Synthesis and purification of highly tritiated aryldiazonium photoprobes for cholinergic binding sites

The synthesis and improved purification procedures of two photoactivatable ligands 3H‐A and 3H‐B (Figure 1) are presented. Particular attention was given to the use of resolutive reversed‐phase HPLC conditions which were found to be essential for the characterization and the elimination of contaminating products and for the obtention of pure diazonium probes at high specific radioactivity (up to 50 Ci/mmol).