Synthesis, radio‐LC–MS analysis and biodistribution in mice of 99m Tc–NIM–BAT

S , S ′‐ bis ‐trityl‐ N ‐BOC‐1,2‐ethylenedicysteamine ( S , S ′‐ bis ‐trityl‐ N ‐BOC–BAT) was conjugated to 2‐nitroimidazole (NIM) through a propylene spacer in order to provide a precursor for a potential technetium‐99 m labelled hypoxia tracer. For labelling with technetium‐99 m, a two‐step one‐pot procedure was developed consisting of deprotection of the ligand by heating in mild acidic conditions and subsequent exchange labelling in the presence of SnCl 2 , tartrate and 99m TcO . The labelling reaction mixture was analyzed using electrospray radio‐LC–MS and the observed mass spectrum corresponding to the main radiometric peak was in accordance with the predicted structure of oxo–Tc(V)–NIM–BAT. 99m Tc–NIM–BAT was purified using RP–HPLC and its biodistribution was evaluated in normal mice at 10 min and 4 h p.i. 99m Tc–NIM–BAT was cleared from plasma mainly by hepatobiliary excretion. Copyright © 2003 John Wiley & Sons, Ltd.