Distribution and location of selenium and other elements in different mitochondrial compartments of human liver by neutron activation analysis

Summary  Vezetéknév     

Determination of As,Cd, Cu,Hg, Mo,Sb, and Se in biological reference materials by radiochemical neutron activation analysis

The elements As, Cd, Cu, Hg, Mo, Sb, and Se were determined in the biological reference materials (RMs) Bowen's Kale, NIST SRM-1577 Bovine Liver, NIST SRM-1549 Milk Powder, and Versieck's 2nd Generation Biological RM Human Serum using two newly developed radiochemical neutron activation analysis (RNAA) procedures. The first is based on sample decomposition in a mixutre of H₂SO₄+HNO₃+H₂O₂ and simultaneous extraction of the elements As, Cd–In, Cu, Mo, and Sb by 0.025M Zn(DDC)₂ in chloroform from 2–4M H₂SO₄ in the presence of 0.01M KI. The second consists of sample decomposition in HNO₃ in teflon bombs heated at 150°C, Hg extraction by 0.01M Ni(DDC)₂ in chloroform from about 1M HNO₃, and Se precipitation by ascorbic acid from about 1M HClO₄. The RNAA procedures were also used for intercomparison analyses of A and P NIST Leaf Materials (NIST candidate SRM-1515 Apple Leaves and NIST SRM-1547 Peach Leaves, respectively), and CZIM Bovine Liver 12-02-01 RM. Very good agreement of results with certified and/or literature values proved the high accuracy of these determinations by the proposed RNAA procedures, even at the sub-ng/g levels.     

The activity of Au supported on various types of carbon in the ring transformation reactions of methyloxirane

Summary  Vezetéknév     

Determination of As,Cd, Hg,Cu and Zn in biological samples by radiochemical neutron activation analysis

In this work, a simple group separation scheme based on extraction for NAA determination of trace of As, Cd, Hg, Cu and Zn in biological materials is described. For this purpose, zinc-diethyldithiocarbamate, Zn(DDC)₂, and methyl isobutyl ketone-iodide have been chosen as reagents. The elements can be extracted successively and quantitatively from strong mineral acids without adjusting pH of the solution, and separated into two groups suitable for gamma-ray spectrometry. Samples of 100–200 mg dry weight were double-sealed into polyethylene bags and irradiated in a swimming pool reactor with a thermal neutron flux of 10¹³n·cm^–2·s^–1 for 44 hours. After a cooling period of 1–3 days, the samples were digested with microgram quantities of carrier in concentrated nitric acid and sulfuric acid at 150°C for 3.5 hours in a teflon bomb, then extracted as described above. The reliability of the analytical method was checked using reference materials Horse Kidney IAEA H-8, Human Hair NIES-5 and Tomato Leaves NBS-1573. Most of the results obtained for reference materials agreed with the certified values¹². Chinese autopsy samples of hair and liver were presented.     

Effect of the surface/bulk doping of lanthanum manganite on the oxygen mobility, reactivity and catalytic activity in the CO oxidation

Summary  Vezetéknév     

Simultaneous determination of iodine and selenium in biological samples by radiochemical neutron activation analysis

Summary Regarding the favourably sensitive nuclear characteristics of iodine and of selenium but the very different half lives of their induced nuclides ¹²⁸I and ⁷⁵Se, a radiochemical neutron activation analysis method for simultaneous determination of these elements in a single sample was developed. It is based on the double irradiation LICSIR technique — Long Irradiation for Se (40h), Cooling (a week or more), Short Irradiation for iodine (1–15 min) with following Radiochemistry. After the second short irradiation, the sample is ignited in an oxygen flask and iodine and selenium are sequentially and selectively extracted as elemental iodine and 5-nitro-2,1,3 benzoselena diazole chelate. With the described method biological samples were analysed and the reliability of the results was checked by the analyses of different standard reference materials. Good agreement with certified values and high radiochemical purity of the spectra show the applicability of the radiochemical separation developed.     

Simultaneous determination of mercury and selenium in biological materials by radiochemical neutron activation analysis

A simple and sensitive radiochemical neutron activation analysis (RNAA) method has been developed for the simultaneous determination of mercury and selenium in biological materials. The radiochemical procedure is based upon the digestion of irradiated samples with sulphuric and nitric acids followed by subsequent extractions of mercury and selenium into toluene, first of mercury from 7.5 M H₂SO₄-0.01M HBr media and after of selenium from 7M H₂SO₄-1 M HBr media. After washing of the organic phases with similar media, the mercury bromide was back-extracted into 0.034M EDTA in 5% aqueous ammonia and the selenium bromide into 0.14M H₂O₂ in aqueous solution. The¹⁹⁷Hg and the⁷⁵Se were counted on a Ge(Li) detector. The precision and accuracy of the method was checked by analysing NBS Standard Reference Materials: orchard leaves and bovine liver.     

Determination of As,Cd, Cr,Cu, Hg,Sb and Se concentrations by radiochemical neutron activation analysis in different Brazilian regional diets

The present paper describes radiochemical separation procedures developed for the determination of seven elements: As, Cd, Cr, Cu, Hg, Sb and Se in different Brazilian regional diets. In the case of the elements As, Hg, Sb and Se, the procedure was based on retention in inorganic exchanger TDO (tin dioxide) and determination of Hg by extraction with Ni(DDC)₂. For determination of Cd, Cr, Cu and Se the procedure chosen was based on retention in inorganic exchanger HMD (hydrated managese dioxide) and extraction of Cu and Cd as diethyldithiocarbamate compounds. The accuracy and precision of the methods studied were tested by means of analyses of different reference materials. Due to the lack of data on trace element levels in Brazilian foodstuffs and diets, these methods were applied to determination of these elements in different Brazilian regional diets. These diets were supplied by the Food and Experimental Nutrition Department of the Faculty of Pharmaceutical Science, University of São Paulo. The daily dietary intake values for these diets are presented for As, Cd, Cr, Cu, Hg, Sb and Se.     

Simultaneous determination of trace uranium and vanadium in biological samples by radiochemical neutron activation analysis

Summary A radiochemical neutron activation analysis (RNAA) for simultaneous determination of uranium and vanadium in a single sample at trace levels is described. The method is based on post-irradiation wet-ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine reagent. From the remaining aqueous phase, uranium is extracted into a toluene solution of tri-n-butyl phosphate. The chemical yields are determined spectrophotometrically for vanadium and by gamma-counting of the added natural uranium carrier for uranium. The method was evaluated by the analysis of reference materials and the results showed a good agreement with the certified values. The method was applied to the determination of vanadium and uranium in five military total diet samples in Slovenia.     

Trace determination of nickel (and cobalt) in biological reference materials by radiochemical neutron activation analysis

Summary Very few biological reference materials are certified for nickel below 1 mg · kg^–1. Neutron activation analysis was only rarely considered as a possible approach; reported sensitivities were usually not very good, unless preconcentration was applied.In the present work, the relatively high fast neutron flux of our TRIGA reactor was used to induce the ⁵⁸Ni(n, p)⁵⁸Co reaction, and ⁵⁸Co (E =811 keV) was radiochemically separated from other radionuclides by classical anion-exchange chromatography in hydrochloric acid. ⁵⁷Co was added to the irradiated sample before decomposition as a radioisotopic yield monitor. By concentrating the final sample fraction and measurement in a well-type HP Ge detector, Ni concentrations down to the 10-g · kg^–1 level could be determined for samples irradiated for 1 day. ⁶⁰Co, produced by neutron capture on ⁵⁹Co, is also coseparated and quantified from the gamma spectrum, so that both elements Ni and Co are determined. Results are reported for a series of NBS and other biological reference materials in the concentration range 10 g-10 mg · kg^–1. Possibilities for further increases in sensitivity are discussed.

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Spurenbestimmung von Nickel (und Cobalt) in biologischen Referenzmaterialien durch radiochemische Neutronenaktivierungsanalyse

     

Very accurate,simultaneous determination of trace amounts of Co and Ni in biological materials by radiochemical neutron activation analysis

A very accurate and sensitive method for the simultaneous determination of trace amounts of Co and Ni in biological materials has been elaborated. The method is based on radiochemical neutron activation. Irradiation of samples in Cd-shielded channel of a nuclear reactor assures balanced activity ratio of⁵⁸Co and⁶⁰Co isotopes and favourable detection limits for both nickel and cobalt. Column chromatography (ion exchange and extraction) has been used for the quantitative and selective isolation of the determined radionuclides. High accuracy of the method has been demonstrated by the analysis of several certified reference materials.     

The simultaneous determination of As,Cd, Co,Hg, Mo,and Zn in fresh water by neutron activation analysis

A radiochemical neutron activation method for the simultaneous determination of arsenic, cadmium, cobalt, mercury, molybdenum, and zinc in fresh water is described. The method is based on anion-exchange separation in hydrochloric acid media followed by simple precipitations. The determination limits, based on analysis of a 5-ml sample without preconcentration, and with a well-type NaI(Tl) detector, are as follows: As, 10^-3 μg l^-1 ; Cd, 6 × 10^-2 μg l^-1 ; Co, 4 × 10^-3 μg l^-1 ; Hg, 7 × 10^-3 μg l^-1 ; Mo, 10^-1 μg l^-1 ; Zn, 2 × 10^-1 μg l^-1. The method is adequate for the analysis of natural fresh waters.     

Development of a radiochemical neutron activation analysis procedure for determination of rhenium in biological and environmental samples at ultratrace level

Summary Radiochemical neutron activation procedures using liquid-liquid extraction with tetraphenylarsonium chloride in chloroform from 1M HCl and solid extraction with ALIQUAT 336 incorporated in a polyacrylonitrile binding matrix from 0.1M HCl were developed for accurate determination of rhenium in biological and environmental samples at the sub-ng ^. g^-1 level. Concentrations of Re in the range of 0.1 to 2.4 ng ^. g^-1 were determined in several botanical reference materials (RM), while in a RM of road dust a value of ~10 ng ^. g^-1 was found. Significantly elevated values of Re, up to 90 ng ^. g^-1 were found in seaweed (brown algae). Results for Re in the brown algae Fucus vesiculosus in which elevated ⁹⁹Tc values had previously been determined suggested possible competition between Re and Tc in the accumulation process.     

A sequential multielement separation scheme for determination of As,Mn, Mo,Cu and Zn in human milk by neutron activation analysis

A simple separation scheme for the analysis of As, Mn, Mo, Cu and Zn using neutron activation is described. It has been checked using three standard reference materials, A-11 milk powder (IAEA) and bovine liver and orchard leaves (USNBS) and found to give acceptable results. This scheme was applied for determination of these trace elements in mature human milk samples. The concentrations of As, Mn, Mo, Cu in samples obtained from two socio-economic groups—low and middle incomes—were not significantly different. However, Zn levels in samples obtained from the poor income group were significantly lower than in those obtained from the other group. Work carried out under Research Contract No. 2598/RB of International Atomic Energy, Vienna. Health Physics Division. Analytical Chemistry Division.     

A study of the iodinated resin column for the determination of iodine in biological fluids by radiochemical neutron activation analysis

The iodinated resin technique for separation of¹²⁸I directly from neutron irradiated biological fluids is attractive due to its rapidity, simplicity and high degree of radiochemical purity; however, some doubts exist about the yields of iodine which can be recovered, particularly from organically bound iodine. In the present study, chemical yields on the resin column were studied for irradiated urine, serum and milk by standard additions of iodide and thyroxine. It was found that yields are not quantitative but lie in the range 80–95%, depending on the matrix, with a variability of up to 6% standard deviation. In addition it was shown that no significant adsorption of iodine occurs on polythene ampoules from irradiated biological fluids of natural pH. Some comparative experiments between the resin technique and the oxygen flask ignition method on fluids before or after drying, respectively, showed satisfactory agreement. It is concluded that the iodinated resin technique is suitable for routine analyses or large scale screening programs.Presented in part at SAC 83, Edinburgh, July 1983.     

Simultaneous determination of rhenium,osmium and iridium in meteoritic samples by neutron activation analysis using simple and effective radiochemical procedures

Simple and effective procedures for the determination of Re, Os and Ir by radiochemical neutron activation analysis are presented. Those elements are separated individually by distillation (for Os) and anion exchange techniques (for Re and Ir) for a single specimen. Reproducibilities of the data obtained by the present procedures are evaluated by replicate analyses of the Allende meteorite sample, and are deduced to be 3% for Re, 6% for Os and 4% for Ir (1). Detection limits for the present procedures are calculated to be 1 ppb for Re, 20 ppb for Os and 5 ppb for Ir. These procedures were applied to Antarctic meteorites and proved to work very effectively for the determination of trace Re, Os and Ir in chondrite meteorites.     

Low-level simultaneous determination of As and Sb in standard reference materials using radiochemical neutron activation analysis with isotopic 77As and 125Sb tracers

Summary The aim of the present work was to develop an older method used in our laboratory based on selective solvent extraction of As and Sb as their iodides with toluene, and by the use of the radioisotopic tracers ⁷⁷As and ¹²⁵Sb, to improve the accuracy by better control of the radiochemical yields. ⁷⁷As was produced for each sample run by concurrent irradiation of a few mg of GeO₂ followed by a rapid separation of ⁷⁷As from ⁷⁷Ge. The radiochemically purified sample fraction containing ⁷⁶⁺⁷⁷As and ^122+125Sb was counted on a Ge detector in good geometry. The -lines of the four nuclides do not mutually interfere so that a combined measurement of As and Sb may be made.The method was applied to IAEA Milk Powder A-11, Animal Muscle H-4, Bowen's Kale and some other SRMs. The results obtained are discussed in the light of literature measurements. From present and previous results, together with data by Heydorn, the presently accepted value for As in Bowen's Kale of 140 ng · g^–1 may be 20% too high.     

An accurate method for the determination of copper in biological materials by neutron activation analysis and extraction chromatography

Distribution coefficients of 14 elements between LIX 70 in toluene and aqueous 1M NaNO₃ solution containing varying concentrations of HCl or suitable buffer, respectively, were determined by batch equilibration. It was shown that very selective separation of Cu from other elements can be achieved on columns with LIX 70 supported on Bio-Beads SM-1. Highly accurate and precise method for the determination of trace amounts of Cu in biological materials was devised by combining NAA with extraction chromatography. Results of copper determination in NBS 1570 /Spinach/, IAEA H-4 /Animal muscle/ and IAEA V-8 /Rye flour/ are presented.