Silicon isotope ratio measurements by inductively coupled plasma tandem mass spectrometry for alteration studies of nuclear waste glasses

Abstract

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 Si-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 O 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 SiO 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 HNO). For SiO, 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. SiOO, SiOO). The developed method was validated by measuring a series of reference solutions with different Si enrichment. Isotope ratio trueness, uncertainty and repeatability were found to be<0.2%, <0.5% and <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.

Various effects of magnetite on international simple glass (ISG) dissolution: implications for the long-term durability of nuclear glasses

“…Aliquots of solution were sampled regularly throughout the experiment for elemental concentration quantification by ICP-OES and silicon isotope ratios quantification by ICP-MS. 57 All samples and standards were purified using BioRad AG50 X-12 (200-400 mesh) cation exchange resin before silicon isotope analysis, as described in detail by Georg et al 58 Silicon isotope ratio measurements were performed on a Thermo Scientific Neptune Plus Multi-Collector Inductively Coupled Plasma Mass-Spectrometer (MC-ICP-MS) at the Institut de Physique du Globe de Paris, France. All measurements were performed in static multicollection mode with Faraday cups attached to 10 11 Ω amplifier resistors.…”

Characterization of SiO2nanoparticles by single particle-inductively coupled plasma-tandem mass spectrometry (SP-ICP-MS/MS)

“…In the case of O 2 , it was also evaluated whether increasing the O 2 gas flow rate for monitoring SiO 2 + as reaction product ion would result in a method suitable for Si determination. However, although this approach was successfully applied by Gourgiotis et al 46 in the context of isotopic analysis of Si for alteration studies of nuclear waste glasses, the method obtained was not sufficiently sensitive for ultra-trace Si determination.…”

Determination of Ultra-trace Tellurium in Steel by ID-ICP-MS/ MS with Liquid-Liquid Extraction

“…The value of τ was 31.8 ns according to the previous study 20 , which was adjusted value by manufacturer. The concentration of Te in spike solution was recalibrated by the reverse isotope dilution (RID) method using following equation (3) 21 .…”