Determination of129I and127I in environmental samples by neutron activation analysis (NAA) and inductively coupled plasma mass spectrometry (ICP-MS)

In order to assess the levels and behavior of¹²⁹I (half-life: 1.6×10⁷ y) and¹²⁷I (stable) in the environment, we have developed analytical procedures involving neutron activation analysis (NAA). Environmental samples collected around Tokaimura, Ibaraki Prefecture, Japan, have been analyzed using this method. Ranges of¹²⁹I and¹²⁷I concentrations in surface soil were 0.9–180 mBq kg^–1 and 1–60 mg kg^–1, respectively. Higher¹²⁹I concentrations were found in soil samples collected from coniferous forests, suggesting a contribution from tree canopies in the deposition of this nuclide. Most of the¹²⁹I in soil, was found to be retained in the first 10 cm. The¹²⁹I/¹²⁷I ratios in wheat fields were lower than those in rice paddy fields.A soil sample collected by IAEA from an area contaminated by the Chemobyl accident was also determined. The¹²⁹I concentration and the¹²⁹I/¹²⁷I ratio were 1.6 mBq kg^–1 and 1.7×10^–7, respectively. The¹²⁹I level in this sample was higher than the values obtained in areas far from nuclear facilities in Japan. It was suggested that the analysis of¹²⁹I in soils in the Chernobyl area may be useful in evaluating the¹³¹I levels at the time of the accident.Analyses of¹²⁹I and¹²⁷I by ICP-MS in water samples were also made. The analytical speed of this method was very high, i.e., 3 minutes for a sample. However, there is a sensitivity limitation for¹²⁹I detection due to interference from¹²⁹Xe with the¹²⁹I peak. The detection limits for¹²⁹I and¹²⁷I in water samples were about 0.5 mBq ml^–1 and 0.1 ng ml^–1, respectively.     

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.     

Distribution and behavior of long-lived radioiodine in soil

The concentration of¹²⁹I in soil in Japan was determined by neutron activation analysis. For the activation analysis, pre-irradiation chemical separation of the iodine was carried out by acid decomposition and distillation and post-irradiation treatment was performed by ion exchange and solvent extraction. The concentration of stable iodine and¹³⁷Cs were also determined and compared with the behavior of¹²⁹I in soil.Soil samples from Ibaraki, Fukui, Fukushima, and Nagasaki Prefectures were analyzed and¹²⁹I was detected in amounts ranging from 10^–7 to 10^–5 Bq/g soil in uncultivated surface soil. There are apparently small variations in the¹²⁹I concentrations in each of the regions analyzed.From depth profile studies in sandy soil, the iodide form of¹²⁹I was found to migrate downward at a relatively rapid rate while other species remain longer in the surface soil.     

Determination of I-129 and I-127 in soil and tracer experiments on the adsorption of iodine on soil

Neutron activation analysis of¹²⁹I and¹²⁷I in soil has been studied. The limit of detection for¹²⁹I in soil was about 0.05 mBq/kg or 1×10^–9 as¹²⁹I/¹²⁷I atom ratio. The range of¹²⁹I concentration in surface soils collected around Tokaimura (Ibaraki Prefecture) was 0.9–41 mBq/kg.Tracer experiments on the adsorption of iodine were also carried out, in order to obtain information on the behaviour of iodine in soil-water systems. Different adsorption patterns of iodide and iodate on soil were found. It was supposed that iodide was adsorbed by the soil fraction which became unstable at about 200° C and iodate by the fraction which was relatively stable to heating.     

Iodine separation procedure for the determination of129I and127I in soil by neutron activation analysis

A radiochemical neutron activation analytical method for the determination of¹²⁹I and¹²⁷I in soil samples was studied. Iodine was separated from the sample prior to the irradiation by volatilization, i.e. by combustion of the sample and trapping of the iodine in an alkaline solution together with a reducing agent. This method enables one to digest samples containing up to 100 g dry matter. The chemical yield was mostly more than 90%. After irradiation the iodine fraction was further purified by solvent extraction. The detection limit of the¹²⁹I/¹²⁷I ratio was 1×10^–9.     

Dry deposition velocity of iodine-129 onto grass as obtained by field measurements in the environment of a nuclear fuel reprocessing plant

The deposition velocity of gaseous organic¹²⁹I species from the exhaust air stack of the Karlsruhe reprocessing plant onto pasture grass was measured by a field experiment. By simultaneously measuring the amount of¹²⁹I deposited per unit area of pasture grass and the time integrated mean air concentration of¹²⁹I a deposition velocity of V_g=5.8×10^–1 /cm s^–1/ onto pasture grass was determined.     

Iodine-129 and natural iodine-127 in deer thyroids from the environment of a small nuclear fuel reprocessing plant and from sites remote from nuclear facilities

Concentrations of the fission product¹²⁹I and natural¹²⁷I were determined in deer thyroids collected in the environment of the small Karlsruhe nuclear fuel reprocessing plant (WAK) and in a region remote from¹²⁹I sources of nuclear facilities. The isotopic ratio¹²⁹I/¹²⁷I in thyroids from the environment of WAK varies from 1.0×10^–6 to 12.9×10^–6, which is about one order of magnitude higher than the¹²⁹I/¹²⁷I ratios in thyroids from deer in a region remote from nuclear facilities. These ratios were between 0.2×10^–6 and 0.7×10^–6.     

The use of liquid scintillation analysis in the monitoring of α emitting and transuranium nuclides in environmental samples

With pulse decay discrimination function and using diisopropylnaphthalene based scintilation cocktail, liquid scintillation analysis (LSA) becomes a rapid and reliable method for monitoring emitting nuclides in environmental samples. Recent developments of instrumentation and cocktail of LSA are described. Procedures and results of monitoring gross activity in vegetable samples and plutonium in soil samples are given. The Minimum Detectable Activity was 4.5×10^–2 Bq/Kg for vegetable samples and was 6.6×10^–5 Bq/g for soil samples.     

Alpha-recoil atoms of plutonium in the environment

The -recoil effect of²³⁹Pu has been observed in environmental samples and theN ₅ ^P /N₅ ratio in these samples has been calculated. This ratio in atmospheric samples is in the range between 10^–5 and 10^–4 (atom/atom). For other contemporary terrestrial samples it is in the range between 10^–7 and 10^–6 (atom/atom), while that of uranium mineral is about 10^–10 (atom/atom). The results further explain the radioactive fallout contamination of our environment by uranium and plutonium isotopes.     

Electrical properties of poly(bis(β-phenoxyethoxy)phosphazene) and its complexes

Electrical and dielectrical properties of poly(bis(-phenoxyethoxy)phosphazene) (I) and its complexes with various content ratios of AgSO₃CF₃ to monomeric unit (0.25/1 (II) and 0.5/1 (III) in molar ratio) were investigated.Dc conductivity of respective samples at 18 °C were 6.1×10^–12, 4.4×10^–9, and 7.1×10^–8 S/m.Dc conduction was considered to be due to ion hopping. Charge mobility ranged from 3×10^–12 to 6× 10^–11 m²/Vs depending on the applied field in sample II. In sample I, a tan peak was found which can be ascribed to molecular relaxation of main chains. The peak vanished upon introducing AgSO₃ CF₃. Temperature dependence of total conductivity ( _T ) measured byac method in the temperature range between –150 °C and 50 °C showed several peaks at the temperatures corresponding to the peak temperatures of tan. Total conductivities of respective samples at 100 kHz were 4.9×10^–7 (69 °C), 1.7×10^–4 (45 °C), and 1.5×10^–4(40°C)S/m.     

Solvent effect and temperature dependence in the interaction of singlet oxygen with α-phenyl-N-tert-butyl nitrone

The solvent effect on the quenching of singlet oxygen by -phenyl-N-tert-butyl-nitrone /PBN/ has been investigated by laser flash photolysis technique registrating luminescence kinetics of¹O₂. The values of the rate constant /k_q/ of the quenching were at 293 K: /9.0±0.4/×10⁶, /4.4±0.3/×10⁶ and /18.3±0.5/×10^{6 –}M^–1 s^–1 in toluene, chloroform and acetonitrile, respectively. The rate constant for the chemical interaction between¹O₂ and PBN, was k_r<1×10⁵ M^–1 s^–1k_q independently of the solvent. At temperatures between 223 and 293 K in toluene E_q=0.4±0.4 kJ mol^–1.     

Molecular Imprinting-Chemiluminescence Determination of Norfloxacin Using a Norfloxacin-Imprinted Polymer as the Recognition Material

A selective molecular imprinting-chemiluminescence method was developed for the determination of norfloxacin by using a norfloxacin-imprinted polymer as recognition material and the Ce(IV)-sodium sulfite-norfloxacin chemiluminescence reaction as the detection system. The chemiluminescence intensity responded linearly to the concentration of norfloxacin within 1.0×10^–71.0×10^–5molL^–1 with a detection limit of 3×10^–8molL^–1. The relative standard deviation for 5.0×10^–7molL^–1 norfloxacin solution was 2.4% (n = 7). This method was applied to the determination of norfloxacin in urine samples, and the results obtained were satisfactory.     

Synthesis of195mPt radiolabelled cis-diamminedichloroplatinum/II/ of high chemical and radiochemical purity using high performance liquid chromatography

An improved method is described for the synthesis of^195mPt-radiolabelled cis-diamminedichloroplatinum/II. An amount of 10 mg of 95% enriched¹⁹⁴Pt was irradiated for 75 h in the hydraulic conveyer of the KUR at a thermal neutron flux of approximately 8.15×10¹³ n.cm^–2.sec^–1 and the^195mPt-radiolabelled CDDP was purified using HPLC. The chemical yield is 61% its chemical purity is greater than 99.74% the radiochemical purity is nearly 100%, and the specific activity is 7.4×10⁶ Bq mg^–1 CDDP/200 Ci mg^–1 CDDP/.     

Application of isotope-dilution laser ablation ICP–MS for direct determination of Pu concentrations in soils at pg g<Superscript>−1</Superscript> levels

The methods available for determination of environmental contamination by plutonium at ultra-trace levels require labor-consuming sample preparation including matrix removal and plutonium extraction in both nuclear spectroscopy and mass spectrometry. In this work, laser-ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) was applied for direct analysis of Pu in soil and sediment samples. Application of a LINA-Spark-Atomizer system (a modified laser ablation system providing high ablation rates) coupled with a sector-field ICP–MS resulted in detection limits as low as 3×10^–13 g g^–1 for Pu isotopes in soil samples containing uranium at a concentration of a few g g^–1. The isotope dilution (ID) technique was used for quantification, which compensated for matrix effects in LA–ICP–MS. Interferences by UH⁺ and PbO₂⁺ ions and by the peak tail of ²³⁸U⁺ ions were reduced or separated by use of dry plasma conditions and a mass resolution of 4000, respectively. No other effects affecting measurement accuracy, except sample inhomogeneity, were revealed. Comparison of results obtained for three contaminated soil samples by use of -spectrometry, ICP–MS with sample decomposition, and LA–ICP–IDMS showed, in general, satisfactory agreement of the different methods. The specific activity of ^239+240Pu (9.8±3.0 mBq g^–1) calculated from LA–ICP–IDMS analysis of SRM NIST 4357 coincided well with the certified value of 10.4±0.2 mBq g^–1. However, the precision of LA–ICP–MS for determination of plutonium in inhomogeneous samples, i.e. if "hot" particles are present, is limited. As far as we are aware this paper reports the lowest detection limits and element concentrations yet measured in direct LA–ICP–MS analysis of environmental samples.Sergei F. Boulyga is on leave from The Radiation Physics and Chemistry Problems Institute, 220109 Sosny, Minsk, Belarus.     

Sorption and desorption of radioiodine on calcareous soil and its solid components

The effect of different solid components of calcareous soil on the retention of I was investigated by a batch technique and selective extraction method, and the effect of -irradiation was also investigated. The sorption and desorption isotherms of I on the one untreated, three treated soils and the calcareous soil irradiated with -rays were determined at 30 °C, pH 8.1±0.2 and in the presence of 1.0×10^–4M or 0.67×10^–5M CaCl₂. It was found that the sorption-desorption hysteresis on the calcareous soil actually occurs on the same time scale, that iodine can be easily transported in the calcareous soil and that the exceptionally high contribution of organic matter to the iodine sorption is demonstrated.     

Spectrophotometric and first-derivative spectrophotometric determination of cadmium witho-hydroxybenzenediazoaminoazobenzene (HDAA)

The synthesis ofo-hydroxybenzenediazoaminoazobenzene (HDAA) is described. Cadmium forms with HDAA in the presence of Triton X-100 a 13 complex, which gives a maximum absorption at 520nm with an apparent molar absorptivity of 1.97 × 10⁵1 · mol^–1 · cm^–1 in pH 10 borax buffer solution and 1.52 × 10⁵1 · mol^–1 · cm^–1 in ammoniacal medium. In both media, Beer's law is followed in the range of 0 –10 g of cadmium in 25ml of solution and the coefficients of variation do not exceed 1.5%. A derivative method has been employed to determine cadmium in certain waste water samples without separation.     

Production of123I on linear electron accelerator using highly-enriched124Xe

Highly enriched xenon¹²⁴Xe /99.85%/ has been used for the experimental production of iodine¹²³I by the /,n/ reaction. As the radiation source served a 30–45 MeV electron beam produced by a linear accelerator and converted by a tungsten converter to -radiation. The yield and radionuclidic purity of¹²³I have been estimated, the content of isotopic impurities /¹²⁴I and¹²⁵I/ being for 30 MeV irradiations lower than 4×10^–3%/.     

Kinetics of the thermal and photochemical decomposition of aquapentacyanoferrate(III) in aqueous solution

Summary The kinetics of the thermal and photochemical decomposition of aquapentacyanoferrate(III) ion in aqueous solution in the presence ofo-phenanthroline was studied spectrophotometrically. The first-order rate constant (k ) at 30° C [I=1 M(NaCl)] for the thermal reaction is (1.49±0.13)×10^–6 s^–1 with H =(158±7)kJ mol^–1 and S=(42±4) JK^–1 mol^–1. The initial quantum yield for the photochemical reaction at pH=7 is independent of the light intensity and is (1.49±0.33)×10^–2 mol einstein^–1.A communication on this subject was presented at the XVI Latinamerican Chemistry Congress held at Rio de Janeiro. Brasil, October 14–20, 1984.     

Levels of artificial radionuclides and uranium in rain water collected from Ibaraki (Japan) following the Tomsk-7 accident in Russia

Measurements of some selected radionuclides were carried out in rain waters collected from Ibaraki Prefecture, Japan, following the nuclear accident at Tomsk-7, Russian Federation, in April 1993. The concentrations obtained for artificial radionuclides were⁹⁰Sr1.8 mBq l^–1,¹³⁷Cs0.1 Bq l^–1,¹³¹I0.1 Bq l^–1 and¹²⁹I4 Bq l^–1. Uranium (²³⁸U) concentrations in rainfalls in April 1993 were 6.3–39 ng l^–1. These data were compared to control values obtained previously and there was no appreciable influence on the radioactivity levels in Japan after the Tomsk-7 accident. Since only limited data on the concentrations of¹²⁹I and uranium in rain water are available, these new analytical results contribute to understanding the background levels for these nuclides.     

Radionuclide concentration in sewage sludge at several location in Austria after the Chernobyl accident

The concentration of the radionuclides¹⁰³Ru,¹³⁴Cs and¹³⁷Cs in sewage sludge samples which were collected between July and September 1986, were measured by -ray spectrometry. High concentration of¹⁰³Ru,¹³⁴Cs and¹³⁷Cs were found in sewage sludge samples from Lower-Austria /Scheibbs, Zwettl/ and Styria /Eisenerz, Leoben/. the radioactivity concentration of¹³⁷Cs was two times higher than that of¹³⁴Cs. Following concentration values were found:¹⁰³Ru 0.1–63.0 nCi kg^–1,¹³⁴Cs 0.3–41.6 nCi kg^–1, and¹³⁷Cs 0.3–83.3 nCi kg^–1. The activity of these nuclides decreased from July 1986 to September 1986.