title: Labeling of aliphatic carboxylic acids using [11C]carbon monoxide.
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.
authors.affiliation: Uppsala University, Department of Biochemistry and Organic Chemistry, Box 576, S-751 23 Uppsala, Sweden. oleksiy.itsenko@kemi.uu.se
authors.forename: Oleksiy
authors.initials: O
authors.lastname: Itsenko
authors.forename: Tor
authors.initials: T
authors.lastname: Kihlberg
authors.forename: Bengt
authors.initials: B
authors.lastname: Långström
mesh_terms: D002248:Carbon Monoxide / Q000032:analysis* / Q000737:chemistry*; D002250:Carbon Radioisotopes; D002264:Carboxylic Acids / Q000032:analysis* / Q000737:chemistry*; D007553:Isotope Labeling / Q000379:methods*
chemical_list: D002250:Carbon Radioisotopes; D002264:Carboxylic Acids; D002248:Carbon Monoxide