Metabolism of Fission Products.

The Zr93 was prepared from neutron bombarded UO2NO32.6H20. The Zr93 was removed from most of the fission products by the iodate method. Further purification was made using HF, and the Zr93 was finally purified by repeated K2CO3 fusions. Intramuscular studies with carrier-free Y88 revealed results similar in character to the earlier intraperitoneal experiments except for much less retention of the administered activity by the intraperitoneal organs. Intrapulmonary experiments revealed a moderate degree of lung retention of activity which ranged from 83 at one day to 6.4 at 64 days after administration. Most of the absorbed Y88 was deposited in the skeleton. Intramuscular experiments with carrier-free Ce140 Ce3 were undertaken to supplement earlier Ce140 intraperitoneal and incomplete intramuscular studies. These studies indicated that while carrier free radiocerium is deposited chiefly in the skeleton, a relatively high uptake occurs in the liver and the rate of elimination apparently is significantly greater than for carrier-free radioyttrium. The lung retention of Ce140 following intrapulmonary administration is somewhat greater than with Y88 and ranges from 67 at 1 day to 9.4 at 64 days after administration. The metabolic behavior of the carrier-free radioactive isotopes of lanthanum, cerium, and praseodymium are quite similar and differ significantly from carrier-free radioyttrium.