Quantification of 226Ra at environmental relevant levels in natural waters by ICP-MS: Optimization, validation and limitations of an extraction and preconcentration approach

François Lagacé; Delphine Foucher; Céline Surette; Olivier Clarisse

doi:10.1016/j.talanta.2017.02.031

Quantification of ²²⁶Ra at environmental relevant levels in natural waters by ICP-MS: Optimization, validation and limitations of an extraction and preconcentration approach

Talanta. 2017 May 15:167:658-665. doi: 10.1016/j.talanta.2017.02.031. Epub 2017 Feb 20.

Authors

François Lagacé¹, Delphine Foucher¹, Céline Surette¹, Olivier Clarisse²

Affiliations

¹ Department of Chemistry and Biochemistry, Université de Moncton, 18 Avenue Antonine Maillet, Moncton, NB, Canada E1A 3E9.
² Department of Chemistry and Biochemistry, Université de Moncton, 18 Avenue Antonine Maillet, Moncton, NB, Canada E1A 3E9. Electronic address: olivier.clarisse@umoncton.ca.

PMID: 28340775
DOI: 10.1016/j.talanta.2017.02.031

Abstract

Radium (Ra) at environmental relevant levels in natural waters was determined by ICP-MS after an off-line pre-concentration procedure. The latter consisted of Ra selective elution from potential interfering elements (i.e. other alkaline earth cations: Ba²⁺, Sr²⁺, Ca²⁺, Mg²⁺) on a series of two different ion exchange resins (AG50W-X8 and Sr-resin). The overall analytical method was optimized according to the instrumental performance, the volume of water sample loaded on resins, and the sample salinity. Longer acquisition time (up to 150 s) was required to ensure stable measurement of Ra by ICP-MS at ultra trace level (1.0pgL^-1). For a synthetic groundwater spiked with Ra at 10.0pgL^-1, the analytical procedure demonstrated efficient separation of the analyte from its potential interfering elements and a complete recovery, independent of the sample volume tested from 10 up to 100mL. For synthetic seawater spiked at a level of 10.0pgL^-1 of Ra, the total load of salts on the two resins should not exceed 0.35g in order to ensure a complete separation and recovery of Ra. The method was validated on natural waters (i.e. groundwater, freshwater and seawater samples) spiked with Ra at different levels (0.0, 0.5, 1.0 and 5.0pgL^-1). Absolute Ra detection limits were determined at 0.020pgL^-1 (0.73mBqL^-1) and 0.12pgL^-1 (4.4mBqL^-1) respectively for 60.0mL of freshwater sample and for 10.0mL of seawater.

Keywords: Environmental samples; ICP-MS; Pre-concentration; Radionuclide; Radium; Trace analysis.