Abstract: The invention relates to a method and a system (100) for selectively processing a sample (130) according to one of a plurality of different assays, for example for detecting a certain target component in the sample. The system comprises a plurality of “specific reagent reservoirs” (120) that contain different sets of reagents, wherein each set is required for one of the assays. Moreover, the system (100) comprises a “universal reagent reservoir” in which reagents for several assays are provided, preferably reagents for all assays. The universal reagent reservoir may preferably be a cartridge (110) in which the processing of a sample (130) can take place and which comprises a plurality of binding sites that are selective for different target components. Depending on the assay to be performed with a sample (130) at hand, the appropriate specific reagent reservoir (121b) is chosen and processed in the universal cartridge (110).