Abstract: The invention relates to a process and a device for parallel fractionating a multiplicity of individual samples (29) within a 3-dimensional separation medium (6), with the subsequent process steps being carried out: A first space (2) which extends essentially across all three space coordinates contains the separation medium (6). A multiplicity of individual samples (29) is arranged close to an interface of the first space (2), with the individual samples (29) being arranged essentially in a planar fashion, i.e. their particular center-of-gravity positions are described by two coordinates. Under the influence of one or more physical parameters, the individual samples (29) are able to migrate essentially perpendicularly to the area of their application through the separation medium (6), and are fractionated in the process according to one or more of their properties.