Isotope exchange and separation factor of238U/235U for the system U(III)/U(IV) in aqueous/organic phases

A study of the isotope exchange reaction U(III)_org/U(IV)_aq in the extraction system: 7M HCl — tributyl phosphate (TBP) — toluene has been performed. For 20 s of contact the results show a separation factor²³⁵U/²³⁸U of 1.014. This large separation factor is explained by the oxidation reaction of²³⁵U(III) and²³⁸U(III).     

Separation of trace elements,In(III), Sn(IV), Sb(V) and Te(IV) by adsorption on activated carbon and graphite

Adsorption behaviour of trace elements, In(III), Sn(IV), Sb(V) and Te(IV) on activated carbon and graphite powder was studied. Adsorption characteristics of the ions enabled the separation of In(III)–Sn(IV), Sn(IV)–Sb(V) and Sb(V)–Te(IV) pairs. Applications to practical separation, milking of^113mIn from¹¹³Sn, removal of tin impurity from¹¹⁹Sb, and milking of¹¹⁹Sb from^119mTe, are presented.     

Separation of99Mo from132Te using thiourea as complexing agent. Application to the separation of99Mo from fission products

A radiochemical method to isolate⁹⁹Mo from¹³²Te, both produced in the fission of²³⁵U, has been developed. The method is based on the formation of a cationic complex of tellurium with thiourea in acid medium which is retained (98.7±0.5)% on a cation exchange resin (Dowex 50W-X8, 100–200 mesh), while (99.8±0.05)%⁹⁹Mo passes through it, due to the non-formation of such complex in the same experimental conditions. The radionuclidic purity of⁹⁹Mo was found to be suitable for the preparation of⁹⁹Mo–^99mTc generators. The retention of⁹⁹Mo on an alumina column as a function of pH was investigated and the best pH range for this purpose was found to be 4.0–4.5.     

Polonium-210 and lead-210 in marine organisms: Intake levels for Japanese

The concentrations of²¹⁰Po and²¹⁰Pb were determined in about 30 species of marine organisms collected mainly from the north-easterm region of Japan to know the levels and distributions of these radionuclides and to estimate their intake levels from marine foods.²¹⁰Po and²¹⁰Pb showed a wide range of concentration in species: 0.6–26 and 0.04–0.54 Bq/kg (wet wt) in fishes, 0.5–220 and 0.2–43 Bq/kg (wet wt) in molluscs, echinoderms and chordatas, and 2.8–4.3 and 0.4–1.3 Bq/kg (wet wt) in algae, respectively. Higher accumulation of²¹⁰Po relative to²¹⁰Pb was found in all of the samples analyzed. The intake levels of²¹⁰Po and²¹⁰Pb by marine foods consumption were roughly estimated to be 0.48–0.69 and 0.022–0.042 Bq/d per person, respectively, on the basis of the statistical data on the consumption of seafood and/or production rates of marine foods.     

Structure and stability of ion pairs A−·K+·H2O with a strong anion

Characteristics of the ion pairs HCOO^–·Na⁺·H₂O, HCOO^–·K⁺·H₂O, and also Na⁺·H₂O and K⁺·H₂O were calculated by the nonempirical Hartree—Fock—Roothan linear-combination-of-atomic-orbitals self-consistent-field (SCF) molecular-orbital method in a two-exponent Dunning basis using an extended set of Huzinaga—Dunning Gaussian functions. The basis was supplemented by polarization functions ofd type for the oxygen atom andp type for the H atom and also by diffusion functions ofp type for the oxygen atom. Characteristics of the ion pairs HCOO^–·Li⁺ and HCOO^–·Na⁺ were calculated taking into account the electronic correlation according to the Möller — Plesset second-order perturbation theory. Significant quantitative difference was observed in the hydration of ionogens and free cations. The stability of the ionogens HCOOMe in aqueous solutions, increasing from Li⁺ to Cs⁺, is not explained by the difference between the energies of complexation and the energies of hydration of the cations. The better solubility of the salt molecule with a cation of smaller radius is due to the higher degree of hydration of that ionogen.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2700–2707, December, 1992.     

Carbamoylmethyl sulfoxides as novel extractants for actinides

The present paper describes a novel type of extractant for actinides called bis (dioctylcarbamoylmethyl) sulfoxide which neither contains phosphorus nor entails the addition of tributyl phosphate as phase modifier for extraction. This extractant, abbreviated as CMSO, has been found to be freely soluble in dodecane and to form no third phase even with concentrations of nitric acid as high as 10M. The distribution ratios for the extraction of Am(III), Pu(IV) and U(VI) at trace levels have been found to be 13, 220 and 11, respectively, from 5M nitric acid using 0.2M CMSO in dodecane and those for back-extraction have been found to be 2×10^–4, 8×10^–3 and 5×10^–2 using 0.01M nitric acid, 0.1M oxalic acid and 0.35M sodium carbonate, respectively. Similar distribution ratios were obtained with the recycled extractant. Extraction was found to be very rapid. Eu(III) and Sr(II) were found to be moderately extracted with distribution ratios of 2 and 0.77, respectively, while the extraction of Cs(I) was negligible (K_D=0.005).     

Gaigranin and gaigrandin — New sesquiterpene lactones fromGaillardia grandiflora

Two new sesquiterpene lactones — gaigranin and gaigrandin — have been isolated from the epigeal part ofGaillardia grandiflora, and their structures have been established on the basis of spectral (IR, PMR,¹³C NMR, and mass) characteristics and x-ray structural analysis.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 79–85, January–February, 1995. Original article submitted October 7, 1994.     

Highly sensitive spectrophotometric determination of trace amounts of platinum(IV) with the molybdate-basic dyes-poly(vinyl alcohol) system

Three highly sensitive spectrophotometric methods for the determination of platinum(IV) have been developed, based on its colour reactions with molybdate and basic dyes (BD) in aqueous solution in the presence of poly(vinyl alcohol). Platinum(IV) reacts with molybdate and BD to form ion — association complexes of composition (BD)₂[Pt (MoO₄)₃]. The molar absorptivities are between 6.83 × 10⁵ and 9.51 × 10⁵ dm³mol^–1cm^–1, the highest value being found with nile blue. Suitable conditions for the reactions and the effects of foreign ions were investigated. The methods can be applied to the spectrophotometric determination of trace amounts of platinum(IV) in some catalysts and ores.     

Ultratrace characterization of AlSiCu sputter targets for Th,U and 35 other elements by neutron activation analysis

Instrumental and radiochemical neutron activation analysis has been applied to a comprehensive trace characterization of AlSiCu sputter targets. By instrumental neutron activation analysis via long-lived indicator radionuclides, up to 33 elements were assayed with detection limits between 0.01 and 200 ng·g^–1. The high activity of⁶⁴Cu and²⁴Na produced from the matrix significantly limits the instrumental performance via short- and medium-lived indicator dionuclides. For this reason, a radiochemical separation was developed based on adsorption of²⁴Na on hydrated antimony pentoxide and extraction of⁶⁴Cu by diethylammonium diethyldithiocarbamate from HCl medium. By this radiochemical method, As, Ga, K, La, Mn, Mo, Re, Sb, U and W could be assayed via medium-lived radionuclides and the achievable limits of detection were between 0.1 and 25 ng·g^–1. Further improvement of detection limits for U and Th was achieved by a selective radiochemical separation of²³⁹Np and²³³Pa on a Dowex 1×8 column in HF and HF/NH₄F medium providing limits of detection for U and Th of 0.06 and 0.02 ng·g^–1, respectively. These techniques were applied to the analysis of two AlSiCu sputter target materials. Results are compared with those of glow discharge mass spectrometry.     

Uranium ore processing: Kinetics of the growth and dissolution of a potential host solid from a model surface

As part of an investigation concerning the fate of²²⁶Ra during uranium ore milling and long-term tailings storage, we have investigated the growth of potential host solids-barium sulfate and lead sulfate-on mica, a model surface. The kinetics of dissolution of barium sulfate-and of a barium sulfate solid containing²²⁸Ra as a trace component into 10^–3M sulfuric acid were subsequently investigated using a flow-cell and radiotracer techniques. It was found that ther dissolution of both the barium sulfate host and the²²⁸Ra trace component was congruent. The dissolution reaction appears to be surface controlled.     

Depth distribution of239,240Pu and137Cs in soils of South Korea

Depth distribution of^239,240Pu and¹³⁷Cs in the soils of South Korea have been studied. The average accumulated depositions were estimated roughly to be 54.8±32.1 Bq·m^–2 for^239,240Pu, 1.6±1.0 Bq· ·m^–2 for²³⁸Pu and 1982.8±929.1 Bq·m^–2 for¹³⁷Cs. The activity ratios of^239,240Pu/¹³⁷Cs in soils were found to be in the narrow range of 0.0153 to 0.0364 with a mean value of 0.0230±0.006. The concentrations of^239,240Pu and¹³⁷Cs in soils decrease exponentially with increasing the soil depth. A significant correlation was found between the concentration of^239,240Pu and that of¹³⁷Cs. The activity ratios of^239,240Pu/¹³⁷Cs tend to increase slightly with increasing soil depth.     

A novel technique for the separation of99mTc from99Mo

A new technique for the separation of^99mTc from low specific activity⁹⁹Mo is reported. A separation based on the principle of precipitation of⁹⁹Mo as calcium molybdate has been investigated. On precipitating⁹⁹MoO ₄ ^2– from alkaline solution as calcium molybdate under controlled conditions, the^99mTcO ₄ ^– is found to remain quantitatively in the supernatant solution with little carry-over of⁹⁹Mo. This calcium molybdate (⁹⁹Mo) could be redissolved and reprecipitated at regular intervals, yielding^99mTc quantitatively in aqueous neutral solutions. Calcium molybdate precipitates containing up to 1.5 GBq of⁹⁹Mo and 130–180 mg of molybdenum were prepared and evaluated. The performance in terms of repeated^99mTc separation gave yields of 75–93% with acceptable readionuclidic and radiochemical purity.     

On the determination of trace impurities in carbon concentrates used in the spectrochemical analysis of extra-pure substances

The effects of concentration of NaCl, employed as the carrier substance in a carbon collector, on line excitation conditions for trace impurities and on other factors which determine detection limita in spectrochemical analysis with a d.c. arc have been studied. It was shown that over the range 4–0.5 per cent NaCl the change in excitation conditions has but a slight effect on the intensity of spectral lines. The major role in the marked lowering of detection limits for trace impurities (Ag, Be, Bi, Cd, Cu, Ga, Ge, In, Mn, Zn, down to n × 10⁻¹⁰ g; Au, Ba, Co, Cr, Ni, Pb, Sb, Sn, Tl—to n × 10⁻⁹ g and for As, B, Pt, Te—n × 10⁻⁸ g) is played by a decline in background intensity and a better coefficient of vapour utilization. For some trace impurities this limit may be improved still further by re-shaping the upper electrode.     

A new triterpene from the leaves ofBetula mandschurica

A new triterpene (I) has been isolated from the unsaponifiable fraction of an ethereal extract of the leaves ofBetula mandschurica to which, on the basis of the results of a physicochemical investigation and a comparison of the¹³C spectra with the spectra of known triterpenes — ocotillone (II) and 20(S)-hydroxydammar-24-en-3-one (III) — the structure of 20(S),24(S)-dihydroxydammar-25-3n-3-one has been assigned. An approach to the determination of the configuration of the asymmetric center at C₂₄ in 24-hydroxy derivatives of tetracyclic triterpenoids with an open side chain by the use of¹³C NMR spectroscopy is proposed.Pacific Ocean Institute of Bioorganic Chemistry of the Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 346–351, May–June, 1980.     

Evaluation of long chain dithiocarbamates as photometric reagents for the determination of trace amounts of uranium

A highly sensitive extractive spectrophotometric method for the determination of U(VI) using octadecyldithiocarbamate (ODDTC) has been developed. The efficiency of ODDTC as a chelating agent is compared with that of hexadecyl, tetradecyl and dodecyl dithiocarbamates. U(VI) reacts with these dithiocarbamates in ethanol to form reddish-brown water-insoluble chelates capable of being extracted into CHCl₃. The molar absorptivities range from 1.16·10 to 4.91·10⁴l·mol^–1·cm^–1, the highest value being found for ODDTC. Suitable conditions for the extraction and the effect of foreign ions were investigated. The method can be used for the determination of trace amounts of U(VI) in water and sand. The results are comparable to ICP-AES method.     

The seed oil of Rindera oblongifolia

Summary The oil of the seeds ofRindera oblongifolia, family Boraginaceae, growing in Central Asia, has been studied for the first time. Among the acids of the triglycerides of the oil five types of monoenoic acid differing by the length of the carbon chain but having the same length of the terminal carbon chain — 18:1⁹, 20:1¹¹, 22:1¹³, 24:1¹⁵, and 26:1¹⁷ — have been detected for the first time. This is the first time that the last of these acids has been found in a seed oil of this family.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 26–29, January–February, 1976.     

Determination of iodine-129 and iodine-127 in environmental samples collected in Japan

Analytical method for the determination of¹²⁹I and¹²⁷I in environmental samples has been developed by using radiochemical neutron activation analysis. The¹²⁹I levels in the samples such as soil (0.9–41 mBq/kg), precipitation (0.002–0.11 mBq/kg), pine needles (1.2–32 mBq/kg) and seaweed (<0.1–17 mBq/kg) collected near the nuclear facilities in Tokaimura were higher than those from the other areas in Japan. The highest¹²⁹I concentration was found in surface soil (0–5 cm), and the highest¹²⁹I/¹²⁷I ratios were found in pine needles and precipitation. The¹²⁹I/¹²⁷I ratio was higher in rice paddy soil than those in wheat field soil collected around Tokaimura, while the concentration of¹²⁹I somewhat higher in wheat field soil.     

Influence of Ba on the electrodeposition of226Ra

A detailed study of the influence of barium on the electrodeposition of²²⁶Ra was made using two different procedures. High yields (80–90%) were attained when the amounts of barium were not very significant. However, the²²⁶Ra yields fell drastically for amounts slightly greater than 0.10–0.15 mg of Ba, according to the electrodeposition procedure. Samples containing trace amounts of barium less than 100–150 g can thus be treated with no barium-radium separation being required.²¹⁰Po was also deposited, although practically no influence of barium on the Po plating was observed. The²²⁵Ra resolution rose uniformly (25 to 55 keV) as the amount of barium rose up to 1 mg. These resolutions allow one to make a direct accurate determination of²²⁶Ra as well as an indirect determination of²²⁴Ra and²²³Ra via measurement of their daughter products.     

Determination of trace amounts of gold in the presence of rare earth elements in rock samples from Makhtesh Ramon (Southern Israel), by instrumental epithermal neutron activation analysis

Epithermal neutron activation analysis (ENAA), followed by high resolution gamma-ray spectrometry, was applied to determine trace amounts of Au in the presence of rare earth elements (REE) from vein samples in the basaltic rocks of Makhtesh Ramon, located in southern Israel. The contribution of¹⁵²Eu (411.1 KeV) to the 411.8 keV peak of¹⁹⁸Au was determined using multiple gamma-peak, ratios derived from Eu standards and mixtures of Au and Eu. The concentration of Au was found to be in the range of 10–80 ppb. A group of rare earth elements: La, Eu, Ce, Tb, Sm, Lu, Yb was identified; the concentration of Eu was found to be 0.5 ppm.     

Investigation of accuracy and precision for determination of the short-lived nuclides by INAA and the Mössbauer-effect

Different reference materials of environmental and geological origin, such as NBS 1633a (Coal Fly Ash, CFA), NBS 1645 (River Sediment, RS), GXR-2, and IAEA Soil-5, were investigated by short time activation analysis. The samples were analyzed in 5 replicates each between 100 to 150 mg, at neutron flux of 1.3 E 12 cm^–2 s^–1, using a high rate — high resolution gamma spectroscopy with a Loss Free Counting (LFC) System to correct the dead time and pile up to 500,000 cps. The results of the measurements indicate that the precision in determination of²⁸Al,^46mSc, and⁵²V is between 1 to 6%. Different evaluation programs (i.e. ALCHEM, AKTAN, and ND-PEAK) were used to calculate the peak areas. The results indicate that, at lower counts, the statistical error of peak area calculation becomes more significant. Finally, Mössbauer spectroscopy was used to investigate the main Fe compounds present in some reference materials.