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International audience; The demand for large and reliable datasets on isotopic composition has increased ingeochemistry and environmental sciences over recent years. We present an automated ionchromatographic separation method using a robotic pipetting arm, termed “ChemCobOne”, toreduce the time of sample separation. Its performance was tested for lithium isotope separationin geological reference materials using a single-step separation with HCl (0.2 mol l-1) and a 2-mlresin volume. This refined lithium purification method does not forfeit precision, accuracy orpurity compared with manual sample processing. In addition, a 7Li value for NASS-6 of 30.99 ±0.50‰ (2s) (95%CI = 0.14‰, n = 44) was determined and the first 7Li values for the granite rock

For the first time, Diffusive Gradient in Thin-films (DGT) focuses on the inorganic iodine species iodate (IO3) and iodide (I). A silver-doped Cl resin (AgdCl), which is known to selectively accumulate I, was used to make a binding gel. Laboratory investigations were designed to verify the suitability of the AgdClDGT method to measure the total I concentration in environmental waters. Total recovery of I was obtained using an elution solution containing 100 mmol L1 KCN. DGT validation experiments in 10 mmol L1 NaCl showed linear accumulation of I over time, contrary to IO3, thus confirming the selectivity of AgdCl-binding gel. The AgdCl-DGT measurement of total I concentration was independent of pH (4.5e8.8) and was not impacted by the presence of bicarbonate (1e5 mmol L1). Finally, the performance of AgdCl-DGT samplers were tested in two continental waters and a synthetic seawater. The AgdCl-DGT samplers measured 27e33% of the total I concentration in the two continental waters up to 24 h of deployment time, whereas the AgdCl-DGT response retrieved the total I concentration in seawater up to 72 h (106 ± 7%). The difference in DGT response was attributed to the low ionic strength of the two continental waters, limiting the application of AgdCl-DGT method to media with higher ionic strength This work has been supported by the ANR (French National Research Agency), under the “Investissement d’Avenir” framework program [Number ANR-11-RSNR-0002]. Veronique Hénin (Met-rohm France) is gratefully thanked for the loan of the Metrosep Asupp 10 guard and analytical columns, and also Gilles Alcalde for the granulometric measurements of AgdCl-resin beads. All experiments were performed at LUTECE (the SEDRE's experimental platform), and elemental and speciation measurements at PATERSON (the IRSN's mass spectrometry platform). This is PATERSON contribution nº 9. Support from the Spanish Ministry of Science and Innovation is gratefully acknowledged (Project PID2019-107033 GB-C21)

International audience; Determination of uranium isotope ratios is of great expedience for assessing its origin in environmental samples. In particular, the isotope ratio 236U/238U provides a powerful tool to discriminate between the different sources of uranium (uranium ore, typical ambient uranium, or anthropogenic uranium). However, in the environment, this ratio is typically below 10-8. This low abundance of 236U and the presence in large excess of major isotopes (mainly 238U and 235U) complicates the accurate detection of 236U signal by mass spectrometry and highly sensitive analytical instruments providing high abundance sensitvity are required. This work pushes the limits of triple quadrupole-based ICP-MS technology for accurate detection of 236U/238U isotope ratios down to 10-10, which is so far mainly achievable by AMS. Coupled with an efficient desolvating module, N2O was used as reaction gas in the collision reaction cell of the ICP-MS/MS. This configuration allows a significant decrease of the uranium polyatomic interferences (235UH+ ions) and an accurate determination of low 236U/238U. The proposed methodology was successfully validated through measurements of certified reference material from 10-7 to 10-9 and then through comparisons with AMS measurement results for ratios down to 10-10. This is the first time that 236U/238U isotope ratios as low as 10-10 were determined by ICP-MS/MS. Below this ratio, interferences became significant and the actual configuration reaches its limit. The possibility of measuring low 236U/238U isotope ratios open the way to a variety of geochemical studies for the determination of uranium sources in the environment.

A new determination of the (229)Th half-life was made based on measurements of the (229)Th massic activity of a high-purity solution for which the (229)Th molality had previously been measured. The (229)Th massic activity was measured by direct comparison with SRM 4328C using 4παβ liquid scintillation counting, NaI counting, and standard addition liquid scintillation counting. The massic activity was confirmed by isotope dilution alpha spectrometry measurements. The calculated (229)Th half-life is (7825 ± 87) years (k = 2), which is shorter than the three most recent half-life determinations but is consistent with these values within uncertainties.

International audience; Chang (1998) and Murdock et al. (2001) performed numerous laboratory and field experiments to define the application scope of the AMP-DGT method. Briefly, the response of AMP-DGT was pH independent in synthetic freshwater (pH 2 – 10) and in sea waters (pH 4.5 – 10) for 8 h of deployment time. During this deployment time, no influence of Na+ (50 µmol L-1 – 0.5 mol L-1) and Ca2+ concentrations (5 µmol L-1 – 10 mmol L-1) were observed at pH 5.5 on Cs uptake by DGT from water. Correct DGT performances were obtained up to 1 month deployment time during field application in the Llyn Trawsfydd Lake (pH 6.1 – 8), before being progressively decreased to 81 % of the expected value after 5 months deployment time. The changes in DGT performances over time were possibly linked to the growth of algae / bacteria biofilm, the temperature impact on diffusion coefficient and the chemical degradation of AMP shown by a gradual loss of its characteristic yellow color. Concerning the last point, factors causing AMP binding gel degradation in DGT unit were not discussed, and their consequences on the accumulation of Cs by AMP-DGT samplers were not clearly identified. This study is dealing with an evaluation of AMP-DGT method under unfavourable conditions to maintain stable AMP binding gel in DGT unit, such as moderately basic environmental water (pH 7 – 9). Laboratory experiments were designed: (i) to identify factors controlling AMP binding gel degradation during storage and DGT deployment and (ii) to assess the possible impact of AMP degradation over time on the DGT response in waters with various chemical composition. Conclusions on potential limitations of AMP-DGT methods will finally be discussed for a better use of this technique for field applications.

Rationale During transient signal acquisition by Multi-Collection Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS), an isotope ratio increase or decrease (isotopic drift hereafter) is often observed which is related to the different time responses of the amplifiers involved in multi-collection. This isotopic drift affects the quality of the isotopic data and, in a recent study, a method of internal amplifier signal synchronization for isotope drift correction was proposed. In this work the determination of the amplifier time constants was investigated in order to validate the method of internal amplifier signal synchronization for isotope ratio drift correction. Methods Two different MC-ICPMS instruments, the Neptune and the Neptune Plus, were used, and both the lead transient signals and the signal decay curves of the amplifiers were investigated. Results Our results show that the first part of the amplifier signal decay curve is characterized by a pure exponential decay. This part of the signal decay was used for the effective calculation of the amplifier first-order time constants. The small differences between these time constants were compared with time lag values obtained from the method of isotope signal synchronization and were found to be in good agreement. Conclusions This work proposes a way of determining amplifier first-order time constants. We show that isotopic drift is directly related to the amplifier first-order time constants and the method of internal amplifier signal synchronization for isotope ratio drift correction is validated. Copyright © 2015 John Wiley & Sons, Ltd.

A new reference material was characterized for (229)Th molality and thorium isotope amount ratios. This reference material is intended for use in nuclear forensic analyses as an isotope dilution mass spectrometry spike. The reference material value and expanded uncertainty (k = 2) for the (229)Th molality is (1.1498 ± 0.0016) × 10(−10) mol g(−1) solution. The value and expanded uncertainty (k = 2) for the n((230)Th)/n((229)Th) ratio is (5.18 ± 0.26) × 10(−5) and the n((232)Th)/n((229)Th) ratio is (3.815 ± 0.092) × 10(−4).

International audience; On-line hyphenated methods between the Multi Collection Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) and a variety of introduction techniques (liquid and gas chromatography, laser ablation…) provide transient signals with specific time-windows. It is now well-known that the isotope ratio drift which is observed during transient signal acquisition is generated from the MC-ICPMS detection system, the introduction techniques, or a combination of both parameters. In this work, the Nd isotope ratios were investigated through a coupling of the MC-ICPMS with Liquid Chromatography (LC). The purpose was to dissociate the isotopic drift coming from the detection system to the drift caused by the introduction technique by using raw isotope data. To this end, the time constants of the MC-ICPMS amplifiers were used, and the isotope drift generated by the detection system was successfully corrected. After this correction, the isotope drift coming exclusively from the LC was highlighted. The use of the Method of Internal Signal Synchronization (MISS) allowed the correction of the chromatographic drift and the calculation of a time lag between the Nd isotopes at 0.0036 s / amu. This is the first time where for an isotope fractionation caused by a specific physicochemical process, a time lag between the isotopes was calculated. We believe that the calculation of time lag values between the isotopes could be a simple and robust method opening up new possibilities for studies of isotope fractionations generated by different introduction techniques directly coupled with the MC-ICPMS.

cited By 15; International audience; The measurement of isotope ratios by Multi Collection Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) in transient signals often shows a drift of the isotope signal ratio during signal acquisition. This "isotopic drift" is generally related to the small and distinct time lags between the responses of the amplifiers involved in the Faraday detector configuration. In this work, a method of synchronization of transient isotope signals for a duration of a few tens of seconds is proposed in order to: (1) quantify the time lags between the amplifiers using the ratios of the raw isotope signals and (2) correct the isotope ratio drifts. The method was successfully tested on lead isotope ratio measurements obtained from two different multi-collector mass spectrometers and setups (flow injection with direct injection and gas chromatography). This approach offered a precise determination of the time lag between the different amplifier systems and an effective correction of the isotope ratio drift. The performances of the methods traditionally used for isotope ratio calculation of transient signals were also compared before and after isotope ratio drift correction. This journal is © the Partner Organisations 2014.

International audience; High-level, long-lived nuclear waste arising from spent fuel reprocessing is vitrified in silicate glasses for final disposal in deep geologic formations. In order to better understand the mechanisms driving glass dissolution, glass alteration studies, based on silicon isotope ratio monitoring of 29Si-doped aqueous solutions, were carried out in laboratories. This work explores the capabilities of the new type of quadrupole-based ICP-MS, the Agilent 8800 tandem quadrupole ICP-MS/MS, for accurate silicon isotope ratio determination for alteration studies of nuclear waste glasses. In order to avoid silicon polyatomic interferences, a new analytical method was developed using O2 as the reaction gas in the Octopole Reaction System (ORS), and silicon isotopes were measured in mass-shift mode. A careful analysis of the potential polyatomic interferences on SiO+ and SiO2+ ion species was performed, and we found that SiO+ ion species suffer from important polyatomic interferences coming from the matrix of sample and standard solutions (0.5M HNO3). For SiO2+, no interferences were detected, and thus, these ion species were chosen for silicon isotope ratio determination. A number of key settings for accurate isotope ratio analysis like, detector dead time, integration time, number of sweeps, wait time offset, memory blank and instrumental mass fractionation, were considered and optimized. Particular attention was paid to the optimization of abundance sensitivity of the quadrupole mass filter before the ORS. We showed that poor abundance sensitivity leads to a significant shift of the data away from the Exponential Mass Fractionation Law (EMFL) due to the spectral overlaps of silicon isotopes combined with different oxygen isotopes (i.e. 28Si16O18O+, 30Si16O16O+). The developed method was validated by measuring a series of reference solutions with different 29Si enrichment. Isotope ratio trueness, uncertainty and repeatability were found to be andlt;0.2%, andlt;0.5% and andlt;0.6%, respectively. These performances meet the requirements of the studies of nuclear glasses alteration and open up possibilities to use this method for precise determination of silicon content in natural samples by Isotope Dilution.

Thermal ionization mass spectrometry (TIMS) is a well established instrumental technique for providing accurate and precise isotope ratio measurements for elements with low first ionization potential. In the nuclear domain, particularly for the study of spent nuclear fuel sample solutions, the reduction of quantities is an important issue in order to decrease the analyst exposition to the radioactive samples. This paper presents experimental results obtained for picogram quantities of samples using electron multipliers (Channeltrons) implanted on the new generation of TIMS associated with the total evaporation (TE) acquisition method. TE method presents some advantages for the measurement of low quantities of samples in relation to the whole sample consumption and the integration of the whole signal. For this study, a Thermal Ionization Mass Spectrometer from IsotopX (Isoprobe-T) equipped with a multi-collector system including Faraday cups and four movable Channeltrons is used. This work is focused on lanthanide elements, and particularly europium, in relation to the importance of their characterization in the spent fuel to validate neutronic calculation codes. In a first approach, europium isotopic ratios by total evaporation method using Faraday cups are obtained for quantities down to 250 pg. The results obtained by TE (Faraday cups only) on such low quantities confirm the potentialities of the method. A reproducibility of 2.5‰ (k = 2), was obtained on the 153Eu/151Eu ratio (n = 11), for natural samples with an accuracy around 1‰. In a second approach the same procedure is tested on Channeltron detectors by reducing the amounts of samples (from 50 pg to 1 pg). In order to obtain accurate isotope results, intrinsic parameters such as applied voltages, dead time and noise were determined. A Channeltron specific intercalibration gain method was also developed, as this parameter was found to be the major source of uncertainties using this type of detectors. The reproducibility on the 153Eu/151Eu ratio was respectively found around 3% (k = 2). These results show the potentialities of isotopic measurements of sub-nanograms quantities and the different sources of uncertainties using total evaporation and Channeltrons on the Isoprobe-T.

The French Atomic Energy Commission has carried out several experiments including the mini-INCA (INcineration of Actinides) project for the study of minor-actinide transmutation processes in high intensity thermal neutron fluxes, in view of proposing solutions to reduce the radiotoxicity of long-lived nuclear wastes. In this context, a Cm sample enriched in 248Cm (∼97%) was irradiated in thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). This work describes a quadrupole ICP-MS (ICP-QMS) analytical procedure for precise and accurate isotopic composition determination of Cm before sample irradiation and of Cm and Cf after sample irradiation. The factors that affect the accuracy and reproducibility of isotopic ratio measurements by ICP-QMS, such as peak centre correction, detector dead time, mass bias, abundance sensitivity and hydrides formation, instrumental background, and memory blank were carefully evaluated and corrected. Uncertainties of the isotopic ratios, taking into account internal precision of isotope ratio measurements, peak tailing, and hydrides’ formations ranged from 0.3% to 1.3%. This uncertainties’ range is quite acceptable for the nuclear data to be used in transmutation studies.

International audience; To improve the precision of isotope analyses of low ion intensities using the Faraday detection system, amplifiers equipped with 10(12) Omega resistors (hereafter 10(12) Omega amplifiers) have been developed. While the behavior of these amplifiers for steady signals has been well investigated, there is no ample evidence regarding the use of 10(12) Omega amplifiers for transient signal acquisition. In this work, we investigated the simultaneous use of amplifiers equipped with 10(12) Omega and 10(11) Omega resistors for transient signal acquisition. Using the equation describing the relationship between the input ion current and the output voltage in the amplifiers, we showed how the transient signal duration influences the accuracy of the isotope ratio measurements. In particular, lead transient signals were investigated using a Neptune Plus MC-ICPMS and Pb-204 and Pb-206 isotopes were measured using 10(12) Omega and 10(11) Omega amplifiers, respectively. The Pb-204/Pb-206 isotope ratio showed an important drift due to a large time lag between 10(12) Omega and 10(11) Omega amplifiers. The time lag was quantified (0.175(3) s) and the isotopic drift was corrected using a method of internal signal synchronization. The Pb-204/Pb-206 drift corrected data obtained from the 10(12)-10(11) Omega amplifier configuration were compared to the data obtained from 10(11)-10(11) Omega amplifiers. Our results point out that for low transient signal intensities (

International audience; The French Atomic Energy Commission has carried out several experiments for the study of minor-actinide transmutation processes in high intensity thermal neutron flux. In this context a Cm sample enriched in $^{248}$Cm (∼97%) was irradiated in a thermal neutron flux at the High Flux Reactor (HFR) of the Laue–Langevin Institute (ILL). The precise and accurate determination of Cf isotope ratios and of $^{249}$Bk/$^{248}$Cm and $^{249}$Cf/$^{248}$Cm elemental ratios in the 248Cm irradiated sample is crucial for the calculation of actinide neutron capture cross-sections. This work describes an analytical procedure for the separation and the isotope ratio measurement of Bk and Cf in the irradiated sample. The Bk and Cf separation is based on a lanthanides separation protocol previously developed by the laboratory. Well-defined retention times for Bk and Cf were obtained by coupling the Ionic Chromatography (IC) with an ICP-QMS. All conditions of element separation by IC and the different steps of the analytical protocol in order to obtain the isotopic and elemental ratios are presented. Relative uncertainties of Cf isotopic ratios range from 0.3% to 0.5% and the uncertainty of the $^{249}$Bk/$^{248}$Cm and $^{249}$Cf/$^{248}$Cm elemental ratios are respectively 6.1% and 3.2%. This level of uncertainty for both isotopic and elemental ratios is in perfect agreement with the requirement for transmutation studies.

International audience; This study is a large project initiated by the French Nuclear Agency, and concerns the development of a new electrolyte system for the separation of lanthanides by isotachophoresis. This new system is based on a leading electrolyte that incorporates 2-hydroxy-2-methylbutyric acid as complexing agent. The optimization of separation conditions (complexing agent concentration, pH, capillary dimensions, injection conditions, and current intensity) performed by experiments on a commercial capillary instrument with contactless conductivity detection, which allows to improve the separation of 13 lanthanides (La to Lu, except Pm and Ho). We have also directly coupled the isotachophoresis to an inductively coupled plasma mass spectrometer to visualize the mono-elementary elution bands and demonstrate the potentiality of the method for isotope ratio measurements. The application to a simulated solution representative of a fraction of fission products present in a MOX spent fuel is presented in this paper to demonstrate the possible application in future on nuclear fuel samples.

International audience; This paper presents the conception and fabrication of a microsystem for lanthanides separation and its coupling with a multicollector inductively coupled plasma mass spectrometer for isotope ratio measurements. The lanthanides separation is based on the isotachophoresis technique and the microsystem conception has been adapted in order to fit with glove box limitations in view of future spent nuclear fuels analysis. The micro-device was tested by using a mixture of standard solutions of natural elements and the separation of 13 lanthanides was successfully performed. The micro-device was then coupled to a multicollector inductively coupled plasma mass spectrometer for the on-line measurements of Nd and Sm isotope ratios. The isotopes of Nd and Sm were acquired online in multicollection mode after separation of the two elements with an injection amount of 5 ng. Results obtained on the Nd and Sm isotope ratio measurements on transient signals are presented and discussed.

The experiments involved in the PHENIX french nuclear reactor to obtain precise and accurate data on the total capture cross sections of the heavy isotopes and fission products require isotopic ratios measurements with uncertainty of a few per mil. These accurate isotopic ratio meaurements are performed with mass spectrometer equipped with multicollector system. The major difficulty for the analyses of these actinides and fission products is the low quantity of the initial powder enclosed in steel container (3 to 5 mg) and the very low quantities of products formed (several μg) after irradiation. Specific analytical developments are performed by Thermal Ionization Mass Spectrometry (TIMS) to be able to analyse several nanograms of elements with this technique. A specific method of acquisition named Total Flash Evaporation was adapted in this study in the case of lanthanide measurements for quantity deposited on the filament in the order of 2ng and applied on irradiated fuel. To validate the analytical approach and discuss about the accuracy of the data, the isotopic ratios obtained by TIMS are compared with other mass spectrometric techniques such as Multiple-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS).

Within the framework of the research undertaken by the French Atomic Energy Commission on transmutation of long-lived radionuclides, targets of highly enriched actinides and fission products were irradiated in the fast neutron reactor Phenix. Precise and accurate measurements of the isotopic and elemental composition of the enriched elements are therefore required. In order to obtain the uncertainties of several permil and to reduce handling time and exposure to analyst on radioactive material, the on-line coupling of ion exchange chromatography with quadrupole inductively coupled plasma mass spectrometry has been associated with the technique of the double spike isotope dilution. We present in this paper the results obtained on an irradiated sample of Europium oxide powder (enriched at 99.13% in 153Eu). After irradiation of around 5 mg of Eu2O3 powder the theoretical calculations predict the formation of several micrograms of gadolinium and samarium isotopes. In relation to the very high activity of the sample after irradiation and the very low quantity of Sm formed, the on-line ion exchange chromatography separation of Gd, Sm and Eu before Sm isotope ratio measurements has been developed for the quantification of the 152Sm/153Eu ratio. These on-line measurements were associated with the double spike isotope dilution technique after calibration of a 147Sm/151Eu spike solution. The external reproducibility of Sm isotopic ratios was determined to be around 0.5% (2σ) resulting in a final uncertainty on the 152Sm/153Eu ratio of around 1% (2σ). These on-line measurements present therefore a robust and high-throughput alternative to the thermal-ionisation mass spectrometry technique used so far in combination with off-line chromatographic separation, particularly in nuclear applications where characterisation of high activity sample solutions is required.

The measurement of U and Pu isotope ratios is of prime interest in nuclear research fields particularly for the management of radioactive waste. One of the major drawbacks in analysing Pu isotopes is the occurrence of 238U–238Pu isobaric interference. In this work we propose to suppress this interference by adding CO2 as a reactive gas in the collision-reaction cell of the MC-ICPMS. We have demonstrated that the different reactivities of Pu and U towards CO2 gas allow accurate and precise Pu and U isotopic measurements on Pu+ and UO2+ forms, by using two different CO2 gas flow rates: 0.4 mL min−1 for Pu+ and 1.5 mL min−1 for UO2+. Parameters like optimum CO2 gas flow in the cell, oxides isotope abundance, instrumental mass bias and memory blank, were carefully evaluated and corrected. The developed analytical method was validated using a transmutation 235U target sample irradiated in the Phenix French fast neutron reactor. A good agreement between isotope ratios of U and Pu measured with CO2 in the cell and U and Pu measured after chemical separation was obtained. The relative difference of the average isotope ratio values between the chemically purified fraction and the direct measurements using CO2 was found to be 0.38% and 0.11% for U and Pu, respectively.