Abstract: To develop new specific receptor-site brain imaging agents labeled with radioiodine for Single Photo Emisson Computed Tomagraphy(SPECT), Four potential'DA receptor imaging agents,~(131)I-labeled IBZM, IBZP, ISPD and ICDM have been prepared from corresponding uniodinated compounds. Among them SPD and CDM are analogs of L-tetrahydropεlmatine, which is the main component of Corydlis,a traditional Chinese medicine, and have both been demonstrated to be a new type of DA receptor antagonists. Using Chloramine-T as oxidant and in pH=3phosphate buffer, over 80% labeling yield was obtained at room temperature. As unlabeled precursors are similar to the radioiodinated products in chemical structures and biological behavior, very efficient purification techniques are required. We uselreverse HPLC to separate labeled products from unlabeled impuritiec. With suitable pH buffer and solvent, we got satisfactory column selectivity and resolution with optimal separation conditions. After labeling vnd HPLC purification, the overall yield was 20—40%.