Supported liquid membrane extraction of 177Lu(III) with DEHPA and its application for purification of 177Lu-DOTA-lanreotide

Abstract

Permeation of 177Lu(III) through supported hexane membrane containing di-(2-ethylhexyl)phosphoric acid (DEHPA) as a carrier has been studied. The donor solution was 0.2 mol dm −3 ammonium acetate buffer, pH 5.0–5.5, that is optimal for peptide labeling, and the acceptor solution was 2 mol dm −3 HCl. A miniaturized supported liquid membrane (SLM) contactor with 10 μl donor and acceptor channel and ultra thin, flat poly(tetrafluoroethene) laminated on polyester fleece (PTFE) was applied in the work reported herein. The donor phase was pumped continuously through the donor channel, while the acceptor was stagnant during the SLM extraction. The influences of carrier concentration and donor flow rate on extraction of 177Lu(III) have been investigated. The results are discussed in the term of mass transfer coefficient, mass transfer resistance and extraction efficiency. Based on the experimental results of SLM extraction of 177Lu(III), this technique has been applied for the separation of free radionuclide from the labeled peptide as a purification procedure within the production of the radiopharmaceutical. An analog of somatostatin, lanreotide, which was conjugated with chelating moiety 1,4,7,10-tetraazacyclododecane- N, N′, N″, N ‴ -tetraacetic acid (DOTA) was labeled with 177Lu(III). The characterization of the labeled conjugate as well as the complexation yield and the efficiency of purification by membrane extraction were carried out by HPLC analysis.