The present invention relates to a method to extract out of water, concentrate and reformulate [18F] fluorides, said method comprising the successive steps of : - passing a dilute aqueous [18F] fluoride solution entering by an inlet (1) in a cavity (6) embodying an electrochemical cell with at least two electrodes (3, 4, 5), flowing in the cavity (6) and coming out of the cavity (6) by an outlet (2), an external voltage being applied to said electrodes, one electrode (4) being used as an extraction electrode, another one (3) being used for polarizing the solution, and configured so that at least the extraction electrode (4), either used as a cathode or as an anode, is in contact with and polarizes a large specific surface area conducting material (7), contained in the cavity (6); - releasing the extracted ions from the surface of the large specific surface area conducting material (7) by turning off the applied external voltage, wherein, during its passage in the cavity (6), the dilute aqueous [18F] fluoride solution entirely crosses and internally soaks the large specific surface area conducting material (7).