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

[111In]-DTPA-D-Phe1-octreotide (OctreoScan®, Mallinkrodt) is widely used for detection of neuroendocrine tumors and has lately been proposed for radionuclide therapy. We found, using HPLC and a GF-250 column (Zorbax®, Hewlett Packard), that OctreoScan® can be separated in two radiolabeled components of about equal amount. The analytical conditions for a quantitative isolation indicate that the two-peptide components of OctreoScan®have different lipophilicity. The isolated components are stable and do not transform into each other at room temperature during 6 hours (shelf-life of OctreoScan®).