This invention relates to the use of a unique apparatus and method for extracting radioactive components from liquids, such as elctrophoresis buffers. In the present invention, the radioactive liquid is pumped or transported by other suitable means and is passed through a cartridge having an elongated chamber that contains an exchange medium. The exchange medium, i.e. exchange resin, is contained within the elongated chamber between an upper frit and a lower frit. Further, the cartridge has a means within the elongated chamber for retaining pressure between the upper frit and the lower frit. The nucleotides, being charged molecules, bind to the exchange medium and are removed from the liquid. The liquid then exits the cartridge and has such a low amount of radioactivity that it can be disposed of to a conventional drain.