Isotope preparation method

A method for purification of 227Th from a mixture comprising 227Th and 223Ra, said method comprising:

• i) preparing a first solution comprising a mixture of 227Th and 223Ra ions dissolved in an aqueous solution of a first mineral acid;
• ii) loading said first solution onto a strong base anion exchange resin;
• iii) eluting 223Ra from said strong base anion exchange resin using a second mineral acid in an aqueous solution;
• iv) optionally rinsing said strong base anion exchange resin using a first aqueous medium;
• v) eluting 227Th from said strong base anion exchange resin using a third mineral acid in an aqueous solution to generate a second solution comprising 227Th, wherein said second solution comprising 227Th has a contamination level of no more than 20 KBq 223Ra per 1 MBq 227Th;
• and at least one of steps vi)-viii):
• vi) assaying for 227Th content of said second solution;
• vii) evaporating the liquid from said second solution;
• and
• viii) forming at least one radiopharmaceutical from at least a portion of the 227Th contained in said second solution.