ABSTRACT
Chemically, the nonprotein radioactivity fraction may be iodide, or some other inorganic form of the element, or, frequently, a mixture of iodide and other forms. Dialysis is a separating technique first employed by Thomas Graham in 1861. A protein solution to be dialyzed usually consists of three components, namely, the protein, small solutes, and the solvent. The purpose of dialysis is to effect a change in small solutes, that is, either to change its concentration, or to remove it altogether, or replace it by different solutes. With the small volumes under consideration, dialysis is conveniently carried out in bags made of dialyzing tubing. The tubing is made of cellophane, which in turn is made of viscose. The chromatographic removal of unbound radioactivity from iodination mixtures by the use of ion-exchange resins is quite a seasoned idea. Since all the known forms of nonprotein radioactivity are anionic, the method of choice for their removal is anion-exchange chromatography.
