Captive Solvent Methods for Fast, Simple Carbon-11 Radioalkylations
Carbon-11 labeled radiopharmaceuticals for receptor studies usually require final purification by high performance liquid chromatography (HPLC). A significant simplification of the apparatus is possible if the radiolabeling reaction can be done directly in the HPLC injection circuit. Captive solvent methods in which the reaction is done in a small volume of solvent absorbed in a porous solid matrix are a general approach to this problem. For N-methylations with [11C] methyl iodide, a basic catalyst may be incorporated in the polymeric or alumina solid phase. Reaction volumes are from 20 to 100 μL. Often no heating or cooling of the reaction column is necessary. The syntheses of [11C]PK11195 and [11C]flumazenil are described to illustrate some of the advantages and limitations of captive solvent methods.
KeywordsHigh Performance Liquid Chromatography Positron Emission Tomography High Performance Liquid Chromatography Methyl Iodide Analytical High Performance Liquid Chromatography
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