common method of trace element analysis whose sensitivity is limited either by interference from other trace elements in the sample or by interference from ambient background radiation in the detection system. In at least two cases, a true low-background facility, such as that at Lawrence Berkeley National Laboratory, substantially enhances senitivity: (1) Ultra-pure silicon, such as that used in semiconductor fabrication. Even after prolonged exposure within a nuclear reactor, minimal observable gamma-ray emitting activities are produced in the silicon. Extrapolated from our 7 gram sample size experiments, parts-per-quadrillion (1.E-15) sensitivity to 23 elements should be obtainable for 400 gram sample sizes. (2) Similarly, the life elements H, C, N, O are effectively inert within the reactor, and this enhances sensitivity to trace elements in, for example, bacteria. Data will be presented for these two cases.     

Elemental analysis of traditional medicinal seeds by instrumental neutron activation analysis

Traditional medicinal seeds prescribed for specific treatment purposes, were purchased from local markets and analyzed by INAA. The samples were irradiated at Es-Salam research reactor, at a power of 5 MW for 6 h. The accuracy of the method was established by analyzing reference materials. Twenty elements were measured, with good accuracy and reproducibility. The concentration of elements determined, was found to vary depending on the seeds. The daily intake of essential and toxic elements was determined, and compared with the recommended values. The probable cumulative intake of toxic elements is well below the tolerance limits.     

Comparison of elemental contents of Korean space foods using instrumental neutron activation analysis

The analysis of mineral contents in space foods is needed to obtain an information on a comprehensive elemental composition as well as the investigation on the effects of human nutrition and health based on the dietary intake of mineral elements. Recently, six items of new Korean space foods (KSFs) such as kimchi, bibimbap, bulgogi, a ramen, a mulberry beverage and a fruit punch which was developed by the KAERI, and the contents of more than 15 elements in the samples were examined by using instrumental neutron activation analysis (INAA). Five biological certified reference materials, NIST SRM were used for analytical quality control. The results were compared with those of common Korean foods reported, and these results will be applied toward the identification of irradiated foods.     

Performance of the updated inaa advance prediction computer program

This paper describes further development and experimental testing of the INAA Advance Prediction Computer Program (APCP). Copies of the APCP written in BASIC-PLUS are finally ready for distribution. Experimental tests with four reference materials are described. The program is extremely useful as a quide to optimum conditions, sample sizes, elements detectable, and INAA lower limits, of detection for any sample matrix of only approximately known major and minor elemental composition. Additional developments in progress are mentioned.     

Characterization of biological macromolecules by electrophoresis and neutron activation

As analytical techniques have become more sensitive, the role of trace elements associated with biological macromolecules has become the subject of many studies in the past twenty years. Many biologically significant macromolecules, such as nucleic acids and proteins, have trace elements essential to their function and structure. Instrumental neutron activation analysis (INAA) contributes useful information in such studies. A procedure combining polyacrylamide gel electrophoresis (PAGE) with INAA and autoradiography has been developed to study biological macromolecules and their associated trace elements. Results from the application of this method to several metalloproteins are presented.