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1.
A new tandem generator system (cation-exchange generator column coupled to anion-exchange), based on the 228Ra as starting radionuclide, for 212Pb/ 212Bi production in the solutions suitable to direct application in biomedical investigations has been developed. Optimum conditions
have been found for retention of Ra, Th and Ac parent radionuclides on the cation-exchange column and repeated elution of
Pb with subsequent concentration on anion-exchange column using HBr and mixed HBr/CH 3OH solutions. It was shown that Pb/Bi could be eluted from anion — exchange column with a small volume of EDTA, DTPA, NaCl
solutions or heated H 2O. The advantages of the tandem generator system for production of short-lived Pb/Bi radionuclides and their application for
biomedical studies are discussed. 相似文献
2.
A generator system, consisting of two anion- and one cation-exchange columns for production of medical α-radionuclides 225Ac and 213Bi, has been developed. The first anion-exchange column was used for periodical separation of 225Ac from Th with 8 M HNO 3, while the second anion-exchange column was employed for purification of 225Ac from Ra and inactive impurities in mixed HNO 3/CH 3OH media. From anion-exchange column 225Ac was stripped with 0.1–0.2 M HNO 3 and loaded directly onto cation-exchange column, used as a generator for repeated isolation of 213Bi. The cation exchange behavior of Bi and other radionuclides of the interest were studied in diluted HCl, HBr and DTPA solutions used as eluents. As result, a simple and effective method for the production and purification of 225Ac and 213Bi suitable for biomedical studies was elaborated. 相似文献
3.
211Pb and its daughters are produced in a generator system which utilizes the distillation of the intermediate daughter 219Rn from 223Ra. The radium is precipitated as the stearate to isolate the parent while allowing the gaseous daughter to emanate. While the yield of the system is low, approximately 10%, the radionuclidic purity is extremely high. No measurable 223Ra is found in the product. 223Ra is separated from its parent, 227Ac, by cation exchange.Deceased.Research supported in part by the Office of Health and Environmental Research, U.S. Dept. of Energy. 相似文献
4.
A procedure for the analysis of 228Ra in drinking water has been developed. The procedure involves separation of radium by an initial coprecipitation with lead sulfate. The isolated Pb(Ra)SO 4 is then dissolved in sodium diethylenetriamine pentaacetate (DTPA). Radium-228 is co-precipitated from this solution with barium sulfate while the DTPA supernate which contains pre-existing 228Ac is discarded. The purified Ba(Ra)SO 4 precipitate is then allowed to ingrow, generating 228Ac, which is then dissolved in DTPA, isolating both 226Ra and 228Ra in the precipitate while 228 Ac remains in the aqueous supernate. The supernate is partitioned against di-(2-ethylhexyl phosphoric acid), HDEHP, dissolved in n-heptane, which retains the 228Ac. Actinium-228 is then stripped from the organic phase by partitioning against 1M HNO 3. Finally, the 228Ac is coprecipitated onto cerium oxalate. The precipitate is collected on a filter and counted in a low-background beta counter. Radium-228 standards with concentrations ranging from 0.044 to 1.6 Bq were used to establish the detector counting efficiency for 228Ac in cerium oxalate samples, as well as monitoring the chemical yield and absorption factors. The resultant average value of 30.3±2.1 cpm/Bq (uncertainty given at 95% level of confidence) was obtained. Various 228Ra cross checks from U. S. Environmental Protection Agency (EPA) with concentrations of 0.063–0.52 Bq/l were analyzed in order to assess the performance of the procedure. The minimum detectable concentration (MDC) of 228Ra in water with this procedure is 0.015 Bq/l. This is based on a one liter aliquot of sample, a 100 min couting period, and a 3 hour decay interval between the end of 228Ac ingrowth and midpoint of counting. Decontamination factor studies were performed to determine the extent of the carry-over of 238U, 226Ra, 210Po, and 90Sr into the final fraction. 相似文献
5.
The concentrations of radium isotopes and the progenies ( 226Ra; 228Ra and 228Th) in three hokutolite samples from Tamagawa hot-spring were measured. These isotopes were analyzed by a well-type HPGe γ-ray
spectrometer for the 351, 911 and 583 keV γ-ray from 214Pb, 228Ac and 208Tl, respectively, each being in radioactive equilibrium with precursors. Concentration of 226Ra and 228Ra were observed to be in the range of 52–85 and 7.1–85 Bq/g, respectively. The activity ratios of 228Ra/ 226Ra and 228Th/ 226Ra provided the estimation of the growth rate (0.09–0.15 mm/y). Estimated 228Ra/ 226Ra activity ratios in hot-spring water from surface of three hokutolite were concordant. 相似文献
6.
Summary The measurement of radium isotopes in natural waters is important for oceanographic studies and for public health reasons.
Radium-226 ( T1/2 = 1620 y) is one of the most toxic of the long-lived alpha-emitters present in the environment due to its long life and its
tendency to concentrate in bones, which increases the internal radiation dose of individuals. The analysis of 226Ra and 228Ra in natural waters can be tedious and time-consuming. Different sample preparation methods are often required to prepare
226Ra and 228Ra for separate analyses. A rapid method has been developed at the Savannah River Environmental Laboratory that effectively
separates both 226Ra and 228Ra (via 228Ac) for assay. This method uses MnO 2 Resin from Eichrom Technologies (Darien, IL, USA) to preconcentrate 226Ra and 228Ra rapidly from water samples, along with 133Ba tracer. DGA Resin ò (Eichrom) and Ln-Resin ò (Eichrom) are employed in tandem to prepare 226Ra for assay by alpha-spectrometry and to determine 228Ra via the measurement of 228Ac by gas proportional counting. After preconcentration, the manganese dioxide is dissolved from the resin and passed through
stacked Ln-Resin-DGA Resin cartridges that remove uranium and thorium interferences and retain 228Ac on DGA Resin. The eluate that passed through this column is evaporated, redissolved in a lower acidity and passed through
Ln-Resin again to further remove interferences before performing a barium sulfate microprecipitation. The 228Ac is stripped from the resin, collected using cerium fluoride microprecipitation and counted by gas proportional counting.
By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized. 相似文献
7.
A sensitive and accurate method for determination of radium isotopes in soil samples by α-spectrometry has been developed 225Ra, which is in equilibrium with its mother 229Th, was used as a yield tracer. Radium in soil samples was fused together with Na 2CO 3 and Na 2O 2 at 600 °C, leached with HNO 3, HCl and HF, preconcentrated by coprecipitation with BaSO 4, separated from uranium, thorium and iron using a Microthene-TOPO chromatographic column, isolated from barium in a cation-exchange
resin column using 0.05M 1,2-cyclohexylene-dinitrilo-tetraacetic acid monohydrate as an eluant, electrodeposited on a stainless
steel disc, and counted by α-spectrometry. The detection limit of the method is 0.43 Bq·kg −1 for 226Ra, 228Ra and 224Ra if 0.50 g of soil sample are analyzed. The method was checked with two certified reference materials supplied by the IAEA,
and reliable results were obtained Fourteen soil samples collected from the refractory industry in Italy were also analyzed.
The mean radiochemical yields for radium were 85.7±4.3%, and the obtained radium concentrations in the soil samples were in
the range of 8.08–3878 Bq·kg −1 for 226Ra, of 1.60–678 Bq·kg −1 for 228Ra and 1.25–550 Bq·kg −1 for 224Ra, with 228Ra/ 226Ra and 224Ra/ 226Ra ratios ranged from 0.159–0.821 and from 0.142 to 0.525, respectively. 相似文献
8.
A simple generator using AG 50Wx8 cation exchange resin has been developed for continual elution of 212Pb and 212Bi from the parent radionuclide 228Th, derived from 232U. Using 0.4 M HCl as an eluent will elute 212Bi while 212Pb is eluted with 2 M HCl. The generator has shown good reproducibility of elution bands. A generator set-up in 2013 has been in continual use over 4 years demonstrating that this generator system has a long and stable lifetime. The generator system presented here has served as a long-term method for attaining no-carrier-added 212Pb and 212Bi radionuclides for homolog studies of flerovium and moscovium. 相似文献
9.
Recovery of 226Ra in analysis is determined using 225Ra separated by anion exchange from 229Th and 233U. Radium is coprecipitated with barium, and purified by ion exchange. 226Ra and 217At (decay product of 225Ra) are measured by α-spectrometry. 228Ra is determined both by β-counting 228Ac and 225Ac separated from 228Ra and 225Ra, and by α-counting its daughters after the decay of 225Ra. Sources for α-spectrometry are prepared by electrodeposition (molecular plating). 相似文献
10.
A rapid, accurate, and precise method is described for the determination of Pb in wine using continuous-flow hydride generation
atomic fluorescence spectrometry (CF-HGAFS). Sample pretreatment consists of ten-fold dilution of wine followed by direct
plumbane generation in the presence of 0.1 mol L −1 HCl and 1% m/v K 3[Fe(CN) 6] with 1% m/v NaBH 4 as reducing agent. An aqueous standard calibration curve is recommended for Pb quantification in wine sample. The method
provides a limit of detection and a limit of quantification of 0.3 μg L −1 and 1 μg L −1, respectively. The relative standard deviation varies between 2–6% (within-run) and 4–11% (between-run) at 3–30 μg L −1 Pb levels in wine. Good agreement has been demonstrated between results obtained by CF-HGAFS and direct electrothermal atomic
absorption spectrometry in analyses of red and white wines within the concentration range of 9.2–25.8 μg L −1 Pb. 相似文献
11.
Elevated concentrations of the radium isotopes 224,226,228Ra exist in the scale and produced water in oil exploration. The activity concentration of 226Ra was calculated from 186.2 keV peak with no usual spectral interference of 185.7 from 235U. The activity concentration of 228Ra was calculated from its first daughter product 228Ac using the 911.2 keV gamma rays since it is a pure beta emitter. The activity concentration of 224Ra was calculated from 212Pb using the 238.6 keV gamma-ray and the secular equilibrium equation with 228Ra. The IAEA 448 (oil contaminated field soil) reference material was used as a quality control for 226,228Ra and but was unreliable for 224Ra using 212Pb. 相似文献
12.
Rapid determination of 222Rn and 220Rn progeny ( 214Pb, 212Pb, 214Bi, 212Bi) is achievable using manganese dioxide (MnO 2) precipitation with analysis by γ-spectrometry. This is of interest to environmental monitoring programmes that utilise gross activity methods to screen for anthropogenic radionuclides. The contribution from these naturally occurring radionuclides (NOR) varies, and is difficult to experimentally measure due to short half-lives ( t ½ = 19.9 m–10.64 h) and low environmental activity (<0.1 Bq L ?1). The extraction efficiency of the technique is above 90%, and above 80% for other nuclides ( 232Th, 238U, 235U, 228Ac, 226Ra, 224Ra, 210Pb, 54Mn). Short-lived NOR have been measured at two surface water locations, and indicates elevated 214Bi activity of 4.0 ± 1.1 Bq L ?1. 相似文献
13.
A new rapid method for the determination of 228Ra in natural water samples has been developed at the SRNL/EBL (Savannah River National Lab/Environmental Bioassay Laboratory) that can be used for emergency response or routine samples. While gamma spectrometry can be employed with sufficient detection limits to determine 228Ra in solid samples (via 228Ac), radiochemical methods that employ gas flow proportional counting techniques typically provide lower minimal detectable activity levels for the determination of 228Ra in water samples. Most radiochemical methods for 228Ra collect and purify 228Ra and allow for 228Ac daughter ingrowth for ~36 h. In this new SRNL/EBL approach, 228Ac is collected and purified from the water sample without waiting to eliminate this delay. The sample preparation requires only about 4 h so that 228Ra assay results on water samples can be achieved in <6 h. The method uses a rapid calcium carbonate precipitation enhanced with a small amount of phosphate added to enhance chemical yields (typically >90 %), followed by rapid cation exchange removal of calcium. Lead, bismuth, uranium, thorium and protactinium isotopes are also removed by the cation exchange separation. 228Ac is eluted from the cation resin directly onto a DGA Resin cartridge attached to the bottom of the cation column to purify 228Ac. DGA Resin also removes lead and bismuth isotopes, along with Sr isotopes and 90Y. La is used to determine 228Ac chemical yield via ICP-MS, but 133Ba can also be used instead if ICP-MS assay is not available. Unlike some older methods, no lead or strontium holdback carriers or continual readjustment of sample pH is required. 相似文献
14.
New method for simultaneous determination of 228Ra and 226Ra by using 3M's EMPORE TM Radium Rad Disks in water has been developed. Both radionuclides 226Ra and 228Ra were counted through their daughter products, 226Ra by conventional radon emanation techniques and 228Ra through its daughter 228Ac by using a proportional counter. Different molarity of diammonium hydrogen citrate were used for elution of 228Ac and 226Ra from EMPORE TM Radium Rad Disks. 79% of 228Ac was eluted in 10 ml of 0.0003M diammonium hydrogen citrate. The recovery of 226Ra was 99% by using 40 ml of 0.2M diammonium hydrogen citrate adjusted by ammonium to pH 7.8. 相似文献
15.
An investigation on the distribution of 226Ra and 228Ra activity concentration in coastal surface sea water from Okha in Gujarat to Ratnagiri in Maharashtra state along the west coast of India was carried out. In-situ pre-concentration technique was used to measure radium isotopes by passing 1,000 L of seawater through MnO 2 impregnated polypropylene filter cartridges at all the locations. 226Ra was estimated using gamma ray peak of its daughter radionuclides 214Bi and 214Pb. 228Ra was estimated from its daughter 228Ac. In the coastal waters, 226Ra and 228Ra activity concentration were observed to be in the range of 1.5–2.9 and 2.5–8.6 Bq m ?3 with a mean of 2.2 and 4.9 Bq m ?3 respectively. The activity of 228Ra was observed to be more than 226Ra in all the locations. The variation in spatial distribution of the radium isotopes activity concentration and its ratio with respect to location is discussed in the paper. The radioactive database obtained represents reference values for coastal environment of India. 相似文献
16.
The construction of a dynamic generator for the separation of carrier-free 224Ra is described. The mother 228Th was extracted on the top of the column with di-(2-ethylhexyl)phosphoric acid on hydrophobized Chromosorb W DMCS. The function of the generator was checked during 6 months by measuring the decontamination of 224Ra from 228Th. Simultaneously the yield of 224Ra was determined as a function of the HCl concentration and of the means of milking. The best results were obtained with 0.01–0.1M HCl; the yield was about 75% of the theoretical value, and the 224Ra contained less than 0.01% of 228Th. 相似文献
17.
An isotopic dilution method has been developed for the determination of 226Ra and 228Ra in sea water and sediments with 223Ra as a yield tracer. An alternative procedure which obviates the need for 223Ra is demonstrated for sediments by the assay of 224Ra and 228Th which occur naturally in sediments. In addition, a direct method for β-counting 228Ra– 228Ac is proposed. Radium, polonium, thorium and uranium isotopes and 210Pb are coprecipitated from sea water with aluminum phosphate carrier. The radium and lead-210 are coprecipitated with lead nitrate in sediment leachings. All radium procedures utilize identical chemical isolation and the cathodic electrodeposition of radium. Subsequently, the α-radiation emitted by 226Ra, 223Ra and 224Ra is determined by pulse-height analysis: the 228Ra- 228Ac and 210Pb- 210Bi are measured by low background anticoincidence β-counting techniques. This method was used for samples containing 10 -11–0.5 · 10 -12 g of 226Ra and 10 -13–10 -15 g of 228Ra and gave a precision of 3–6% and 5–10% respectively, even though radium levels an order of magnitude less can be measured. The 226Ra method is applicable to all environmental samples, whereas 228Ra determinations are limited to applications where the activity ratio is greater than 0.1. This method is especially attractive for studies of parent-daughter disequilibria. 相似文献
18.
Summary A method for the determination of low-level radium isotopes in mineral and environmental water samples by alpha-spectrometry
has been developed. Radium-225, which is in equilibrium with its mother 229Th, was used as a yield tracer. Radium were preconcentrated from water samples by coprecipitation with BaSO 4and iron (III) hydroxide at pH 8-9 using ammonia solution, then isolated from uranium, thorium and iron using a Microthene-TOPO
chromatography column at 8M HCl, separated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylenedinitrilotetraacetic
acid monohydrate at pH 8.5 as an eluant, and finally electrodeposited on a stainless steel disc in a medium of 0.17M (NH 4) 2C 2O 4at pH 2.6 and current density of 400 mA . cm -2, and counted bya-spectrometry. Optimum experimental conditions for radium separation, purification and electrodeposition
have been studied and discussed in the paper. The lower limits of detection of the method are 0.11 mBq . l -1for 226Ra, 228Ra and 224Ra, respectively, if 2 l of water are analyzed. The method has been checked with a certified reference material IAEA-Soil-6
supplied by the International Atomic Energy Agency and reliable results were obtained. Eighteen water samples collected in
Italy have been analyzed with the method, the mean radiochemical yields for radium were 86.2±6.5%. The obtained radium concentrations
were in the range of 0.50-60.8 mBq . l -1for 226Ra, of 0.10-25.7 mBq . l -1for 228Ra, and of£LLD-7.97 mBq . l -1for 224Ra. The 228Ra/ 226Ra and 224Ra/ 226Ra ratios were in the range of 0.189-4.45 and£LLD-0.941, respectively. 相似文献
19.
The concentrations of 226Ra, 210Po and 210Pb have been measured, by high efficiency 5″ × 5″ NaI(Tl) gamma ray spectrometer and chemical deposition method, in surface
water samples from major rivers Kali, Sharavathi and Netravathi of coastal Karnataka. Measurements of 226Ra, 210Po and 210Pb in surface water from these rivers are important because the river water is main source of potable water in this region
due to inadequate supply of treated water. The mean activity of 226Ra, 210Po and 210Pb in the surface water of the river Kali was found to be 5.13 mBq L −1, 1.28 and 1.37 Bq L −1, for Sharavathi River the mean activity was found to be 3.37 mBq L −1, 1.30 and 1.44 Bq L −1. In Netravathi River the mean activity of 226Ra, 210Po and 210Pb was found to be 3.30 mBq L −1, 1.00 and 1.20 Bq L −1. From the measured concentration of 226Ra, 210Po and 210Pb, the Effective dose to the population of the region was computed. The results of these systematic studies are presented
and discussed in the paper. 相似文献
20.
Summary Barium-137m radioisotope generator of the chromatographic column elution mode based on loading 1.5 g 6-tungstocerate(IV) gel
matrix with ~54 kBq of fission-produced 137Cs is described. The elution performance of the generated 137mBa radionuclide was investigated as a function of chemical composition of the eluent, flow rate, elution frequency, and age
of the generator system. At comparable conditions, 137mBa eluates with 0.9% NaCl-0.1M HCl eluent had higher elution yields and radionuclidic purity than with 0.1M NH 4Cl-0.1M HCl eluent. The generator has been repeatedly eluted for 311 days by passing 4810 ml of the saline eluent (10 ml ×
481 elution operations) at a flow rate of 3.0 ml/min. Barium-137m eluates of high and reproducible elution yields, chemical
and radionuclidic purities of (≥ 99.99%) were obtained. 相似文献
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