Determination Of 226Ra Research Articles

Rapid determination of 226Ra in urine samples

A new radiochemical separation method has been developed for rapid analysis of (226)Ra in urine samples. In this method, radium is separated from urine matrix using cation and anion exchange column chromatography. A (224)Ra tracer is added, together with its parent in the (228)Th standard, for chemical recovery correction. After separation, the sample is precipitated with hydrous titanium oxide and then prepared for counting by creating a thin-layer counting source using BaSO(4) micro-precipitation. The radium isotopes are then counted by alpha spectrometry. Replicate spike and blank samples were analysed for validation of the procedure. The detection limit was determined to be 0.22 Bq l(-1) with 4 h of counting for 20 ml of urine sample. Using this method, the results can be reported within an 8 h turn-around time. This method is suitable for quick dose assessment of (226)Ra exposure following a radiation emergency.

Improvement of a method for the sequential determination of 210Pb, 226Ra, and uranium isotopes by LSC and alpha-particle spectrometry

In a previous paper the authors proposed a sequential method for the determination of isotopes of uranium, thorium, radium, and lead from environmental samples using alpha-particle spectrometry and LSC techniques. Although the radiochemical yields were suitable when the assays were performed on synthetic samples, application to real environmental samples caused a major decrease in the radiochemical yield, especially for uranium in inorganic samples (soils). A modification of the procedure is described that overcomes this drawback.

Rapid determination of 226Ra in drinking water samples using dispersive liquid-liquid microextraction coupled with liquid scintillation counting

A new radioanalytical method was developed for rapid determination of 226Ra in drinking water samples. The method is based on extraction and preconcentration of 226Ra from a water sample to an organic solvent using a dispersive liquid-liquid microextraction (DLLME) technique followed by radiometric measurement using liquid scintillation counting. In DLLME for 226Ra, a mixture of an organic extractant (toluene doped with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone) and a disperser solvent (acetonitrile) is rapidly injected into the water sample resulting in the formation of an emulsion. Within the emulsion, 226Ra reacts with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone and partitions into the fine droplets of toluene. The water/toluene phases were separated by addition of acetonitrile as a de-emulsifier solvent. The toluene phase containing 226Ra was then measured by liquid scintillation counting. Several parameters were studied to optimize the extraction efficiency of 226Ra, including water immiscible organic solvent, disperser and de-emulsifier solvent type and their volume, chelating ligands for 226Ra and their concentrations, inorganic salt additive and its concentration, and equilibrium pH. With the optimized DLLME conditions, the accuracy (expressed as relative bias, Br) and method repeatability (expressed as relative precision, SB) were determined by spiking 226Ra at the maximum acceptable concentration level (0.5 Bq L−1) according to the Guidelines for Canadian Drinking Water Quality. Accuracy and repeatability were found to be less than −5% (Br) and less than 6% (SB), respectively, for both tap water and bottled natural spring water samples. The minimum detectable activity and sample turnaround time for determination of 226Ra was 33 mBq L−1 and less than 3 h, respectively. The DLLME technique is selective for extraction of 226Ra from its decay progenies.

Determination of 40K, 226Ra and 232Th concentration and radiation dose assessment in titanium enamel frits use in polishing household utensils in Ghana

As part of monitoring the exposure of the Ghanaian public to natural radioactivity, radioactivity concentrations in titanium enamel frits use for coating, spraying and decorating steel bowls were investigated. Samples collected from Ghana Utensil Manufacturing Company in Ghana were analyzed using γ-ray spectrometry with a high purity germanium detector. The samples were found to contain an average absorbed dose rate of 509.38 nGy h−1, while an average annual effective dose was calculated to be 2.50 mSv.

Simultaneous Determination of 226Ra and 228Ra in Water by Liquid Scintillation Spectrometry

Radium is a naturally occurring alkaline earth metal that is present in soils, water, plants, and foods in low concentrations. In the analysis of radium in trace amounts, co-precipitation is the favoured way of separating an element from its matrix. In this case, radium is co-precipitated with barium. The purity and yield of the extraction is controlled by adsorption onto the barium sulfate precipitate and pH manipulation controls the solubility of certain products. This technique enables the removal of interfering lead-210 to yield a purified radium source for analysis, which is done using liquid scintillation spectrometry. The analytical results of spiked water samples are in good agreement with the known activities of radium-226 and radium-228 standard reference materials. Minimum detectable limits for radium-226 and radium-228 are calculated to be 0.01 and 0.06 Bq L–1, respectively. The method provides a fast, reliable, and accurate alternative to traditional radium isotope analysis based on α and gamma spectrometry.

Application of in-house method for determinationof radium isotopes in environmental samples usingthe Liquid Scintillation counting technique

A method for determination of 226Ra and 228Ra in environmental samples using the α-β coincidence liquid scintillation counting (LSC) has been developed. Radium were preconcentrated from environmental samples by coprecipitation with BaSO4, then purified from others radionuclide interferences using the cation column exchange (Bio-Rad AG 50 W-X4 resin with 200-400 mesh size and H+ form) and operating in warm temperature which is between 70-80oC. Then, the Ba(Ra)SO4 precipitate was filtered through the Millipore filter paper, dried and weighed to calculate chemical yield. The activity concentration of radium isotopes in mixture of liquid scintillation cocktails were measured using LSC after being stored for over 21 days to allow the growth of the progeny nuclides. The method has been validated with a certi-fied reference material supplied by the International Atomic Energy Agency and reliable results were obtained. The radiochemical yields for radium were 59% - 90% and recovery was 97% and 80% for 226Ra and 228Ra, respectively. Sixteen seawater and fish flesh samples collected in Kapar coastal water have been analyzed with the developed method. The obtained radium activity concentrations in seawater were in the range of 02.08 ± 0.82 mBq/L to 3.69 ± 1.29 mBq/L for 226Ra and 6.01 ± 3.05 mBq/L to 17.07 ± 6.62 mBq/L for 228Ra. Meanwhile, the activity concentrations of 226Ra and 228Ra in fish flesh were in the range of 11.82 ± 5.23 – 16.53 ± 6.53 Bq/kg dry wt. and 43.52 ± 16.34 – 53.57 ± 19.86 Bq/kg dry wt., respectively.

Measurement of Radioactivity of <sup>238</sup>U, <sup>226</sup>Ra, <sup>232</sup>Th and <sup>40</sup>K in Soil of Different Geological Origins in Northern India

Radioactivity of the nuclides 238U, 226Ra, 232Th and 40K was measured in soil by γ-ray spectrometry using HPGe detector. A criterion was set in order to analyse soil samples from plain, semi-hilly and hilly areas in northern India. More than three γ-ray energy peaks were used for the determination of 226Ra and 232Th activity concentrations to obtain more accurate results. Some of these peaks have interfering energies, which was caused by the limited resolution of the detector, but they were resolved theoretically and used in the analysis because of their significance in reducing the random error to its minimum level. Relationships between the measured radionuclides have been discussed elaborately. Radionuclides 238U and 226Ra were found in disequilibrium with ratio of specific activities 238U/, 226Ra) less than unity for most of the samples. In some cases this disequilibrium may be significant enough to modify the γ-ray dose factors.

Development and validation of a technique for the determination of 226Ra and 228Ra by liquid scintillation in liquid samples

Radium isotopes are dispersed in the environment according to their physicochemical characteristics. Considering their long half-lives and radiological effects, (226)Ra and (228)Ra are very important issues in radiological protection. In Brazil, radium isotopes represent an exposure problem both in nuclear fuel cycle installations and in high natural radiation background areas. The experimental part of this work includes the development of a technique for the determination of (226)Ra and (228)Ra by liquid scintillation with potential application in biological samples. Radium was concentrated and then separated from other constituents of the sample by co-precipitation/precipitation with Ba(Ra)SO(4). The precipitate was filtered and weighted to calculate the chemical yield. The filter containing the precipitate of Ba(Ra)SO(4) was transferred to a scintillation vial. Two methods were used to prepare the sources. The first one consisted of the addition of water (8 ml), Instagel XF (8 ml) and UltimaGold (4 ml) in the vial containing the filter and the precipitate, forming a gel suspension. In the second method, the precipitate was dissolved with 0.2 M ethylene-diamine-tetra-acetic-acid solution (9 ml) and 11 ml of scintillation solution (Optiphase Hisafe 3) was added to the vial, forming an aqueous and an organic phase. The solutions obtained were counted in a low background scintillation spectrometry system (Quantulus) suitable for the detection and identification of both alpha and beta particles for the determination of (226)Ra and (228)Ra. The activity values of (226)Ra and (228)Ra calculated by the two methods are in good agreement with the reference values, indicating that both methods are suitable for the determination of (226)Ra and (228)Ra.

Determination of 226Ra and 228Ra in slightly mineralised natural waters

A radiochemical method for simultaneous separation of 226Ra and 228Ra from natural waters by precipitating the radionuclides in the form of chromates that have low solubility in weak acetic acid has been described. For analytical purposes the change into soluble state was achieved through high-temperature melting the radium chromates precipitate with sodium and potassium carbonates at certain ratios. The chemical yield for radium-226 amounted to 87.1 ± 1.4% at the efficiency of counting 92.8 ± 0.7%. Calculated in series of 20 parallel determinations, reproducibility of the method was 7%. The chemical yield in separating radium-228 made up 63.8 ± 1.1%.

Determination of 226Ra in urine samples by Q-ICP-MS: A method for routine analyses

Abstract The determination of 226 Ra, one of the most radiotoxic of the naturally occurring radioisotopes is very important for human health. The bladder and kidneys receive a significant dose of radiation when radioactive isotopes are excreted through the urine. Since most of the methods already developed to determine 226 Ra are time consuming, the aim of this work is to establish a time saving procedure, particularly suitable for routine analyses, to isolate 226 Ra in urine with a preliminary purification in order to measure it by Q-ICP-MS (Inductively Coupled Plasma Mass Spectroscopy). The detection limit of the method is 6.3 mBq L −1 . By using such methodology it is possible to process a large set of samples in 2–3 days.

Application of ICP-QMS for the determination of ultratrace-levels of 226Ra in geothermal water and sediment samples

A rapid, accurate and less labor intensive approach to determining 226Ra in environmental samples was examined; this utilized quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS). The procedure used chemical separation by ion exchange chromatography to remove most of the matrices after coprecipitation with BaSO4. The average chemical recovery of the NIST SRM preparation method ranged from 60.5 to 85.9% using 133Ba as internal tracer by gamma counting. This technique was capable of completing a 226Ra measurement within 3 min. It did not require an in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent 226Ra as is needed for liquid scintillation analyzer (LSA). The method detection limits for the determination of 226Ra in geothermal water and sediment samples were 0.02 mBq L−1 (0.558 fg L−1) and 0.10 Bq kg−1 (2.79 fg g−1), respectively. The results obtained with various natural samples and the suitability of the method when applied to various environmental matrices such as geothermal water and sediment are discussed. When ICP-QMS was compared to double-focusing magnetic sector field inductively coupled plasma mass spectrometry (ICP-SFMS), good agreement was obtained with a correlation coefficient, r2 = 0.982.

Inter-comparison exercise for determination of 226Ra, 232Th and 40K in soil and building material

A nationwide inter-comparison exercise for the determination of activity concentration of (226)Ra, (232)Th and (40)K in soil and building material was organized by the National Institute for Radiological Protection (NIRP), CDC, China. The primary purpose of this work was to assess the accuracy and precision of gamma-spectrometry analyses. Activity concentrations of (226)Ra, (232)Th and (40)K were determined by gamma-ray spectrometry in accordance with established inter-comparison procedures. A total of 15 laboratories participated in this programme. All participants reported their comparison results for a total of 87 data sets for three nuclides in soil and building material. The overall measurement results of samples for inter-comparison showed a good agreement with the reference values, with nearly 87% of the participants producing acceptable results. Some influential factors in measurement comparisons are also discussed in this paper on the basis of reported results.

Low level determination of 226Ra in water using a micro-precipitate track method for large-scale environmentalmonitoring

In the present paper a method has been developed for the determination of 226Ra inwater by the detection, using a solid-state nuclear track detector (SSNTD), of alpha particles from 226Ra in equilibriumwith 222Rn in micro-precipitates collected on a filter. The micro-precipitates were preparedfrom environmental water samples by collection of radium with lead asPb/RaSO4. Several factorsaffect the 226Ra precipitation on the filter and its recovery, in particular the filter pore size. Therefore in thisexperiment Whatman #42 and Millipore filters with different pore sizes were used. Using a0.45 µm Millipore filter, the recovery efficiency was increased up to 96%, and the alphaself-absorption and scattering decreased remarkably. For efficient detection of alphas from 226Ra/222Rn in equilibrium, three types of SSNTD were used—polycarbonate (PC)electrochemically etched (ECE), CR-39 and LR-115 chemically etched(CE). By preparing a standard micro-precipitate on a filter with known 226Ra/222Rn characteristics, the calibration response of each detector and its minimum detection limit(MDL) were determined.

EC comparison on the determination of 226Ra, 228Ra, 234U and 238U in water among European monitoring laboratories

In anticipation of new European requirements for monitoring radioactivity concentration in drinking water, IRMM organized an interlaboratory comparison on the determination of low levels of activity concentrations (about 10-100 mBq L(-1)) of the naturally occurring radionuclides (226)Ra, (228)Ra, (234)U and (238)U in three commercially available mineral waters. Using two or three different methods with traceability to the International System of Reference (SIR), the reference values of the water samples were determined prior to the proficiency test within combined standard uncertainties of the order of 3%-10%. An overview of radiochemical separation and measurement methods used by the 45 participating laboratories are given. The results of the participants are evaluated versus the reference values. Several of the participants' results deviate by more than a factor of two from the reference values, in particular for the radium isotopes. Such erroneous analysis results may lead to a crucial omission of remedial actions on drinking water supplies or to economic loss by an unjustified action.

226Ra and 228Ra determination in mineral waters—Comparison of methods

A comparison of different radiochemical separation procedures and measurement techniques used to determine the activity concentration of (226)Ra and (228)Ra in water is made with respect to accuracy, detection limits and turn-around time. Radium-226 activity concentration was determined by the radon emanation technique, alpha-particle and gamma-ray spectrometry. To determine the (228)Ra activity concentration, four different techniques were used: low-level liquid scintillation counting, low-level proportional counting, alpha-particle and low-level gamma-ray spectrometry.

A sequential method for the determination of 210Pb, 226Ra, and uranium and thorium radioisotopes by LSC and alpha-spectrometry

A procedure for the determination of (210)Pb, and alpha-emitting radioisotopes of uranium, thorium, and radium from the same aliquot of a sample has been proposed. The key step consisted in the recovery of Pb(II) and Ra by precipitation of insoluble Pb(NO(3))(2), the uranium and thorium radioisotopes remaining in solution. Afterwards, the fractions were handled by specific, well consolidated procedures. Lead-210 was determined by the LSC technique while the uranium, thorium, and radium radioisotopes were measured with silicon alpha-spectrometers. The procedure was applied to a reference sample and several environmental samples obtaining satisfactory results.

Determination of 3H, 226Ra, 222Rn and 238U in Austrian ground- and drinking water

Screening measurements for 3H, 226Ra, 222Rn and 238U in ground water were performed within a ground- and drinking water project in Austria. The aim of this project is to get an overview of the distribution of natural radionuclide activity concentration levels in ground water bodies. In some cases this water is used for drinking water abstraction. In this paper methods and results of the screening measurements are presented. Regions with high activity concentrations were identified and in these regions further investigation for 228Ra, 210Pb and 210Po will be conducted.

Determination of 228Ra in human bone ash containing significant quantities of 40K and Ca2+

The determination of 228Ra by means of γ-spectrometry, in material containing significant quantities of 40K and Ca2+ such as bone ash results in increased values of counting uncertainty and lower limit of detection (LLD) because of a significant contribution from the Compton continuum of 40K. However, 40K is widely removed from bone ash if 228Ra is coprecipitated with barium sulfate. As a result, the counting uncertainty and LLD are significantly reduced. A method is presented for determination of very low activity concentrations of 228Ra. Impurities introduced by precipitation are negligible when applying high resolution γ-spectrometry.

234U and 238U in mineral water: reference value and uncertainty evaluation in the frame of an interlaboratory comparison

In 2007/2008 the Institute for Reference Materials and Measurements (IRMM) organised an interlaboratory comparison (ILC) on the determination of 226Ra, 228Ra, 234U and 238U activity concentrations in mineral water. This paper describes the determination of the reference values for the activity concentrations of 234U and 238U by radiochemical separation and α-particle spectrometry performed at two independent laboratories. The experimental uncertainty of the reference values is discussed in detail.

Determination and differentiation of 226Ra and 222Rn by gamma-ray spectrometry in drinking water

The analysis of 226Ra in natural waters can be tedious and time-consuming. For the determination and differentiation of activities of 226Ra and 222Rn in drinking water by γ-ray spectrometry a simple and fast method is presented. Activities of 226Ra > 0.5 Bq L−1 can be determined according to stabilization of the sample without further procedures. For a more sensitive detection sample volumes of up to 5 litres are applicable by a rapid precipitation procedure without large expenditure. Further laborious enrichment methods are not necessary. Thus, detection limits of 0.1 Bq L−1 can be obtained when using sample volumes of 5 litres. Therefore the method is suitable for the monitoring of radioactivity in drinking water samples in accordance with the legal guidance of the European Union.