New micro-methods for the determination of radio-iodine

Rapid methods have been developed for the retention and concentration of radio-iodine. Radio-iodine in the iodide form was retained by precipitate exchange on a column of silver chloride precipitated onto polyurethane foam. For large volumes of sample it was expedient to liberate iodide in the form of iodine, which was then steam-distilled or expelled by carbon dioxide and collected on a column of polyurethane foam impregnated with colloidal silver. The best way to measure the activity was to compress the foam and use a well-type Nal(Tl) detector. A thorough study was made of methods for digestion of various foodstuffs without loss of iodine. The time of digestion was reduced significantly by the addition of sodium hypochlorite or magnesium nitrate and hydrogen peroxide, even with samples as large as 5-1000 g.