Instrumental neutron activation analysis of Al,V and Ti employing252Cf as a thermal neutron source

A rapid method for the determination of Al, V and Ti has been developed and is used for the analysis of these elements in different ores and alloys. An isotopic neutron source²⁵²Cf having a thermal neutron flux of the order of 8.5×10⁷ n·cm^–2 sec^–1 has been used for thermal neutron bombardment. Activity measurements were performed on a HPGe detector coupled to a PC based MCA unit. Depending on the half-life of the (n, ) product, different irradiation and cooling times were employed and thus the elements of interest were analyzed sequentially.     

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

     

Extraction-spectrophotometric determination of uranium(VI) with PAR and N-octylacetamide

A new and simple method for selective spectrophotometric determination of uranium(VI) with 4-(2-pyridylazo)resorcinol (PAR) and N-octylacetamide into benzene over pH 7.0–9.0 is described. The molar absorptivity of the complex with 9 different amides is in the range of (0.40–3.2)·10⁴ 1·mol^–1·cm^–1 at the absorption maximum. Out of these, the most sensitive compound N-octylacetamide (OAA) was chosen for detailed studies in the present investigation. The detection limit of the method is 0.008 g U·ml^–1. The system obeys Beer's law in the range of 0–5 g U·ml^–1. The method is free from interferences of most of the common metal ions except vanadium(V) and copper(II), which are masked by proper masking agents. The composition of the complex is determined by curve-fitting method. The method has been applied for the recovery of the metal from rock samples and synthetic mixtures.     

INAA of trace impurities in aluminium clads

As a contribution to nondestructive neutron assay of reactor grade aluminium, a number of elements have been investigated qualitatively and quantiatively using a vertical channel in the IRT-5000 reactor with a thermal neutron flux of 7.6·10¹²n·cm^–2·s^–1. The -ray spectra of irradiated samples were analysed with a 30 cm³ Ge(Li) detector connected to an HP-computer and a 4096 channel analyser. The following impurities have been determined: Sc, Ca, Cr, Fe, Ni, Co, Zn, As, Sb, W, Au, Th and U, while Lu and Hf have been determined qualitatively only.     

Analytical possibilities of the BOR 60 reactor

The analytical potential of a fast neutron reactor has been studied. The maximum density of the neutron flux is 2.5·10¹⁵ cm^–2·s^–1 at a maximum energy of 450 keV. The determining reaction for activation analysis at this reactor is an (n, n) reaction. The possibility of selectively determining Pb, Hg, Cd, Au, Ag and other elements at a level of 10^–5–10^–8% is demonstrated. This activation technique allows rapid determination of these elements.     

Determination of cobalt,nickel and copper in steel and in radioactive wastes using desferrioxamine “B”

A simple and sensitive spectrophotometric method for the determination of cobalt, nickel and copper with desferrioxamine-B (desferal) is described. The sensitivity of the colour reactions of cobalt, nickel and copper is increased by introducing desferal. The pH range for the formation of Co II, Ni II or Cu II-desferal. Chelates is 4.5–8.5, 5.5–9, and 6.5–9.5, respectively. The molar absorptivities of the chelates are 1.2·10⁵, 5.6·10⁴ and 4.8·10⁴ at 545 nm, 390 nm and 680 nm, respectively. Beer's law is obeyed up to 10 g/ml of metal ion. The effect of desferal concentration, pH, standing time and interfering ions are discussed. The method was applied to the determination of trace amounts of cobalt, nickel and copper in steel and simulated radioactive wastes.     

Determination of trace concentration of boron in ADU by the nuclear track technique

A method for the determination of boron concentration in extracted (NH₄)₂ U₂O₇·H₂O (ADU) has been used. One ml of the aqueous solution is irradiated with thermal neutrons from a 10 Ci Am/Be neutron source with a flux of 0.2·10⁵ n·cm^–2·s^–1 and thermal column in the IRT-5000 with a flux of about 10⁷ n·cm^–2·s^–1. The alpha-activity due to the reaction¹⁰B(n, )⁷Li is recorded by a CR-39 alpha track detector. After the exposure, the alpha tracks are made visible in an optical microscope at magnification of 800X by etching the detector in 6N NaOH, and the track density is determined using calibration curves of known concentrations of boron. The boron concentration of the extracted ADU was found to be 5 ppm.     

Elemental composition studies of fugitive and ambient air dust particulates from a thermal power station by instrumental neutron activation analysis

In order to assess the source of pollutants and the atmosphere quality in and around a thermal power plant, fugitive dust particulates from seven different locations and ambient air dust from six locations have been analyzed for 32 elements (As, Au, Ba, Br, Ce, Cl, Co, Cr, Cs, Cu, Eu, Fe, Ga, Hg, Hf, K, La, Lu, Mg, Mn, Na, P, Rb, Sb, Sc, Se, Ta, Tb, Te, Th, W and Yb) by employing instrumental neutron activation analysis (INAA). The method involves the irradiation of samples and comparator standards in a thermal neutron flux range of 10¹²–10¹³ n·cm^–2·s^–1 in a nuclear reactor for 10 min and 1 day followed by high resolution -spectrometry. Wide differences have been observed in the mean elemental concentrations of Fe, Co, Br, Mn, As, P. Ba and Cu in fugitive and ambient dust particulates coliected from these different locations. Further, a comparison of the elemental contents of the dust particulates from the plant with environmental standards (Urban Particulate Matter, Coal Fly Ash, Vehicle Exhaust and Coal) show significantly lower or comparable amounts of toxic and pollutant elements in the environmental samples.     

Measurement of30Si as a tracer by neutron-induced prompt gamma-ray analysis

The application of stable isotope analysis using neutron-induced prompt -ray analysis (PGA) with cold/thermal neutron beams for the tracer study of geological materials are discussed. Silicon has three natural isotopes differing in abundance:²⁸Si (92.23%),²⁹Si (4.67%) and³⁰Si (3.10%). For the purpose of the assessment of Si migration in engineered barrier material, enriched³⁰Si can be used as a tracer due to its nuclear and chemical properties. Isotope analysis of³⁰Si was performed by PGA during the tracer study. Neutron intensity at the sample position was 1.4·10⁸ n¢cm^–2·s^–1, 2.4·10⁷ n·cm^–2·s^–1 for cold and themal neutron guided beams of JRR-3M, respectively. Calibration curves and analytical sensitivity of³⁰Si were determined based on measurement of standard samples. BG and detection limits for³⁰Si analysis were also measured in Japanese bentonite (Kunigel V1 and Kunipia F) and their pore water. Fiffteen elements were determined simultaneously using PGA.     

Spectrophotometric determination of nickel(II), palladium(II) and copper(II) in presence of each other and other ions with 1-(o-carboxyphenyl)-3-hydroxy-3-phenyltriazene

Summary 1-(o-Carboxyphenyl)-3-hydroxy-3-phenyltriazene was found to be an excellent spectrophotometric reagent for the determination of nickel(II), palladium(II) and copper(II). At pH 6.8–8.3, 2.4–3.5 and 2.2–3.8, nickel, palladium and copper form greenish yellow, yellowish orange and light green complexes with maximum absorption at 410, 410, 400 nm, respectively. The systems obey Beer's law with optimum ranges from 0.25 to 2.0 ppm for Ni(II), 0.5–4.0 for Pd(II) and 0.5–4.0 for Cu(II); the elements form 11 complexes with the instability constants 2.1×10^–5, 1.5×10^–5 and 2.0×10^–5, resepctively. Effects of other anions and cations on the colour systems have been studied and procedures for the determination of Ni(II), Pd(II) and Cu(II) in presence of each other are described.

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Spektrophotometrische Bestimmung von Nickel(II), Palladium(II) und Kupfer(II) nebeneinander und in Gegenwart anderer Ionen mit Hilfe von 1-(o-Carboxyphenyl)-3-hydroxy-3-phenyltriazen

Zusammenfassung Ni, Pd und Cu bilden mit dem Reagens bei pH 6,8–8,3, 2,4–3,5 bzw. 2,2–3,8 grünlich-gelbe, gelblich-orange bzw. hellgrüne Komplexe mit Absorptionsmaxima bei 410, 410 bzw. 400 nm. Das Beersche Gesetz wird in den Bereichen 0,25–2,0, 0,5–4,0 bzw. 0,5–4,0 ppm befolgt. Die Elemente bilden 11-Komplexe mit den Instabilitätskonstanten 2,1 · 10^–5, 1,5 · 10^–5 bzw. 2,0 · 10^–5. Der Einfluß anderer Kationen und Anionen wurde untersucht und Arbeitsvorschriften werden angegeben.

     

The validation of a method for determining the migration of trace elements from food packaging materials into food

A new radiotracer method has been developed to measure the migration of trace elements from food contact packaging into four standard food simulants; acetic acid, ethanol, olive oil, deionised water. A sample of material is irradiated in a thermal neutron flux of 10¹⁶n·m^–2·s^–1 to activate the trace elements and produce a range of radionuclides. The sample is then placed in the food simulant and the migration of the radionuclides is monitored by performing -ray spectrometry on a sample of the simulant. Any radionuclides measured must be due entirely to the migration of the elements present in the plastic, since the simulant itself is not radioactive. Preliminary studies have shown that detection limits of around 0.2g·dm^–2 (0.002 mg/kg) can be achieved for antimony in a sample of polyethylene terephthalate. This method can now been extended to measure migration into real foods. This will highlight any differences between the standard simulants currently used and real foods. Since the method only involves irradiation of the packaging material, any food matrix can be studied.     

Determination of traces of uranium in tungsten and molybdenum by radiochemical neutron activation analysis via the fission product140Ba

A radiochemical separation procedure has been developed to determine traces of uranium in tungsten and molybdenum. In this procedure the fission product¹⁴⁰Ba, as indicator nuclide for uranium, is selectively separated from the matrix activities and from all other long-lived activation and fission products and obtained at high purity. The radionuclide in the final fraction is sufficiently pure so that it can be measured with high counting efficiency by -counting. The separation procedure consists of two steps: a cation-exchange separation to separate barium from the anionic matrix tungste or molybdate, and many other elements. In the second step the Ba-fraction is further purified by precipitation of barium as barium chloride in 8M hydrochloric acid. The precipitate is then dissolved in water for -counting via the Cerenkov effect. The chemical yield for barium is 94.6±2.6%. When samples of 0.1 g, a thermal neutron flux of 2·10¹³ n·cm^–2·s^–1, an irradiation time of 10 hours and a measuring time of 2 hours were applied, then the detection limit of uranium was 4 ng/g.Presented at the 3rd Intern. Conf. on Nuclear and Radiochemistry, Vienna, September 7–11, 1992.     

Separation of fluoride ion by extraction with triphenyltin chloride. Application for NAA of fluorine by means of 14-MeV neutrons

The separation of fluoride by extraction with toluene solution of triphenyltin chloride has been studied. Quantitative isolation of fluoride from solutions with a wide acidity range (pH 4.0–11.5) has been established. It is suggested that interferences by Ca, Mg, Fe, and Al can be avoided by masking these elements using sulfate and hydroxyde ions. Interference by phosphate ions can be overcome in a similar fashion. The halogenated species can be masked by mercury nitrate. Detection limit for fluorine determination is about 3 g for a neutron generator flux of 2·11¹¹ n·cm^–1·s^–1. A method for fluorine assay in water using a neutron generator with a detection limit of 1 ppm has been developed.     

A study by pulse radiolysis of the radiation-chemical transformation of aqueous solutions of hydrazine in the presence of oxygen

It is shown by pulse radiolysis that in aqueous solutions of hydrazine containing oxygen the radical N₂H₃ reduces oxygen to O₂ ^– at pH > 7 (k 3·10⁹ dm³· mole^–1·sec^–1), while this reaction does not occur for the protonated form N₂H₄ ⁺ at pH < 7 (k, 5·10⁶ dm³·mole^–1·sec^–1). The rate constants for the disappearance of O₂ ^– have been determined in the pH range from 4 to 12. Rate constants have been calculated for the reaction of O^– with N₂H₄ [k=(1.6 ±0.2)·10⁹ dm³·mole^–1·sec^–1] and of O₃with N₂H₄ [k=(1.2 ±0.2)·10⁶ dm³· mole^–1·sec^–1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 341–345, February, 1991.     

Retention of Progesterone by an Activated Carbon: Study of the Adsorption Kinetics

The process by which progesterone in an ethanol solution is retained by Merck granular activated carbon involves a reversible mechanism that conforms to a kinetic equation of unity partial order in both the progesterone concentration in solution, the coverage fraction () of the adsorbing surface and (1–). Over the temperature range 10–40°C, the specific adsorption rate varies from 5.8·10^–5 to 1.3·10^–4 s^–1. The thermodynamic activation functions for the process are H*=41.6 kJ/mol and S*=–0.20 kJ/K·mol. The rate of the adsorption-desorption process is primarily determined by diffusion of progesterone molecules in the pores of the sorbent.     

Trace element analysis of some shaving powders commonly marketed in Nigeria using instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) technique has been employed viak ₀ approximation method to determine elemental composition of five shaving powders commonly marketed in Nigeria. Fe displayed the highest concentrations in the range 1000–2000 g·g^–1. Na and Zn concentrations were established in the range 200–400 g·g^–1. Heavy elements like Ga, La, Cr, Co, Ag, Ce and Nd concentrations were noted in the lower range of 1–10 g·g^–1 Br, As, Sb, Sm, Eu, W, Cs, Tb, Yb, Hf, Ta, Th and U concentrations were established in even lower traces in the <1 g·g^–1 range. Results obtained for a certified reference material, CANMET BL-1 and CERT (in house) Kaolin standard compared favourably with the literature values thus establishing the results presented for the shaving powders.     

Interference by neutron induced second order nuclear reaction in activation analysis of platinum group elements after a nickel sulphide fire assay preconcentration

In determining the trace platinum group elements and gold in rocks and ores by the neutron activation analysis after a nickel sulphide fire assay preconcentration, there are interferences due to nuclides produced from second order nuclear reactions. This paper presents the degree of interference calculated over the ranges of long irradiation times and of reactor neutron flux from 1·10¹³ to 1·10¹⁵ n·cm^–2·s^–1. According to the results of these calculations, every one of the second order interfering reactions on the PGE+Au, except the¹⁹⁷Au(n, )¹⁹⁸Au(n, )¹⁹⁹Au reaction, can be neglected under the long irradiation time or high reactor neutron flux. Special attention is given to the interference from gold in the determining platinum.     

Elemental analysis in bed sediment samples of Karnafuli estuarine zone in the Bay of Bengal by instrumental neutron activation analysis

The concentration of rare earths and other elements have been determined in the bed sediment samples of Karnafuli estuarine zone in the Bay of Bengal by instrumental neutron activation analysis (INAA). The samples and the standards soil-5, soil-7, coal fly ash and pond sediment were prepared and simultaneously irradiated for short and long time at the TRIGA Mark-II research reactor facility of Atomic Energy Research Establishment, Savar, Dhaka. The maximum themal neutron flux was of the order of 10¹³ n·cm^–2·s^–1. After irradiation the radioactivity of the product nuclides was measured by using a high resolution high purity germanium detector system. Analysis of -ray spectra and quantitative analysis of the elemental concentration were done via the software GANAAS, it has been possible to determine the concentration level of 27 elements including the rare earths La, Ce, Sm, Eu, Tb, Dy and Yb and uranium and thorium.     

Neutron activation analysis of low level lithium in water samples

For determining low level lithium concentrations in water, a neutron activation method based on the measurement of tritium radioactivity produced by⁶Li(n,)³H reaction has been developed. This method is specific and free from interference by other chemical elements. Using a low background liquid scintillation counter for tritium measurement, the detection limit is approximately 0.3 ppm during irradiation at a thermal neutron flux density of 1.1·10⁷n·cm^–2·s^–1 for 6 hours by a small nuclear reactor and liquid scintillation counting for 2000 minutes     

Synthetic multielement standard samples for serial neutron activation analysis of biological materials

New synthetic standard samples (SSB-1 and SSB-2), produced on the basis of phenol-formaldehyde resin in the shape of tablets are suggested. The samples are intended for INAA of biological materials. SSB-1 and SSB-2 samples contain Se, Cr, Au, Sb, Ag, Rb, Fe, Zn, Co and Ca, Ba, Hg, Sn, Br, Cs, Ni, Sc and Na. The concentrations of these elements are chosen so that the maximum statistical error of -quantum registration by the semiconductor detector should not exceed 3% when irradiating samples in a neutron flux of 10¹³ n·cm^–2·s^–1.