Separation of two labeled components of [In-111]-OctreoScan by HPLC

[In-111]-DTPA-D-Phe(1)-octreotide (OctreoScan(R), Mallinkrodt) is widely us ed for detection of neuroendocrine tumors and has lately been proposed for radionuclide therapy. We found, using HPLC and a GF-250 column (Zorbax(R), Hewlett Packard), that OctreoScan(R) can be separated in two radiolabeled c omponents of about equal amount. The analytical conditions far a quantitati ve isolation indicate that the two-peptide components of OctreoScan(R) have different lipophilicity. The isolated components are stable and do not tra nsform into each other at room temperature during 6 hours (shelf-life of Oc treoScan(R)).