Osmium-191/iridium-191m generator based on silica gel impregnated with tridodecylmethylammonium chloride.

A new separation system for an 191Os/191mIr generator is described. The system is composed of two columns in a series: a main column, packed with silica gel impregnated with tridodecylmethylammonium chloride (loaded with high activity 191Os as an osmyl chloride); and a scavenger column, packed with activated charcoal. Iridium-191m is eluted from the generator by pH 1 saline. For clinical use the eluate is buffered by succinate solution before injection. This new system is characterized by high performance (approximately 25% 191mIr recovery with 5 X 10(-4)% 191Os breakthrough) and long shelf-life (3 wk). The buffered eluate is sterile, pyrogen-free, and nontoxic, and contains no 192Ir. It is suitable for first-pass radionuclide angiocardiography with a very low radiation dose to the patient.