Long-lived Ra isotopes by counting or by mass spectrometry: What’s the better method?
The radium isotopes 226Ra and 228Ra have traditionally been determined by counting methods, mostly by gamma counting, or via their shorter-lived daughter isotopes. With increasing sensitivity of mass spectrometers, in particular ICP-MS, attempts have been made to measure 226Ra and 228Ra via mass spectrometry. While the more abundant (in terms of atoms) 226Ra is relatively well established and several datasets have been published, only a few analyses have been published for 228Ra. ICP-MS methods, if fully developed, promise improved precision and therefore an extended applicability of radium isotopes. However, there are still a number of unresolved issues that prevent mass spectrometric techniques from being used more widely. Complications often arise from (1) pre-concentration methods, often including manganese dioxide, and strontium or barium salts. (2) Separation of adsorbers and carriers from the Ra-containing solution (3) Availability of a 228Ra-spike for isotope dilution methods and (d) Sensitivity of the mass spectrometer, which also needs to allow controlling possible interferences. Here I will give an overview of the pros cons of counting vs. mass spectrometry, and discuss possible ways to address some of the key problems for radium measurements via ICP-MS.
Helmholtz Research Programs > PACES II (2014-2020) > TOPIC 1: Changes and regional feedbacks in Arctic and Antarctic > WP 1.5: Southern Ocean physics, biodiversity, and biogeochemical fluxes in a changing climate