"High specific activity" radiotracers for metallo-toxicological studies: cyclotron and nuclear reactor production,radiochemical separation and "quality control": platinum,iridium, gold,copper and gallium

Very High Specific Activity RadioNuclides, HSARN, are a powerful tool to label a wide variety of chemical elements and compounds present in the biosphere in ultra-trace amounts. Medium and high Z radionuclides, can be produced by irradiation in light-ions accelerator and sometimes nuclear reactor. If the nuclear reaction product has atomic number different from irradiated target, it is possible separating the radioactive nuclide from irradiated target, without addition of isotopic carrier. These kinds of radionuclides are named No Carrier Added, NCA, and their specific activity is very high and can reach values close to the theoretical Carrier Free one. The true specific activity must be determined by use of very sensitive radioanalytical techniques. If a low isotopic dilution factor is obtained, these radiotracers are used to label inorganic species and complexes of elements, which are presently introduced into the echo-systems by human activities. New production methods for NCA Pt, Ir, Au, Cu and Ga radiotracers are presented, with some details on radiochemistry and quality controls.     

Preparation of high specific activity radiotracers for radioanalytical studies

High specific activity radiotracers are very suitable for studies related to the toxicological impact of trace elements onto human health. In order to investigate the metabolic behaviour of Low Level Exposure (LLE) to trace elements, it is necessary to carry out in-vitro and in-vivo experiments with tracers whose concentration is of the same order of magnitude as the present environmental exposure values (ng-g/kg day). Preparations, separations and purifications of some No Carrier Added (NCA) radiotracers (⁴⁸V,^95m,96Tc,^{195m,g,197m,g}Hg,¹⁹⁹Au,²⁰²Tl) produced by either cyclotron or nuclear reactor irradiation, are presented and discussed. This work reviews the more recent advances in this field carried out by our groups.     

Sequential substoichiometric radiochemical separation of selenium,thallium and cadmium

A procedure for sequential radiochemical separation of Se(IV), Tl(I) and Cd(II) has been developed. This procedure involves substoichiometric solvent extraction of these ions with 2-mercaptobenzothiazole (2-HMBT) under different experimental conditions.     

Catalytic activity of chromium,manganese, vanadium,tungsten, and molybdenum oxides in the hydrogenation of ethylene

Conclusions The catalytic activity of the oxides of Cr, W, Mn, Mo, and V in the hydrogenation of ethylene increases with decrease in the degree of oxidation of the cation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1679–1680, July, 1977.     

Vanadium(III) as an analytical reagent: The titrimetric determination of iron, copper, thallium, molybdenum, uranium, vanadium, chromium and manganese

Vanadium(III) solutions can be used in direct titrations of iron(III), copper(II), thallium(III), molybdenum(VI), uranium(VI), vanadium(V), chromium(VI) and manganese(VII) in milligram amounts. The titrations are done at 70-80 degrees for iron(III), copper(II), thallium(III), molybdenum(VI) and at room temperature for vanadium(V), chromium(VI) and manganese(VII). Uranium(VI) is titrated at 70-80 degrees in presence of iron(II). The vanadium(III) solution is prepared by reduction of vanadium(V) to vanadium(IV) with sulphur dioxide, followed by addition of phosphoric acid and reduction with iodide, and is reasonably stable.     

Activation analysis of vanadium in high alloy steels using manganese as internal standard

A method has been developed for the determination of vanadium in high alloy steels by radioactivation analysis. Manganese present in the steel sample is used as an internal standard, thus permitting accurate correction of neutron flux irregularities between sample and reference. The method was tested on 4 National Bureau of Standard samples having a vanadium content from 0.014 up to 2.04% and a widely differing composition as regards other alloy constituents. The results obtained by radioactivation in the Belgian Reactor BRI and the Amsterdam 28 MeV deuteron cyclotron show satisfactory accuracy as well as precision.     

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%.     

Surface morphology of electrolytic deposits of vanadium, cobalt, and manganese oxides

The surface morphology of V₂O₅, Co₂O₃, and MnO₂ electroplated under different electrolysis conditions was studied. The nature of the electrocrystallization of these materials was suggested on the basis of the analysis results.     

Atomic-absorption spectrophotometric determination of antimony, arsenic, bismuth, tellurium, thallium and vanadium in sewage sludge

Electrothermal atomic-absorption spectrophotometry (AAS), by use of a graphite furnace, in conjunction with sample pretreatment by homogenization, was evaluated as a rapid method for the determination of bismuth, thallium and vanadium in sewage sludge. This method was compared with use of flame, electrothermal and hydride-generation (for bismuth) AAS in conjunction with conventional acid digestion and dry-ashing pretreatments and was found to be applicable to this type of sample. Comparisons were also made between flame and hydride-generation AAS in conjunction with an acid digestion pretreatment for the determination of antimony, arsenic and tellurium in sewage sludge. The hydride-generation technique was considered the better for waste-water samples because of its greater sensitivity.     

Cyclotron production, radiochemical separation and quality control of platinum radiotracers for toxicological studies

The increasing concentration of Pt, Pd and Rh in the environment is mainly due to the release of these elements from the catalytic converters of the motorvehicles. This situation makes it necessary to carry out metallotoxicological experiments on both cell cultures and laboratory animals, in order to assess their impact on living organisms after a Long Term and Low Level Exposure (LLE). Both nuclear reactions^natIr(p,xn) and^natOs(α,xn) were investigated in the energy range up to 45 MeV for protons and 38 MeV for alpha-particles, in order to optimize the irradiation parameters for the production of^188,189,191Pt. Several sets of thin- and thick-target excitation functions were determined experimentally by cyclotron irradiation at both Milano and Ispra cyclotrons. This paper reports the irradiation parameters studied and adopted and two radiochemical procedures for the separation of radio-Pt from an Os target, as well as from ruthenium, iridium and gold impurities. These procedures were used to obtain very high specific activity Pt radionuclides in No Carrier Added (NCA) form. Radionuclidic, radiochemical and chemical purity measurements were carred out by the use of several techniques like ψ-spectrometry, ion-exchange radio-chromatography, atomic absorption spectrometry and neutron activation analysis.     

Spectrophotometric determination of vanadium(V) and its application to vanadium steel containing chromium,molybdenum, manganese,and nickel

Promethazine hydrochloride forms a red colored species with vanadium(V) in 6.0–7.5 M phosphoric acid. A 16-fold molar excess of the reagent is necessary for full development of color intensity. Beer's law is valid over the concentration range of 0.1–7.0 ppm. The optimum concentration range as evaluated by Ringbom's method is 0.5–7.0 ppm. The sensitivity of the reaction is 0.005 μg cm^?2 and the molar absorptivity is 9.60 × 10³ liter mol^?1 cm^?1 at 517 nm. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions were reported. Vanadium in vanadium steel containing chromium, molybdenum, manganese, and nickel was determined.     

Spectrophotometric determination of vanadium(v) and its application to vanadium steels containing chromium, molybdenum, tungsten and manganese

A newly synthesized reagent, N-o-toluoyl-N-o-tolylhydroxylamine is used in a sensitive and selective spectrophotometric method for determination of vanadium(V). The method has been successfully applied to vanadium determination in Mn-Mo-Cr-V steels. The system in 2-6M hydrochloric acid medium obeys Beer's law at 510 nm in the range of vanadium concentration from 0.5 to 10.0 mug ml .     

Synthesis of radioactive tributyl[113Sn]tin of high specific activity for use in environmental fate studies

A method of synthesis of tributyl[¹¹³Sn]tin,­(n/C₄H₉)₃¹¹³Sn(IV), from commercially avail-­able inorganic ¹¹³Sn(IV) is presented. Inorganic tin is first extracted in diethyl ether and reacted with C₄H₉MgCl to produce tetrabutyltin, (C₄H₉)₄¹¹³Sn, which is then debutylated with HgCl₂. The resulting tributyl[¹¹³Sn]tin chloride is isolated from the reaction mixture by successive extractions with hexane and aqueous Na₂S₂O₃. The yield is 40–60% and the product obtained is >98% pure. It has the same specific activity as the starting ¹¹³Sn(IV), i.e. up to 550 MBq mg⁻¹ Sn, making it suitable for use in environmental fate and toxicology studies at concentrations relevant of those found in the aquatic environment. © 1998 John Wiley & Sons, Ltd.     

A simple method for preparation of high specific activity128I

The preparation of high specific activity¹²⁸I by neutron activation of KIO₃ is described. The¹²⁸I^– produced in a Szilard-Chalmers process is eluted with a water-isopropylamine mixture which dissolves only KI but not KIO₃.     

A radiochemical method of separation of carrier-free vanadium from scandium and bulk amount of titanium

A method for the separation of carrier-free vanadium from scandium and bulk amount of titanium has been developed. Vanadium has been produced through the reaction^natTi(d,n)^48,49V with 8 MeV deuterons from the Variable Energy Cyclotron, Calcutta. The separation is performed with Dowex 1×8, 50–100 mesh fluoride from anion exchange resin which retains all the scandium and titanium with 4.5M hydrofluoric acid as eluent, while vanadium(V) is easily eluted. The chemical yield of vanadium was >85%.     

Application of radiochemical neutron activation and flame atomic absorption spectrometry for the determination of manganese in blood

The triplet-triplet absorption spectra of various aromatic compounds in benzene solution were studied by pulse radiolysis. It has been found that methylation of naphthalene characteristic absorption band in this group of compounds at 430±10 nm (naphthalene, 2-methylnaphthalene, 2,6-dimethylaphthalene, anthracene, phenanthrene, pyrene and fluorene); new bands appeared with phenanthrene and pyrene at 495 and 525 nm respectively. The decay remains of the first order in the whole group with similar rate constant values. Diphenyl and 1,1-dinaphthyl show significant changes in their T-T spectra in comparison with the preceding group of compounds. T-T spectrum of o-terphenyl differs significanly from those of p-and m-isomers, which can be caused by greater overlapping of electron orbitals in o-isomer molecule. Aromatic ketones show a complex picture both in spectra and decay kinetics.     

高比容量二氧化钌电极材料制备

以无定型Ru O2·x H2O和金属Ru粉末为反应物,采用高温固相反应制备了Na型层状氧化钌(NaRu O2),通过离子交换反应对Na-Ru O2实现了剥离,得到了氧化钌纳米层胶体分散液。将氧化钌纳米层分散液冷冻干燥处理后得到了氧化钌重组物(ERRu O2)。通过XRD和SEM对制备试样进行了分析表征。电化学测试结果表明,在0.5 mol L-1H2SO4水溶液中,当电流密度为0.25 A g-1时,ERRu O2电极比电容高达645 F g-1,远远高于前驱体Ru O2·x H2O的比电容(367 F·g-1),并且ERRu O2电极表现出与前驱物相似的循环稳定性,是一种性能优异的超级电容器电极材料。     

Preparation of tagged sodium dodecylbenzenesulfonate of high purity and specific radioactivity

Radioactive tagging of a surface active agent, commonly known as a “surfactant” is described. Sodium dodecylbenzenesulfonate was chosen because it is one of the principal surfactants used in household detergents. To increase the radiochemical yield, the tagged sulfuric acid was concentrated and the minimum amount of non-radioactive 30% fuming sulfuric acid needed to complete the sulfonation determined. The dodecylbenzene used was fractionated from “Neolene-400” using chromatographic methods. The difference in isomers was detected by infrared spectra and refractive indices. Two methods of introducing the radioactive sulfur were employed. The purity of the products obtained was determined from their respective infrared spectra. The final product had a specific radioactivity of 1.24 millicuries per gram of surfactant. Its purity was about 99%. Some experiments using the product are described.