An immunological method for the purification of radiolabelled thyroxine

A method for the removal of iodothyronine and iodide impurities from radiolabelled thyroxine is described. The principle of the method is to bind iodothyronine contaminants to specific antisera, and then to separate the antiserum-bound contaminants and iodide from the thyroxine by column chromatography. As reported here, the method is optimised for the removal of more than 98% of contaminating 3,5,3'-triiodothyronine and 99.8% of contaminating iodide from between 10 ng and 100 ng of thyroxine, where the molar ratio of thyroxine: 3,5,3'-triiodothyronine before purification is greater than or equal to 10:1. Recovery of purified thyroxine is more than 80%. The performance of the method is superior to that of preparative dialysis.