A simple technique for the automated production of no-carrier-added [1-11C]acetate

A simple technique is described for the automated production of [1-11C]acetate, an important radiopharmaceutical for studies of human myocardial oxygen metabolism with positron emission tomography. The technique is based on the 11C-carboxylation of a small quantity of commercial methylmagnesium bromide solution contained within a narrow-bore low-volume Teflon™ tube, the use of 0.1 M hydrochloric acid to flush the radioactivity out of the tube through a millipore filter and into saturated sodium chloride solution, and purification of the product by reverse phase HPLC with isotonic saline as eluent. The [1-11C]acetate is collected in a small volume (ca. 3 mL) and after sterile filtration is ready for intravenous injection into human subjects. The product is obtained in high radiochemical yield (average 72%, decay-corrected) and radiochemical purity (>99%) within 16 min from radionuclide production. Since the procedure avoids phase extraction or distillation, it was easily automated using valves and equipment that were switched from a programmable logic controller.