Nitrogen supported solvent evaporation using continous-flow microfluidics

In this work we demonstrate a continuously operating microfluidic device for solvent removal and exchange for chemical syntheses by means of a supporting gas. The glass device consists of three sections: (i) three merging microchannels to create an annular gas–liquid stream; (ii) a serpentine channel with a heater underneath to allow efficient evaporation of the volatile solvent; (iii) a section with side capillaries to separate the liquid from the gas phase. We demonstrate the performance of the device for the removal of acetonitrile from an acetonitrile–water mixture. We achieved efficient removal of acetonitrile within a few seconds for flow rates of 20–30 µL min-1 and a nitrogen pressure of 1.2 bar. In three steps, acetonitrile was reduced from 50 wt% in the feed solution to 1 wt% in the final solution. We believe that the device can be easily applied to other solvent mixtures

18F-labelling innovations and their potential for clinical application

An impressive variety of new methodologies for the preparation of 18F-labelled tracers and ligands has appeared over the last decade. Most strategies of the newly developed radiofluorination methods predominantly aim at products of high molar activity by ‘late-stage’ labelling of small (hetero)aromatic molecules and the use of transition metals. This is accompanied by the improvement of technical procedures, like preparation of reactive [18F]fluoride and automated syntheses. The newly introduced procedures reflect a high innovative level and creativity in radio(pharmaceutical) chemistry at present, which are based on modern chemical methods and deep mechanistic insights. Taking also automation and quality control into consideration, major recently developed radiofluorination methods, most of those still under development, are compiled here in view of their potential for clinical PET imaging and thus the ability to advance molecular imaging