The invention provides a method for the purification of complexed 227Th from a mixture comprising complexed 227Th and 223Ra (complexed or in solution), said method comprising: i) preparing a first solution comprising a mixture of complexed 227Th ions and 223Ra ions in a first aqueous buffer ii) loading said first solution onto a separation material iii) eluting complexed 227Th from said separation material whereby to generate a second solution comprising complexed 227Th iv) Optionally rinsing said separation material using a first aqueous washing medium The invention additionally provides a purified 227Th solution, a pharmaceutical product and its use in treatment of disease such as cancer and a kit for generation of such a product.
