The present invention relates to a method for the generation of Ra of pharmaceutically tolerable purity comprising: i) preparing a generator mixture comprising Ac Th and Ra in a first aqueous solution comprising a first mineral acid ii) loading said generator mixture onto a DGA separation medium (e.g. resin) iii) eluting said Ra from said DGA separation medium using a second mineral acid in a second aqueous solution to give an eluted Ra solution and iv) stripping the DGA separation medium of said Ac and Th by flowing a third mineral acid in a third aqueous solution through the DGA separation medium in a reversed direction The invention further relates to high purity radium 223 formed or formable by such a method as well as pharmaceutical compositions comprising such radium 223 of pharmaceutical purity.
