A device for providing analyte to an analyzer is described. In some examples, the device comprises a substrate comprising a plurality of wells formed therein at predetermined locations. Each of the wells can be capable of containing an analyte without mixing with analytes in other of the wells. Each of the wells can also have a well exit to allow analyte to exit therefrom. A channel can be in flow communication with at least one of the well exits, and can guide analyte ions exiting therefrom to the mass analyzer. The wells may be filled prior to use in association with the mass analyzer. The substrate may be used as part of a fraction collector if desired.