Rapid 'on-column' preparation of hydrogen [ 11 C]cyanide from [ 11 C]methyl iodide via [ 11 C]formaldehyde.

Hydrogen [ 11 C]cyanide ([ 11 C]HCN) is a versatile 11 C-labelling agent for the production of 11 C-labelled compounds used for positron emission tomography (PET). However, the traditional method for [ 11 C]HCN production requires a dedicated infrastructure, limiting accessibility to [ 11 C]HCN. Herein, we report a simple and efficient [ 11 C]HCN production method that can be easily implemented in 11 C production facilities. The immediate production of [ 11 C]HCN was achieved by passing gaseous [ 11 C]methyl iodide ([ 11 C]CH 3 I) through a small two-layered reaction column. The first layer contained an N -oxide and a sulfoxide for conversion of [ 11 C]CH 3 I to [ 11 C]formaldehyde ([ 11 C]CH 2 O). The [ 11 C]CH 2 O produced was subsequently converted to [ 11 C]HCN in a second layer containing hydroxylamine- O -sulfonic acid. The yield of [ 11 C]HCN produced by the current method was comparable to that of [ 11 C]HCN produced by the traditional method. The use of oxymatrine and diphenyl sulfoxide for [ 11 C]CH 2 O production prevented deterioration of the molar activity of [ 11 C]HCN. Using this method, compounds labelled with [ 11 C]HCN are now made easily accessible for PET synthesis applications using readily available labware, without the need for the 'traditional' dedicated cyanide synthesis infrastructure.