An electrophoretic device concentrating charged macromolecules to a predetermined final solution volume.

An apparatus for electrophoretic concentration of charged macromolecules to a predetermined final solution volume has been developed. The concentration process has a yield of near 100%, which implies that it is possible to predetermine the final macromolecule concentration as well. Both the final macromolecule solution volume and concentration are nearly independent of the electrophoresis time when it exceeds a certain minimum value. The electric field strength across the boundary containing the concentrated macromolecule solution is very low. This considerably reduces macromolecule aggregation, adsorption, and denaturation at this boundary compared to conventional electrophoretic concentrator designs. Both one-stage and two-stage versions of the apparatus have been developed. The one-stage version easily yields a 10-fold and the two-stage version a 50-fold concentration of the macromolecules. Typical macromolecule solution start volumes are 20-50 ml.