Comparison of radium-226 separation methods based on chromatographic and extraction resins for its determination by ICP-MS in drinking waters

Over the past century, human activities have contributed to the release of ²²⁶Ra (t_½ = 1,600 y) in the environment, increasing the potential risks for human exposure and thus prompting scientists to monitor it. Inductively coupled plasma mass spectrometry (ICP-MS) is an alternative to alpha-spectrometry for the quantification of ²²⁶Ra. However, the performances of radioanalytical procedures are rarely compared in a rigorous framework, which means that researchers may choose one on subjective factors or guesses.

This article compares five published methods for the separation and preconcentration of ²²⁶Ra in drinking waters based on chromatographic and extraction resins prior to its analysis by ICP-MS. We evaluated the turnaround time, generated wastes, and final cost of each protocol as the economic aspect can be an important criterion when selecting a method, particularly for sustainable environmental monitoring. Our results showed that ²²⁶Ra was successfully separated and preconcentrated, yielding recoveries ranging between 84% and 105%. Method detection and quantification limits of respectively 2–7 fg L⁻¹ (0.1–0.3 mBq L⁻¹) and 6–24 fg L⁻¹ (0.2–0.9 mBq L⁻¹) were achieved when the separation method was coupled with ICP-MS. The turnaround times ranged between 6 and 21 hours, whereas the cost of the methods varied between 40 and 132 USD.

This study highlights for the first time that methodologies recently published on the evaluation of ²²⁶Ra levels in drinking water by ICP-MS have comparable figures of merit. Our results offer essential insights into the selection of the most suitable separation method.