Determination of vanadium in biological tissue by anion exchange chromatography and neutron activation analysis

A method is described for determination of vanadium in biological tissues. This method consists of a wet digestion of the tissue with nitric acid followed by anion exchange chromatography, neutron irradiation, and radioassay. The chromatographic separation will allow the decontamination of vanadium from radioactivatable sodium and chlorine which are present in large quantities in biological tissues. The validity of the method is evaluated by employing NBS-SRM 157 and 157a Bovine Liver employing the method of standard additions. The method is successfully applied to human, cow and rat liver specimens. The detection limit of the method is one ppb.     

Determination of gold in low grade ores and concentrates by anion exchange separation followed by neutron activation

The beneficiation of tailings from Kolar Gold Mines involves the flotation of sulphides. Appreciable amounts of arsenic and antimony are expected to accompany gold in this process. The activation analysis of gold in these samples is facilitated by a preseparation of gold from arsenic and antimony. The present paper describes a method for the rapid analysis of gold in the concentration range 0.5 to 50 ppm using a simple pre-irradiation separation, with the recovery of gold being evaluated by an isotope dilution technique using¹⁹⁸Au tracer.     

Ion exchange separation of trace amounts of uranium and thorium in tantalum for neutron activation analysis

Separation method of a few ppb of uranium and thorium in tantalum metal by ion exchange for neutron activation analysis was established. After dissolving tantalum metal by hydrofluoric acid, uranium and thorium were separated from tantalum using cation exchange resin column in 0.5M hydrofluoric –0.65M boric acid media. Both of the yields for uranium and thorium during separation were above 95% and the remaining amount of tantalum be lowered below 400 ng.     

Substoichiometry in neutron activation analysis technique

Neutron activation analysis has become one of the most sensitive and selective analytical technique for the determination of trace elements in a wide variety of matrices. Neutron activation involves the irradiation of the test sample and a standard of the element to be determined with thermal neutrons in a reactor, followed by dissolution of the test sample in the presence of carrier of the element to be determined. The carrier and radioisotopes are separated from the bulk of other induced activities (employing precipitation, solvent extraction, ion exchange etc.) and then the activity induced in the sample is measured on a suitable detector. The standard is treated identically. From the ratios of the activity of the sample and standard and the weight of the standard irradiated, the concentration of element in the test sample is calculated. A rapid, selective and sensitive method of radiochemical separation is subtoichiometric extraction in which the same amount of carrier is added to the irradiated test sample and standard. Exactly the same amount of reagent is added to both the sample and standard but in substoichiometric amounts, followed by the separation of the species formed by extracting it with an organic solvent. The activities of the extracts are measured. The amount of element present in the sample is calculated with help of the ratio of the activities and the weight of the standard taken. The advantages of the method are discussed. Application of substoichiometry in neutron activation has been elucidated with reference to the determination of Au in various samples by substoichiometric neutron activation analysis.     

An automated facility for neutron activation analysis

A fully automated neutron activation analysis (NAA) facility has been constructed at the Whiteshell Nuclear Research Establishment. This high-capacity facility has been designed for use with a wide variety of neutron sources, including Canada's SLOWPOKE II and MAPLE research reactors. Its pneumatic transfer system is driven by a Square-D Model 500 programmable controller, linked in turn to a Nuclear Data ND6700 computer/spectrometer. Custom software for data entry and system control has been combined with Nuclear Data software for gamma-spectrum acquisition and processing to create a flexible, easy-to-use facility for NAA. Its design and performance are discussed.     

Rapid separation of radiogallium from Zn and Cu targets using anion exchange technique

A simple, non-destructive and rapid radiochemical separation of radiogallium from Zn and Cu targets by ion-exchange chromatography using Amberlyst 21b was studied. The separation yield was high, while the chemical impurity in the separated radiogallium (inactive Zn or Cu) was low (<0.4 μg). The final product was obtained in the form of gallium citrate in a single step method technique that avoided the time consumption and corrosive evaporation.     

Instrumental neutron activation analysis of Na in biological materials

Sodium contents in seven mixtures of biological materials from varying aliquants of wheat flour and oyster tissue were analyzed using the INAA (instrumental neutron activation analysis) method. The samples were activated in the thermal column (TC) of the 1 MW TRIGA reactor at our laboratory. To analyze and compare the measured results, the ratioa of the epithermal neutron flux to the thermal neutron flux was determined in the TC, the rotating rack (RR) and the pneumatic terminal (PT). Due to the negligible interferences of²⁴Mg(n, p)²⁴Na and²⁷Al(n, )²⁴Na to²³Na(n, )²⁴Na, the Na results were obtained with 97% accuracy and 99% precision. It is shown that the method is suited for accurately determining Na contents in 12 various biological materials, especially for the samples that are low in Na content. From the cadmium ratio measurements of Au (4.9 eV resonance of¹⁹⁸Au) and Sm (8 eV resonance of¹⁵³Sm), ratios ofa_e/₀ were determined at 0.0011, 0.052 and 0.053 in the TC, RR and PT activation positions, respectively.     

Determination of praseodymium in lanthanum compounds by neutron activation and ion exchange separation

Summary A procedure was developed to determine small amounts of praseodymium in lanthanum compounds by neutron activation analysis. After irradiation of the sample in a reactor praseodymium is separated from lanthanum by anion exchange and Pr-142 is measured by a gamma-ray spectrometer. From the high decontamination factor of 110⁸ a detection limit of 5ppb praseodymium in lanthanum may be calculated. Because of the strong activation of lanthanum, the handling of samples with activities of about 1 Ci La-140 would be required. For the analyses carried out here with respect of sample weights, neutron flux and irradiation time a detection limit of 2.4ppm was obtained.

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Bestimmung von Praseodym in Lanthanverbindungen durch Neutronenaktivierung und Ionenaustausch

Zusammenfassung Zur Bestimmung von geringen Mengen Praseodym in Lanthanverbindungen wurde ein auf Neutronenaktivierungsanalyse basierendes Verfahren entwickelt. Nach Bestrahlung der Probe im Reaktor wird Praseodym mit einem Anionenaustauscher von Lanthan getrennt und Pr-142 mit einem Gamma-Spektrometer gemessen. Der mit der Trennung erreichte Reinigungsfaktor von 110⁸ würde eine Nachweisgrenze von etwa 5ppb Praseodym in Lanthan erlauben. Wegen der starken Aktivierung des Lanthans würde das aber den Umgang mit Proben von ca. 1 Ci La-140 erfordern. Mit den hier gewählten Probenmengen, Neutronenflüssen und Bestrahlungszeiten wurde eine Nachweisgrenze von 2,4ppm erreicht.

Presented at the Ulmer Symposium Analytische Chemie — Elementanalyse mit chromatographischen Methoden, Sept. 19–21, 1979, D-7900 Ulm     

Use of a nitrate-form anion exchange resin for the determination of traces of gold in copper and cadmium by neutron activation analysis

A method is described for the determination of traces of gold in copper and cadmium by neutron activation analysis, using anion exchange resin as a preconcentration agent: gold was separated from large amount of copper or cadmium with Cl-form Dowex 1X8 AG, 100–200 mesh, resin. To reduce the interfering activities, the resin was irradiated in NO ₃ ⁻ -form and washed with dilute hydrochloric acid after irradiation.¹⁹⁸Au in the resin was then counted with a Ge(Li) or NaI(Tl) detector. The chemical yields were more than 99%. The concentration factors of gold for copper and cadmium samples were 1.1×10⁸ and 2.7×10⁶, respectively. The analytical results of gold in 99.99% copper and 99.999% cadmium were 65 and 0.15 ppb, respectively. The blank was 0.05 ng Au per 200 mg of wet resin.     

A technique for reducing interferences in epithermal neutron activation analysis

A new epithermal neutron activation technique is described. The technetium is based on the existence of non-overlapping resonance peaks in the neutron absorption cross-section spectra for the nuclides present in the sample to be analyzed. By this method it is possible to reduce some of the interfering activities with respect to the sought activity by using appropriàte filters. An experiment has been carried out to demonstrate the validity of the technique.     

Studies on neutron activation analysis using ion exchange preconcentration

Three convenient procedures are described for applying anion exchange resins to the preconcentration and irradiation support in neutron activation analysis. For each procedure the amounts of interferences were determined. The effect of the form, cross-linkage, pore size, and particle size of the resins on the elimination of interferences was investigated. Some other associated problems are also presented, viz. effect of concentration and temperature of washing solution, effect of irradiation time, and comparison with filter     

Instrumental neutron activation analysis technique using subsecond radionuclides

The fast irradiation facility Mach-1 installed at the Danish DR 3 reactor has been used in boron determinations by means of Instrumental Neutron Activation Analysis using¹²B with 20-ms half-life. The performance characteristics of the system are presented and boron determinations of NBS standard reference materials as well as fertilizer materials are compared by literature value and spectrophotometric measurements, respectively. In both cases good agreement is obtained.     

Weak anion and cation exchange mixed-bed microcolumn for protein separation

To separate proteins with a wide distribution of pIs under the conditions compatible to online tryptic digestion (with preferable pH=8.0), weak anion and cation exchange chromatography (WAX/WCX) mixed‐bed microcolumn has been developed. With a mixture of five proteins with pIs ranging from 4.2 to 11.4, the effect of WAX/WCX ratio on the separation performance was investigated, and an optimum packing ratio of 1:1 w/w was obtained. Moreover, the undesirable hydrophobic interaction between the proteins and the stationary phase was suppressed with 10% ACN v/v added in the mobile phases. Under the optimized conditions compatible to tryptic digestion, basic and acidic proteins were resolved simultaneously, with RSDs of relative retention time on six columns less than 6%, indicating the good resolution and packing reproducibility. Furthermore, one RPLC fraction of proteins extracted from rat middle brain and the whole protein mixture extracted from rat liver were analyzed, respectively. The results demonstrated better separation performance on WAX/WCX microcolumns than that on both weak anion exchange chromatography and weak cation exchange chromatography at pH ～8. We anticipate that WAX/WCX microcolumns are promising for the integration of protein separation and tryptic digestion aiming at high‐throughput proteome study.     

Determination of uranium by neutron activation analysis using substoichiometric separation

Three analytical methods for uranium by neutron activation are described. The methods are based on the substoichiometric separation of barium or lanthanum, which are the fission products of uranium-235 by neutron irradiation. Uranium contents in high purity materials were determined by the methods, which were found to be useful for the determination of a trace amounts of uranium.     

Evaluation of the determination of iodine in drinking well water by neutron activation analysis and separation by isotope exchange

The determination of total iodine in drinking and well water by neutron activation analysis and separation of¹²⁸I (T=25.0 min) by isotope exchange has been examined at the 5–15 ng.ml^–1 level. Using the Lazy Suzan of a Triga Mark-II reactor, the capacity is 5 samples per hour at a precision of 15–20% per aliquot and no apparent systematic bias.     

An application of the monostandard epithermal neutron activation technique for the analysis of domestic phosphate ores

The trace elements As, Co, Eu, Ga, La, Sb, Sc, Sm, U and W and the major constituents Fe and Na were determined in four domestic phosphate rocks by the monostandard epithermal neutron activation technique. Samples of 0.1 g were irradiated in the Egyptian 2 MW ERR-1 reactor under Cd cover, and the induced gamma activities measured after 6 h, 7 d and 8 w with a Hp Ge detector coupled to a computerized multichannel analyzer. Uranium has been used as a monostandard due to its relatively high resonance integral value (I₀=274.6 b) and because it is one of the elements to be determined more accurately. The present data are compared with those obtained by instrumental neutron activation analysis (INAA) method performed at Institute of Radiochemistry, Karlsruhe. The observed discrepancies do not exceed 12% in average. The present method is a practical alternative for trace element analysis.     

An algorithm for data processing in neutron activation analysis

An algorithm for processing NAA data is described. Input data are the output data from a multichannel pulse-height analyzer with a microprocessor. This algorithm permits to calculate the concentrations of the analyzed elements (using a standard or a standard curve), the error of concentrations in the analysis of one or several parallel samples and the sensitivity of the analysis according to Currie's criteria in counts, g and g/g. Some other intermediate data (e.g. corrected net area of the peaks, parameters of the standard curve) may have individual importance in differenct cases.     

Radio-isotope neutron activation analysis for vanadium,manganese and tungsten in alloy steels

An instrumental neutron activation method for V, Mn and W in alloy steels with a ²⁴¹ Am/Be isotopic neutron source is described. The samples were irradiated to induce the nuclear reactions ⁵¹V(n, γ) ⁵²V, ⁵⁵Mn(n, γ)⁵⁶Mn, and ¹⁸⁶W(n, γ)¹⁸⁷W. The activities were measured with a NaI(TI) detector. Interferences on the measured photopeaks were shown to be negligible by measuring the half-lives of ⁶²V, ⁵⁶Mn and ¹⁸⁷W.These thre elementes were determined in the range 1.5–12.9% in special steels; manganese in the range 0.5–1.6% was measured in cast irons. Calibration was done by comparison with results from wet chemistry and x-ray fluorescence spectrometry. The processing times for the vanadium, manganese and tungsten determinations were 11 min, 3 h and 26.3 h, respectively, but these were reduced greatly by intoruding a scheme wherein six samples were simultaneously irradiated and the ⁵⁶Mn and ¹⁸⁷W nuclides were measured sequentially for a series of 66 samples. The average processing time was reduced to 45 min for tungsten with a precision of 4.0% and accuracy of 3.4% and 22.8 min for manganese with a precision of 3.8% and accuracy of 3.1%.     

Radiochemical separation of rhenium with crown ether for neutron activation analysis in rocks

The extraction behavior of perrhenate with crown ethers has been studied and methods for the separation and determination of rhenium have been developed. Perrhenate anion can be quantitatively extracted into nitrobenzene by benzo-15-crown-5 (B15C5) from 2M potassium hydroxide and back-extracted by sodium phosphate buffer solution. The molar ratio of B15C5 to KReO₄ in the extracted species is probably 21. Rhenium was satisfactorily determined by neutron activation method in rock samples.