Determination of ultratrace impurity elements in high purity niobium materials by on-line matrix separation and direct injection/inductively coupled plasma mass spectrometry

The determination of 52 impurity elements in niobium materials (niobium metal, niobium oxide (V), and niobium pentaethoxide) was performed by inductively coupled plasma mass spectrometry (ICP-MS) with on-line anion exchange matrix separation as well as direct nebulization. Niobium material samples were decomposed with a mixture of hydrofluoric acid and nitric acid to prepare 10% niobium solutions. In the on-line anion exchange matrix separation/ICP-MS, the niobium and hydrofluoric acid concentrations in sample solution were adjusted to 5% and ca. 8 M, respectively. The solution was then injected into the carrier stream from the sample loop of injection valve to pass through an anion exchange resin column. In the anion exchange separation, niobium in the fluoro-complex form was adsorbed on the resin, while impurity elements were eluted. The eluted elements were introduced into ICP-MS for the determination of 25 impurity elements. On the other hand, 27 impurity elements could not be separated well from niobium matrix under the above anion exchange conditions, and then the sample solution with the niobium concentration of max. 0.2% containing internal standard elements was injected from the sample loop of injection valve directly to introduce into ICP-MS. As a result, 52 impurity elements in three kinds of niobium materials could be determined at the ng g⁻¹ level.     

The distribution of trace elements in normal human liver determined by semi-automated radiochemical neutron activation analysis

The eight segments of five normal human livers are analysed for 25 trace elements by radiochemical NAA. This consits of an automated wet destruction of the samples and two distillations, followed by ion exchange procedures. Ru is used as triple-comparator for the standardisation. Short-lived and matrix-isotopes are standardised by the Bowen's kale powder. The results reveal that the coefficient of variation within the liver is smaller than 10% for the elements Cd, Cl, Cs, Cu, Fe, K, Mg, Mn, Rb, Se and Zn. The highest range observed for the elements As, Br, Co, Cr, Hg, La, Mo, Na and Sb within a liver is smaller than the range observed between the five livers.     

Neutron activation as a routine method for the determination of trace elements in water

By freeze-drying the following elements can be determined in natural water except sea water: Au, Ba, Br, Ca, Ce, Co, Cr, Eu, Fe, K, La, Mo, Na, Sb, Sc, Se, U, Zn. Some problems may arise with respect to As and Hg. Cu, Cd and Ni can only be determined if present in high concentrations. Separation by adsorption on charcoal in presence of complexing agents gives yields between 75 and 100% for the following elements in sea water: Ag, Au, Cd, Ce, Co, Cr, Eu, Fe, Hg, La, Mo, Sc, Se, U, Zn (As 67%, Sb 56%). Activation or use of labelled ions and study of exchange give information about mobility of trace elements in suspended matter.     

Determination of Impurities in Gallium Oxide by NAA

Neutron activation analysis has been applied to determine 12 elements, viz. Na, Mn, As, Fe, Co, Zn, Se, Sc, Cr, Sb, Hf and Ta in high-purity Ga₂O₃. The first 7 elements could be determined by anion exchange separation and isopropyl ether extraction, and the last 8 elements by instrumental method. It is recommended that the first 3 elements are determine by one of the radiochemical modes and the others by the instrumental method.     

Concentrations of some elements in the coastal sea sediments: Bays with marinas

Summary Surface sediments and sediment cores from two bays in the Adriatic sea (Punat Bay and Soline Bay, Croatia) have been analyzed for a number of elements, in particular: Ti, V, Mn, Fe, Cu, Zn, As and Pb, by using XRF. Maps of elemental distribution in surface sediments show increased concentrations for some elements present in antifouling paints (Cu, Zn, Pb) near the service areas in the villages or marinas. Core profiles for these elements were used to evaluate the environmental impact of newly constructed marinas. Source partition indicates the influence of other sources located in near by villages. The critical factor in these considerations was shown to be water exchange with the open sea.     

Comparative study of the Hartree–Fock and the Hartree–Fock–Slater method

The Hartree–Fock method (standard Roothaan closed-shell HF –LCAO theory) and the Hartree–Fock–Slater method (restricted HFS –LCAO –DV method developed by Baerends and Ros) have been compared with emphasis on the respective one-electron equations and on the matrix elements of the respective Fock operators. Using the same STO basis in the two cases, the matrix elements of the Fock operators and of their separate one-electron, Coulomb, and exchange contributions have been calculated for the same orbitals and density of the ground state of the diatomic molecule ZnO. The effects of methodical (exchange potential) and numerical (DV method, density fit) differences between the HF and HFS methods on the various matrix elements have been analyzed. As expected the methodical effect prevails and is responsible for the higher (less negative) values of the matrix elements of the HFS Fock operator compared to those of the HF Fock operator. Numerical effects are observable also and are caused by the difference in integration procedures (DV method), not by the density fit.     

Analyse systematique des elements traces dans l'eau de mer par activation neutronique

The trace elements in sea water, particularly the pollutant elements (Cu, Cd, As, Zn, Hg and Cr) are present in very low concentrations (in the order of 10^?9 g/ml). For the determination of the concentration of these elements the neutron activation analysis has been used successfully. The separation of the impurities has been studied using radioactive tracers by coprecipitation with carriers and on ion exchange resins. The preconcentration technics applied before the irradiation introduces too large “blank” values, which can be reduced by etching the containers with HF—EDTA. In order to have representative samples, the water must be quickly frozen after taking out from the sea. With these precautions, the method developed allows to analyse samples of 3 ml volumes. The results of sea water sample analyses from different areas are presented.     

高分辨ICP-MS测定涂料中痕量砷形态分布的研究

为建立高分辨率电感耦合等离子体质谱法(HR-ICP-MS)测定涂料中砷化合物形态分布的分析方法,应用离子交换树脂和溶剂萃取相结合的分离技术分离涂料中As(Ⅲ)、As(Ⅴ)、MMA(甲基胂酸)、DMA(二甲基胂酸)等4种砷化合物,试液直接用HR-ICP-MS法同时测定上述4种砷化合物,在高分辨质谱测量模式下避免了大量的质谱干扰,考察了采用内标元素对基体效应的校正,应用标准加入法进行定量分析,确定了实验的最佳测定条件。结果表明,方法的检出限为0.002μg/g,样品的加标回收率为98.2%～104.2%,相对标准偏差为0.72%～2.61%。该法具有简单、快速、准确等优点,应用涂料中砷化合物的4种不同形态砷的测定,结果满意。     

Determination of phosphorus traces in platinum alloys by two-phase isotope exchange

The method of ZEMAN and KRATZER for the determination of phosphorus traces by means of two-phase isotope exchange was modified for the determination of phosphorus in pure platinum or pure platinum alloys. It was found that Pt, Rh, Ag, and As do not interfere with the determination. Among the elements usually present in platinum metal or platinum alloys, only gold interferes. It was removed by extraction from 7M HCl by MIBK and AmOAc. Hydrochloric acid also interferes but it can be removed by evaporation. The analytical procedure is given for the solution obtained by pressure decomposition of the sample (0.5 g) in a steel bomb with PTFE inlay. It is possible to determine >2 ppm P (approximate error −10%). Using a calibration dependence instead of the well known equation for isotope exchange, the content of P in the standard solution labelled with³²P need not be known.     

Determination of major components and trace elements in ancient silver by thermal neutron activation analysis

Thermal neutron activation of minute samples of ancient silver objects has provided useful information concerning their silver, copper and gold content. The results of such analysis of eighteen Sasanian silver objects are discussed together with consideration of the sampling problems involved. In order to extend these measurements to include other elements, an isotopic exchange system has been developed to separate other activities present in irradiated silver specimens quantitatively from the silver, copper and gold activities. Following exchange with cuprous and silver iodides it has been possible to count quantitatively the activity of fourteen additional elements: As, Br, Co, Cr, Fe, Hg, Ir, K, Mn, Na, Sb, Sc, Se and Zn. Research supported in part by the U. S. Atomic Energy Commission.     

Opportunities and challenges of high-pressure ion exchange chromatography for nuclide separation and enrichment

With the rapid development of the nuclear industry, more-stringent requirements are proposed for high-level radioactive waste liquid treatment and the enrichment of isotope products. High-pressure ion exchange chromatography has been widely accepted for the fine separation of elements and nuclides due to its advantages, such as high efficiency, environmental friendliness, ease of operation, and feasibility for large-scale industrial applications. Here, we summarized the evolution of high-pressure ion exchange chromatography and the relevant research progress in ion exchange equilibrium and related separation technology. The prospects for application of high-pressure ion exchange chromatography to rare earth elements, actinide elements and isotope separation were discussed. High-pressure ion exchange chromatography represents a promising strategy for the extraction of rare earth elements and actinide elements from high-level radioactive waste liquid, as well as being an effective method for the automated production of high purity isotope products with great environmental benefits.     

Radiochemical separation methods for the determination of some toxic elements in biological reference materials

The present paper describes radiochemical separation procedures developed for the determination of the elements As, Cr, Hg, Sb and Se in biological reference materials. The methods chosen utilize ion exchange, retention on inorganic exchangers and solvent extraction techniques for the isolation of the elements of interest. These procedures are more rapid than previously used methods, such as distillation and precipitation. As to the sample dissolution, the following procedures were tested using radioactive tracers and reference materials: treatment of the materials in teflon bombs with a mixture of HNO₃+H₂SO₄ or HNO₃ only in a normal oven, and with HNO₃ in a microwave oven using specially designed digestion bombs.     

Determination of rare-earth elements in steels by radiochemical neutron activation analysis

For the separation of rare-earth elements from steel, with a cation exchange resin, separation experiments were performed on NIST reference materials of SRM-363 and SRM-364. Iron, Na, Cr, Mn, Co, Cu, As, Mo, Sb and W were separated in 2M hydrochloric acid, five rare-earth elements, La, Ce, Pr, Nd and Sm and three other elements, Hf, Zr and Ba were separated using 8M nitric acid. Each element was determined by a single comparator method using two monitors, gold and cobalt.     

Geochemical profile of Chautauqua Lake sediments

Neutron activation analysis techniques were used to study sediments from Chautauqua Lake. The concentrations of Eu, Na, Mn, K, Br, As, Ga, La, Hf, Cs, Tb, Sc, Fe, Ta, Sb were determined and compared with similar data for the bedrock and soils surrounding the lake. The lake sediments are found to be enriched in Na, Mn, Br, As, Hf, Tb, Ta, and Sb relative to the surrounding source beds. High pairwise linear correlation coefficients (R～0.9) were found between the concentrations of antimony, cesium, and scandium. For many elements a relationship was indicated between their concentrations and the clay fraction of the sediment, possibly due to the higher cation exchange potential of the clay minerals.     

An accurate procedure for multielement neutron activation analysis of trace elements in biological materials

A procedure for radiochemical neutron activation analysis of biological materials for As, Cd, Co, Cu, Ga, Hf, Mg, Mn, Na, Sb, Sc, Se, Zn, and the rare-earth elements (REE) has been developed. Maximum control over accuracy has been emphasized. Samples are digested under reflux in the presence of carrier for every element determined, and a chemical yield is measured for every element assayed. The procedure has been tested by replicate analysis of National Bureau of Standards bovine liver sample (SRM-1577). Values agree to within their uncertainties with those given by NBS for the 9 elements of this group that they have analyzed. Accuracies at the 90% confidence level for elements in the liver sample are estimated as better than ±10% for Cu, Na, and Zn, between ±10 and ±25% for As, Co, Hg, La, Mn, and Se, and between ±25 and ±50% for Cd, Sb, Sc, and Sm.     

Determination of U and Th in tungsten by radiochemical neutron activation analysis

A radiochemical separation method using an anion exchange resin has been applied to 4N grade tungsten for determining U, Th and 4 other elements. While tungsten remained in the resin, Na, K and As were separated with 0.05M HCl and 1M HF and then U, Th and Cr were eluted with 1M HCl and 1M HF. The separation yield of neptunium (U) was influenced largely by the amount of thorium, but this influence could be neglected as the concentration of the thorium was below 0.5g/ml. The content of these elements were calculated by a single comparator method using monitors, gold and cobalt. The detection limits of U and Th are 4.0 and 1.2 ppb, respectively.     

封闭压力酸溶-ICP-MS法分析地质样品中47个元素的评价

对封闭压力酸溶－ICP－MS法同时测定地质样品中47个元素的效果和适用范围进行了实测评价。并对溶样条件进行了优化。实验结果表明，HF－HNO3高温高压酸溶是一种有效的样品分解方法，在所测定的47个元素中，大部分元素如Li,Be,Ti,V,Mn,Co,Ni,Cu,Zn,As,Zr,Nb,Mo,Cd,In,Sn,Sb,Hf,Ta,W,Tl,Pb,Bi等在大多数标样中在三种取样量下都可以得到满意的回收率。而Sc,Cr,Ga,Y,REE,Rb,Cs,Sr,Ba,Th,U等元素在大部分样品中则随取样量减少，回收率上升，在一些样品中，当取样量降至25mg时，可以获得满意的回收率。用王水代替HNO3复溶残渣，利用氯离子的络合作用促进复溶，使许多元素的回收率有了明显的提高。     

use of fixion 50X8 cation exchange plates for heterogeneous isotope exchange in radiochemical analysis

A method for the simultaneous isolation of a number of elements (In, Y, Zn, Co, Cd) from their mixture has been developed. The method is based on heterogeneous isotope exchange between the radionuclide of the element to be determined in the solution and a cation exchange plate saturated with the inactive form of the same element. The investigations were carried out with “Fixion 50X8” plates (Hungary) measuring 1 cm². 5–6 ml of the test solution was used. In order to properly choose the optimum saturation conditions of the plates with the element to be determined the kinetics of sorption and isotope exchange and the pH were studied. It can be excepted that in the future this procedure will be widely used in the radioanlytical isolation and determination of many elements by isotope exchange and activation analysis. The automation of this radioanalytical procedure for serial analysis will become possible owing to the simplicity and elegance of the experimental technique.     

The use of neutron activation in dietary reference material analysis

Summary Results for a number of trace elements in a total human diet material (USDIET-1), obtained by the application of both INAA and RNAA are presented. Several dietary reference materials such as NBS SRM 1577A, and BCR CRM Single Cell Protein were also analyzed, and these results are also given. Combining measurements on short and long lived radionuclides, the INAA approach is useful for the determination of about 20 elements. In order to expand the elemental coverage or improve detection limits, RNAA was also explored in two modes: separation of radionuclides using organic ion exchange resins and the use of hydrated manganese dioxide. This combination is applicable to 15 trace elements. For example, using RNAA, the following results were obtained for USDIET-1: Cd=31.8, Mo=280, Cr=71, Ag=4, As=117 and Sb=9.4 g/kg. In the INAA mode, special attention was given to Al, F and Se. The F content of USDIET-1 was found to be 840 mg/kg, a rather high value, resulting from handling USDIET-1 by Teflon tools. By applying INAA and RNAA under two different laboratory conditions, it has been demonstrated that, even for the so-called difficult to determine elements like Cr, As or Mo, consistent results can be obtained. Thus, NAA promises to be a strong tool for human nutritional studies.

---

Einsatz der Neutronenaktivierung für Nahrungsmittel-Referenzmaterialien

     

Untersuchungen an oxidischen Katalysatoren. XXIV [1]. Adsorptions- und katalytische Eigenschaften von CeNaY- und CrNaY-Zeolithen

Studies on Oxide Catalysts. XXIV. Adsorption and Catalytic Properties of CeNaY and CrNaY Zeolites The adsorption of benzene, n-butylamine and ammonia(isotherms and heats of adsorption) on CeNaY and CrNaY zeolites of different exchange degrees has been measured. The acidic properties were characterized by titration with n-butylamine. As function of exchange degree the adsorption and catalytic properties (cracking of cumene) both change in the same manner. Whereas the reaction rate constants up to exchange degrees of 40–50% change only insignificantly, they are exponentially increasing at higher exchange degrees. The energies of activation are nearly independent of the degree and run to 23–25 kcal mol^?1.