Microfluidic reactor having an annular reaction chamber

A microfluidic reactor has a reaction chamber which is configured as an annular channel. It is provided that segments have been formed in the annular channel such that a sequence of inlets and outlets (allows an alternation between the process fluids (A and B) to take place. Furthermore, particles which circulate in the annular channel and can be used, for example, for the adsorption and desorption of ions may be provided in the annular channel. In this way, the ions concerned can, for example, be extracted from the process fluid (A) and transferred into the process fluid (B). In a method, the reactor can be used for example for the purpose of obtaining 18F− ions from water enriched therewith and feeding them to a solvent such as acetonitrile. In the further course of the method, the 18F− ions can be used for producing a radiopharmaceutical (for example FDG).