THE TRANSITION FROM TECHNEGAS TO PERTECHNEGAS

We set out to determine the oxygen concentration of the argon-oxygen m ixture in the technegas generator where technegas-like behavior change s to pertechnegas-like behavior which allows [Tc-99m]pertechnetate to enter the solution. Methods: We prepared radioaerosols analogous to te chnegas and pertechnegas, with oxygen concentrations between 0% and 5% . They then were examined by thin-layer chromatography using saline as a solvent to measure the amount of [Tc-99]pertechnetate moving with t he solvent front as a function of oxygen concentration. Results: The a mount of mobile pertechnetate markedly increased when the radioaerosol s were created in an atmosphere containing between 0.1% and 0.2% oxyge n. The transition from technegas-like to pertechnegas-like behavior oc curs when the oxygen-argon gas mixture contains lower concentrations o f oxygen than those used in the preparation of pertechnegas. Conclusio n: Argon intended for the preparation of technegas should contain no m ore than 0.1% oxygen.