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.     

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.     

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.     

Determination of90Sr by thin layer radiochromatography

A simple method for the determination of⁹⁰Sr by using thin layer chromatography on silica gel or cellulose pretreated with calcium oxalate is proposed. In these conditions a complete separation between strontium and its daughter yttrium is obtained. Radioactivity of separated elements was measured by a linear multiscanner analyzer and the results were computer processed to obtain the activity of⁹⁰Sr. The method has been applied to samples of water and milk subjected to a very simple extraction procedure. Under the experimental conditions used, the detection limit is about 25 mBq of deposited radioactivity, which corresponds to about 6 Bq/l.     

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.     

The simple radiochemical determination of 90Sr in environmental solid samples by solvent extraction

Determination of ⁹⁰Sr in environmental solid samples is a challenging task because of the presence of so many other radionuclides in samples of interest. This problem was dealt with by radiochemical separation of strontium followed by yttrium separation and Cerenkov counting of the high-energy ??-particle emissions of ⁹⁰Y in order to quantitate ⁹⁰Sr. In this work, an improved method is described for the determination of ⁹⁰Sr in soil samples, through the separation of the daughter ⁹⁰Y at equilibrium. The procedure is based on the HDEHP solvent extraction in combination with liquid scintillation spectrometry (LSS). A low background Quantulus has been optimized for low level counting of Cerenkov radiation emitted by the hard ??-emitter ⁹⁰Y. The analytical quality of the method has been checked by analyzing IAEA Soil-375 reference materials. The analytical method has also been successfully applied to the determination of ⁹⁰Sr for moss-soil samples in inter-laboratory exercises through IAEA??s ALMERA network. The chemical recovery for ⁹⁰Y extraction ranged from 80 to 85% and the counting efficiency was 73% in the window 25?C400 keV.     

A simple radiochemical determination of90Sr in environmental samples

A simple procedure for the determination of⁹⁰Sr in environmental samples is described. The method uses the different solubilities of the oxalates of calcium and strontium in presence of a large excess of calcium. For this reason the method is especially suited for Ca-rich samples, as e.g., bones or soils. However, after addition of supplementary calcium it works equally well for other types of samples. The method was tested by analyzing the IAEA Certified Reference Materials soil, animal bone and algae.     

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.     

Strontium isolation from natural samples with Sr resin and subsequent determination of 90Sr</p> </p>

The reliability of an ⁹⁰Sr determination method was tested using an Sr extraction chromatographic resin for strontium isolation. The ⁹⁰Sr-content in samples of vegetables, soil and water (obtained from Environmental Measurement Laboratory, USA) were determined and the results were controlled by classical methods and by using an anion-exchanger and an alcohol solution of nitric acid for the strontium isolation. These methods were previously tested by determining ⁹⁰Sr in IAEA 326 and 327 samples of soil. It is shown that the isolation process with Sr resin is simpler and faster than the classical and mixed solvent anion-exchange methods. The efficiency of isolation on a Sr column depends on the resin quantity and separation conditions; and is the highest with a Sr column, compared to the classical and anion-exchange methods. Experimental data and theoretical models were used to calculate the parameters that enable the estimation of optimum dimensions of the column for isolation. A simple relation is proposed for the calculation of breakthrough volume, which defines the sample and eluent volumes for an optimal strontium isolation.</p> </p>     

Bestimmung von90Sr auf der Ionex-Säule in Milch und Knochen Unter Berücksichtigung der Komplexen Eigenschaften Einiger Reagenzien

The determination of⁹⁰Sr is extremely difficult in biological materials by chemical meth ods owing to the quantity of calcium associated. The problem consists of the quantitative removal of calcium and of the selective extraction of⁹⁰Sr using strontium carrier. It can be solved by precipitation and extraction methods, or by ion exchange chromatography. Following our previous works, experimental evidence is presented using ion exchange technique for these purposees, where complex compounds are used as eluents for calcium removal. For the determination of⁹⁰Sr in milk and bones, calcium was removed with 1,2-diamino-cyclohexane-N,N,N′,N′-tetraacetic acid (CyDTA) eluent from Amberlite IR-120 column. Our results show that compounds of chelatone type used as eluents with a strong acidic cation exchanger column are the most convenient, for they prefer to compound with ligands of weaker or mean complexibility (hydrochloric acid, citric acid and lactic acid).      

Studies on soil samples mineralization conditions preceding the determination of 90Sr

Some results of the extraction of strontium and yttrium from soil samples by concentrated nitric acid are described. The concentration of Sr and Y in the solid was determined by XRF method. The results obtained allowed to elaborate the conditions of acid leaching and to propose an analytical procedure for the determination of ⁹⁰Sr in samples without their total dissolution.     

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.     

Separation of Sr in combination of ion exchange and Sr resin with alcohol-nitric acid solution and rapid determination of <Superscript>90</Superscript>Sr in wine and soil samples

This paper describes the procedures of isolating strontium from wine and soil samples which enable creating of procedure for rapid determination of ⁹⁰Sr. The method of determination of ⁹⁰Sr includes binding of Sr on the cationic exchanger IR-120 from the sample and simultaneous elution from the cation column and binding on the Sr column, separation of Sr on Sr resin with HNO₃ even in presence of alcohols and subsequent Cherenkov counting. Sr can be efficiently bind on Sr resin and separated from the other elements with lower acid concentrations in the presence of a low portion of alcohol, or even from a wine sample without the loss of Sr resin capacity. The binding strength of Sr on Sr resin decreases with the rising of HNO₃ concentration (1–5 M) in the presence of 13% of ethanol or methanol, and with the rising of the alcohol portion in constant concentration of HNO₃. Application of cation exchanger for Sr binding in phase of sample preparation decreases Sr column loading and improve Sr recovery. The method allows the determination of ⁹⁰Sr activities in wine and soil sample lower than 10 mBq in reasonable time.     

Determination of strontium radioisotopes in soils

Summary A method is proposed for determination of radiostrontium in soils which is based on selective strontium separation by liquid-liquid extraction with dicyclohexano-18-crown-6 in chloroform, loading of the extract on a thin-layer plate and TLC separation of strontium and yttrium radioisotopes using a circular procedure. The method allows the separate determination of ⁸⁹Sr and ⁹⁰Sr. The strontium chemical yield is more than 90%, the detection limit is about 0.5 Bk/g, RSD is equal to 2–5%.     

A rapid method for the determination of radiostrontium in river water

A rapid analytical method, applicable for the selective separation and determination of⁹⁰Sr and⁸⁹Sr in river water, is described. Strontium is extracted from the water sample at pH 10.5 by TTA/TOPO in cyclohexane in the presence of Tiron as masking agent for interfering ß-emitters. Radiostrontium is measured by liquid scintillation after back-extraction into 1N nitric acid. The distribution coefficient of strontium is over 400 and the separation factors from other radionuclides are higher than 5.0×10³.     

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.     

Rapid determination of 89,90Sr in wide range of activity concentration by combination of yttrium, strontium separation and Cherenkov counting

The methodology for the rapid determination of ^89,90Sr in wide range of activity concentration is given. Methodology is based on simultaneous separation of strontium and yttrium from samples by mixed solvent anion exchange chromatography, mutual separation of ^89,90Sr from ⁹⁰Y by hydroxide precipitation and quantitative ^89,90Sr determination by Cherenkov counting within 3 days. It is shown that Y and Sr can be efficiently separated from alkaline, alkaline earth and transition elements as well as from lanthanides and actinides on the column filed by strong base anion exchanger in nitrate form and 0.25 M HNO₃ in mixture of ethanol and methanol as eluent. Decontamination factor for Ba, La and other examined elements except calcium is low and can not affect quantitative determination in predictable circumstances. Methodology for quantitative determination by Cherenkov counting based on following the changes of sample activity over time is described and discussed. It has been shown that ^89,90Sr can be determined with acceptable accuracy when ⁸⁹Sr/⁹⁰Sr ratio is over 10:1 and that separation of Y enables reliable determination of ⁸⁹Sr and ⁹⁰Sr in wide range of ⁸⁹Sr/⁹⁰Sr ratios (60:1) and in some cases in presence of other yttrium and strontium isotopes. The methodology was tested by determination of ^89,90Sr in Analytics crosscheck samples (nuclear waste sample) and ERA proficiency testing samples (low level activity samples). Obtained results shows that by using of low level liquid scintillation counter it can be possible to determine ⁸⁹Sr and ⁹⁰Sr in wide range of concentration activity (1–1,000 Bq/L/kg) with uncertainty below 10% within 2–3 days. Results also show that accuracy of determination of ⁸⁹Sr (and ⁹⁰Sr) strongly depends on the determination of difference between separation and counting time when activity ratio of ⁸⁹Sr/⁹⁰Sr is high. Examination the influence of media and vial type on background radiation and counting efficiency has shown that lowest limit of determination can be obtained by using of HNO₃ in plastic vials as counting media, because in this combination figure of merit is maximized. For the recovery of 50% and 100 min of counting time estimated MDA is 55 Bq and 90 Bq for ⁹⁰Sr and ⁸⁹Sr, respectively. Analysis of combined uncertainty shows that it mainly depends on uncertainty of efficiency and recovery determination, uncertainty of activities determination for both isotopes and level of background radiation.     

Radiochemical analysis of90Sr in milk,soil and plants by solvent extraction

A universal and fast method of⁹⁰Sr determination in environmental matrices (raw and dried milk, plants, soils) has been elaborated. Solvent extraction method of daughter⁹⁰Y by tributyl phosphate was used. The method of strontium determination is compatible with determination of other transuranic elements (americium, plutonium) and there is no need to check the chemical yield of strontium.     

Methodology for determination of 89Sr and 90Sr in radiological emergency: I. Scenario dependent evaluation of potentially interfering radionuclides

Early determination of ⁸⁹Sr and ⁹⁰Sr in radiological emergency is hampered by the presence of interfering short-lived fission products. In this study, three commonly used radioanalytical strategies for ⁸⁹Sr and ⁹⁰Sr were evaluated theoretically considering their suitability in a nuclear explosion scenario. The methods were evaluated with respect to the need for decay time of interfering short-lived strontium and yttrium isotopes, and reduction of other known interfering nuclides prior to measurement. The strategy shown to be most successful included initial separation of strontium and determination of ⁸⁹Sr, followed by an yttrium separation and counting of ⁹⁰Y. ⁸⁹Sr and ⁹⁰Sr could be determined about 5 and 9 days after a nuclear explosion, respectively.     

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.