226Ra and 228Ra determination in environmental samples by alpha-particle spectrometry

A complete methodology for Ra-226 and Ra-228 determination by alpha-particle spectrometry in environmental samples is being applied in our laboratory using Ra-225 as an isotopic tracer. This methodology can be considered highly suitable for the determination of these nuclides when very low absolute limits of detection need to be achieved. The Ra-226 determination can be performed at any time after the isolation of the radium isotopes from the analyzed samples while the Ra-228 determination needs to be carried out at least six months later through the measurement of one of its grand-daughters. The method has been validated by its application to samples with known concentrations of these Ra nuclides, and by comparison with other radiometric methods.