Determination of trace impurities in palladium by neutron activation analysis

Trace amounts of Ir, Au, Ag, Pt, Zn, Mn, and Cu were determined in high purity palladium by destructive and instrumental neutron activation analysis (NAA). The latter version of NAA was employed for the determination of Ir, Au and Ag. Special attention was paid to a new non-destructive method for the determination of silver traces in palladium. The results obtained by both versions of NAA are critically discussed and compared.     

Determination of trace impurities in tin by neutron activation analysis

Two methods are described to determine indium and managenese in high-purity tin. In the first method indium and manganese are separated from the tin and antimony matrix activities on Dowex 1X8 anion exchanger. Tin and antimony are adsorbed in 10M HF while indium and manganese are eluted. In the second method the incident γ-ray intensity due to the tin matrix is reduced by placing a lead absorber between the sample and the detector. The reproducibility and the sensitivity of both methods are of the order of 10 ppb for manganese and of 1 ppb for indium for 1 g samples and a neutron flux of 10¹¹ n·cm⁻²·sec⁻¹. Aspirant of the N. F. W. O.     

Determination of trace impurities in platinum by neutron activation analysis

Determination of trace impurities in platinum by neutron activation analysis was carried ont by combining the advantages of ion exchange chromatography and Ge(Li spectrometry. Owing to the development of a new ion exchange separation scheme which assures high decontamination factors with respect to matrix activities and practically quantitative yields, ppm and sub ppm amounts of Au, Cu, Ir, K, La, Mn, Pd and Zn were determined in 10 mg samples of pure platinum metal. No determinations of the chemical yield were necessary. Several other elements could be determined, if present, without essentially changing the procedure.     

Determination of trace impurities in tin by neutron activation analysis

Arsenic, selenium and antimony were determined in four different tin samples. After distillation from HBr?H₂SO₄ medium arsenic and selenium were precipitated with thioacetamide, and antimony was subsequently separated by deposition on iron powder. The separated samples were counted on a high-resolution Ge(Li) γ-spectrometer. The sensitivity of the method is highly satisfactory.     

Determination of trace impurities in tin by neutron activation analysis

A method was developed for the determination of 15 trace elements in tin. High-purity tin samples (99.9999% and 99.999%) as well as tin of technical quality were analysed. Reactor neutron activation of the tin samples was followed by distillation of the matrix activities from a HBr−H₂SO₄ medium and Ge(Li) gamma-ray spectrometry of the distillation residue. The sensitivity of the method is generally high. For the high-purity samples the detection limits vary from 0.02 ppb (scandium) to 200 ppb (iron) for irradiation of 1 g of tin for 1 week at a thermal flux of 5·10¹²n·cm⁻². ·sec⁻¹. To decontaminate the surface of the tin samples, pre- and post-irradiation etching procedures were applied. The efficiency of these etching techniques was studied.     

Determination of impurities in nuclear fuel element components by neutron activation analysis

Neutron activation analysis methods for the determination of impurities in zirconium cladding material and uranium oxide are described. Detection limits for the elements Al, Cd, Cr, Co, Cu, Hf, Fe, Mn, Ni, W and U in zirconium are below that required by the ASTM B 352-79 standard. The method has been tested on the NIST SRM 360a Zircaloy-2 from which the elements Na, Mg, Al, Ca, V, Cr, Fe, Co, Ni, Cu, Eu and U have been detected. The values for Cr, Fe, Ni and Cu are compared with the certified values. A method for the pre-irradiation separation of the elements Mg, Na, Al, K, Sc, Ca, V, Mn, Cr, Fe, Co, Cu, Zn, Rb, Zr, Cd, Cs, REE and Hf from uranium has been developed. A neutron activation analysis method for the determination of those elements in uranium is described. The method is tested by the analysis of the IAEA reference sample SR-54/64. The elements Al, Mn, V, Cu, Cr, Co, Ni and Fe have been detected and the results compared with the certified values.     

Determination of trace impurities in nickel-based alloy using neutron activation analysis

A radiochemical neutron activation analysis procedure has been applied to investigate 40 major, minor, and trace impurities in nickel-based alloy. The extensive use of these alloys in the electronic industry, telecommunications, manufacturing of aircraft engine turbine blades and chemical equipments desires for their precise characterization. The concentration of nickel in the nickel-based alloy was found to be 56.8%, whereas Fe, Cr, Ca, Mg, Ce, Mn, Na and V were the major components of the alloy, which constituted to more than 26%. The rest of the elements was present in minor or trace levels. Most of the rare earth elements except Ce were also present in trace amounts. Neutron activation analysis technique was preferably used because of its good sensitivity and multielement determination capabilities for the characterization of high purity materials. The comparison of RNAA and INAA indicated improvement in the detection limits utilizing radiochemical separation procedures developed in the present work.     

Study of trace impurities in heroin by neutron activation analysis

Sixty-two heroin samples were analyzed for their contents of 15 trace elements (Au, Ba, Br, Ca, Ce, Co, Cr, Fe, La, Na, Sb, Sc, Sm, Th, and Zn) by neutron activation analysis (NAA). Large variations of elemental concentrations between samples were found to possess statistical significance. Of all the elements calcium was the most abundant element, followed by zinc and sodium. The concentrations of Au, Ce, Co, La, Sb, Sc, Sm, and Th in all the samples were below 1 mg·g⁻¹. Classification of these heroin samples was achieved by the application of hierarchical cluster analysis. The results show that NAA can provide useful information on the origin of the illicit drugs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of trace element levels in polyethylene by instrumental neutron activation analysis

Elements Al, As, Au, Br, Cl, Co, Cr, Cu, Fe, Hg, K, La, Mn, Mo, Na, Sb, Sc, Sm, V, and Zn were determined by INAA in several brands and batches of high pressure polyethylene (PE) Bralen (Slovnaft Bratislava, Czechoslovakia). A large scatter of trace element contents was found in both granules and foils, indicating an inhomogeneous distribution for the majority of the above mentioned elements present as impurities in PE. Larger amounts of the elements Al, Mn, and Sb were found in foils than in granules. Blank values resulting from using of PE Bralen as a canning material for INAA were compared to trace element concentration in human hair samples, too.     

Determination of trace impurities in rhodium metal by destructive and non-destructive neutron activation analysis

Trace amounts of Ir, Au, Cu, Pd and Pt were determined in rhodium metal by instrumental neutron activation analysis with Ge(Li) spectrometry as well as by the radiochemical version of the method. The latter was based on a specially developed procedure of the dissolution of Rh, followed by group separation with the aid of ion exchange chromatography. The results obtained by destructive and non-destructive methods are critically discussed and compared. Special attention was paid to self-shielding effect and an accurate method of the correction of this effect is presented.     

Determination of the trace element levels in atmospheric pollutants by neutron activation analysis

An investigation of the potentials of neutron activation analysis for the routine analysis of trace elements present in atmospheric pollutants is discussed. Various techniques including sequential air sampling, multiple neutron irradiation, high resolution γ-ray spectrometry, chemical isolation, high flux neutron irradiation and X-ray spectrometry have been employed to determine the levels of Pb, Al, V, I, Cl, Mn, Cu, Br, Na, La, Mo, Au, Cr, Fe, Ni, Se, Zn, Ag and Co in atmospheric pollutants. The results of the analysis of nearly two hundred samples collected from the Buffalo New York area during 1968–1969 are reported. Presented at the Fourth Annual Conference on Trace Substances in Environmental Health, University of Missouri, Columbia Missouri, USA (June, 1970).     

Determination of impurities in high-purity solvents by neutron activation analysis

The determination of impurities in high-purity solvents, (acetone, isopropanol, trichloroethylene and trichlorotrifluoroethane) used in the production of integrated circuits was carried out by reactor neutron activation analysis. A special vacuum evaporation technique was used for the preconcentration of the solvents. The results showed that sodium and iron are the main impurity components in the solvents and on the other hand the quality of the solvents satisfies the specifications required by high-technology standards. The suspended solid particles in solvents were counted by a Microscopic Image Analysis System (MIAS).     

Determination of trace element concentrations of indian cigarette tobacco by instrumental neutron activation analysis

Lung cancer and smoking are associated. Epidemiological studies show that not only lung cancer but other chest diseases have causative relationship with smoking. Cigarette tobacco and smoke contains many carcinogens. Inorganic and metallic constituents of cigarette tobacco and smoke have not been studied as extensively as the organic compounds. Since some of the metals are highly toxic and also carcinogenic, authors have attempted to measure the levels of some of the trace elements of Indian tobacco by instrumental neutron activation analysis, and compared the results with the tobacco of America, Germany, Iran and New Zealand.     

Determination of trace element pathways in a petroleum distillation unit by instrumental neutron activation analysis

The concentrations of 11 trace and minor elements (Na, Al, S, Cl, Ca, V, Mn, Ni, As, Br, I) have been measured by instrumental neutron activation analysis in a sample of crude oil from Venezuela, and in 7 of its distillates and in the final residue produced in a primary distillation unit. Concentrations range from 0.5 ppb to 2.0%. The elements have been classified in 4 categories on the basis of their distributions among the fractions analyzed. The results on concentrations have also been used to establish elemental balances in the distillation unit studied operating under steady-state conditions. Only S and V have been found to give rise to losses by emission.     

Determination of impurities in tantalum by a radiochemical neutron activation analysis

A radiochemical separation method using Dowex 1×8 (200–400 mesh) has been applied to two tantalum metals of 99.9% purity. While tantalum was still retained on the resin, the elements Na, K, Cr, Mn, Fe, Co and Zn were separated with 2M HF and subsequently the elements Sc, As, Zr, Mo, Eu, W and Hf with a mixture of 0.5M HF and 3M HCl. The separation yields for all impurities was 98–100%. Elemental contents were calculated by a single comparator method using two monitors.     

Single-crystal trace element analysis in rock-forming minerals by instrumental neutron activation analysis

We have developed an INAA techniques for analyzing single crystals extracted from rocks. Trace element contents have been measured in a large variety of mineral species, as well as isotopic ratios of some REE in minerals related to natural fission reactions. The sensitivity of INAA allows to avoid the main shortcomings of usual mineral geochemistry: (1) only very short quantities of minerals are needed (down to a few g), so that even very sparse minerals could be analyzed, (2) purity of minerals is carefully checked, and (3) the heterogeneity of a population may be studied. The method is especially useful when applied to minerals acting as tracers for some element families, e.g. REE in Ca-bearing minerals (fluorite, apatite, titanite, gamet) and Zr-bearing minerals, or chalcophile elements (Co, Ni, As, Sb, Mo, Ag, Au and Se) in sulfides. We present an application of the method to the Oklo U deposit in Gabon showing that features outlined above are of special interest for the study of hydrothermal processes.     

Determination of trace elements in food by neutron activation analysis

Neutron activation analysis (NAA) methods have been developed for the determination of major, minor and trace elements in duplicate diets and individual food items. These include a cyclic instrumental NAA (CINAA) method for measuring Se content through its short-lived nuclide^77mSe; epithermal INAA (EINAA) for I and As; conventional INAA for Br, Ca, Cl, Co, Cr, Fe, K, Mg, Mn, Na, Rb, Sb, Sc, Sn and Zn; combination of EINAA and INAA for Al; radiochemical NAA (RNAA) for As, Au, Co, Cu, Fe, Hg, Mo, Sb, Se and Zn; and preconcentration NAA (PNAA) for U and Th. Accuracy of measurements have been evaluated by analyzing a number of biological and diet reference materials. Multielement concentrations of diets and foods have been measured by these methods.     

Determination of trace elements in petroleum by neutron activation analysis

Instrumental neutron activation analysis (INAA) and Ge(Li) spectrometry have been used to determine Sc, Cr, Fe, Co, Ni, Zn, As, Se, Sb, Eu, Au, Hg, and U in crude petroleum. The technique involves no chemical separations and no pre-concentration of the samples by ashing is necessary, thus avoiding contamination or loss of volatile elements. The estimated detection limits in ppb for the elements are Sc (0.1), Cr (0.16), Fe (400.0), Co (0.6), Ni (1.1), Zn (200.0), As (6.0), Se (23.0), Sb (1.0), Eu (0.58), Au (0.11), Hg (4.3), U (1.5). Precision values ranged from 0.1% to 15% (relative standard deviation). Interferences in the Co and Fe determinations due to fast neutron reactions (n, p) and (n, α) on Ni isotopes are small and are easily corrected. Losses of As, Se, and Hg due to escape of volatile gases during irradiation are negligible     

Determination of trace elements in petroleum by neutron activation analysis

Using thermal neutron activation and a large-volume high-resolution Ge(Li) γ-ray spectrometer, the feasibility of the determination of the concentrations of Na, S, Cl, K, Ca, V, Mn, Cu, Ga, and Br in crude oils has been demonstrated. This instrumental method, which requires neither a chemical separation technique nor pre-concentration or post-concentration of trace elements by ashing, eliminates many inherent errors associated with chemical determination. The method is sensitive, precise and suitable for routine analysis. Fast neutron (n, p) and (n, α) reactions do not appreciably interfere and where necessary corrections may be applied. Loss of volatile elements, e.g. chlorine and bromine, due to recoil during irradiation is negligible.     

Radiochemical neutron activation analysis of trace impurities in high purity aluminum

Rapid radiochemical neutron activation analysis (RNAA) procedures were developed and employed for the determination of 32 trace impurities in high purity aluminum thin foils. Anion exchange column chromatography was developed for the sequential group chemical separation of various elements which helped in reducing the spectral interferences and improving the sensitivity of the method. The procedure is simple and requires a very short time to separate the elements in three groups for radiometric assay. To determine very low contents of uranium and thorium,²³⁹Np and²³³Pa as activation products were separated using anion exchange and coprecipitation methods. The impurity contents were found to be low, therefore, their adverse effects on microelectronic devices would be negligible. Our data could partially be compared with the data reported in literature.