Recovery of Radioactive Iodine from Urine

Abstract

SINCE the cost of radioactive iodine being used in New Zealand is increased by air-freight charges and radioactive decay during transit to about four times that obtaining in the United Kingdom, methods for the recovery of radioactive iodine from the urine of patients are of especial concern to the therapeutic programme of the Endocrinology Research Committee. While other methods have been used with comparative success, the silver precipitation¹ method seemed to offer the best prospects of development. The primary difficulty is that the addition of small amounts of silver nitrate to urine results in the formation of colloidal silver halides. Craig and Jackson¹ overcame this by the addition of larger amounts of silver nitrate and by allowing five hours or longer for the halides to sediment. It has been found here that the formation of colloidal silver iodide can be avoided by precipitating the silver nitrate as chloride in a suspension of Gooch asbestos before contact with the urine. The method of Craig and Jackson is considerably improved if, instead of silver nitrate, such a preformed silver chloride asbestos suspension is added to the acidified urine. The iodide of the urine is fixed on the precipitate, which can be filtered off immediately and washed with dilute sulphuric acid before further treatment. There is thus a considerable saving in time and a purer product is obtained in the next stage.