Reversed phase free ion selective radiotracer extraction (RP-FISRE): A new tool to assess the dynamic stabilities of metal (-organic) complexes, for complex half-lives spanning six orders of magnitude

This paper introduces reversed phase free ion selective radiotracer extraction (RP-FISRE) as a new tool to assess the stability of metal complexes, as illustrated by the assessment of the stability of [177Lu]Lu-DOTA-octreotate. To this end, the TUDelft-developed FISRE, where the released metal is column-retained and the complex eluted, was changed into RP-FISRE, where the complex is column-retained and the released metal is eluted. This change in the approach allows for studies to be performed with high stability complexes. This paper presents RP-FISRE, the strength of the radiotracer approach, and the first-ever kd data on the release of 177Lu from [177Lu]Lu-DOTA-octreotate. •A new Radiotracer-based RP-FISRE technique developed.•First-ever data on kd's for 177Lu-DOTAtate.•Rate constants kd of the dissociation of Lu-DOTA-Octreotate (ML, MHL, MH2L forms) determined as kML=1.1 10–8s−1, kMHL=7.4 10−6s−1, kMH2L=1.1×10–4s−1.