New Trends in the Automation of Solvent Extraction for the Production of Radionuclides: From Macro- to Microscale Systems

Solvent extraction (SE), also called liquid-liquid extraction (LLE), is based on the selective partitioning of solutes between two immiscible solvent phases. It is very effective even at the trace level with high selectivity. It is also simple and cost-effective, but unfortunately difficult to automate. For this reason, this separation technique has been largely abandoned in the field of separation of radioisotopes for medical applications to make way for resin-based separation methods, whose basic chemical principles are often similar to the SE ones. Recently, there has been a resurgence of interest in SE for the separation of radiometals produced by cyclotrons, and the technique has been automated on both the macro and micro scales. Indeed, the emerging field of flow chemistry allows SE to be easily automated and operated in a continuous manner, resulting in even improved efficiency and reliability. This chapter provides a review of SE automation technology and its evolution.