Determination of radium isotopes in mine waters through alpha- and beta-activities measured by liquid scintillation spectrometry

This paper presents a method for the determination of radium isotopes in mineralised mine waters, based on the separation of alpha-and beta-intensities measured in the precipitate by a liquid scintillation spectrometer in two time intervals (1 day and 7 days) after radium precipitation. The count rates of alpha-particles give not only the concentration of alpha emitters (R-226 and Ra-224), but also make possible to find the beta-counting efficiency of the system and through that - to determine the concentration of the beta-emitting radium isotope (Ra-228) with higher accuracy. An improved chemical procedure was elaborated. By this method radium isotopes in different water samples were determined, in wide range of concentrations, from about 0.06 Bq/dm(3) in potable water to more than 100 Bq/dm(3) in some mine brines. As an example some analytical results are given. The detection limit, defined as three standard deviations, is - for both radium isotopes -0.03 Bq/dm(3) (for initial volume of water sample equal to about 1 dm(3) and for counting time of each measurement not longer than 1 hour).