A fast and convenient method for robotic preparation of [C-11]flumazenil avoiding HPLC purification

A new approach for robotic preparation of [C-11]flumazenil with recovery of the final product by SPE technique has been developed. A hydrogen-bond-ass isted methylation in a suspension of potassium fluoride absorbed on alumina was followed by purification using a standard Sep-Pak Neutral Alum N Light cartridge. As a result, the contamination of the final product with its pr ecursor Ro 15-5528 was reduced to similar levels as obtained by traditional semi-preparative HPLC. The synthesis of [C-11]flumazenil was operated by t he commercially available robot Anatech RB-86. The formulated solution of [ C-11]flumazenil was obtained within 18 min starting from trapping of [C-11] methyl iodide. The simplicity of this method and the use of disposable mate rials for purification instead of HPLC may be advantageous for routine clin ical use.