Separation of radioactive strontium from natural samples by means of mixed-solvent anion exchange

A new procedure for isolation and determination of⁹⁰Sr in real natural samples is presented. It consists of bringing natural samples in a soluble form suitable for separation on an ion-exchange column, separation of calcium from strontium by means of the anion exchanger Amberlite CG-400 and 0.25M HNO₃ in methanol as eluent for calcium, and the determination of⁹⁰Sr using a low level -counter after elution with H₂O, scavenging steps and SrCO₃ precipitation. The method was tested with IAEA standards of natural samples with known contents of⁹⁰Sr, and water samples, where the concentration of⁹⁰Sr was previously determined by the standard IAEA procedure. The results obtained show that it is possible to isolate and determine low levels of⁹⁰Sr in natural samples. The procedure is favorable because of the simple separation of radioaactive strontium without using fuming nitric acid.     

Seasonal variations of atmospheric210Pb and7Be concentrations at Kumamoto, Japan and their removal from the atmosphere as wet and dry depositions</p> </p>

Summary A relatively simple chemical separation procedure has been developed for the simultaneous determination of⁸⁹Sr and ⁹ 0Sractivities in water samples and on aerosol-filters of the Nuclear Power Plant (NPP) Paks origin. The procedure combines the cation-exchange chromatographic (Dowex 50 WX 8 resin) and solid phase extraction (EIChroM Sr.Spec?, DC18C6 crown ether) steps. The beta-radiation of radionuclides can be measured directly after the chemical separation by LSC. The activities of⁸⁹Sr,⁹⁰Sr and⁹⁰Y are calculated from an over determined set of equations using a method of constrained optimization technique. The equations are based on LSC measurements performed in three counting windows plus the⁹⁰Sr-⁹⁰Y decay law. The chemical yield of strontium is determined by ICP-AES. The lowest limits of detectable activity, for the measurement time of 600 minutes, are 30 mBq/sample and 18 mBq/sample for⁸⁹Sr and⁹⁰Sr, respectively.     

89Sr/90Sr-Determination in soils and sediments using crown ethers for Ca/Sr-separation

A radiochemical procedure is described for the sensitive determination of⁸⁹Sr and⁹⁰Sr activity concentrations in soil and sediment samples. After leaching the sample with hydrochloric acid, Sr is separated from most of the soluble matrix constituents and Ca by solvent extraction using dicylclohexano-18-crown-6 in trichloromethane. After backextraction with a EDTA-solution (ethylene diamine tetra acetate), Sr is purified by several precipitation steps from traces of matrix constituents and radionuclides which might interfere the beta measurements of⁸⁹Sr,⁹⁰Sr and⁹⁰Y. The detection limits are about 0.2 Bq/kg and 0.4 Bq/kg for⁹⁰Sr and⁸⁹Sr respectively. The procedure can be applied to all kind of environmental samples with small modifications of the sample preparation steps prior to analysis.     

Experimentelle Bewertung Einiger FAktoren,die die90Sr-Bestimmung in Milch und Knochen auf dem Prinzip der Fällung Wesentlich Beeinflussen

A survey is given on the basic factor affecting the determination of⁹⁰Sr in milk and bones by removal of the excess calcium by precipitation. Strong co-precipitation of calcium and strontium takes place using fuming nitric acid, potassium hexacyano-ferrate, EDTA, ethanol-ether mixture and butanol-(1) due to partial precipitation, recrystallization and adhesion processes where thepH value of the environment plays an improtant role. The obtained results show very limited applicability of these agents for the determination of⁹⁰Sr in biological materials because of low accuracy and reproducibility. This conclusion is especially valid for the method of rapid determination of⁹⁰Sr with EDTA according toWelford andSutton. In this work a method is given for the determination of⁹⁰Sr in milk and bones using potassium hexacyanoferrate.      

Rapid and accurate determination of89/90Sr in radioactive samples by Cerenkov counting

An improved and rapid method for determination of⁹⁰Sr via its daughter nuclide,⁹⁰Y, in aqueous samples from the low-level radioactive wastes by Cerenkov counting was established. This technique is applicable to beta particles maximum energies greater than 0.263 MeV in aqueous solution. A comparison of⁹⁰Sr determination by Cerenkov counting and standard wet chemical separation techniques indicates a high degree of correlation and excellent agreement. For a 20 ml aqueous sample following the prescribed experimental conditions and a 60 min counting interval, the detection limit was 0.20 dpm/ml (0.10 pCi/ml), and the relative deviation is less then 5%.     

In situ neutron activation analysis of and the neutron capture cross-section for90Sr+

Neutron activation analysis has been investigated as an in situ method for determination of⁹⁰Sr. The thermal neutron capture cross-section for the⁹⁰Sr(n, γ)⁹¹Sr reaction has been measured to be 14.0±2.4 mb which is in disagreement with the currently accepted literature value. The suitability of this reaction and the fast neutron reactions⁹⁰Sr(n, p)⁹⁰Rb and⁹⁰Sr(n, α)⁸⁷Kr, for the in situ determination of⁹⁰Sr is discussed.     

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.     

Bestimmung des Gehaltes an90Sr und89Sr in Proben tierischer und pflanzlicher Herkunft

A method is described for the determination of⁸⁹Sr and⁹⁰Sr in samples of plant and animal origin. The Rehak-Feddersen method was modified to measure⁹⁰Sr. Modification was made in the sample preparation and in the toluene-HDEHP [di(2-ethylhexyl)phosphoric acid] extraction. After the extraction of yttrium, strontium is separated with nitric acid and—calculating with a correction factor—⁸⁹Sr can directly be determined. Namely,⁸⁹Sr can be measured in an aqueous solution by a liquid scintillation technique with an efficiency of 30% while⁹⁰Sr with 1.4% only. Quenching of the solution—depending on the composition—which may influence the measurement of⁹⁰Y and⁸⁹Sr was also examined. Detection limits and reproducibilities are given. Finally, evaluation of the experimental data is reported.      

The use of liquid scintillation spectrometry for the determination of radionuclidic purity of 90Y from a radiochemical 90Y/90Srgenerator

Summary An extraction technique for the separation of ⁹⁰Sr from a high excess of⁹⁰Y has been developed. This procedure can be used for the determination of trace amounts of⁹⁰Sr in⁹⁰Y prepared by a radiochemical⁹⁰Y/⁹⁰Sr generator by liquid scintillation.     

A rapid and accurate method for the determination of strontium-90 in environmental soil

A rapid and accurate method for the determination of⁹⁰Sr in environmental soil has been developed; the procedure includes soil leaching by hydrochloric acid, oxalate precipitation, decontamination from²¹⁰Bi, separation by HDEHP extraction chromatography column, yttrium oxalate precipitation and -counting. The interference of²¹⁰Bi was found and studies have been made for the decontamination of⁹⁰Y from²¹⁰Bi by Bi₂S₃ precipitation giving a decontamination factor of 1.05·10³. The analytical results obtained by the improved rapid method for 12 soil samples were comparable to that obtained by a previous method within a relative error of 20%. Studies of vertical distribution of⁹⁰Sr in an environmental soil profile have shown that 90% of the⁹⁰Sr deposits in the 30 cm surface soil of the earth with a highest concentration of 3.40 Bq/kg. When 50 g soil was analyzed, the yield of yttrium was 73±17% with a detection limit of 0.26 Bq/kg.     

Determination of137Cs and90Sr in milk by the static method with an ion exchanger

This paper presents the method of⁹⁰Sr and¹³⁷Cs determination from 10 litres of milk. The preconcentration is made by the static method with a strong acid cation exchanger (OSTION KS).¹³⁷Cs from the eluent (8M HCl) is selectively eliminated with ammonium molybdophosphate and then the^137mBa gamma activity measured, using NaI(T1) detector.⁹⁰Sr as⁹⁰Y is determined after achievement of the radioactive equilibrium and measured by flow proportional counter. The method appears to be accurate, reproducible and permits to determine³² mBq¹³⁷Cs and 13 mBq⁹⁰Sr in the samples.     

Preparation of animal tissue samples for the determination of90Sr and actinides

A unique procedure permitting the determination of⁹⁰Sr and actinides in the same protion of sample, with good chemical yields of all analytes, is presented. Animal tissue samples containing bone are ashed, spiked with^{2 3 2}U,^{2 4 2}Pu,^{2 4 3}Am and^{8 5}Sr and solubilized. The actinides and strontium are gathered and separated by a series of coprecipitations with, cerium hydroxide and cerium fluoride. Actinide separation and determination and purification and determination of⁹⁰Sr are accomplished by a combination of several well-known procedures. The laboratory method consistently results in high chemical yields of all the analytes and overcomes interferences from phosphates and calcium.     

Natural radioactivity in building materials utilized in the State of Kuwait

A simple radiochemical procedure is described for the determination of⁹⁰Sr in brines, which are very highly concentrated in sodium, calcium, potassium, magnesium, chloride and sulfate ions. The method is based on the different solubility of yttrium as compared to that of strontium, calcium and magnesium in ammonium chloride solutions, and utilizes Eichroms resin TRU·Spec for the purification of the yttrium fraction. The overall time required for the⁹⁰Sr analysis (excluding the counting time) is less than one day. Because the procedure involves only rather simple steps, it is well suited for routine analyses of large sample numbers.     

Artificial radioactive contamination of sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of¹³⁷Cs were determined by in 11 sediment samples, collected along the Romanian sector of the Danube river and the Black Sea coast during 1994 γ-ray spectrometry. The concentrations of⁹⁰Sr in the same sediment samples were determined by β-counting of the⁹⁰Y oxalate, precipitated after strontium separation using a strontium extraction chromatography column. The concentration distributions of¹³⁷Cs and⁹⁰Sr are compared with the²³⁸Pu and^239,240Pu concentration distributions in the same samples, reported in a previous paper. The accumulation potential of¹³⁷Cs,⁹⁰Sr and plutonium isotopes in the river and sea sediments analysed is discussed.     

Determination of137Cs,90Sr and fallout Pu in the volcanic soil of Korea

The cumulative depositions of¹³⁷Cs,⁹⁰Sr and fallout Pu in the volcanic ash soil of Korea were determined. The average accumulated depositions of¹³⁷Cs,⁹⁰Sr and fallout Pu in the volcanic soil were much higher than those in other forest sites of Korea. From depth profiles, it was found that¹³⁷Cs,⁹⁰Sr and^239,240Pu in the volcanic soil are more mobile than those in other forest sites of Korea, and that the downward movement of⁹⁰Sr is faster than¹³⁷Cs and^239,240Pu. A significant correlation was found between the concentration of¹³⁷Cs and those of⁹⁰Sr and^239,240Pu. The activity ratios of²³⁸Pu/^239,240Pu and²⁴¹Pu/^239,240Pu in soils are close to those observed in the cumulative deposit from the global fallout of nuclear weapon testings.     

A rapid method for the determination of strontium-90 in powdered milk

A method in which⁹⁰Y the daughter product of⁹⁰Sr decay is extracted by tributyl phosphate (TBP) from ashed powdered milk is described. The⁹⁰Y which is in equilibrium with⁹⁰Sr is back-extracted into the aqueous phase and coprecipitated with milligram amounts of ferric hydroxide. The proposed procedure makes it possible to obtain thin planar sources convenient for low level gas counters. The overall detection efficiency of 45.5% for⁹⁰Y (including chemical recovery of yttrium) was achieved. The detection limit for 200 g powdered milk samples and 10 000 s counting time was 0.065 Bq·kg^–1. The concentration of⁹⁰Sr in three-year old samples (after Chernobyl accident) ranged from 0.81 to 1.31 Bq·kg^–1.     

Chemical study on the separation and purification of promethium-147

A chemical process for the separation of¹⁴⁷Nd/¹⁴⁷Pm from fission products of synthetic radioactive waste solution has been developed. The process includes: (1) denitration, (2) removal of high concentration of uranium by 30% TBP/kerosene extraction, (3) removal of⁹⁵Nb,¹⁰³Ru,¹³⁷Cs and part of⁹⁰Sr by 50% TBP/dodecane extraction, (4) separation of¹⁴⁷Nd/¹⁴⁷Pm from part of⁹⁰Sr and⁹⁵Zr by oxalic acid precipitation, and (5) removal of¹⁴⁴Ce by mixture of 0.4M D2EHPA and 0.2M TBP extraction. Experimental results indicate that the recovery of¹⁴⁷Nd/¹⁴⁷Pm in the final separated solution is about 90%. The purification of¹⁴⁷Nd and¹⁴⁷Pm from some other rare earth elements, viz.¹⁵³Sm,¹⁵⁴Eu and¹⁴⁴Ce was further investigated by using a Dowex 50W×8 ion-exchanger. Parameters of flow rate, eluent concentration and pH were examined. The results show that the recovery and radionuclide purity of¹⁴⁷Nd plus¹⁴⁷Pm under the present separation conditions are 77.8% and 98.6% for diethylenetriaminepentaacetic acid (DTPA) and 87.3% and 99.5% for nitrilotriacetic acid (NTA), respectively.     

Improved method for the separation of radioactive strontium from various samples by mixed solvent anion exchange

Procedures for the separation and determination of⁹⁰Sr in liquid samples, with cation and anion exchangers have been described. Strontium, yttrium and other cations bind to the cation exchanger and are eluted from the column by means of nitric acid. Separation of yttrium and strontium from other cations is carried out on columns filled with strong base anion exchangers in nitrate form with alcoholic solutions of nitric acid. This separation method enables the determination of⁹⁰Sr through yttrium on a low-level gas flow α, β-counter, as well as through strontium on a lowlevel liquid scintillation counter by means of Cherenkov counting. Such procedures have been tested by the determination of⁹⁰Sr in water, wine, medium radioactive liquid waste samples, milk and clover samples. For comparison, the determination has also been carried out by the standard method. It has been showed that the developed procedures might produce a high efficiency in strontium separation and a satisfactory accuracy of determination.     

New method for90Sr determination in liquid samples

A method has been developed for measuring⁹⁰Sr activity in liquid samples. After concentrating strontium from the sample by coprecipitation with calcium phosphate, the residue is dissolved in 8N HNO₃ and passed through an extraction chromatographic column (Sr.Spec) containing a new material that selectively retains strontium. This is eluted from the column with 0.05N HNO₃ and counted by liquid scintillation. Measurement is performed using a double window method, that allows a rapid and single determination of⁹⁰Sr.     

Depth distribution of137cesium,90strontium and210lead in sediments of lake Mondsee,Austria

¹³⁷Cs,⁹⁰Sr and²¹⁰Pb were determined in sediment cores from lake Mondsee /Austria/. The depth profiles show that¹³⁷Cs remains undisturbed, i.e. its distribution corresponds to the fallout deposition pattern.⁹⁰Sr, however, has been transported into the upper sediment layers. In this upper zone nearly constant levels of⁹⁰Sr and also of²¹⁰Pb/²¹⁰Po/were found. Comparison of the⁹⁰Sr and¹³⁷Cs profiles indicates that chemical processes must be responsible for the translocation of⁹⁰Sr as well as²¹⁰Pb, and not bioturbation, i.e. mixing of upper sediment layers by benthic organisms.Dedicated to Prof. Dr. Karl Schlögl, University of Vienna, for his 60th birthday.