Abstract: A radioactive material such as an unstable isotopic gas is provided to a receiving chamber (1) directly from a source to form a purified or enriched bubble. The bubble is passed to a fluid handling set for preparation of the reagent or other delivery system. In an exemplary embodiment trace amounts of nitrogen-13 are concentrated in a receiving chamber and passed into a small bubble of carrier gas. The carrier gas is then delivered into a fluid handling set. The fluid handling set connects to a pressure syringe (50) and a passive syringe (60), and further includes a plurality of flushable valves (22-27) interconnected as a closed unit by tubing (21) to form a switchable or finite state flow network in which the pressure syringe may back flush the tubing, mix the isotope in a delivery liquid, and transfer the mixed liquid to an output for diagnostic imaging or other use.