Disclosed is a method for the generation of 223Ra of pharmaceutically tolerable purity comprising: - preparing a generator mixture comprising 227Ac, 227Th and 223Ra in a first aqueous solution comprising a first mineral acid； - loading said generator mixture onto a DGA separation medium； - eluting said 223Ra from said DGA separation medium using a second mineral acid in a second aqueous solution to give an eluted 223Ra solution； and - stripping the DGA separation medium of said 227Ac and 227Th by flowing a third mineral acid in a third aqueous solution through the DGA separation medium in a reversed direction.
