The radiopharmaceutical targets of this project are 11C labeled raclopride and 11C labeled RO 15-1788 (flumazenil). This project has three major phases: 1) generation of 11C carbon dioxide at an established specific activity; 2) conversion of carbon dioxide into methyl iodide while retaining the specific activity at high values, and 3) incorporation of methyl iodide into the desired ligand. In order to produce high specific activity ligands, a method to analyze the specific activity of the 11C carbon dioxide was developed. This procedure is based on the reaction of the trityl anion, generated from triphenylmethane and butyl lithium, with carbon dioxide to form the corresponding acid. Analysis of the carboxylic acid is carried out using high pressure liquid chromatography. The specific activity of the 11C carbon dioxide using the JSW-1710 cyclotron is ca. 500 Ci/mmol. The specific activity of the 11C carbon dioxide from the CS-30 has been determined indirectly at 4-6Ci/umol using the analysis of the specific activity of the final radiopharmaceutical. Comparison of the specific activity obtained from the CS-30 cyclotron and the JSW-1710 will be undertaken.
