A method for preparing a radiolabeled pharmaceutical. The method comprises passing a mixture that includes a radiolabeled compound through a column that contains an ion exchange resin to retain the radiolabeled compound on the ion exchange resin. At least a portion of the mixture passes through the column without being retained on the ion exchange resin. The method further comprises eluting the radiolabeled compound off the ion exchange resin using an eluting solution (e.g., a sodium chloride solution) to form a radiolabeled pharmaceutical.
