Marine samples often show the lowest radionuclide concentrations of the environment. As a consequence, radiochemical separation methods for marine samples, optimised for the detection of both anthropogenic and natural radionuclides by alpha, beta, gamma and mass-spectrometric techniques, are continuously being developed.
- Gamma spectrometry: for example, in the case of 137Cs in seawater, separation from other gamma emitting radionuclides is needed in order in order to improve the detection limit, by eliminating scatter radiation. This can for instance be achieved by replacing the commonly used 134Cs chemical yield determinant with a known amount of stable Cs.
- Alpha spectrometry: high quality radiochemistry is fundamental to i) obtain thin sources that permit to obtain high resolution spectra and ii) separate interfering radionuclides with similar alpha particle energy.
- Mass-spectrometric techniques (ICP-MS and AMS): the main purposes of radiochemical separation are i) to reduce all isobaric and polyatomic interferences, and ii) fixing the radionuclide in a matrix that allows high ionization efficiency in the ion source. In RML methods have been focused on ultra low activity concentrations and isotopic ratio determination with ICP-MS and AMS for both natural and anthropogenic radionuclides.