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Published on: February 20, 2013
Labeling of aliphatic carboxylic acids using [11C]carbon monoxide
Oleksiy Itsenko1, Tor Kihlberg, Bengt Långström
1Uppsala University, Department of Biochemistry and Organic Chemistry, Box 576, S-751 23 Uppsala, Sweden. oleksiy.itsenko@kemi.uu.se
Abstract:
Here we present a protocol for labeling aliphatic carboxylic acids with the positron-emitting radionuclide 11C (t(1/2) = 20.4 min) at the carboxyl position using [11C]carbon monoxide via photoinitiated free radical-mediated carbonylation. A solution of an alkyl iodide in a homogenous binary organic solvent-water mixture is introduced into a high-pressure photochemical reactor containing [11C]carbon monoxide. Then the reactor contents are pressurized to 40 MPa and irradiated with ultraviolet light for 6 min. The labeled product is purified using HPLC. All manipulations with radioactivity including the labeling synthesis are carried out on an automated Synthia system. In a typical case, 3.19 GBq of purified [1-(11)C]1,10-decanedicarboxylic acid (with a specific radioactivity of 188 GBq/micromol) can be obtained within 35 min after the end of a 10-microAh bombardment. Compared to previous labeling methods, this protocol is compatible with a wider range of functional groups, utilizes less-sensitive precursors, and is less subject to isotopic dilution.
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