A simple and rapid method for activation analysis of uranium in human teeth was proposed. The nuclear reaction of235U (n, f) 140Ba was used and the activity of140La in equilibrium with140Ba was measured. The barium fraction was separated in the form of barium chloride from the hydrochloric acid solution of the irradiated teeth sample, and then purified by the use of cation exchange resins. The radiochemical purity of the final lanthanum fraction was high enough. Several teeth samples were analysed, giving the uranium contents of 24-44 ppb.
Wilzbach exposure, platinum-catalyzed exposure and chemical reduction methods were applied for tritium labeling of a new local anesthetic 2-methyl-2-n-propylaminopropion-o-toluide hydrochloride (LA-012) . The highest specific activity of 1.65 mCi/mg was obtained by catalytic hydrogenation of brominated product of LA-012, which was prepared by direct bromination of LA-012. A commercial local anesthetic prilocaine could be also labeled with tritium by catalytic hydrogenation of brominated product of prilocaine like LA-012, and high specific activity of 1.5 mCi/mg was obtained. However, lidocaine did not give any brominated product available for catalytic hydrogenation. 3H-Lidocaine with a specific activity of 0.84 mCi/mg was prepared from3H-xylidine, which was obtained by catalytic hydrogenation of 4-bromoxylidine with tritium.
To know the biological fate of a new local anesthetic 2-methyl-2-n-propylaminopropion-o-toluide hydrochloride (LA-012), the absorption, the excretion, the distribution and the metabolism of the drug were studied in guinea pig by using tritium labeled LA-012. 3H-LA-012 was found to be well absorbed when injected intramuscularly in the guinea pig. Ten minutes after3H-LA-012 was given to a guinea pig, the highest concentration was found in the kidney. Lung and spleen had appreciable levels whereas very low levels were present in the liver and blood. Most of the administered radioactivity were excreted in the urine within 24 hours. Only a few percent of the excreted radioactivity was present as unchanged3H-LA-012, and more than 90 percent were metabolites including conjugates. Liver was found to be the chief organ for the metabolism of LA-012. The drug was metabolized mainly by oxidative reactions, hydroxylation and N dealkylation.