共查询到20条相似文献,搜索用时 62 毫秒
1.
Analysis of the artificial radionuclide 99Tc in environmental samples requires a chemical separation due to its low concentration, and therefore the use of a chemical yield tracer is peremptory. From a practical viewpoint, Re can be used for this purpose, due to its chemical similarities with Tc. Thus, the use of a radioactive tracer for Tc recovery calculation can be avoided. However, results from a recent intercomparison exercise showed that using of Re as a chemical yield tracer appears to underestimate the Tc concentration relative to the result obtained with isotopes of Tc. In the present work, the methodology used to design a simple separation method for the measurement of 99Tc in environmental samples is described. Tc recovery is estimated throughout the Re recovery calculation by the isotope dilution technique coupled with ICP-MS (ID-ICP-MS) technique. For chemical separation, a chromatographic resin is used. Interfering elements are removed using a resin washing step carefully designed to avoid any element fractionation between Re and Tc; the care taken in this step is of major importance to assure the equivalence of the chemical recoveries for both elements. Agreement is tested using five replicates of five seaweed samples. The average recoveries for 95mTc and Re were 93±6 and 95±7%, respectively, those are within the uncertainty intervals for each other. The results explained here demonstrate the possibility of applying Re chemical recoveries to calculate the Tc concentrations with the advantage of not introducing systematic errors. 相似文献
2.
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). 相似文献
3.
M. Yamamoto Syarbaini K. Kofuji A. Tsumura K. Komura K. Ueno D. J. Assinder 《Journal of Radioanalytical and Nuclear Chemistry》1995,197(1):185-194
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. 相似文献
4.
N. Matsuoka T. Umata M. Okamura N. Shiraishi N. Momoshima Y. Takashima 《Journal of Radioanalytical and Nuclear Chemistry》1990,140(1):57-73
A radioanalytical procedure has been developed for the determination of99Tc in environmental samples. The procedure consists of precipitation, solvent extraction, ion exchange, electrodeposition and radiation measurement. Rhenium was used as a non-isotopic carrier of99Tc. On the basis of 3σ counting error, the detection limits were 4.9·10?5 Bq/l, 7.4·10?3 Bq/kg wet and 7.4·10?2 Bq/kg dry for water, biota and soil samples, respectively. Sea water, seaweeds (brown algae) and soils were collected to evaluate the present levels of99Tc in Japan. The level of99Tc in sea water was ca. 1·10?4 Bq/l around Japan. Among the seaweeds (brown algae), Ishige okamurai showed the highest concentration of 5.8·10?2 Bq/kg wet tissue and the highest concentration factor of 583. The level of99Tc in the organic rich surface soil was ca. 1 Bq/kg dry soil in Fukuoka. 相似文献
5.
Boris Remenec Silvia Dulanská Veronika Pau?ová L’ubomír Mátel 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):403-407
This paper describes a simple and rapid method of 99Tc pre-concentration, separation and purification by using AnaLig? Tc02 gel in two stages or AnaLig? Tc02 gel in a first stage and TEVA? resin in a second stage, which are commercially available from IBC advanced technologies, Inc. and Eichrom technologies,
Inc., respectively. The method is suitable for analyzing large volume concentrate samples in a relatively short time. The
use and effectiveness of AnaLig? Tc02 and Eichrom’s TEVA? resin were successfully tested by analysis of evaporator concentrate samples which belong to the class of most difficult
matrices to analyze. 相似文献
6.
K. Tagami S. Uchida M. García-León 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):147-151
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. 相似文献
7.
Lixiong Wang Lei Tang Tongzai Yang Yanqiu Yang Liang Yang 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):739-742
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. 相似文献
8.
D. M. Beals 《Journal of Radioanalytical and Nuclear Chemistry》1996,204(2):253-263
An isotope dilution/inductively coupled plasma mass spectrometric method (ID/ICP-MS) for measuring the concentration of technetium-99 in aqueous samples was developed at the Savannah River Technology Center (SRTC). The procedure is faster than radiometric tecniques, is less subject to interferences, and has equal or better detection limits. It is currently being used to measure the concentration of99Tc in samples of Savannah River water collected in the vicinity of the Savannah River Site. In this method one liter samples of water are spiked with97Tc. After equilibration, the technetium is extracted from the sample with a chromatographic resin. Interfering elements, molybdenum and ruthenium, are either not retained by the resin or are washed off with, dilute nitric acid. The technetium is then eluted with more concentrated nitric acid, and the99Tc/97Tc ratio in the eluant is measured with an ICP-MS. The99Tc concentration in the original sample is calculated from the99Tc/97Tc ratio. The chemical recovery of the extraction procedure is greater than 90%. The detection limit of the instrument, taken as three times the background counts atm/z=99, is 0.6 part per trillion (ppt). The detection limit of the procedure, taken as three times the standard deviation of several reagent blank analyses, is 0.33 pCi/l. 相似文献
9.
Summary The recent developments of extraction chromatography and ICP-MS made easier the determination of 99Tc in environmental samples. However, in the non-contaminated area, a pre-concentration procedure is necessary, because usually a large amount of sample is used for analysis. In this study, the ferrous ion (Fe2+) added as a reductant can make chemical yield from 50 to 80%, when larger than 100 liter water samples or 500 g soil samples are analyzed. The extraction chromatography with TEVA resin (EIChrom) and the measurement by ICP-MS have been developed using 95mTc and 103Ru as yield tracers. Detection limits of 3σ are 0.054 mBq/kg for 500 g soil and 0.032 µBq/lfor 500 l water. A pond named Hinotani, Mie Prefecture in the central part of Japan, was selected to be investigated as a natural system in a non-contaminated area. Surface soil near this pond, pond water and sediment were collected and analyzed for 99Tc. In a high fall-out area, Okuetsu, Fukui Prefecture forest soil was collected and analyzed. The 99Tc in the surface (0-5 cm) was 10.5±0.8 mBq/kg. The 99Tc in Hinotani surface (0-5 cm) soil were 0.77±0.06 mBq/kg less than in Okuetsu. Technetium-99 has been determined in pond water, sediment (0-5 cm) and shrimps in the Hinotani pond, 0.25±0.02 mBq/l, 3.3±0.3 mBq/kg, 1.5±0.2 mBq/kg, respectively. 相似文献
10.
The concentration of99Tc in IAEA reference materials has been determined with an ICP-MS as 0.86±0.07 Bq·kg−1 dry for IAEA-373 (grass) and 0.25±0.02 Bq·kg−1 dry for IAEA-375 (soil). These being sufficiently higher than the detection limits of typical measurement methods, both materials
can be used as reference materials for determining low-level99Tc in environmental samples. 相似文献
11.
K. G. Lahoda M. D. Engelmann O. T. Farmer N. E. Ballou 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(3):509-513
Experimental results are provided for the sample analyses for technetium in charcoal samples placed in-line with a Savannah
River Site (SRS) processing stack effluent stream as a part of an environmental surveillance program. The method for Tc removal
from charcoal was based on that originally developed with high purity charcoal. Presented is the process that allowed for
the quantitative analysis of 99Tc in SRS charcoal stack samples with and without 97Tc as a tracer. The results obtained with the method using the 97Tc tracer quantitatively confirm the results obtained with no tracer added. All samples contain 99Tc at the pg·g−1 level. 相似文献
12.
J.W. Grate 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(1):181-189
A method utilizing extractive scintillating resin for 99Tcmonitoring in aqueous solutions is presented. These extractive scintillatorscombine analyte selective uptake and scintillating properties to produce dualfunctionality analytical resins. These resins were produced by (1) co-locatedextraction chromatographic resin and plastic scintillating beads, (2) immobilizingfluors in macroporous polystyrene supports to which chains of monomethylatedpolyethylene glycol have been grafted and (3) co-immobilizing organic scintillatingfluors and a quaternary ammonium extractant (Aliquat-336) within macroporousacrylic and polystyrene supports. The first and third resins selectively extractpertechnetate ions from dilute acid whereas the second resin selectively extractspertechnetate ions from high ionic strength solutions. These resins were utilizedin ~0.20 ml pore volume columns while 99Tc was continually monitoredwith commercially available scintillation detection systems. Manual and automatedmicrofluidics were used to deliver sample and reagent solution for loadingand elution of the 99Tc. The detection efficiencies were determinedto be 45 and 70% for acrylic and polystyrene based resins, respectively, andindependent of extractant. Minimum detectable 99Tc concentrationusing the Aliquat-336/acrylic-based resin was 6.2 Bq . l –1 for a 50-mlsample and 30-minute count time. The new methodology was applied towards analysisof contaminated groundwater samples and nuclear waste simulants. 相似文献
13.
S. Mattsson 《Journal of Radioanalytical and Nuclear Chemistry》1978,45(2):341-347
The99Tc-content in99mTc-pertechnetate separated from99Mo by distillation or extraction has been studied with a plastic scintillation detector. The identification of the measured
activity was achieved by beta-spectrometry, chemical separation and half-life studies. The frequency distribution of the99Tc/99mTc-ratios in the different samples was observed to be log-normal. The most likely activity ratio was 0.4·10−6, the maximum value being 5·10−6. The specific activity of “instant” pertechnetate is approximately a factor of 60 lower than that normally recorded in pertechnetate
derived from daily eluted column generators. The low specific activity of “instant” pertechnetate is primarily explained by
the long time between separation and usage and secondly by the low yield of Tc in the distillation and extraction processes.
In several of the “instant” pertechnetate solutions the carrier concentration exceeded the reductive capacity of the stannous
ions in “kits” with small amounts of Sn(II) in usable form. 相似文献
14.
For99Tc separation from environmental samples, liquid-liquid extraction, ion-exchange chromatography and coprecipitation, have been described. Although these methods are removing matrix elements, some combinations of them is necessary for purification and concentration of Tc. Besides, the procedures are time-consuming and generally a week or more is needed to purify Tc in the samples. In this study, a novel extraction chromatographic resin for the separation and preconcentration of Tc from several kinds of solutions is described. The material is shown to retain Tc efficiently and selectively from these solutions. Sorbed Tc is readily recovered using 5 ml of 12M HNO3 and the recoveries with95mTc are more than 97% for all sample solutions. 相似文献
15.
Rozas Saroa López Julen Idoeta Raquel Herranz Margarita 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(8):3335-3341
Journal of Radioanalytical and Nuclear Chemistry - In this work, two Tc radiochemical isolation methods—a conventional method by Triskem TEVA® resin and a rapid method by Empore?... 相似文献
16.
C. L. Liu S. S. Li X. Y. Wang Z. M. Wang H. F. Wang R. J. Li C. T. Xin B. Li L. Jiang C. Z. Jia 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(2):411-413
The migration of 99Tc in unsaturated Chinese loess was investigated in-situ with a tracer method. Quartz containing 3H (HTO) and 99Tc (99TcO4
-) was introduced into the bottom of an experimental pit which was then backfilled at the field test site. Then core soil samples were taken and cut vertically into 1 cm long slices. The slice samples were analyzed by liquid scintillation techniques in the laboratory. The results indicate that the migration pattern of 99Tc was quite similar to that of 3H and the vertical diffusion coefficients of 99Tc and 3H were calculated as (4.7±0.4).10-2 cm2/d and (7.8±0.4).10-2 cm2/d, respectively. 相似文献
17.
Due to the lack of a stable technetium isotope, and the high mobility and long half-life, 99Tc is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. 99Tc is also an important tracer for oceanographic research due to the high technetium solubility in seawater as TcO4−. A number of analytical methods, using chemical separation combined with radiometric and mass spectrometric measurement techniques, have been developed over the past decades for determination of 99Tc in different environmental samples. This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of 99Tc. Due to the extremely low concentration of 99Tc in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal of the interferences for detection of 99Tc are the most important issues governing the accurate determination of 99Tc. These aspects are discussed in detail in this article. Meanwhile, the different measurement techniques for 99Tc are also compared with respect to advantages and drawbacks. Novel automated analytical methods for rapid determination of 99Tc using solid extraction or ion exchange chromatography for separation of 99Tc, employing flow injection or sequential injection approaches are also discussed. 相似文献
18.
N. R. Das 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(3):883-885
A simple chromatographic procedure for clean separation of the important radionuclide,99m Tc, in the equilibrium mixture,99Mo−99mTc, has been demonstrated. Separation of pure99mTc has been achieved by preferential extraction of the radioisotope through an anion exchange resin column of Amberlite IRA-410
using Na-ascorbate solution at pH 7 as an eluent. The radiochemical purity of the separated radiotracer has been verified
by taking recourse to γ-ray spectrometry. The potentiality of the developed procedure lies in the facts that the eluting agent,
ascorbic acid, itself h got its own biomedical importance as Vitamin C and the concerned radioisotope can be obtained in both
Tc(IV) and Tc(VII) states as per requirement for diagnostic purposes. 相似文献
19.
Coma A. Tarancón A. Bagán H. García J. F. 《Journal of Radioanalytical and Nuclear Chemistry》2019,321(3):1057-1065
Automated methods for the analysis of radionuclides potentially increase laboratory productivity by reducing operator intervention and increasing the number of samples that can be treated in a given time. To this end, here we report a new openview automated modular separation system which can be used in combination with PSresin, in this case, for the analysis of 99Tc. Quality parameters of this method using the automated system were comparable to those obtained manually and quantification of water samples spiked with low levels of 99Tc resulted in deviations lower than 10% for all the samples analysed.
相似文献20.
Solvent extraction separation of99mTc from99Mo using methyl ethyl ketone(MEK) has been found to be an effective method of obtaining99mTc of medicinal purity from low specific activity99Mo. The authors have investigated the effect of alkali and molybdenum concentration on the extraction of99Mo and99mTc into methyl ethyl ketone. The possibility of methyl ethyl ketone forming enol and condensation products and its effect
on the final extraction efficiency and purity of99mTc has been studied. Sodium molybdate has been found to have a good salting out effect on99mTc pertechnetate and hence99mTc extraction can be better accomplished from low specific activity99Mo solutions. The ketone seems to form traces of condensation products in the extraction procedure. These have been found
to be coextracted with99mTc into MEK but did not affect the extractability of99mTc. It was observed that neutral alumina column removes these condensation products from MEK containing99mTc. Alternately these could be filtered off by acidification of the final aqueous99mTc solution. The studies indicate that under optimum experimental conditions methyl ethyl ketone separates99mTc from99Mo with high efficiency and yields99mTc of high purity suitable for use in nuclear medicine in the form of various labelled compounds. 相似文献