COLUMN EXTRACTION METHOD FOR RAPID PREPARATION OF [C-11] ACETIC AND [C-11] PALMITIC ACIDS

A rapid method suitable for the routine preparation of [C-11]acetic and [C-11]palmitic acids is described. The reaction of [C-11]carbon dioxide with a Grignard reagent and purification by liquid-liquid extraction were carried out in a liquid layer supported by a commercially available kieselguhr, Extrelut(R) (Merck). [C-11]Carbon dioxide was efficiently trapped into a reagent solution kept by an Extrelut column and the free [C-11]fatty acid formed by quenching with diluted HCl was sequentially extracted by flowing an appropriate organic solvent from the reaction column into the solvent and then from the solvent into a short column of Extrelut for [C-11]acetic acid or silica gel for [C-11]palmitic acid. Thus, using this on-line method based on column extraction, [C-11]acetic acid was prepared in over 90% radiochemical yield and [C-11]palmitic acid in approx. 50% radiochemical yield, within 15 min, with the same system and procedure.