Determination Of 210Po Research Articles

Rapid determination of 210Po in water samples

A new rapid method for the determination of 210Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that can be used for emergency response or routine water analyses. If a radiological dispersive device event or a radiological attack associated with drinking water supplies occurs, there will be an urgent need for rapid analyses of water samples, including drinking water, ground water and other water effluents. Current analytical methods for the assay of 210Po in water samples have typically involved spontaneous auto-deposition of 210Po onto silver or other metal disks followed by counting by alpha spectrometry. The auto-deposition times range from 90 min to 24 h or more, at times with yields that may be less than desirable. If sample interferences are present, decreased yields and degraded alpha spectrums can occur due to unpredictable thickening in the deposited layer. Separation methods have focused on the use of Sr Resin™, often in combination with 210Pb analysis. A new rapid method for 210Po in water samples has been developed at the SRNL that utilizes a rapid calcium phosphate co-precipitation method, separation using DGA Resin® (N,N,N′,N′ tetraoctyldiglycolamide extractant-coated resin, Eichrom Technologies or Triskem-International), followed by rapid microprecipitation of 210Po using bismuth phosphate for counting by alpha spectrometry. This new method can be performed quickly with excellent removal of interferences, high chemical yields and very good alpha peak resolution, eliminating any potential problems with the alpha source preparation for emergency or routine samples. A rapid sequential separation method to separate 210Po and actinide isotopes was also developed. This new approach, rapid separation with DGA resin plus microprecipitation for alpha source preparation, is a significant advance in radiochemistry for the rapid determination of 210Po.

Determination of 210Po in various foodstuffs and its annual effective dose to inhabitants of Qena City, Egypt

The concentration of 210Po was determined in different foodstuffs of plant origin purchased from markets in Qena City, Upper Egypt. Measurement of 210Po has been carried out using alpha spectrometry technique in different food categories such as vegetables, fruits, cereals beverages and herbs. The general range of 210Po activity levels ranged widely from <0.010–18.6±0.910mBqg−1, with minimum being in cereal samples and maximum being in beverage samples. Tea samples recorded highest activity concentrations of 210Po with lowest value of 10±0.54 mBqg−1 for Crown tea and highest value of 18.6±0.910mBqg−1 for El maabad tea. The daily intake of 210Po from food consumption reveals that vegetables are the biggest contributors, while beverages are the lowest. The effective ingestion dose has been estimated for Qena City residents and it was found in the range 0.008–38.3μSvy−1.

Polonium ( 210Po) and lead ( 210Pb) in marine organisms and their transfer in marine food chains

The determination of 210Po and 210Pb was performed in marine organisms from the seashore to abyssal depths, encompassing a plethora of species from the microscopic plankton to the sperm whale. Concentrations of those radionuclides ranged from low values of about 5 × 10 −1 Bq kg −1 (wet wt.) in jellyfish, to very high values of about of 3 × 10 4 Bq kg −1 (wet wt.) in the gut walls of sardines, with a common pattern of 210Po > 210Pb.These radionuclides are primarily absorbed from water and concentrated by phyto- and microzooplankton, and then are transferred to the next trophic level along marine food chains. Investigation in epipelagic, mesopelagic, bathypelagic and abyssobenthic organisms revealed that 210Po is transferred in the marine food webs with transfer factors ranging from 0.1 to 0.7, and numerically similar to those of the energy transfer in the marine food chains. As 210Po preferentially binds to amino acids and proteins, its transfer in food chains likely traces protein transfer and, thus, 210Po transfer factors are similar to ecotrophic coefficients. 210Pb is transferred less efficiently in marine food chains and this contributes to increased 210Po: 210Pb activity ratios in some trophic levels.

Determination of 210Po and uranium in high salinity water samples.

A method for the determination of uranium and 210Po in high salinity water samples has been elaborated. Both radionuclides are preconcentrated from 0.5 dm3 saline media by co-precipitation with hydrated manganese dioxide, followed by dissolution of the precipitate in 200 mL of 1 M HCl. Uranium isotopes 235U and 238U can be directly determined by ICP MS method with a detection limit of 0.01 ppb for 238U. Prior to a selective determination of 210Po, the majority of other naturally occurring α-emitting radionuclides (uranium, thorium and protactinium) can be stripped from this solution by their extraction with a 50% solution of HDEHP in toluene. Finally, 210Po is simply separated by direct transfer to an extractive scintillator containing 5% of trioctylphosphine oxide in Ultima Gold F cocktail and determined by an α/β separation liquid scintillation technique with detection limit below 0.1 mBq/dm3.

Polonium (210Po), uranium (238U) and plutonium (239+240Pu) in the biggest Polish rivers

In the paper the results of determination of 210Po, 238U and 239+240Pu radionuclides in the biggest Polish rivers are presented. Our results show the Vistula and the Oder as well as three Pomeranian Rivers are important sources of these radionuclides for the southern Baltic Sea.

Determination of 210Po and 210Pb concentrations in atmospheric deposition in İzmir (Aegean sea-Turkey)

Abstract The natural radionuclide 210Pb was analysed in rainwater samples in Izmir by radiometric methods. The samples were collected continuously from January 2000 through December 2003 depending on the frequency of rain. The levels of 210Pb in the samples were found to vary between 9 ± 1 and 198 ± 6 mBq l−1 with an average value of 51 ± 0.5 mBq l−1. 210Po activity concentration in total (wet and dry) deposition has also been investigated in the study from November 2001 to April 2003 and the results were found to vary between 2 ± 0.4 and 35 ± 3 mBq l−1. The average value of 210Po activity concentration is found as 8 ± 0.5 mBq l−1. 210Po/210Pb activity ratios were derived as between 0.03 and 1.09. The annual 210Po and 210Pb fluxes were 12 and 48 Bq m−2 y−1, respectively.

Method validation in solvent extraction for 210Po determination from groundwaters

The suitability of solvent extraction for 210Po analysis from groundwater samples was assessed using three extractive scintillation cocktails, POLEX, TOPO and TNOA. Validation of the extraction method was carried out using both distilled water samples with some radionuclides added and real groundwater samples. Extraction of polonium from spiked waters was successful and no co-extraction of 234U or 238U occurred. However, the extraction results from groundwaters differed greatly from the spiked water samples. The main interfering nuclides were 234U and 238U, which led to incorrect results in 210Po analysis. Due to the co-extraction of uranium from real groundwaters, validation of the method was unfeasible.

Bioassay of 210Po in human urine and internal contamination of man

The deliberate poisoning of A. Litvinenko in London in late 2006 with 210Po, attracted attention to the difficulties in identifying internal contamination with alpha emitting radionuclides and to the limited knowledge available on the cycling of many naturally occurring radioisotopes in the body and their baseline concentration values in humans. To cope with the emergency caused by the spread of high 210Po activity, which contaminated several people and places in London, we were called upon to analyze urine samples in potentially contaminated people. A reference group of adult humans was also selected for determination of baseline 210Po values to be used for comparative purposes. Concentrations of 210Po in urine samples from three Portuguese citizens that have been at contaminated places, in London, ranged from 2.3 to 4.1 mBq·L−1 while in the reference group 210Po concentrations ranged from 0.5 to 4.8 mBq·L−1. Analytical quality of results was ensured through participation in an international inter laboratory comparison exercise on 210Po determination in aqueous samples. Results indicated that people potentially exposed to 210Po in London were not internally contaminated with the radionuclide used as a poisoning agent, and the levels of this radionuclide measured in the urine were similar to the naturally occurring levels in the reference group. Polonium levels in urine and in man are discussed in the light of 210Po levels in the human diet.

Sequential determination of 210Po and uranium radioisotopes in drinking water by alpha-particle spectrometry

Procedures for the sequential determination of low level 210Po and uranium radioisotopes in drinking water by alpha-particle spectrometry are presented. After addition of 208Po and 232U tracers, the radionuclides were preconcentrated from water samples by co-precipitation on Fe(OH) 3 or MnO 2 at pH 9 using ammonia solution. The 210Po source was prepared by spontaneous deposition onto a copper disc either before or after uranium separation. The uranium source for alpha-particle counting was prepared by micro co-precipitation with CeF 3. The procedures were tested on mineral water and the results obtained are compared.

Determination of Polonium-210 in various foodstuffs after microwave digestion

Natural radioactivity is associated with the vast mineral resources in South Africa in such concentrations that the radionuclides from the natural uranium and thorium decay series are found to pose concern for public exposure to communities living around these areas. The radiological impact of all operations is monitored as part of the license obligations, imposed by the South African National Nuclear Regulator Act [1]. Two main pathways giving rise to significant exposures are of interest: (a) direct ingestion resulting from regular and continuous use of contaminated water for drinking purposes, and (b) regular consumption of fish and other food products harvested from and/or grown in contaminated areas. To measure the individual nuclides in foodstuffs at the required sensitivity level in order to evaluate the yearly dose due to an individual source at a screening level of 25 μSv/a, one is faced with a required lower limit of determination (LLD) of 0.1 to 0.5 Bq/kg for certain foodstuffs. For some of the nuclides this LLD can only be obtained with radiochemical separation through acid destruction of dried foodstuffs followed by individual element separations. In this study the digestion of foodstuffs in an open-vessel microwave system followed by the determination of 210Po through radiochemical separation by spontaneous deposition onto silver discs and subsequent measurement by α-spectrometry, has been evaluated. The levels of 210Po in a variety of foodstuffs were determined and the estimated dose for the adult age group, resulting from consumption was evaluated. The dose from 210Po varied from 4 to 250 μSv/a for the various foodstuffs, with the largest intake from fish (about 0.5 Bq/day). The assessment of natural radionuclides in foods allowed us to evaluate the items that present the highest risk to the population, and compare this to the limits established by the National Nuclear Regulator (NNR). Not much data of this kind is available in South Africa. However, one would need more accurate consumption/intake values to calculate the actual yearly dose and the potential radiological impact on the public.

210Po determination in urines of people living in Central Italy

This paper presents the results of the monitoring programme on the urines of people living in an area of Central Italy (near the Republic of S. Marino) to evaluate the background level of the 210Po excretion rate (mBq day −1) in this region. The volunteers were subdivided in five age classes and in every age class groups of males and females, cigarette smokers and non-smokers were taken into account. The results indicated that the 210Po excretion rate was widely distributed within each group of volunteers. The 210Po excretion rate was <30 mBq day −1 for 93.2% of people. The obtained results are discussed and some conclusion, based upon the average values, was drawn.

Method validation of a procedure for determination of 210Po in water using DDTC solvent extraction and Sr resin

For the determination of 210Po in water samples, two alternative procedures (a) DDTC solvent extraction and (b) extraction chromatography using Sr Resin were selected and then validated in terms of trueness, repeatability and reproducibility with a tap water spiked with a known amount of 210Po. In this work the optimization conditions for the auto-deposition of Po for source preparation were also studied.

Quantification of measurement uncertainty in the sequential determination of 210Pb and 210Po by liquid scintillation counting and alpha-particle spectrometry

Methodologies for the quantification of measurement uncertainties associated with the determination of 210Pb- and 210Po-specific activities by liquid scintillation counting (LSC) and alpha-particle spectrometry are presented, and are demonstrated using the soil reference material IAEA-326. Major contributors to the combined uncertainty associated with the measurement result of 210Pb were the uncertainties of net count rates in the 210Pb energy region of the sample spectrum and in the 210Bi energy region of the blank spectrum. The predominant sources of uncertainty in the measurement of 210Po were the uncertainties of net count rates in the regions of interest of 209Po and 210Po. The relative standard uncertainty of 210Po exponentially increases with the time interval between the sampling date and the separation date of Po, and this effect is strongly dependent on the 210Po/210Pb activity ratio. When the specific activity of 210Pb is much higher than that of 210Po in the sample, the relative standard uncertainty of the 210Po determination increases significantly within a short time interval between the sampling date (or reference date) and the separation date of Po in samples.

Determination of 210Pb and 210Po in soil or rock samples containing refractory matrices

A new method has been developed for determination of 210Pb and 210Po in soil or rock samples containing refractory matrices. The samples were first fused with Na 2CO 3 and Na 2O 2 at 600 °C for pre-treatment and then 210Pb and 210Po were sequentially leached out at 200–250 °C with HNO 3+HF, HClO 4 and HCl. About 10% of the leaching solution was used for 210Po determination, carried out by spontaneous deposition of polonium on a silver disc from a weakly acidic solution that contained hydroxylamine hydrochloride, sodium citrate and 209Po tracer, measurement being made by α-spectrometry. The remains of the leaching solution were used for determination of 210Pb, conducted by precipitation as sulphate, purification with Na 2S as PbS in 6 M ammonium acetate, separation from α-emitters by an anion-exchange resin column, source preparation as PbSO 4, and measurement with a β-counter. The procedure has been checked with two certified IAEA reference materials, showing good agreement with the recommended values. The lower limits of detection for 1 g of analysed soil or rock samples were found to be 0.75 Bq kg −1 for 210Po and 2.2 Bq kg −1 for 210Pb. A variety of solid sample species analysed through use of the procedure gave average yields of 90.0±9.8% for 210Po and 88.4±7.1% for 210Pb.

Determination of 210Po and 210Pb in hydrometallurgical samples using liquid scintillation counting

Measurement of 210 Po by alpha-spectrometry and 210 Pb by beta-spectrometry provide accurate methods of determination at low levels of activity, however, both techniques are time consuming and provide no scope for “in-line' evaluation. The main objective of this work was to investigate the suitability of liquid scintillation counting (LSC) to provide a fast analytical procedure for the determination of these radionuclides in hydrometallurgical process samples which are typically acidic, coloured and contain many different matrix ions.

210Pb and 210Po determination in environmental samples using liquid scintillation counting and alpha spectrometry

A simple radiochemical procedure has been developed to determine 210Pb and 210Po in environmental samples from the same matrix. Sediment samples are decomposed by leaching with mineral acids or by microwave digestion, while water samples are pre-concentrated. One part of the resulting solution, spiked with 209Po, is used for 210Po determination by spontaneous deposition onto nickel disks (α-spectrometry). The other part is assayed for 210Pb, separating the Pb either by anion-exchange (sediment samples), or by solvent extraction (water samples). The 210Pb source is finally prepared by precipitation as oxalate and the chemical recovery determined by gravimetry. The 210Pb activity concentration is determined by liquid scintillation. A standard sediment sample supplied by IAEA and spiked water samples were analysed to check the procedure. The 210Pb and 210Po measurements agreed well with the certifications, deviations being less than 10%. The mean recoveries for Pb and Po were (70±12)% and (77±8%) for sediments, and (70±10)% and (81±7)% for waters, respectively.

Inhalation of 210Po and 210Pb from cigarette smoking in Poland

The carcinogenic effect of 210Po and 210Pb with respect to lung cancer is an important problem in many countries with very high cigarette consumption. Poland has one of the highest consumptions of cigarettes in the world. The results of 210Po determination on the 14 most frequently smoked brands of cigarettes which constitute over 70% of the total cigarette consumption in Poland are presented and discussed. Moreover, the polonium content in cigarette smoke was estimated on the basis of its activity in fresh tobaccos, ash, fresh filters and post-smoking filters. The annual effective doses were calculated on the basis of 210Po and 210Pb inhalation with the cigarette smoke. The results of this work indicate that Polish smokers who smoke one pack (20 cigarettes) per day inhale from 20 to 215 mBq of 210Po and 210Pb each. The mean values of the annual effective dose for smokers were estimated to be 35 and 70 μSv from 210Po and 210Pb, respectively. For persons who smoke two packs of cigarettes with higher radionuclide concentrations, the effective dose is much higher (471 μSv yr −1) in comparison with the intake in diet. Therefore, cigarettes and the absorption through the respiratory system are the main sources and the principal pathway of 210Po and 210Pb intake of smokers in Poland.

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Sequential separation of 210Pb and 210Po in environmental samples allows the determination of these naturally occurring radionuclides with good chemical yields and low detection limits. After sample mineralization, part of the leaching solution is used for 210Po determination which does not require any further treatment and essentially quantitative recoveries are obtained, using a standard 209Po tracer. The remaining part of the leaching solution is used for 210Pb determination. Starting from 3 g sediment (30 l water), the lower limits of detection of the method are 1.4 Bq kg−1 (0.14 mBq 1−1) for 210Pb and 0.25 Bq kg−1 (0.016 mBq 1−1) for 210Po. The procedure has been checked by analysing two certified reference materials, supplied by IAEA, and reliable results have been obtained.

Determination of 210Po in Reagent Samples by Alpha-Ray Spectrometry Using Extraction Chromatographic Resin

The determination of 210Po in phosphoric acid reagent by alpha-ray spectrometry using extraction chromatographic resin is presented. The decontamination factors of interference elements were measured. It was observed that HCl, HNO3, ascorbic acid, thioacetamide and Cu were free from 210Po but Pb contain small amounts of 210Po. 210Po in phosphoric acid samples was ranged from <8 to 2.4 Bq/l. The detection limit of 210Po in 50 ml of phosphoric acid is 8 mBq/l with a counting time of 1 day undercounting efficiency of 30%.

Improvements on lead-210 and polonium-210 determination in environmental materials

Improvements in analytical methodology for the determination of210Pb and210Po in environmental materials have been the subject of continuing study. Early work showed that the most time-consuming part of the analysis was the wet ashing stage. Investigations have now been carried out to improve this part of the analytical scheme. This paper describes a modified method that has been developed and tested and which has been in routine use for about one year. The time required for the analysis has been reduced and the spectral quality of the sources has been improved. Test samples gave chemical recoveries that were higher, but this improvement has not yet been observed in operational work. Some analytical schemes in which210Pb and210Po are to be determined in the same sample require the addition of stable lead carrier. In some cases, this can lead to the addition of significant quantities of210Po. The results of an investigation of the210Po content of various lead carriers are described and the implications of their use on the determination of210Po in environmental materials are discussed.