Abstract: A method and apparatus is described for separating complex mixtures of components, particularly bio-organic molecules, preferably on the basis of two independent physical characteristics. A sample initially is resolved in a first stage to yield a fluid stream containing the components of the sample longitudinally separated. The fluid stream then is aligned incident to the inlet face of a gel slab positioned in a electric field, having a field strength sufficient to force the separated and charged components from the flowing stream into the gel slab substantially simultaneously with exposure of said charged components to the electric field. Gel electrophoresis of the sample can then proceed in a known manner.