Patent Number: 052788750
Section: claims

1. A process for the synthesis of .sup.11 C-labeled methyl iodide which comprises a .sup.11 CO.sub.2 -producing process of producing carbon dioxide gas labeled with .sup.11 C, supplying .sup.11 CO.sub.2 gas to a reaction vessel and bubbling the .sup.11 CO.sub.2 gas into a reducing agent solution in the reaction vessel to reduce the .sup.11 CO.sub.2 gas to yield an intermediate, a reducing agent solution-removing process of evaporating the reducing agent solution after the termination of the bubbling, and a .sup.11 CH.sub.3 I synthesis process of synthesizing .sup.11 CH.sub.3 I from the intermediate produced by the reduction in the bubbling process and terminating the evaporation in the reducing agent solution-removing process based on a variation of the temperature in an exhaust tube for discharging the vapor of the reducing agent solution connected with the reaction vessel. 2. The process of claim 1, wherein said bubbling process of bubbling the .sup.11 CO.sub.2 gas into the reducing agent solution in the reaction vessel is terminated by terminating the supply of the .sup.11 CO.sub.2 gas based on a variation in radiation produced upon supplying the .sup.11 CO.sub.2 gas into the reaction vessel. 3. An apparatus for the synthesis of .sup.11 C-labeled methyl iodide which comprises a target box in which .sup.11 CO.sub.2 gas is produced, a reaction vessel in which .sup.11 CH.sub.3 I is synthesized from said .sup.11 CO.sub.2 gas and a temperature sensor for detecting the temperature of an exhaust tube and deciding a termination point for discharging the vapor of a reducing agent solution which has reduced .sup.11 CO.sub.2 gas. 4. The apparatus of claim 3, which further comprises a transfer tube connecting said target box and said reaction vessel with radiation detecting means for deciding a termination point for bubbling of .sup.11 CO.sub.2 gas provided adjacent the transfer tube.