A self-shielded, sterile and cartridge-based radioisotope concentrator device coupled to 99m Tc/ 188 Re generators to increase the 99m Tc/ 188 Re-concentration of the generator eluate was developed based on new aminoalkylfunctionalized silica sorbent which conditionally catches and release 99m Tc/ 188 Re to concentrate the daughter nuclide of the generator eluates. The cartridge can be used for multiple elutions with an overall concentration factor of [100 and daughter nuclide recovery yield of [85 %. This device can be used for 10 days extension of 99m Tc-generator life-time, saving about 20 % of the generator activity and for ''early'' generator-elution programs, under which the generator is eluted at an optimized build-up time for increasing the effectiveness of 99m Tc/ 99 Mo utilisation.