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Fluorine‐18 labelling of lower fatty acid esters by heterogeneous exchange on gas chromatographic columns
Author(s) -
Karim H. M. A.,
Stöcklin G.
Publication year - 1977
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580130409
Subject(s) - chemistry , yield (engineering) , extraction (chemistry) , bromine , chromatography , ion exchange resin , gas chromatography , hydrolysis , labelling , ion exchange , fluorine , fatty acid , organic chemistry , ion , biochemistry , materials science , metallurgy
Fluorine‐18 produced via the reaction chain 6 Li(n,α)t, 16 O(t,n) 18 F by reactor irradiation of Li 2 CO 3 was directly recovered in carrier‐free form with a 90% yield by repeated extractions with water. A simple apparatus was used for simultaneous extraction and fast loading of an exchange resin with 18 F . Dowex 1×4 in the acetate form was found to be best suited for a gas phase 18 F ‐for‐Br exchange in α‐bromofatty acid esters. The 18 F ‐loaded exchange resin was brought into a gas chromatographic column followed by an analytical column for the separation of the 18 F ‐labelled product from the unchanged bromine compound. The dynamic technique combines synthesis and purification and allows a fast and carrier‐free production of 18 F ‐α‐fluorofatty acid esters with boiling points up to about 300 °C. α‐fluoroacetic acid ethyl ester and α‐fluorovaleric acid methyl ester have been labelled carrier‐free with yields of 64% (at 170 °C) and 39% (at 190 °C), respectively. Kinetic studies on the yield determining factors have also been carried out.