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.     

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 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.     

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.     

Determination of90Sr in environmental and biological materials with combined HDEHP solvent extraction-low liquid scintillation counting technique

Low level⁹⁰Sr in environmental and biological samples is determined using a combined HDEHP solvent extraction-liquid scintillation procedure. Yttrium-90 is selectively extracted from nitric acid solution into 5% di(2-ethylhexyl) phosphoric acid (HDEHP) in toluene, and⁹⁰Y in the organic phase is measured directly using an ultra low level liquid scintillation spectrometer.The working program of the Quantulus counter has been optimized. As the counting efficiency using liquid scintillation counting is high and the stripping and precipitation of Yttrium-90 oxalate is omitted, this procedure is simpler and more timesaving than traditional methods. The chemical recoveries of⁹⁰Y were 85.1% for soil, 75.7% for milk and 65.3% for bone. The detection limit is 8 mBq.     

Adaptation of a radioanalytical method for strontium-90 to different kinds of environmental samples and its application for the investigation of some samples in the Riyadh region

A relatively simple and rapid radioanalytical method, limited to milk, is adapted for investigating soil, biological and water samples for⁹⁰Sr. The method is based on a selective separation and successive counting of equilibrium quantities of its daughter 90Y, which can be extracted by tributyl phosphate from nitrate medium and stripped by conc. ammonia solution. 90Y is separated from possible iron and measured by Cerenkov counting. The procedure is thoroughly tested with certified reference materials and used lately for determining⁹⁰Sr in some environmental samples in the Riyadh region. The results obtained are given and discussed.     

Determination of 90 Sr in milk by solvent extraction of 90Y (author's transl)

In order to replace the conventional method using violent fuming nitric acid, a new method for the determination of 90 Sr in milk has been developed by using the solvent extraction with bis (2-ethylhexyl) phosphoric acid (HDEHP). The daughter nuclide 90Y in a radiochemical equilibrium with its parent 90Sr was extracted with 2:1 HDEHP-toluene from the acid solution (1M HCL) of milk ash sample prepared by dry-ashing. After stripping with 8M HCL, 90Y, together with stable yttrium added as carrier, was precipated as oxalate to prepare beta-counting source. The radiochemical purity was confirmed by decay curve. The decontamination of strontium was checked by applying non-dispersive fluorescence X-ray analysis using 133Ba as irradiating source. Bone samples of cow were also analyzed by the same method and the results were compared with those obtained by other methods. The duplicate crosschecking analyses of finely ground bone samples were carried out to examine the effectiveness of this method. This simple new method was found to be very effective for the routine analysis of 90Sr in these samples.     

On a Pure Instrumental Method of 90Sr Determination in Bone Samples

An attempt is presented for the measurement of ⁹⁰Sr in real animal bone samples using gamma-ray spectrometry only with germanium detector. Gamma-ray spectra of bone samples are de-convoluted and the residue bremsstrahlung effect from ⁹⁰Sr-⁹⁰Y beta-radiation is observed. The validation of the proposed method was done by standard ⁹⁰Sr determination including radiochemical separation and liquid scintillation spectrometry (LSS). The Pearson correlation factor obtained between the activity determined by LSS and the proposed instrumental method was 0.57, with the achieved efficiency of 0.12%. Possible improvements of the method are suggested.     

A new method for the carrier-free production of 90y from 90sr-90y mixture and 89sr from neutron-irradiated y2o3

The extraction of strontium(II) and yttrium(III) ions from aqueous solutions at various pH values into methyl isobutyl ketone containing I-phenyl-3-methyl-4-caprylpyrazolone-5 is described. Quantitative extraction of Sr and Y at pH 8.6–10 and pH 2.8–5.4 respectively is utilized for the carrier-free production of ⁹⁰Y from ⁹⁰Sr–⁹⁰Y mixtures and ⁸⁹Sr from neutron-irradiated yttrium oxide. A clean separation of these elements from each other and more than 95% calculated activities were recovered     

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.     

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.      

Preparation of 90Y by the 90Sr-90Y Generator for Medical Purpose

The production of ⁹⁰Y by ⁹⁰Sr-⁹⁰Y generator was studied. ⁹⁰Sr was adsorbed on a column with Aminex A-5 resin. The daughter radionuclide ⁹⁰Y was eluted with 0.7M -hydroxyisobutyrate (-HIB, pH 5.4). Radionuclidic, radiochemical and chemical purities were >98% and yield >85%. After converting into chloride form ⁹⁰YCl₃-solution (pH:1) was used for preparing injectable yttrium citrate and labeling some other radiopharmaceuticals. Furthermore, a fast ITLC-method for the determination of ⁹⁰Sr in ⁹⁰Y-eluate was developed.     

Rapid determination of 90Sr/90Y in water samples by liquid scintillation and Cherenkov counting

Strontium-90 (⁹⁰Sr) is a ubiquitous contaminant at nuclear facilities, found at high concentrations in spent nuclear fuel and radioactive waste. Due to its long half-life and ability to be transported in groundwater, an accurate method for measuring ⁹⁰Sr in water samples is critical to the monitoring program of any nuclear facility. To address this need, a rapid procedure for sequential separation of Sr/Y was developed and tested in groundwater samples collected from an area of riverbed affected by a ⁹⁰Sr groundwater plume. Sixteen samples, plus spike and water blanks, were analyzed. Five different measurements were performed to determine the ⁹⁰Sr and yttrium-90 (⁹⁰Y) activities in the samples: direct triple-to-double-coincidence ratio (TDCR) Cherenkov counting of ⁹⁰Y, liquid scintillation (LS) counting for ⁹⁰Sr following radiochemical separation, LS counting for ⁹⁰Y following radiochemical separation, Cherenkov counting for ⁹⁰Y following radiochemical separation and LS counting of the Sr samples for ⁹⁰Y in-growth. The counting was done using a low-level Hidex 300SL TDCR counter. Each measurement method was compared for accuracy, sensitivity and efficiency. The results following Cherenkov counting and radiochemical separation were in very good agreement with one another.     

The solvent extraction of carrier-free90Y from90Sr with crown ethers

A simple solvent extraction method has been developed for the separation of⁹⁰Y from⁹⁰Sr. Crown ether dissolved in chloroform was used as a selective reagent and organic picrate anion was chosen as a counter ion. The effect of various factors on the extraction separation of strontium and yttrium in the system have been studied. The extraction equilibrium constant of strontium logK _ex=9.15 was obtained from the study of the distribution coefficient versus the crown ether concentration. The separation method was simple, resulted high purity (>99.9%) and quantitative yield, and took less than half an hour.     

Feasibility study of an analytical method for detecting <Superscript>90</Superscript>Sr in soil using DGA resin and Sr resin

This study investigated an analytical method for detecting ⁹⁰Sr in soil samples for the routine monitoring of environmental radioactivity. Mineral acid leaching and fusion methods were first used to digest the soil sample, and the analytical results were compared. DGA resin was employed to separate ⁹⁰Y, being a daughter of ⁹⁰Sr. Then, ⁹⁰Y was analyzed by liquid scintillation counter (LSC). These analytical results were compared with those obtained using Sr resin, which is a well-known, simple and reliable separation method. With the DGA resin approach a minimum detectable activity of ~0.28 Bq kg^?1 was detected in a 50 g sample, with 180 min of counting time, 70% recovery and ~97% counting efficiency using a LSC.     

Radiochemical determination of 90Sr and 86Sr in soil

Summary A modified HCl-leach method for the radiochemical ⁹⁰Sr and ⁸⁹Sr determination in soil has been developed. The sample is leached by HCl in the presence of the Sr-carrier. Then bi- and trivalent ions are separated by a combination of complexation and ion exchange. The separation of strontium and calcium is performed by fuming nitric acid. After further purification, strontium carbonate is precipitated and the activity of ⁹⁰Sr and ⁸⁹Sr is measured. ⁹⁰Sr determined by the isolation of ⁹⁰Y and by measuring its activity. The ⁹⁰Sr and ⁸⁹Sr content in soil is calculated from the measured activities of yttrium oxide and strontium carbonate by considering the counting efficiencies for ⁹⁰Y, ⁹⁰Sr and ⁸⁹Sr beta rays, the chemical yields of strontium and yttrium and the time of ⁹⁰Y growth from ⁹⁰Sr.

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Radiochemische Bestimmung von ⁹⁰Sr und ⁸⁹Sr in Boden

Zusammenfassung Eine modifizierte Auslaugungsmethode für die radiochemische Bestimmung von ⁹⁰Sr und ⁸⁹Sr im Boden wurde entwickelt. Die Probe wird in HCl in Gegenwart des Sr-Trägers ausgelaugt und die zwei- und dreiwertigen Ionen dann durch eine Kombination von Komplexierung und Ionenaustausch getrennt. Die Strontiumtrennung von Calcium erfolgt mit rauchender Salpetersäure. Nach weiterer Reinigung wird SrCO₃ gefällt und die Aktivität von ⁹⁰Sr und ⁸⁹Sr bestimmt. ⁹⁰Sr wird durch Isolierung und Zählung von ⁹⁰Y ermittelt. Der ⁹⁰Sr- und ⁸⁹-Sr-Gehalt im Boden wird aus der Aktivität von Y₂O₃ und SrCO₃ unter Berücksichtigung der Zählausbeute für ⁹⁰Y-, ⁹⁰Sr- und ⁸⁹-Sr-beta-Strahlen, aus der gravimetrischen Bestimmung von Strontium und Yttrium und aus der Zeit der ⁹⁰Y-Entstehung aus ⁹⁰Sr bestimmt.

     

Rapid determination of radiostrontium in seawater samples

A new method for the determination of radiostrontium in seawater samples has been developed at the Savannah River National Laboratory (SRNL) that allows rapid pre-concentration and separation of strontium and yttrium isotopes in seawater samples for measurement. The new SRNL method employs a novel and effective pre-concentration step that utilizes a blend of calcium phosphate with iron hydroxide to collect both strontium and yttrium rapidly from the seawater matrix with enhanced chemical yields. The pre-concentration steps, in combination with rapid Sr Resin and DGA Resin cartridge separation options using vacuum box technology, allow seawater samples up to 10 L to be analyzed. The total ⁸⁹Sr + ⁹⁰Sr activity may be determined by gas flow proportional counting and recounted after ingrowth of ⁹⁰Y to differentiate ⁸⁹Sr from ⁹⁰Sr. Gas flow proportional counting provides a lower method detection limit than liquid scintillation or Cerenkov counting and allows simultaneous counting of samples. Simultaneous counting allows for longer count times and lower method detection limits without handling very large aliquots of seawater. Seawater samples up to 6 L may be analyzed using Sr Resin for ⁸⁹Sr and ⁹⁰Sr with a minimum detectable activity (MDA) of 1–10 mBq/L, depending on count times. Seawater samples up to 10 L may be analyzed for ⁹⁰Sr using a DGA Resin method via collection and purification of ⁹⁰Y only. If ⁸⁹Sr and other fission products are present, then ⁹¹Y (beta energy 1.55 MeV, 58.5 day half-life) is also likely to be present. ⁹¹Y interferes with attempts to collect ⁹⁰Y directly from the seawater sample without initial purification of Sr isotopes first and ⁹⁰Y ingrowth. The DGA Resin option can be used to determine ⁹⁰Sr, and if ⁹¹Y is also present, an ingrowth option with using DGA Resin again to collect ⁹⁰Y can be performed. An MDA for ⁹⁰Sr of <1 mBq/L for an 8 h count may be obtained using 10 L seawater sample aliquots.     

Yttrium-90 adsorption on various soils of successive horizons in Poland

The adsorption of ⁹⁰Y on various types of soil samples representing successive horizons was studied. The adsorption process can be described by a Freundlich isotherm and was influenced by the soil type and the horizon's depth. Hydrogen ions did not have a significant influence on the adsorption of ⁹⁰Y. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Yttrium-90 adsorption on various soils of successive horizons in Poland

The adsorption of ⁹⁰Y on various types of soil samples representing successive horizons was studied. The adsorption process can be described by a Freundlich isotherm and was influenced by the soil type and the horizon's depth. Hydrogen ions did not have a significant influence on the adsorption of ⁹⁰Y. This revised version was published online in July 2006 with corrections to the Cover Date.