Determination of 135Cs and 135Cs/137Cs Atomic Ratio in Environmental Samples by Combining Ammonium Molybdophosphate (AMP)-Selective Cs Adsorption and Ion-Exchange Chromatographic Separation to Triple-Quadrupole Inductively Coupled Plasma–Mass Spectrometry

Identification of the origin of radiocesium released into the environment in areas remote from nuclear accident and military test sites using the 135Cs/137Cs isotopic signature

The isotopic signature of radionuclides provides a powerful tool for discriminating radioactive contamination sources and estimating their respective contributions in the environment. In this context, the ¹³⁵Cs/¹³⁷Cs ratio has been tested as a very promising isotopic ratio that had not been explored yet in many countries around the world including France. To quantify the levels of radioactivity found in the environment, a new method combining a thorough radiochemical treatment of the sample and an efficient measurement by ICP-MS/MS has been recently developed. This method was successfully applied, for the first time, to soil and sediment samples collected in France in two mountainous regions preferentially impacted either by global fallout from nuclear weapons testing (i.e., the Pyrenees) or by the Chernobyl accident (i.e., the Southern Alps). The ¹³⁵Cs/¹³⁷Cs ratios measured on twenty-one samples ranged from 0.66 ± 0.04 and 4.29 ± 0.21 (decay-corrected to January 1st, 2022) corresponding to the characteristic signatures of the fallout from Chernobyl and global fallout associated with the nuclear weapons testing, respectively. Moreover, large variations of both the ¹³⁷Cs mass activity and the studied isotopic ratio recorded by most samples from the southern Alps suggest varying proportions of these two ¹³⁷Cs sources. For these samples, the contribution of each source was estimated using this new tracer (¹³⁵Cs/¹³⁷Cs) and compared with the mixing contribution given by activity ratio: ^239+240Pu/¹³⁷Cs. This work has successfully demonstrated the applicability of the ¹³⁵Cs/¹³⁷Cs isotopic signature to nuclear forensic studies and could be extended to better evaluate the environmental impact of nuclear facilities (i.e., NPP, waste reprocessing).

Innovative ICP-MS/MS Method To Determine the 135Cs/137Cs Ratio in Low Activity Environmental Samples

The ¹³⁵Cs/¹³⁷Cs isotopic ratio is a powerful tool for tracing the origin of radioactive contamination. Since the Fukushima accident, this ratio has been measured by mass spectrometry in several highly contaminated environmental matrices mainly collected near nuclear accident exclusion zones and former nuclear test areas. However, few data were reported at ¹³⁷Cs environmental levels (<1 kBq kg^-1). This is explained by the occurrence of analytical challenges related to the very low radiocesium content at the environmental level with the large presence of mass interferences, making ¹³⁵Cs and ¹³⁷Cs measurements difficult. To overcome these difficulties, a highly selective procedure for Cs extraction/separation combined with an efficient mass spectrometry measurement must be applied on a quantity of ca. 100 g of soil. In the current research, an innovative inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) method has been developed for the ¹³⁵Cs/¹³⁷Cs ratio measurement in low activity environmental samples. The use of ICP-MS/MS led to a powerful suppression of ¹³⁵Cs and ¹³⁷Cs interferences by introducing N₂O, He, and, for the first time, NH₃, into the collision-reaction cell. By adjusting the flow rates of these gases, the best compromise between a maximum signal in Cs and an effective interference elimination was achieved allowing a high Cs sensitivity of more than 1.10⁵ cps/(ng g^-1) and low background levels at m/z 135 and 137 lower than 0.6 cps. The accuracy of the developed method was successfully verified by analyzing two certified reference materials (IAEA-330 and IAEA-375) commonly used in the literature as validation samples and three sediment samples collected in the Niida River catchment (Japan) impacted by the Fukushima fallout.

Universal N2O Reaction Gas To Remove Spectral Interferences of Nonmetallic Impurity Elements by Inductively Coupled Plasma Tandem Mass Spectrometry Analysis of High-Purity Magnesium Alloys

Using N₂O as a universal reaction gas, a new strategy was proposed for the highly sensitive interference-free simultaneous determination of nonmetallic impurity elements in high-purity magnesium (Mg) alloys by ICP-MS/MS. In the MS/MS mode, through O-atom and N-atom transfer reactions, ²⁸Si⁺ and ³¹P⁺ were converted to the oxide ions ²⁸Si¹⁶O₂⁺ and ³¹P¹⁶O⁺, respectively, while ³²S⁺ and ³⁵Cl⁺ were converted to the nitride ions ³²S¹⁴N⁺ and ¹⁴N³⁵Cl⁺, respectively. The ion pairs formed via the ²⁸Si⁺ → ²⁸Si¹⁶O₂⁺, ³¹P⁺ → ³¹P¹⁶O⁺, ³²S⁺ → ³²S¹⁴N⁺, and ³⁵Cl⁺ → ¹⁴N³⁵Cl⁺ reactions by the mass shift method could eliminate spectral interferences. Compared with the O₂ and H₂ reaction modes, the present approach delivered much higher sensitivity and lower limit of detection (LOD) of the analytes. The accuracy of the developed method was evaluated via standard addition method and comparative analysis by sector field ICP-MS (SF-ICP-MS). The study indicates that in the MS/MS mode, use of N₂O as reaction gas can provide interference-free conditions and sufficiently low LODs for analytes. The LODs of Si, P, S, and Cl could reach down to 17.2, 4.43, 10.8, and 31.9 ng L^-1, respectively, and the recoveries were in the range of 94.0-106%. The determination results of the analytes were consistent with those obtained by SF-ICP-MS. This study presents a systematic method for the precise and accurate quantification of Si, P, S, and Cl in high-purity Mg alloys by ICP-MS/MS. The developed method provides valuable reference that can be expanded and applied to other fields.

Recent Development on Determination of Low-Level 90Sr in Environmental and Biological Samples: A Review

In the context of the rapid development of the world's nuclear power industry, it is vital to establish reliable and efficient radioanalytical methods to support sound environment and food radioactivity monitoring programs and a cost-effective waste management strategy. As one of the most import fission products generated during human nuclear activities, ⁹⁰Sr has been widely determined based on different analytical techniques for routine radioactivity monitoring, emergency preparedness and radioactive waste management. Herein, we summarize and critically review analytical methods developed over the last few decades for the determination of ⁹⁰Sr in environmental and biological samples. Approaches applied in different steps of the analysis including sample preparation, chemical separation and detection are systematically discussed. The recent development of modern materials for ⁹⁰Sr concentration and advanced instruments for rapid ⁹⁰Sr measurement are also addressed.

Determination, Separation and Application of 137Cs: A Review

In the context of the rapid development of the world's nuclear power industry, it is necessary to establish background data on radionuclides of different samples from different regions, and the premise of obtaining such basic data is to have a series of good sample processing and detection methods. The radiochemical analysis methods of low-level radionuclides ¹³⁷Cs (Cesium) in environmental and biological samples are introduced and reviewed in detail. The latest research progress is reviewed from the five aspects of sample pretreatment, determination, separation, calculation, application of radioactive cesium and the future is proposed.

226Ra and 137Cs determination by inductively coupled plasma mass spectrometry: state of the art and perspectives including sample pretreatment and separation steps

Achieving precise and accurate quantification of radium (²²⁶Ra) and cesium (¹³⁷Cs) by inductively coupled plasma mass spectrometry (ICP-MS) is of particular interest in the field of radiological monitoring and more widely in environmental and biological sciences. However, the accuracy and sensitivity of the quantification depend on the analytical strategy implemented. Eliminating interferences during the sample handling step and/or during the analysis step is critical since presence of matrix elements can lead to spectral and non-spectral interferences in ICP-MS. Consequently, before the ICP-MS analysis, multiple sample preparation approaches have been applied to purify and/or pre-concentrate environmental and biological samples containing radium and cesium through years, such as (co)-precipitation, solid phase extraction (SPE) or dispersive SPE (dSPE). Separation steps using liquid chromatography and capillary electrophoresis can also be useful in complement with the abovementioned sample preparation techniques. The most attractive sample handling technique remains SPE but efficiency of the extraction procedures is currently limited by sorbent specificity. Indeed, with the recent advances in ICP-MS instrumentation, it becomes indispensable to eliminate residual interferences and improve sensitivity. It is in this direction that it will be possible to meet analytical challenges, e.g. analyzing radium and cesium at concentrations below the pg L^-1 range in complex matrices of small volumes, as they are found for instance in pore waters or in biological samples. Development of new innovative sorbents based for example on hybrid and nanostructured materials has been reported with the aim of enhancing sorbent specificity and/or capacity. In the present review, the performances of the different analytical approaches are discussed, followed by an overview of applications.

A review on the use of lichens as a biomonitoring tool for environmental radioactivity

Lichens have been widely used as a biomonitoring tool to record the distribution and concentration of airborne radioactivity and pollutants such as metals. There are limitations, however: although pollutants can be preserved in lichen tissues for long periods of time, not all radioactive and inert elements behave similarly. The chemical species of elements at the source, once captured, and the mode of storage within lichens play a role in this biomonitoring tool. Lichens are a symbiotic association of an algal or cyanobacterial partner (photobiont) with a fungal host (mycobiont). Lichens grow independently of the host substrates, including rocks, soils, trees and human-made structures. Lacking a root system, lichen nutrient or contaminant uptake is mostly through direct atmospheric inputs, mainly as wet and dry deposition. As lichens grow in a large variety of environments and are resilient in harsh climates, they are adapted to capture and retain nutrients from airborne sources. The context of this review partially relates to future deployment of small modular reactors (SMRs) and mining in remote areas of Canada. SMRs have been identified as a future source of energy (electricity and heat) for remote off-grid mines, potentially replacing diesel fuel generation facilities. For licensing purposes, SMR deployment and mine development requires capabilities to monitor background contaminants (natural radioactivity and metals) before, during and after deployment, including for decommissioning and removal. Key aspects reviewed herein include: (1) how lichens have been used in the past to monitor radioactivity; (2) radiocontaminants capture and storage in lichens; (3) longevity of radiocontaminant storage in lichen tissues; and (4) limitations of lichens use for monitoring radiocontaminants and selected metals.

N2O as a Universal Reaction Gas to Overcome Spectral Interference in Determining Metal Impurities in Mg(TFSI)2 Electrolytes for Rechargeable Magnesium Batteries by Inductively Coupled Plasma Tandem Mass Spectrometry

A new strategy for the determination of metal impurities in magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)₂) electrolytes for rechargeable magnesium batteries using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was proposed. Mg(TFSI)₂ was dissolved in 1,2-dimethoxyethane (DME), and 13 metal impurity elements were directly determined. Since N₂ has a lower O atom affinity (1.6 eV) than the O atom (5.2 eV), N₂O was a more effective O atom transfer gas than O₂. In the MS/MS mode, N₂O was selected as the reaction gas, and high sensitivities and low limits of detection (LODs) of analytes were obtained by mass shift methods. The accuracy of proposed analytical methods was assessed by the spike recovery experiments and comparative analyses using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). LODs were in the range of 0.18-26.6 ng kg^-1, the recoveries were 92.5%-107%, and the relative standard deviation (RSD) was 2.0%-5.3%. No significant difference was observed between the ICP-MS/MS and SF-ICP-MS results at a 95% confidence level. The measurement realized the rapid determination of 13 metal impurity elements in Mg(TFSI)₂ using N₂O as a reaction gas with high sensitivity, accuracy, and precision. The method was applied for the analysis of Mg(TFSI)₂ products with satisfactory results.

Strategies to overcome interferences in elemental and isotopic geochemical analysis by quadrupole inductively coupled plasma mass spectrometry: A critical evaluation of the recent developments

Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS) instruments were introduced into geochemical and mineral exploration laboratories nearly four decades ago, providing a technique that could meet their longstanding requirement for the precise and accurate determination of several groups of trace elements and isotopes in geological materials such as rocks, minerals, ores, soils, sediments, and natural water samples. Despite its popularity among geochemists, the technique suffered from spectral and non-spectral interferences some of which seriously affected the quality of the data generated. These interferences have also had a significant impact on the ability of ICP-MS systems to achieve low detection limits. Over the last three decades, technical advances such as the development of high-resolution (HR)-ICP-MS, cool plasma, collision/reaction cell technology (CCT), dynamic reaction cell (DRC) technology, collision reaction interface (CRI), kinetic energy discrimination (KED), tandem mass spectrometry (ICP-MS/MS)/triple quadrupole ICP-MS, and multi-quadrupole ICP-MS have been introduced to eliminate/minimize many of these interferences, with each technique having its strengths and limitations. These technologies have extended the range of elements that can be measured accurately not only in geological materials, but also in several other matrices, with lower detection limits than before. In addition, other methods such as internal standardization, isotope-dilution, standard addition and matrix-matching calibrations have contributed to improving the quality of the data. This paper provides a review of these new developments from the geochemical analysis point of view.

Determination of low-level 135Cs and 135Cs/137Cs atomic ratios in large volume of seawater by chemical separation coupled with triple-quadrupole inductively coupled plasma mass spectrometry measurement for its oceanographic applications

Radioisotopes of cesium are powerful tracer for oceanographic studies. In this work, a novel method was developed for determination of ultra-low level ¹³⁵Cs and ¹³⁷Cs in seawater using triple-quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). Cesium was pre-concentrated from up to 45 L seawater samples using ammonium molybdophosphate (AMP) adsorption, following a selective leaching of cesium using Sr(OH)₂. The cesium was further purified from interfering elements using AMP-PAN and cation-exchange chromatography. Sr(OH)₂ leaching was found to be an effective approach for selective exchange of cesium from the AMP sorbent without dissolution, which avoids the problem of separation of huge amount of NH₄⁺ and MoO₄^2- in the following steps. The decontamination factors for barium and rubidium with the developed method were more than 4 × 10⁷ and 800, respectively. The separated ¹³⁵Cs and ¹³⁷Cs were measured using ICP-MS/MS by employing N₂O as reaction gas to further elimination of isobaric (i.e. ¹³⁵Ba and ¹³⁷Ba) and polyatomic ions interferences. A detection limit of 1.5 × 10^-16 g L^-1 for ¹³⁵Cs in seawater was achieved. The concentrations of ¹³⁵Cs in seawater from Baltic Sea, Danish straits and Roskilde Fjord were determined using the developed method to identify the sources of ¹³⁵Cs, the water masses exchange in this region was investigated using ¹³⁵Cs and ¹³⁷Cs.

Determination of Characteristic vs Anomalous 135Cs/137Cs Isotopic Ratios in Radioactively Contaminated Environmental Samples

A contamination with the ubiquitous radioactive fission product ¹³⁷Cs cannot be assigned per se to its source. We used environmental samples with varying contamination levels from various parts of the world to establish their characteristic ¹³⁵Cs/¹³⁷Cs isotope ratios and thereby allow their distinction. The samples included biological materials from Chernobyl and Fukushima, historic ashed human lung tissue from the 1960s from Austria, and trinitite from the Trinity Test Site, USA. After chemical separation and gas reaction shifts inside a triple quadrupole ICP mass spectrometer, characteristic ¹³⁵Cs/¹³⁷Cs isotope signatures (all as per March 11, 2011) were obtained for Fukushima- (∼0.35) and Chernobyl-derived (∼0.50) contaminations, in agreement with the literature for these contamination sources. Both signatures clearly distinguish from the characteristic high ratio (1.9 ± 0.2) for nuclear-weapon-produced radiocesium found in human lung tissue. Trinitite samples exhibited an unexpected, anomalous pattern by displaying a low (<0.4) and nonuniform ¹³⁵Cs/¹³⁷Cs ratio. This exemplifies a ¹³⁷Cs-rich fractionation of the plume in a nuclear explosion, where ¹³⁷Cs is a predominant species in the fireball. The onset of ¹³⁵Cs was delayed because of the longer half-life of its parent nuclide ¹³⁵Xe, causing a spatial separation of gaseous ¹³⁵Xe from condensed ¹³⁷Cs, which is the reason for the atypical ¹³⁵Cs/¹³⁷Cs fractionation in the fallout at the test site.

Determination of 135Cs concentration and 135Cs/137Cs ratio in waste samples from nuclear decommissioning by chemical separation and ICP-MS/MS

Determination of ¹³⁵Cs concentration and ¹³⁵Cs/¹³⁷Cs atomic ratio is of great importance in characterization of radioactive waste from decommissioning of nuclear facilities. In this work, an effective analytical method was developed for simultaneously determination of ¹³⁵Cs and ¹³⁷Cs in different types of waste samples (steel, zirconium alloy, reactor coolant, ion exchange filter paper and spent ion exchange resin) by coupling AMP-PAN, AG MP-1M and AG 50 W-X8 chromatographic separation with ICP-MS/MS measurement. Decontamination factors of 7.0 × 10⁶ for Co, 6.0 × 10⁶ for Ba, 4.2 × 10⁵ for Mo, 3.2 × 10⁵ for Sn and 2.1 × 10⁵ for Sb were achieved using the chemical separation procedure. The overall chemical yields of cesium were higher than 85%. A detection limit of 3.1 × 10^-14 g/g for ¹³⁵Cs was achieved for 0.2 g stainless steel sample or spent resin. The developed method was validated by analysis of standard reference materials (IAEA-375) and successfully applied for analysis of zirconium alloy, steel, ion exchange filter paper and spent ion exchange resin from nuclear power reactors. The obtained ¹³⁵Cs can be used to evaluate the long-term environmental impact and provide useful information for waste disposal. The measured ¹³⁵Cs/¹³⁷Cs ratio in reactor coolant, as a characteristic information, might be useful for source identification and localization of leaked fuel element. The neutron flux of the leaked fuel element can be estimated based on the measured ¹³⁵Cs/¹³⁷Cs atomic ratios in the reactor coolant water. The developed method is simple and rapid (8 samples/day) for the determination of ¹³⁵Cs concentrations and ¹³⁵Cs/¹³⁷Cs ratios in various waste samples from nuclear decommissioning.

Determination of Ultralow Level 135Cs and 135Cs/137Cs Ratio in Environmental Samples by Chemical Separation and Triple Quadrupole ICP-MS

An analytical method was developed for the determination of ultralow level ¹³⁵Cs in environmental samples by chromatographic separation of cesium with AMP-PAN and AG50W-X8 columns and sensitive measurement of cesium isotopes with triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). Cesium was simply released by acid leaching using aqua regia from environmental solid samples and preconcentrated on AMP-PAN column. The cesium adsorbed on the column was effectively eluted with NH₄Cl solution without dissolving the AMP. The excessive amount of NH₄Cl in the eluate was removed by sublimation in the presence of small amount of LiCl. The remaining barium and other interfering elements such as Mo, Sn, Sb, and Li were efficiently removed using cation exchange chromatography (AG50W-X8). The decontamination factors of this procedure are above 4 × 10⁷ for barium and 4 × 10⁵ for molybdenum; the chemical yields of cesium are more than 85% for samples of less than 10 g. This method enables to separate cesium from large size of samples for the determination of ultralow level ¹³⁵Cs, avoiding the problem of removal of a huge amount of Mo in the dissolved AMP. Intrinsic ¹³⁷Cs in the environmental samples measured by gamma spectrometry before and after separation was used as internal isotope dilution standard for quantitative determination of ¹³⁵Cs without complete release and recover of radiocesium. The interference of barium (¹³⁵Ba and ¹³⁷Ba) to the ICP-MS measurement of ¹³⁵Cs and ¹³⁷Cs was further suppressed to 8 × 10^-5 by using N₂O as the reaction gas in ICP-MS/MS at a flow rate of 0.7 mL/min, so a total suppression of 2 × 10^-12 for Ba was achieved, making the isobaric interference of Ba isotopes to the measurement of ¹³⁵Cs and ¹³⁷Cs in environmental samples negligible. A detection limit of 9.1 × 10^-17 g/g for ¹³⁵Cs and ¹³⁷Cs was achieved for 60 g samples. The developed method was validated by analysis of standard reference materials (IAEA-375, IAEA-330, and IAEA-385) and successfully applied for the determination of ¹³⁵Cs concentrations and ¹³⁵Cs/¹³⁷Cs ratios in soil samples collected from Denmark, Sweden, and Ukraine. The ¹³⁵Cs/¹³⁷Cs isotopic ratios in Danish soil (2.08-2.68) were significantly higher than that from Sweden and Ukraine (0.65-0.71), indicating different sources of radiocesium. This work demonstrated the application of ¹³⁵Cs/¹³⁷Cs as a unique fingerprint for discriminating the sources of radioactive contamination and estimating their contribution to the total inventory, which will be useful for nuclear forensics and environmental tracer studies.

Determination of Ultratrace Level 135Cs and 135Cs/137Cs Ratio in Small Volume Seawater by Chemical Separation and Thermal Ionization Mass Spectrometry

The atomic ratio of ¹³⁵Cs/¹³⁷Cs is a powerful fingerprint for distinguishing the source terms of radioactive contamination and tracing the circulation of water masses in the ocean. However, the determination of the ¹³⁵Cs/¹³⁷Cs ratio is very difficult due to the ultratrace level of ¹³⁵Cs (<0.02 mBq/m³) and ¹³⁷Cs (<2 Bq/m³) in the ordinary seawater samples. In this work, a sensitive method was developed for determination of ¹³⁵Cs concentration and ¹³⁵Cs/¹³⁷Cs ratio in seawater using chemical separation combined with thermal ionization mass spectrometry (TIMS) measurement. Cesium was first preconcentrated from seawater using ammonium molybdophosphate-polyacrylonitrile column chromatography and then purified using cation exchange chromatography to remove the interferences. With this method, decontamination factors of 6.0 × 10⁶ for barium and 1800 for rubidium and a chemical yield of more than 60% for cesium were achieved. By using glucose as an activator, the ionization efficiency of cesium was significantly improved to 50.6%, and a constant high current of Cs⁺ (20 V) can be maintained for more than 180 min, which ensures sensitive and reliable measurement of low level ¹³⁵Cs and ¹³⁷Cs. Detection limits of 4.0 × 10^-17 g/L for both ¹³⁵Cs and ¹³⁷Cs for 200 mL seawater were achieved, which enables the accurate determination of ¹³⁵Cs concentration and ¹³⁵Cs/¹³⁷Cs ratio in a small volume of seawater samples (<200 mL). The developed method has been validated by analysis of seawater reference material IAEA-443. Seawater samples collected from the Greenland Sea, Baltic Sea, and Danish Straits have been successfully analyzed for ¹³⁵Cs concentrations and ¹³⁵Cs/¹³⁷Cs ratios, and the results showed that ¹³⁵Cs concentrations in the seawater of the Baltic Sea is much higher than that in the Greenland Sea, which is attributed to the high deposition of Chernobyl accident derived radiocesium in the Baltic Sea region.

Direct Quantitation of 135Cs in Spent Cs Adsorbent Used for the Decontamination of Radiocesium-Containing Water by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

The long-term safety assessment of spent Cs adsorbents produced during the decontamination of radiocesium-containing water at the Fukushima Daiichi nuclear power plant requires one to estimate their ¹³⁵Cs content prior to final disposal. ¹³⁵Cs is usually quantified by inductively coupled plasma mass spectrometry (ICP-MS), which necessitates the elution of Cs from Cs adsorbents. However, this approach suffers from the high radiation dose from ¹³⁷Cs that is present in the contaminated water and Cs adsorption irreversibility. To address these challenges, we herein employed laser ablation ICP-MS for direct quantitation of ¹³⁵Cs in Cs adsorbents and used a model Cs adsorbent prepared by immersion of a commercially available Cs adsorbent into radiocesium-containing liquid waste to verify the developed technique. Crushing and subsequent coating with a nitrocellulose-based curing agent provided a thin flat surface and thus allowed for stable solid sampling during laser ablation. The use of the ¹³⁵Cs/¹³⁷Cs ratio and ¹³⁷Cs radioactivity obtained by gamma spectrometry achieved simple and precise quantitation of ¹³⁵Cs. The obtained ¹³⁵Cs/¹³⁷Cs ratio of 0.41 ± 0.02 well agreed with that obtained for the original liquid waste sample by solution nebulization measurements, and the proposed method was concluded to be suitable for large-scale ¹³⁵Cs quantitation, requiring only very small (<10 mg) samples with total ¹³⁷Cs radioactivity.

Novel and Innovative Interface as Potential Active Layer in Chem-FET Sensor Devices for the Specific Sensing of Cs. ACS APPLIED MATERIALS & INTERFACES 2019;11:47635-47641. [PMID: 31769645 DOI: 10.1021/acsami.9b18188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

An innovative novel interface has been designed and developed to be used as a potential active layer in chemically sensitive field-effect transistor (Chem-FET) sensor devices for the specific sensing of Cs⁺. In this study, the synthesis of a specific Cs⁺ probe based on calix[4]arene benzocrown ether, its photophysical properties, and its grafting onto a single lipid monolayer (SLM) recently used as an efficient ultrathin organic dielectric in Chem-FETs are reported simultaneously. On the basis of both optical and NMR titration experiments, the probe has shown high selectivity and specificity for Cs⁺ compared to interfering cations, even if an admixture is used. Additionally, Attenuated Total Reflectance Fourier Transform Infra Red (ATR-FTIR) spectroscopy was successfully used to characterize and prove the efficient grafting of the probe onto a SLM and the formation of the innovative novel sensing layer.

Spatial pattern of plutonium and radiocaesium contamination released during the Fukushima Daiichi nuclear power plant disaster

Plutonium and radiocaesium are hazardous contaminants released by the Fukushima Daiichi nuclear power plant (FDNPP) disaster and their distribution in the environment requires careful characterisation using isotopic information. Comprehensive spatial survey of ¹³⁴Cs and ¹³⁷Cs has been conducted on a regular basis since the accident, but the dataset for ¹³⁵Cs/¹³⁷Cs atom ratios and trace isotopic analysis of Pu remains limited because of analytical challenges. We have developed a combined chemical procedure to separate Pu and Cs for isotopic analysis of environmental samples from contaminated catchments. Ultra-trace analyses reveal a FDNPP Pu signature in environmental samples, some from further afield than previously reported. For two samples, we attribute the dominant source of Pu to Reactor Unit 3. We review the mechanisms responsible for an emergent spatial pattern in ^134,135Cs/¹³⁷Cs in areas northwest (high ¹³⁴Cs/¹³⁷Cs, low ¹³⁵Cs/¹³⁷Cs) and southwest (low ¹³⁴Cs/¹³⁷Cs, high ¹³⁵Cs/¹³⁷Cs) of FDNPP. Several samples exhibit consistent ^134,135Cs/¹³⁷Cs values that are significantly different from those deposited on plant specimens collected in previous works. A complex spatial pattern of Pu and Cs isotopic signature is apparent. To confidently attribute the sources of mixed fallout material, future studies must focus on analysis of individual FDNPP-derived particles.

Simultaneous determination of radiocesium ((135)Cs, (137)Cs) and plutonium ((239)Pu, (240)Pu) isotopes in river suspended particles by ICP-MS/MS and SF-ICP-MS

Due to radioisotope releases in the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, long-term monitoring of radiocesium ((135)Cs and (137)Cs) and Pu isotopes ((239)Pu and (240)Pu) in river suspended particles is necessary to study the transport and fate of these long-lived radioisotopes in the land-ocean system. However, it is expensive and technically difficult to collect samples of suspended particles from river and ocean. Thus, simultaneous determination of multi-radionuclides remains as a challenging topic. In this study, for the first time, we report an analytical method for simultaneous determination of radiocesium and Pu isotopes in suspended particles with small sample size (1-2g). Radiocesium and Pu were sequentially pre-concentrated using ammonium molybdophosphate and ferric hydroxide co-precipitation, respectively. After the two-stage ion-exchange chromatography separation from the matrix elements, radiocesium and Pu isotopes were finally determined by ICP-MS/MS and SF-ICP-MS, respectively. The interfering elements of U ((238)U(1)H(+) and (238)U(2)H(+) for (239)Pu and (240)Pu, respectively) and Ba ((135)Ba(+) and (137)Ba(+) for (135)Cs and (137)Cs, respectively) were sufficiently removed with the decontamination factors of 1-8×10(6) and 1×10(4), respectively, with the developed method. Soil reference materials were utilized for method validation, and the obtained (135)Cs/(137)Cs and (240)Pu/(239)Pu atom ratios, and (239+240)Pu activities showed a good agreement with the certified/information values. In addition, the developed method was applied to analyze radiocesium and Pu in the suspended particles of land water samples collected from Fukushima Prefecture after the FDNPP accident. The (135)Cs/(137)Cs atom ratios (0.329-0.391) and (137)Cs activities (23.4-152Bq/g) suggested radiocesium contamination of the suspended particles mainly originated from the accident-released radioactive contaminates, while similar Pu contamination of suspended particles caused by the accident could be neglected as the (240)Pu/(239)Pu atom ratios (0.182-0.208) were within the range of global fallout.

Isotopic signature of selected lanthanides for nuclear activities profiling using cloud point extraction and ICP-MS/MS

The presence of fission products, which include numerous isotopes of lanthanides, can impact the isotopic ratios of these elements in the environment. A cloud point extraction (CPE) method was used as a preconcentration/separation strategy prior to measurement of isotopic ratios of three lanthanides (Nd, Sm, and Eu) by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). To minimise polyatomic interference, the combination of interferents removal by CPE, reaction/collision cell conditions in He and NH3 mode and tandem quadrupole configuration was investigated and provided optimal results for the determination of isotopic ratio in environmental samples. Isotopic ratios were initially measured in San Joaquin soil (NIST-2709a), an area with little contamination of nuclear origin. Finally, samples collected from three sites with known nuclear activities (Fangataufa Lagoon in French Polynesia, Chernobyl and the Ottawa River near Chalk River Laboratory) were analysed and all exhibited altered isotopic ratios for (143/145)Nd, (147/149)Sm, and (151/153)Eu. These results demonstrate the potential of CPE and ICP-MS/MS for the detection of altered isotopic ratio in environmental samples collected in area subjected to nuclear anthropogenic contamination. The detection of variations in these isotopic ratios of fission products represents the first application of CPE in nuclear forensic investigations of environmental samples.

135Cs activity and 135Cs/137Cs atom ratio in environmental samples before and after the Fukushima Daiichi Nuclear Power Plant accident

(135)Cs/(137)Cs is a potential tracer for radiocesium source identification. However, due to the challenge to measure (135)Cs, there were no (135)Cs data available for Japanese environmental samples before the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. It was only 3 years after the accident that limited (135)Cs values could be measured in heavily contaminated environmental samples. In the present study, activities of (134)Cs, (135)Cs, and (137)Cs, along with their ratios in 67 soil and plant samples heavily and lightly contaminated by the FDNPP accident were measured by combining γ spectrometry with ICP-MS/MS. The arithmetic means of the (134)Cs/(137)Cs activity ratio (1.033 ± 0.006) and (135)Cs/(137)Cs atom ratio (0.334 ± 0.005) (decay corrected to March 11, 2011), from old leaves of plants collected immediately after the FDNPP accident, were confirmed to represent the FDNPP derived radiocesium signature. Subsequently, for the first time, trace (135)Cs amounts before the FDNPP accident were deduced according to the contribution of global and FDNPP accident-derived fallout. Apart from two soil samples with a tiny global fallout contribution, contributions of global fallout radiocesium in other soil samples were observed to be 0.338%-52.6%. The obtained (135)Cs/(137)Cs database will be useful for its application as a geochemical tracer in the future.

Ultra-trace determination of (90)Sr, (137)Cs, (238)Pu, (239)Pu, and (240)Pu by triple quadruple collision/reaction cell-ICP-MS/MS: Establishing a baseline for global fallout in Qatar soil and sediments

The development of practical, fast, and reliable methods for the ultra-trace determination of anthropogenic radionuclides (90)Sr, (137)Cs, (238)Pu, (239)Pu, and (240)Pu by triple quadruple collision/reaction cell inductively coupled plasma mass spectrometry (CRC-ICP-MS/MS) were investigated in term of its accuracy and precision for producing reliable results. The radionuclides were extracted from 1 kg of the environmental soil samples by concentrated nitric and hydrochloric acids. The leachate solutions were measured directly by triple quadrupole CRC-ICP-MS/MS. For quality assurance, a chemical separation of the concerned radionuclides was conducted and then measured by single quadrupole-ICP-MS. The developed methods were next applied to measure the anthropogenic radionuclides (90)Sr, (137)Cs, (238)Pu, (239)Pu, and (240)Pu in soil samples collected throughout the State of Qatar. The average concentrations of (90)Sr, (137)Cs, (238)Pu, (239)Pu, and (240)Pu were 0.606 fg/g (3.364 Bq/kg), 0.619 fg/g (2.038 Bq/kg), 0.034 fg/g (0.0195 Bq/kg), 65.59 fg/g (0.150 Bq/kg), and 12.06 fg/g (0.103 Bq/kg), respectively.

Inductively coupled plasma - Tandem mass spectrometry (ICP-MS/MS): A powerful and universal tool for the interference-free determination of (ultra)trace elements – A tutorial review

This paper is intended as a tutorial review on the use of inductively coupled plasma - tandem mass spectrometry (ICP-MS/MS) for the interference-free quantitative determination and isotope ratio analysis of metals and metalloids in different sample types. Attention is devoted both to the instrumentation and to some specific tools and procedures available for advanced method development. Next to the more typical reaction gases, e.g., H2, O2 and NH3, also the use of promising alternative gases, such as CH3F, is covered, and the possible reaction pathways with those reactive gases are discussed. A variety of published applications relying on the use of ICP-MS/MS are described, to illustrate the added value of tandem mass spectrometry in (ultra)trace analysis.

Analysis of Japanese radionuclide monitoring data of food before and after the Fukushima nuclear accident

In an unprecedented food monitoring campaign for radionuclides, the Japanese government took action to secure food safety after the Fukushima nuclear accident (Mar. 11, 2011). In this work we analyze a part of the immense data set, in particular radiocesium contaminations in food from the first year after the accident. Activity concentrations in vegetables peaked immediately after the campaign had commenced, but they decreased quickly, so that by early summer 2011 only a few samples exceeded the regulatory limits. Later, accumulating mushrooms and dried produce led to several exceedances of the limits again. Monitoring of meat started with significant delay, especially outside Fukushima prefecture. After a buildup period, contamination levels of meat peaked by July 2011 (beef). Levels then decreased quickly, but peaked again in September 2011, which was primarily due to boar meat (a known accumulator of radiocesium). Tap water was less contaminated; any restrictions for tap water were canceled by April 1, 2011. Pre-Fukushima (137)Cs and (90)Sr levels (resulting from atmospheric nuclear explosions) in food were typically lower than 0.5 Bq/kg, whereby meat was typically higher in (137)Cs and vegetarian produce was usually higher in (90)Sr. The correlation of background radiostrontium and radiocesium indicated that the regulatory assumption after the Fukushima accident of a maximum activity of (90)Sr being 10% of the respective (137)Cs concentrations may soon be at risk, as the (90)Sr/(137)Cs ratio increases with time. This should be taken into account for the current Japanese food policy as the current regulation will soon underestimate the (90)Sr content of Japanese foods.