Determination Of 99Tc Research Articles

Determination of 99Tc in solid environmental samples by combining alkali fusion and rapid separation using TRans Uranium elements resin in alkali medium to triple quadrupole inductively coupled plasma mass spectrometry

Determination of 99Tc in various environmental samples is important not only for radioactive assessment but also for geochemical studies. In this work, we aim to develop a method for the monitoring of 99Tc in solid environmental samples. Alkali fusion instead of acid digestion was used for the dissolution of Tc from the sample. Therefore, the loss of Tc during sample preparation was negligible. The adsorption behavior of Re (as an analog of Tc) on the TRans Uranium elements (TRU) resin was investigated. Based on the results, for the first time, a simple separation method for Tc was established by using TRU resin in alkaline solution. Water was used for the elution of Tc from the resin column and the eluent could be directly injected to triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) for Tc measurement. The chemical recoveries for solid environmental samples (< 1 g) were beyond 85% and the whole analytical procedure could be finished within 3.5 h. High decontamination factors were obtained for the interfering elements. Mo isobaric interference was further removed by the introduction of O2 into the instrument as reaction gas. The detection limit of 99Tc was calculated to be 0.04 pg g-1 (for 1 g solid sample). Th developed method was suitable for the rapid monitoring of 99Tc in solid environmental samples for emergency response. Geological samples were used for method validation and the method was finally used for the determination of 99Tc in real radioactive contaminated samples.

A comparison study on the use of Dowex 1 and TEVA-resin in determination of 99Tc in environmental and nuclear coolant samples in a SIA system with ICP-MS detection

This work refers to a comparative study of sorbents widely used in determinations of 99Tc such as TEVA resin and Dowex 1. Despite having a similar functional group of quaternary amines, both materials represent different chromatographic methods—extraction (TEVA resin) and anion exchange (Dowex 1)—which provides a diverse range of their properties significant in determination of 99Tc in flow conditions. The comparative tests, carried out in a SIA-LOV (Sequential Injection Analysis—Lab-on-Valve) system combined with mass spectrometric (ICP-MS) detection, considered several factors that are crucial from the standpoint of resin´s utility such as sorption capacity, durability, or selectivity, critical in 99Tc separation from interferences. The developed and optimized analytical procedure based on the application of the TEVA resin provided determinations of 99Tc at minimum detectable limit (MDL) 6.00 mBq L-1 in 50 min and has been successfully employed in analyses of samples from nuclear industrial and research units (reactor coolant and sewage) as well as from the river surrounding the nuclear reactor. The method proved to be sufficient for routine analysis of water samples in accordance with EPA standards. The reliability of the method was confirmed in the analysis of the BH standard provided by the NPL for inter-laboratory proficiency tests. The 99Tc recovery for all real samples was evaluated as 80–100%.

Determination of 99Tc in fresh water using TRU resin by ICP-MS

Technetium-99 (99Tc) determination at trace level by inductively coupled plasma mass spectrometry (ICP-MS) is challenging because there is no readily available appropriate Tc isotopic tracer. A new method using Re as a recovery tracer to determine 99Tc in fresh water samples, which does not require any evaporation step, was developed. Tc(VII) and Re(VII) were pre-concentrated on a small anion exchange resin (AER) cartridge from one litre of water sample. They were then efficiently eluted from the AER using a potassium permanganate (KMnO4) solution. After the reduction of KMnO4 in 2 M sulfuric acid solution, the sample was passed through a small TRU resin cartridge. Tc(VII) and Re(VII) retained on the TRU resin were eluted using near boiling water, which can be directly used for the ICP-MS measurement. The results for method optimisation, validation and application were reported.

Determination of 99Tc in environmental samples and depleted uranium penetrators using ICP-MS

A new method was developed for the determination of 99technetium (Tc) by ICP-MS. We report, for the first time, an activity of 99Tc for the reference material IAEA-315. For the IAEA-375, IAEA-373 and IAEA-381, our results confirmed the values already reported in the literature. The developed method was used for analysing sediments from the Yenisei river (collected downstream of a nuclear fuel reprocessing plant) and for characterizing corrosion products of depleted uranium penetrators that were fired during the Balkan conflict.

Design and performance of an automated radionuclide separator: Its application on the determination of 99Tc in groundwater

A modular automated radionuclide separator for 99Tc (MARS Tc-99) has been developed for the rapid and reproducible separation of technetium in groundwater samples. The control software of MARS Tc-99 was developed in the LabView programming language. An automated radiochemical method for separating 99Tc was developed and validated by the purification of 99mTc tracer solution eluted from a commercial 99Mo/99mTc generator. The chemical recovery and analytical time for this radiochemical method were found to be 96±2% and 81min, respectively.

Determination of 99Tc in aqueous solutions of various cationic compositions using a varian 725-ES inductively coupled plasma optical emission spectrometer

A procedure was developed for determining the gravimetric concentration of 99Tc in aqueous solutions from spent nuclear fuel reprocessing without their preliminary separation, using an inductively coupled plasma optical emission spectrometer (ICP-OES). The optimal conditions for minimizing spectral and matrix interferences were determined. They allowed the lower limit of Tc determination in process salt solutions to be decreased from 1 to 0.25 mg l−1.

Determination of technetium-99 from complex matrix

This paper reports an approach that can be used for efficient separation and determination of 99Tc (as pertechnetate) after contamination of the environment by nuclear materials. The samples were decomposed by fusion in a mixture of potassium hydroxide and potassium nitrate. After fusion, technetium remains as the pertechnetate anion (TcO4 −). The technetium was isolated from the sample by technique combining solvent extraction, anion exchange, then, again, solvent extraction. After separation, 99Tc was measured by isotope-dilution mass spectrometry with 97Tc as spike. This method yielded nanogram detection limits for 99Tc.

Methodological studies of the determination of 99Tc in matrix-rich environmental samples

A few experiments testing technetium behavior at different conditions for complex matrixes (soils, sediments) were performed. It was confirmed that the incineration of samples soaked with ammonia can be done without technetium losses. Next, for the precipitation of iron(III) hydroxide at different pH levels, the degree of co-precipitation of technetium was studied. It can be helpful during purification of very matrix-rich and massive samples. Finally the technetium and rhenium fractionation during separation of technetium from the environmental samples was studied. This test clearly showed limitations for using Re as yield tracer during 99Tc analyses in case of mineral matrixes.

Determination of 99Tc in soil samples using molecular recognition technology product AnaLig® Tc-02 gel

The purpose of this study was to test a method for 99Tc determination in soil samples from locality Bratislava Podunajske Biskupice by using solid phase extraction technique with a new sorbent AnaLig® Tc-02—molecular recognition technology product. The method is suitable for analyzing soil samples in a relatively short time and high recoveries. The use and effectiveness of AnaLig® Tc-02 were successfully tested by analysis of soil and spiked soil samples.

Sequential extraction separation for determination of technetium-99 in radwastes by ICP-MS

An approach based on sequential extraction separation and the subsequent ICP-MS measurement was introduced to determine 99Tc in radioactive wastes. The radwastes were firstly alkaline-fused and the 99Tc was separated by a sequential solvent extraction prior to ICP-MS measurement. NaDDC was selected as a chelation reagent in the solvent extraction processes. The influence of HCl and matrix concentration on the recovery yield and the effectiveness of removing isobar and unwanted radionuclides, such as 137Cs, 54Mn, 60Co and 110mAg, were evaluated. The designed sequential extraction procedure was optimized by an extraction experiment. The proposed technique is proven to be a simple and practical alternative for 99Tc determination in low-level radioactive wastes; chemical separation of 99Tc can be simplified and preconcentration such as precipitation and/or ion exchange, before the solvent extraction, can be excluded.

The use of 99mTc as a tracer in the determination of 99Tc by ICP-mass spectrometry

The aim of this paper is to carry out a deep study on the possibilities of using 99mTc from 99Mo–99mTc clinical isotope generators to trace the radiochemical separations for 99Tc measurements by ICP-MS. By appropriately defining a minimum detectable mass concentration (MDMC) for the mass spectrometer it is possible to conclude that such use is acceptable for a wide range of activities of the tracer. The MDMC increases from 0.41 to 0.51 ppt when the amount of 99mTc added to the samples ranges from 0 to 2 MBq. The purification of the final sample from Ru must be the main objective of the 99Tc measurement method, since its presence noticeably enhances the 99Tc MDMC.

Preconcentration and Analysis of Strontium-90 and Technetium-99 from Hanford Groundwater Using Solid Phase Extraction

Solid-phase extraction disks produced by 3M and Eichrom were evaluated for routine use in supporting the Hanford Groundwater Monitoring Project. Both disk formats contain Sr- or Tc-selective extractants, bound in a filter support, that act to preconcentrate and isolate the isotope of interest. The 3M Empore™ Sr Rad Disks and Tc Rad Disks were tested with respect to precision, accuracy, radiochemical yields, interferences, and volume-load variation. The Empore™ and Eichrom solid-phase extraction disks were applied to the 90Sr and/or 99Tc determination in representative Hanford groundwater samples with varying chemical and isotopic compositions. Results were compared to standard analytical methods. Both the Empore™ and Eichrom Tc extraction disks produced consistently higher radiochemical yields, lower detection limits, and greater accuracy than the standard analysis method. The Empore™ Sr extraction disks produced comparable radiochemical yields, detection limit, and accuracy relative to the standard method; however, total uncertainties were lower.

Determination of 99 Tc in bentonite clay samples using inductively coupled plasma mass spectrometry

A method was developed for the determination of 99Tc at low concentrations in clay samples. The chemical treatment of the samples prior to chemical separation and analysis comprised leaching with sulphuric acid/ sodium bromate. After leaching, pertechnetate was extracted with Alamine-336/chloroform and then back-extracted into nitric acid. Detection was carried out using inductively coupled plasma mass spectrometry, ICP-MS. The instrumental detection limit was 0.45 pg/mL, which corresponds to 0.28 mBq/mL. With the use of a desolvating nebuliser, the detection limit was lowered by about a factor of five. The results were compared with a method using radiometric detection.

Comparison of a radiation counting method and ICP-MS for the determination of99Tc in environmental samples

Results of99Tc measurements between radiation and non-radiation counting methods were compared using four radiation sources for which99Tc has been previously determined with a gas-flow proportional counter or a GM counter. Each99Tc source consisted of a stainless steel planchet bound by mylar films. Seaweeds collected from the Irish Sea were analyzed and99Tc was electroplated on the planchet. The99Tc in each sample was separated and measured again by inductively coupled plasma mass spectrometry (ICP-MS). Tc was continuously removed from each sample with 2M HNO3 and 2M NaOH. After the solution containing Tc was adjusted to 0.1M HNO3, Tc was extracted on a novel extraction chromatographic resin to separate it from Ru. The total recoveries for Tc on the planchet samples were almost the same with an average of 91%. The results of99Tc measurements by both radiation and non-radiation counting methods agreed well with each other.

Determination of technetium in sea-water using ion exchange and inductively coupled plasma mass spectrometry with ultrasonic nebulisation

An enrichment–separation scheme employing a strong-base type anion-exchange resin was developed for the determination of99Tc in sea-water by inductively coupled plasma mass spectrometry utilising ultrasonic nebulisation with membrane desolvation. Samples were processed through an anion-exchange column to enrich Tc and to eliminate sea-water matrix ions. The limit of detection for 99Tc in sea-water based on processing a 14 ml sample was 0.03 ng l–1. Accuracy was verified with spike recovery experiments. The potential for rapid on-line sample processing via a microcolumn–flow injection system was demonstrated.

Determination of99Tc in fuel leachates using extraction chromatography

A simple technique using a combination of cation exchange and solid phase extraction chromatographic resins has been developed for the separation of99Tc from other radionuclides present in nuclear fuel leachates. Quantification of the isolated99Tc is accomplished using liquid scintillation counting. The method provides consistently high recoveries (>96%), generates small amounts of waste compared to classical methods, and requires less analysis time.

Determination of99Tc in rain and dry fallout by ICP-MS

Due to the difficulty of99Tc analysis, data are insufficient for discussing its behavior in the environment. In this study, we focused on the determination of99Tc in rain and dry fallout samples. The samples were collected monthly at Nakaminato, Japan, from June 1993. They were concentrated by heating on a hot plate without any loss of Tc. The solution was filtrated and then a liquid-liquid extraction (LLX) with trioctylamine (TOA), which works as a liquid anion exchanger, was carried out. Technetium was extracted from 5% HNO3 solution into the organic phase with a high extractability. After being back-extracted from TOA/xylene into 1M K2CO3, LLX with cyclohexanone was used to remove ruthenium, which has a stable isotope of mass 99. Technetium was back-extracted into deionized water, and the solution was measured by inductively coupled plasma mass spectrometry (ICP-MS). The average recovery under the experimental conditions was 67% and the instrumental detection limit was 0.04 ppt (0.03 mBq/mL).

Determination of99Tc in coastal seawater collected in Fukuoka, Japan

(ICP-MS) on coastal seawater in the general environment in Japan. Technetium was enriched on iron hydroxide by repetitive co-precipitation method from a large volume of seawater and separated from impurities by solvent extraction and ion-exchange techniques. The concentrations of 99Tc were 1.0 to 7.4 /A3ql ~, which was one order of magnitude lower than the level reported on seawater from general environment by beta-ray counting. Concentrations of ~37Cs determined on the same seawater were 3.7 and 3.9 mBql 1. The activity ratio of 9~I'c]~TCs was calculated to be 2,7x10 "4. This ratio was very close to the value expected for fallout from nuclear tests.

Determination of low-level99Tc in environmental samples by high resolution ICP-MS

An analytical method has been developed for the determination of low-level99Tc in environmental samples by High Resolution ICP-MS. The method consists of leaching of99Tc by HNO3 and separation by three different solvent extractions with 30% TOA-xylene, MEK, and cyclohexanone. Finally, purification of99Tc was made by using an anion exchange resin column to reduce dissolved solids content. The final solution was adjusted to 1M HNO3 for introducing into the HR-ICP-MS. The accuracy and precision of the method was confirmed to be satisfactory by applying this technique to the determination of99Tc in IAEA marine algae sample (AG-B-1). Measurements of99Tc using 0.5–2.5 g of sediment samples from the Irish Sea, UK, were successfully performed by the present method.

Determination of 99Tc in nuclear samples by inductively coupled plasma mass spectrometry

Different approaches for the determination of 99Tc in various nuclear samples are described. Technetium has been determined in leachates of spent fuel and vitrified highly active waste using the elemental response curve of the instrument. It has been observed that Tc is preferentially leached from spent fuel under oxidizing conditions (30% H2O2) indicating that the pertecnectate ion should be the leached species. It has also been determined in spent fuel dissolver solutions by the method of standard additions using other elements present in the sample as internal standards. Zirconium, Mo and Ru showed to be adequate internal standards for the determination of Tc in those samples. The formation of several polyatomic ions containing Tc was observed at high Tc concentrations. Peaks at m/z 115, 131 and 147 were assigned to TcO+, TcO2+ and TcO3+, the TcO2+ being the predominant polyatomic ion. The ratios of the polyatomic ion to the main 99Tc peak were estimated with the help of Rh as internal standard. The influence of plasma operating conditions on the relative abundance of those polyatomic ions has been studied. It was also observed that Tc suffers from a long and persistent memory effect.