An overview is given of the possible applications of nanotechnology to optimise existing separation methods and to enable new methods. Attention is paid to nanotechnological contributions in the fields of HPLC, CEC, sieves, Brownian ratchets and preconcentration units. A brief description is also given of some selection/separation mechanisms that occur in biological (cell) structures and possible future applications of these mechanisms in separation devices are investigated. Especially the active transport in discrete events occurring in cells is mentioned as a potentially powerful separating mechanism.