Low-level 226Ra determination in groundwater by SF-ICP-MS: optimization of separation and pre-concentration methods

Abstract

Background: Inductively coupled plasma mass spectrometry (ICP-MS) techniques have been widely used for analysis of long-lived environmental radionuclides. In this paper, we present an optimization of the sector field (SF)-ICP-MS technique for the analysis of 226 Ra in groundwater samples using a method of pre-concentration of radium in water samples. Methods: The separation protocol and a sequential application of ion exchange and extraction chromatography have been optimized, and related polyatomic interferences and matrix effects affecting the

The analysis of 226Ra in 1‐liter seawater by isotope dilution via single‐collector sector‐field ICP‐MS

“…This study used an intermediate resolution of 2000 to demonstrate the absence of these interferences, in contrast with other studies that used low‐resolution mode for HR‐ICP‐MS measurement of Ra in environmental samples (Park et al 1999; Sharabi et al 2010; Copia et al 2015). Although the sensitivity in low‐resolution is almost 10 times higher than in high/intermediate resolution, possible molecular interferences may not be well separated from the 226 Ra peak resulting in incorrect values at fg g −1 levels of Ra.…”

“…However, the concentration of Ba in these matrices is higher relative to seawater. The presence of Mg and Ca in groundwater, for example, may affect the sensitivity of HR‐ICP‐MS (Copia et al 2015). Therefore, an additional column separation might be necessary (repeat column 1 or 2) to purify Ra in these matrices.…”

“…Analysis of 226 Ra by mass spectrometry may present analytical limitations resulting from instrumental sensitivity and spectral interferences (Lariviere et al 2006). Barium, for example, behaves chemically like Ra due to its similar ionic potential, and along with other alkaline earth metals in the sample, may cause molecular interferences (e.g., 88 Sr 138 Ba + ) on the mass spectrometric measurements of 226 Ra (Epov et al 2003;Larivière et al 2005;Zoriy et al 2005;Copia et al 2015). Foster et al (2004) showed that the mass difference between the 226 Ra and interference peaks is only 0.2 amu.…”

Snowmass2021 Cosmic Frontier White Paper: Calibrations and backgrounds for dark matter direct detection

“…Two ICP-MSs are installed into a ISO 6 class cleanroom: a high-resolution double focusing HR-ICP-MS (Element 2, Thermo Fisher Scientific), and a last-generation single quadrupole ICP-MS with collision/reaction cell (Agilent 7850). Detection limits ranging from ppq to ppt are usually achievable for Th and U, and limits in the sub-ppq range were attained for determinations of 226 Ra [345].…”

Association of Radionuclide Isotopes with Aquifer Solids in the Midwestern Cambrian–Ordovician Aquifer System

“…In the laboratory, Ra sorption to solid phases such as clay and transition-metal oxides (e.g., Fe, Mn) has been verified. − At the laboratory scale, contaminant–solid interactions can be examined via sequential extraction of rock core obtained from aquifer systems to determine contaminant distribution between various solid phases. Due to the low concentrations of concern, counting methods used to analyze Ra in solution often require large sample volumes (>500 mL) and/or generate relatively high analytical detection limits, which limits applicability in situations where sample volume is limited. − Analytical techniques such as multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) can measure isotopes of contaminants at ultratrace levels in the small sample volumes produced by laboratory experiments. − …”