Yield Tracer Research Articles

Simultaneous determination of femtogram levels of 237Np, 239Pu, and 240Pu in environmental solid samples using extraction chromatography and ICP-MS/MS

An analytical method based on triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) was developed for simultaneous determination of femtogram levels of 237Np, 239Pu, and 240Pu in environmental samples. By carefully controlling the valence states of Np and Pu in the entire separation procedure using a simple single extraction chromatographic column (TK200), the consistent behavior of Np and Pu was achieved, allowing for the reliable application of 242Pu as the chemical yield tracer for 237Np, 239Pu, and 240Pu. A high decontamination factor of 3.2 × 107 for the most critical interfering element, uranium, was achieved in the chemical separation step. The interferences of 238U1H+ and peak tailing of 238U+ during the measurement of plutonium isotopes were effectively eliminated by utilizing 7.5 mL/min He–1.1 mL/min CO2 as reaction gases in the octupole collision/reaction cell and employing sequential quadrupole mode for mass separation in ICP-MS/MS. Specifically, the interference of 238U1H+ was reduced to 10−6 and the peak tailing of 238U+ to 10−10, surpassing the performance of measurement method without reaction gases by 3 orders of magnitude. The developed method enables the accurate determination of femtogram levels of 237Np, 239Pu, and 240Pu in the samples with U/Np and U/Pu atom ratios of up to 1017 and 1012, respectively. The developed method was validated by analyzing standard reference materials and spiked soil samples.

Rapid determination of 99Tc in water samples using Ti(OH)3-TcO2 co-precipitation and TK200 resin by liquid scintillation counting

A novel method for the determination of 99Tc in water samples was developed using stable Re as a chemical yield tracer and TiCl3 as a reducing agent. The influences of several experimental parameters, including TiCl3 concentration, HCl concentration and reaction time, on the reduction of TcO4− and ReO4− as well as Ti(OH)3-TcO2-ReO2 co-precipitation were investigated. Tc(VII) and Re(VII) retained on TK200 resin were effectively eluted by 5 mL of 1 mol/L NH4SCN, which can be directly mixed with the scintillation cocktail for liquid scintillation counting. The results show that the chemical behaviors of Tc and Re are very consistent in the whole procedure. The decontamination factors of potential interferences from β-emitting nuclides mainly released from nuclear fuel reprocessing plants were also evaluated, and the minimum detectable activity concentration was calculated to be 0.08 Bq/L for 99Tc in water samples with a counting time of 2 h.

Investigation of self-attenuation of 210Pb (46 keV) gamma ray in sediment, certified reference material and high-density minerals: Implication to precise measurement of 210Pb

High resolution gamma spectrometry is one of the most widely used techniques in the measurements of environmental level 210Pb in sediment from coastal and freshwater environments and such measurements are needed to establish 210Pb chronology for the past 100–150 years. Precise measurement of 210Pb in sediment and soil requires appropriate self-absorption correction for its low-energy (46.5 keV) gamma radiation due to differences in the matrix between the sample and standard used to calibrate the instrument. Here we report a method that involves precise determination of 210Pb activity in sediment sample by calibrating the HPGe well detector with RGU-1-IAEA Certified Reference Material for well-defined geometries. A comparison of the 210Pb activity obtained from gamma-ray spectrometry with that obtained from alpha spectrometry via 210Po, using 209Po as yield tracer, indicates good agreement. We propose an empirical relation between the absolute efficiencies and packing densities of sample in a well-defined geometry (cylindrical counting vial) by affecting the count rate of 210Pb and its progenitor, 226Ra (via 214Pb and 214Bi). The effects of self-attenuation of 46.5 keV (210Pb), for naturally-occurring high-density minerals (apatite, titanite, monazite, and cerite) are evaluated. Specific activity of 210Pb on apatite measured by alpha and gamma spectrometry are compared. This study is relevant and useful for precise measurements of gamma-emitting environmental radionuclides such as 210Pb, 7Be, 137Cs as well as 226Ra.

Solid-phase extraction of 225Ac using ion-imprinted resin and 243Am as a radioactive tracer for internal dosimetry and incorporation measurements

Actinium-225 is a highly radiotoxic alpha-emitting radionuclide, which is currently in the spotlight owing to its promising radiotherapeutic applications in nuclear medicine. Personnel involved in the production and handling of actinium-225 is exposed to a risk of accidental incorporation of this radionuclide. Radiological protection regulations require regular monitoring of incorporation and internal dosimetry assessment for workers manipulating open radioactive sources. Urine is often used as a biological sample for measuring the incorporation of actinides, however it requires a radiochemical separation with a certified metrological tracer to enable quantitative determination. There is no stable, nor sufficiently long-lived radioactive isotopes of actinium to provide a metrological yield tracer. In this article, we propose an application of an ion-imprinted polymer resin to extract actinium-225 from urine employing americium-243 as a radioactive tracer. The radiochemical separation was followed by a quantitative determination with alpha-spectrometry. Solid-phase extraction of both actinides from urine using ion-imprinted polymer resin resulted in good radiochemical yields: 57.7 ± 16.5% (n = 17) for actinium-225 and 62.8 ± 18.0% (n = 17) for americium-243. Equivalent recoveries showed that americium-243 is a suitable yield tracer for the determination of actinium-225 with an ion-imprinted polymer resin. Combined with a different measurement technique, this method can be applied for the separation of other isotopes of actinium, such as actinium-227.

Rapid analysis of 237Np and Pu isotopes in small volume urine by SF-ICP-MS and ICP-MS/MS

Internal contamination with alpha-particle emitting actinides, such as 237Np, 239Pu, 240Pu, is likely to bring a large amount of dose to the tissues of persons even if the intake amount is small. To provide timely information for prompt decision-making in radiation emergency therapy, we developed a simple and rapid method for urinary bioassay to determine ultra-trace 237Np and Pu isotopes using SF-ICP-MS and ICP-MS/MS. To avoid polyatomic interferences and tailing effects from U, 237Np and Pu isotopes were collected after removing U effectively using a simple single chromatographic column packed with 2 mL AG MP-1M anion exchange resin, exhibiting a high decontamination factor of 108 for 238U. The overall chemical fractionation between 237Np and 242Pu for the whole analytical procedure was 0.974 ± 0.064 (k = 2), allowing us to measure 237Np and Pu isotopes using 242Pu as a yield tracer with yields of 76 ± 5%. Using ICP-MS/MS with low background provided the method detection limits for 237Np, 239Pu, 240Pu, and 241Pu of 0.025, 0.025, 0.015, and 0.020 fg mL−1, respectively, for 20 mL of urine sample. Those were comparable to detection limits of SF-ICP-MS with high sensitivity. Subsequently, three urine reference materials with Pu spike, provided by the Association for the PROmotion of Quality COntrol in RADiotoxicological Analysis (PROCORAD), France, were analyzed by the developed method and the conventional alpha spectrometry technique for validation. Finally, the developed method was successfully employed to measure the contamination level of 237Np, 239Pu, 240Pu, and 241Pu in urine samples collected during decorporation therapy using DTPA, after a Pu inhalation exposure accident in Japan. The high throughput (9 h for 12 samples), simplicity, low cost, and high sensitivity of the method will allow greater numbers of related laboratories to be involved in screening activities for unexpected actinide exposure, such as in the case of a large scale radiological disaster.

Rapid and efficient autoclave digestion for the extraction of iodine-129 from urine samples

A new method was developed to extract 129I from urine samples and measure it using accelerator mass spectrometry (AMS). The samples were pre-treated in an autoclave with hydrogen peroxide and were then acidified with nitric acid, followed by the precipitation of iodine as silver iodide (AgI) for measurement by AMS. This new procedure is substantially faster than previous methods for the extraction of iodine from urine and results in less chemical waste. The efficiency and reproducibility of this method were evaluated by using 125I as a yield tracer, eventually giving a recovery above 99%. To achieve this, several iterations of the method were required. The method was then successfully applied to measure 129I/127I isotopic ratios and 129I concentrations in 25 human urine samples. The AMS results for 129I in urine ranged 3.3 × 106 atoms/L to 884 × 106 atoms/L and the isotope ratio (129I/127I) in human urine ranged from 7.38 × 10−12 to 3.97 × 10−10 with a median of 1.29 × 10−10. This new method will be useful for investigations into the sources of iodine in the human diet and their relative importance for iodine sufficiency.

Simple and sensitive determination of radium-226 in river water by single column-chromatographic separation coupled to SF-ICP-MS analysis in medium resolution mode

This article describes a novel and simple method to measure ultra-trace 226Ra in river water samples at fg L−1 (mBq L−1) levels as a means for surveying 226Ra in an unintended contamination in river water. To simplify the procedure, a single column was used for separation and purification; 10 mL of AG 50W-X8 resin was packed into a 10 mL Eppendorf pipette tip, which was used as a separation column. A 500 mL sample solution was loaded, and interfering elements were removed with 80 mL 4 M HCl in 20% ethanol. Subsequently, Ra together with Ba was eluted by 20 mL 5 M HNO3 prior to SF-ICP-MS analysis; this allows the naturally existing Ba in water samples to be employed as a yield tracer for 226Ra analysis. Using the medium mode of SF-ICP-MS, the instrumental detection limit of 380 fg L−1 (10 mBq L−1) was obtained. An extremely low method detection limit of 0.46 fg L−1 (0.02 mBq L−1) was achieved with 500-fold pre-concentration. Finally, the developed technique was applied to analyze natural water samples collected from Japanese rivers, in which the 226Ra concentrations varied in the range of 0.7–49.6 fg L−1 (0.03–1.82 mBq L−1).

Analysis of 210Po, 210Bi, and 210Pb in atmospheric and oceanic samples by simultaneously auto-plating 210Po and 210Bi onto a nickel disc

210Po and 210Pb are commonly measured to study particle cycling and particulate organic carbon export (POC) flux from the upper ocean. 210Bi is a potential oceanographic tracer. However, no convenient and rapid analytical method for 210Bi has been developed in the marine environment due to its short half-life (5 days). The aims are to study factors influencing the simultaneous auto-plating of 210Po and 210Bi onto nickel disc and to develop an effective ship-board procedure for the rapid measurement of 210Po, 210Bi, and 210 Pb at sea. The results suggest that the optimal conditions for auto-deposition of 210Po and 210Bi were achieved by using a 25 mm diameter nickel disc in 60 mL acidic solution (pH = 0.5) for 16 h at 25 ± 1 °C. By adding 209Po and 207Bi as yield tracers to the sediments, recoveries of Po and Bi were >90%. If 210Po or 210Bi were in equilibrium with 210Pb, 210Po and 210Bi could also be potential proxies for 210Pb in sedimentary chronology. The overall recoveries of 209Po and 207Bi were >70% for rainwaters and >60% for seawater samples, respectively, which indicates this analytical procedure is also applicable to marine and atmospheric environments. This method allows the rapid measurement of 210Bi on a ship and help to obtain its vertical profile or spatial distribution in the marine environment within 1–2 days.

A novel chronometry technique for dating irradiated uranium fuels using Cm isotopic ratios

A novel chronometry method is developed to date irradiated nuclear fuels. It is based on the measurement of two Cm isotopic ratios (244Cm/246Cm and 245Cm/246Cm) and does not require the addition of a yield tracer. The method relies on the decay of 244Cm while the 245Cm/246Cm ratio is considered constant after irradiation. Feasibility is demonstrated using different types of irradiated fuels with known irradiation history. A precision of 5 year is reached so far but clear potential for improvement has been identified. The novel chronometry method represents a promising alternative to existing dating techniques for nuclear materials.

Adaptation of an Analytical Procedure for Concurrent Determination of Np and Pu in clay samples

AbstractNp and Pu are two important actinides of concern for the safe long-term disposal of nuclear waste. Both actinides are, in addition, constituents of global nuclear fallout. Investigation of their environmental behavior requires ultra-sensitive analytical methods, but current methods for a concurrent determination in clay minerals are lacking. In the present study, a Pu isotope was investigated for use as a non-isotopic yield tracer for Np in extraction, purification, and mass spectrometric determination of Np and Pu isotopes in clay materials. Inductively coupled plasma mass spectrometry was used in this developmental study, but the method is intended for future ultra-trace analysis of global-fallout Np and Pu in clay-rich soil materials by the more sensitive accelerator mass spectrometry. Another field of application may be the investigation of diffusion patterns of actinides in compacted clay liners and potential host rocks for radioactive waste disposal. The analytical procedure includes the following steps: (1) extraction of Np and Pu from clay samples; (2) adjustment of Np and Pu to Np(IV) and Pu(III); (3) pre-concentration of Np and Pu by co-precipitation with iron hydroxide; (4) adjustment of Pu to Pu(IV); (5) extraction chromatographic separation of Pu and Np from iron and matrix elements; and (6) determination of Np and Pu by mass spectrometry. The analytical procedure was applied successfully to spiked montmorillonite and illite test portions of up to 1 g. High chemical yields near 90% were obtained for both Np and Pu. The suitability of Pu as a non-isotopic tracer for Np was indicated by Np/Pu chemical yield ratios close to unity. Accurate pH adjustment during the reductive co-precipitation and short processing times are vital to obtain high chemical yields and Np/Pu yield ratios close to unity.

Simultaneous determination of ultra-trace level 237Np and Pu isotopes in soil and sediment samples by SF-ICP-MS with a single column chromatographic separation

This work presents a method developed for simultaneous analysis of ultra-trace level 237Np and Pu isotopes in soil and sediment samples by sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). 242Pu was used as a yield tracer for 237Np as well as for Pu isotopes. A simple single chromatographic column packed with anion exchange resin (AG MP-1M) was used for the separation of 237Np and Pu isotopes from the matrix elements and other potential interferences. The SF-ICP-MS measurement precision of the 237Np/242Pu atom ratio for sub-fg/mL level 237Np and 242Pu was 0.97%, and the overall fractionation between 237Np and 242Pu for the whole analysis procedure was 1.010 ± 0.038. Besides, the single column chromatographic separation realized high decontamination factor of U (1.8 × 106 to 1.7 × 107), and that ensured the interference effect of 238U to the 237Np, 239Pu and 240Pu measurements was negligible or could be easily corrected. Four standard reference materials were analyzed for method validation, and the results illustrated 242Pu was an effective non-isotopic tracer for 237Np determination. Finally, the developed method was successfully employed in the analysis of the global fallout level of 237Np and Pu isotopes in Japanese paddy soil samples to study their environmental behaviors.

An improved method for radium-isotopes quartet determination by alpha-particle spectrometry by using 225Ra (229Th) as isotopic tracer

A new method for the determination of radium quartet (223,224,226,228Ra) in environmental samples by alpha-particle spectrometry with PIPS detectors is described. This uses 225Ra as yield tracer, in equilibrium at the beginning with 229Th. Thorium is removed from the sample by using AG1X8 anion-resin, and then radium isotopes are isolated and purified with a cation-exchange column Biorad AG50X8, verifying that Ac has been fully removed from the sample to ensure the good evaluation of the Ra yield (average decontamination factor > 92%). Finally, the counting source of radium is obtained by micro-precipitation with BaSO4. This method produces high spectral resolution (<35 keV), and quantitative Ra recoveries (>70%). In this new method, NH4Ac in 0.1 M HNO3 is used to remove the 225Ac contained in the sample in order to avoid its future spectral interference in the yield calculation. The method has been validated by using certified reference samples with known concentrations of radium isotopes.

Migration path and isotope tracing of 137Cs and 239 + 240Pu in estuary sediments: a case study of Liao River estuary in China

Currently, the distribution characteristics and transport processes of the radionuclides 137Cs and 239 + 240Pu in the sediments of estuaries are still a controversial issue. Thus, in the present study, we investigated the distribution characteristics, sources and migration path of 137Cs and 239 + 240Pu in sediment cores of the Liao River estuary (LRE), China, and evaluated the relative contributions of the Pacific Proving Grounds (PPG) and riverine sources of Pu for the sediments in this area. We used 137Cs and Pu isotopes for dating the sediments and estimated the sedimentation rates by the two radionuclides in the LRE. Seven sediment samples were collected using a box corer from the Liao River estuarine wetland and tidal flat in the LRE in October 2012 and April 2015, respectively. The activities of 137Cs in the various samples were determined by γ spectrometry using HP-Ge detectors with 60% relative counting efficiency. Approximately 2–5 g of sediment were spiked with 242Pu (ca. 1 mBq) as a chemical yield tracer for Pu isotopic analysis at the School of Radiation Medicine and Protection, Soochow University. The measurement of Pu isotopes (239Pu, 240Pu, 242Pu) was performed by a sector field ICP-MS. In order to quantitatively differentiate the relative proportions of global fallout and PPG, we employed a two-end member mixing model to estimate their contributions. The average values of 137Cs, 239 + 240Pu activity concentrations, and 240Pu/239Pu atom ratios in the surface sediment samples of the LRE were 6.727 ± 0.251 mBq g−1, 0.294 ± 0.024 mBq g−1, and 0.188 ± 0.049 (1σ), respectively. The average 240Pu/239Pu atom ratios ranged from 0.180 ± 0.034 to 0.199 ± 0.021 in sediment cores from the east and west sides of the LRE. For core LT-2 values for 137Cs and 239 + 240Pu concentrations were from below the detection limit: 3.380 ± 0.414 and 0.036 ± 0.007 to 0.105 ± 0.007 mBq g−1. The mean 240Pu/239Pu atom ratio 0.217 ± 0.050 (1σ) in sediment core LT-2 lies between the global fallout and PPG close-in fallout. We found that atmospheric fallout is the main source of Pu in sediment cores from the east and west sides of the LRE. For core LT-2, atmospheric fallout and riverine input (~ 73.4%) are the major sources of Pu with the source of the rest of Pu (~ 26.6%) attributed to the PPG via the Tsushima Warm Current and the coastal water of the East China Sea. The sedimentation rates (means 0.62–0.8 cm year−1) estimated by the two radionuclides were in good agreement and without any statistically significant difference.

Rapid method to determine 226Ra in steel samples

The rapid measurement of 226Ra in steel samples is very important in the event of a radiological emergency. 226Ra (T 1/2 = 1600 y) is a natural radionuclide present in the environment and a highly toxic alpha-emitter. Due to its long life and tendency to concentrate in bones, 226Ra ingestion or inhalation can lead to significant committed dose to individuals. A new method for the determination of 226Ra in steel samples has been developed at the Savannah River Environmental Laboratory. The new method employs a rugged acid digestion method that includes hydrofluoric acid, followed by a single precipitation step to rapidly preconcentrate the radium and remove most of the dissolved steel sample matrix. Radium is then separated using a combination of cation exchange and extraction chromatography, and 226Ra is measured by alpha spectrometry. This approach has a sample preparation time of ~ 8 h for steel samples, has a very high tracer yield (> 88%), and removes interferences effectively. A 133Ba yield tracer is used so that samples can be counted immediately following the separation method, avoiding lengthy ingrowth times that are required in other methods.

237Np analytical method using 239Np tracers and application to a contaminated nuclear disposal facility

Environmental 237Np analyses are challenged by low 237Np concentrations and lack of an available yield tracer; we report a rapid, inexpensive 237Np analytical approach employing the short lived 239Np (t1/2 = 2.3 days) as a chemical yield tracer followed by 237Np quantification using inductively coupled plasma-mass spectrometry. 239Np tracer is obtained via separation from a 243Am stock solution and standardized using gamma spectrometry immediately prior to sample processing. Rapid digestions using a commercial, 900 W “Walmart” microwave and Parr microwave vessels result in 99.8 ± 0.1% digestion yields, while chromatographic separations enable Np/U separation factors on the order of 106 and total Np yields of 95 ± 4% (2σ). Application of this method to legacy soil samples surrounding a radioactive disposal facility (the Subsurface Disposal Area at Idaho National Laboratory) reveal the presence of low level 237Np contamination within 600 m of this site, with maximum 237Np concentrations on the order of 103 times greater than nuclear weapons testing fallout levels.

A sequential determination of 90Sr and 210Po in food samples.

The latest EU Council Regulation 2016/52/Euratom updates the emergency limits on radionuclides in foods including 210Po and 90Sr, two of the most important radionuclides for radiological dose from the ingestion pathway. A novel and straightforward method has been developed for sequential determination of 90Sr and 210Po in food samples using ultra low-level liquid scintillation counting and alpha-particle spectrometry. For 90Sr analysis, the method makes use of stable strontium as yield tracer, and 210Po is determined through self-deposition using 209Po as a yield tracer. The quantification limit for this method is 25.0 and 2.0Bqkg-1 for 90Sr and 210Po, respectively. The proposed radiochemical separation can be completed within 2days for a batch of 12 samples. The radiochemical procedure was validated by its application for the measurement of IAEA certified reference materials, and through participation in a national intercomparison exercise. Results are also presented in seafood from the Mediterranean coast.

Quantitation of lead-210 (210Pb) using lead-203 (203Pb) as a “Massless” yield tracer

Determination of Pb-210 (210Pb) in aqueous solution is a common radioanalytical challenge in environmental science. Widely used methods for undertaking these analyses (e.g., ASTM D7535) rely on the use of stable lead (Pb) as a yield tracer that takes into account losses of 210Pb that inevitably occur during elemental/radiochemical separations of the procedures. Although effective, these methods introduce technical challenges that can be difficult to track and potentially introduce uncertainty that can be difficult to quantify. Examples of these challenges include interference from endogenous stable Pb in complex sample matrices; contamination of stable Pb carrier with 210Pb; and high detection limits due to counting efficiency limitations. We hypothesized that many of these challenges could be avoided by the use of the electron-capture, gamma-emitting isotope, 203Pb as a chemical yield tracer in the analysis of 210Pb.A series of experiments were performed to evaluate the efficacy of 203Pb as a tracer. Four different matrices were analyzed, including a complex matrix (hydraulic-fracturing produced fluids); and samples comprising less complicated matrices (i.e., river water, deionized water, and tap water). Separation techniques and counting methodologies were also compared and optimized. Due to a relatively short-half life (52 h), 203Pb tracer is effectively massless for the purposes of chemical separations, allowing for reduced chromatography column resin bed volumes. Because 203Pb is a gamma emitter (279 keV; 81% intensity), recovery can be determined non-destructively in a variety of matrices, including liquid scintillation cocktail. The use of liquid scintillation as a counting methodology allowed for determination of 210Pb activities via 210Pb or 210Po; and recoveries of greater than 90% are routinely achievable using this approach. The improved method for the analysis of 210Pb in aqueous matrices allows for the analysis of complex matrices, at reduced cost, while providing greater counting flexibility in achieving acceptable detections limits.

Annual Effective Dose of &lt;sup&gt;210&lt;/sup&gt;Po from Sea Food Origin (Oysters and Mussels) in Korea

Background: Ingestion of 210Po laden seafood accounts for a substantial amount of the effective dose of 210Po. Among seafood items, mollusks, especially domestically produced oysters and mussels, are highly enriched in 210Po and are consumed in large quantities in Korea. Materials and Methods: Oysters and mussels around the Korean coasts were collected from major farm areas in November 2013. Samples were spiked with an aliquot of 209Po as a yield tracer, and they were digested with 6 mol·L-1 HNO3 and H2O2. The 210Po and 209Po were spontaneously deposited onto a silver disc in an acidic solution of 0.5 mol·L-1 HCl and measured using an alpha spectrometer. The activity concentrations of 210Pb and 210Po were decay corrected to the sampling date, accounting for the possible in-growth and decay of 210Po. Results and Discussion: 210Po activity concentrations in oysters were in a range from 41.3 to 206 Bq·(kg-ww)-1 and mussels in a range from 42.9 to 46.7 Bq·(kg-ww)-1. The 210Po activity concentration of oysters in the turbid Western coast was higher than the Southern coast. The 210Po activity concentration of the oysters was positively correlated (R2 = 0.89) with those of the suspended particulate matter in the surface water. The calculated annual effective dose of 210Po from oysters and mussels consumed by the Korean population was 21-104 and 5.01-5.46 μSv·y-1. The combined effective dose due to the consumption of oysters and mussels appears to account for about 35 ± 19% of that arising from seafood consumption in the Korean population. Conclusion: The annual effective dose of 210Po for oysters in the Korean population was found to be higher than other countries. The total annual effective dose of 210Po due to consumption of oysters and mussels consumed in Korea was found to be 76 ± 42 μSv ·y-1 , accounting for 28 ± 16% of the total effective dose of 210Po from food in Korea.

Rapid determination of 210Pb and 210Po in water and application to marine samples

Measurement of radionuclides in marine samples, specifically radioactive pairs disequilibrium, has gained interest lately due to their ability to trace cutting edge biogeochemical processes. In this context, we developed a fast, direct method for determining 210Pb and 210Po water through the use of ultra low-level liquid scintillation counting and alpha-particle spectrometry respectively and through Eichrom Sr resins for the Po-Pb separation. For 210Pb analysis, the method uses stable lead as a yield tracer measured by a robust ICP-MS technique, and 210Po is determined through self-deposition using the conventional 209Po yield tracer. The improvements of the method over other techniques are: a) the analysis can be completed within 6 days, simplifying other methods, b) very low limits of detection have been achieved −0.12 and 0.005mBqL−1 for 210Pb and 210Po, respectively – and c) most of the method could be carried out in on-board analysis. We applied the method to different aqueous samples and specifically to marine samples. We determined 210Pb and 210Po in the dissolved fraction of Mediterranean Sea water and an estuary at the South-West of Spain. We found that it can be successfully employed to marine samples but we recommend to i) use a minimum of 20L water to measure the 210Pb in the dissolved phase by LSC and lower volumes to measure total concentrations; ii) wait for 210Pb and 210Bi in secular equilibrium and measure the total spectrum to minimise the limit of detection and improve accuracy.

Determination of 226Ra in drinking water samples by alpha spectrometry

A method for the determination of 226Ra in drinking water samples by alpha spectrometry is described. The method uses 225Ra as yield tracer. Radium was purified using Ln Resin® and cation exchange resin, and electrodeposited onto a stainless steel disc from a solution of ammonium oxalate in nitric acid. This method produced high spectral resolutions and high recovery yields of 226Ra. Furthermore, the method allowed significant reduction in time required for the determination of 226Ra in drinking water samples, around 3 days, in comparison with other methods, which can reach 20 or 38 days to quantify this radionuclide.