The invention relates to a transfer unit for receiving in particular a porous disc-shaped medium from a first treatment device, having an upper part, wherein the upper part comprises a fixing edge that can be connected to an edge of the medium for removing the medium from the first treatment device, wherein the upper part comprises an opening closed by a removable cover, by means of which successive treatments in a further treatment device can be performed. The invention further relates to a method wherein an upper part of a transfer unit is placed on a disc-shaped medium disposed in a first lower part of a first treatment device and exposed to the liquid sample and is connected to an edge of the medium, wherein the upper part is lifted off from the first lower part with the disc-shaped medium connected thereto, and is placed on a further lower part of a corresponding treatment device, and is further processed through an opening in the upper part.