Cs, Am and Pu isotopes as tracers of sedimentation processes in the Curonian Lagoon–Baltic Sea system

¹³⁷Cs, ²⁴¹Am and Pu isotopes were analyzed in seawater, bottom sediments (BS) and suspended particulate matter samples collected in the Baltic Sea during 1997–2011. The particle size distribution and sequential extraction studies were carried out with the aim to better understand the association of radionuclides with particles and their bonding patterns in the BS. δ¹³C_org was applied for identification of sources of organic matter in the studied area. It has been found that massic activities of ¹³⁷Cs in BS varied from 2.1 to 588 Bq/kg. High correlation of ¹³⁷Cs massic activities with total organic carbon (TOC) in BS (r = 0.75) and with clay minerals (r = 0.95) was found. ^239,240Pu massic activities in BS varied from 0.03 to 7.5 Bq/kg. High correlation with TOC was found for ^239,240Pu (R = 0.98) as well as for ²⁴¹Am (r = 0.96). δ¹³C_org in the studied samples ranged from ?22.3 to ?31.8 ‰.     

Modell eines durch Rüttlung verdechteten Dispersionsmediums

Ohne Zusammenfassung     

Radiochemical assay of stability of14C-cytostasan solutions during preparation and storage

Cytostasan, 5-[Bis(2-chloroethyl)amino]-1-methylbenzimidazolyl-2-butyric acid, is an antineoplastic agent which degrades spontaneously in water solutions yielding two hydrolysis products, monohydroxy- and dihydroxycytostasan. We developed a stability-indicating radiochemical assay based on ion-pair extraction to investigate the stability of solutions of¹⁴C-cytostasan under conditions that might be expected when the drug is being prepared and stored for pharmacokinetic studies in animals. The possibility of using the distribution coefficient of¹⁴C-cytostasan as an indicator of stability was investigated in the extraction system benzene-dicarbolide of cobalt-0.5N HClO₄. The mechanism of extraction is believed to be that of ion-pair forming process between the hydrophobic anion and the protonized cytostasan. Since no extraction of hydroxy derivates was observed the value of the distribution coefficient of the parent drug appears to be a suitable indicator of the stability of¹⁴C-cytostasan solutions.     

Extraction-chromatographic separation of137mBa from137Cs

The possibilities of extraction-chromatographic separation of^137mBa from¹³⁷Cs in genetic succession were studied, using columns filled with support beads loaded with the extractant H⁺[)–(3)–1,2–B₉C₂H₁₁]₂Co^–, further referred to as dicarbolide-H⁺, in nitrobenzene. The dependence of the amount of separable activities on experimental conditions was established. Optimal conditions were selected for the separation process. The effects of isotopic and nonisotopic carriers of^137mBa on the separation and the degree on saturation of extraction-chromatographic column with Ba²⁺ ions were evaluated. The effects of acidity of the elution solutions, of flow-through velocity, the amount of elution solution and the quality of carrier beads on the separation process were assessed. The extraction-chromatographic yield was calculated and the number of possible repeated elution cycles for^137mBa with saline and some other eluents was determined.     

Extraction of radiostrontium from the mixture of radionuclides in milk using dicarbolide of cobalt

The possibilities of radiostrontium extraction from milk after the isolation of radiocesium were investigated. The polyhedral complex of the type H⁺[(π-/3/-1,2-C₂B₉H₁₁)₂Co⁻], further referred to as dicarbolide-H⁺, in nitrobenzene was used for the extraction. The increase of values and larger differentiation of distribution ratios in the extraction of ion associates of radionuclides were achieved by hydrophobizing with polyethyleneglycol (PEG). The changes of the distribution ratios of⁹⁰Sr,⁸⁹Sr and⁹⁰Y with PEG concentration were studied, and ranges of the highest synergic effect, changing with different extraction agent concentrations in extraction from water solutions and a fresh milk were determined. The influence of milk dilution and nitric acid concentration upon the value of distribution ratio in radiostrontium extraction using dicarbolide-H⁺ and the optimum PEG concentration were investigated. Under suitably selected conditions of radiostrontium isolation, the distribution ratios of some potential contaminants were determined. The influence of nonisotopic carrier Ca²⁺ upon radiostrontium extraction was examined. The possibilities of purification of isolated radiostrontium using reextraction were investigated. A selective and quick analytical procedure was suggested for radiostrontium isolation after the separation of radiocesium from a mixture of fission and activated radionuclides in milk using extraction by dicarbolide-H⁺. The chemical yield is about 98% and⁹⁰Sr is determined by liquid scintillation technique.     

Separation of137Cs and90Sr from mineralizates of biological materials by dicarbolide of cobalt

The distribution of some radionuclides in the course of¹³⁷Cs and⁹⁰Sr extraction and scrubbing between organic and water phase was determined.¹³⁷Cs and⁹⁰Sr were isolated from the mixture of radionuclides in mineralized biological materials. Dicarbolide of cobalt i. e. 3,3′-commo-bis[undecahydro-1,2-dicarbo-3-closo-dodecaborate] was used as an extracting agent. Quantities of the extracted radionuclides were determined by gamma spectrometric technique. Single and repeated extraction of⁹⁰Sr with 0.01M resp. 0.1M dicarbolide of cobalt in nitrobenzene and scrubbing of coextracted radionuclides by 0.5M HNO₃ were studied. The extraction of⁹⁰Sr was investigated from solutions of a hydrofobizing agent in the same way. Finally, the quantitative extraction of¹³⁷Cs followed by the extraction of⁹⁰Sr from mixtures of radionuclides in a mineralized biological material was studied. Extraction yields from dry and wet mineralizates of biological tissues, from urine and milk were compared. Suitable working conditions for the separation procedures were selected.     

Ion-pair extraction of carbanilate local anaesthetics from biological materials

Pentacaine, heptacaine and carbisocaine, new local anaesthetics of Czechoslovak origin, are weak bases of the carbanilate type. Their pK_A values are 8.6, 8.9 and 8.8, respectively. The technique of ion-pair extraction was found to be more effective than usual access using the extraction of nonionized species. The counter-ion ClO₄ was chosen as the most efficient. The extraction yield of pentacaine into benzene from strongly acidic media (IN HClO₄) of biological matrix after subsequent scrubbing of coextracted metabolites into a buffer of pH 9.6 is over 90%. The radiochemical purity is better than 92%.     

Extraction of137Cs by cobalt dicarbolide

The possibility of the use of chlorinated cobalt dicarbolide, H⁺C₄B₁₈H₁₅Cl₇Co⁻, it nitrobenzene for the selective extraction of¹³⁷Cs from mixtures of⁹⁵Zr−⁹⁵Nb,¹⁰⁶Ru-¹⁰⁶Rh and¹⁴⁴Ce was studied. The effect of aqueous phase acidity on the distribution ratio of Cs, Ru and Zr as well as the effect of the amount of isotopic and non-isotopic carriers of alkali metals on the distribution ratio were determined. Separation factors for cesium from ruthenium, zirconium and cerium were calculated, all being extracted from nitric acid solutions. The efficiency of cesium separation was verified by gamma-spectrometry.     

Isolation of137Cs from excreta by dicarbolide of cobalt

Extraction by polyhedral complex compound of the formula H⁺ [(π-(3)-1,2-B₉C₂H₁₁)₂Co⁻] further on referred to as dicarbolide-H⁺ and its chloro-derivate H⁺[B₁₈C₄H₁₅Cl₇Co⁻] further on referred to as Cl-dicarbolide-H⁺ in nitrobenzene was used for the analysis of¹³⁷Cs in urine and faeces after internal contamination. The dependence of distribution ratio on the acidity of analysed solutions was determined. The effect of urine dilution was assessed as well as the effect of various concentrations of the extraction agents on the distribution ratio of¹³⁷Cs. The effect of phase ratio at the different concentrations of isotopic carrier was assessed, as well as the effect of potassium ions on the decrease of the distribution ratio at the extraction of¹³⁷Cs by dicarbolide-H⁺ or its chloro-derivate. The possibility of isolation of¹³⁷Cs by extraction and the isolation of¹³⁷Cs by ion-exchange absorbents and by ammonium molybdophosphate was compared. The values of distribution coefficient were determined at various concentrations of nitric acid and the isotopic carrier. The dependence of coextraction of some activated radionuclides and fission products by dicarbolide-H⁺ on the nitric acid concentration in the solute was determined. The effect of mass of contaminated faeces on the value of the distribution ratio of¹³⁷Cs by the extraction was evaluated. As a result, a suggestion was given for the rutine isolation procedure of¹³⁷Cs extraction with dicarbolide-H⁺ from the excreta contaminated by a mixture of radionuclides.