Patent ID: 7718046

Claim:
A method for directing at least one analyte in a solution containing a pseudostationary phase, the pseudostationary phase having a retention factor for said at least one analyte, said method comprising the steps of: establishing a steady-state spatial gradient in the retention factor in the pseudostationary phase for the at least one analyte; and moving the at least one analyte in the solution, so that the concentration of the at least one analyte is caused to change at one or more positions along said gradient, wherein said moving the at least one analyte is accomplished using a combination of an applied electric field and an applied bulk solution flow, wherein: the pseudostationary phase is an ionic pseudostationary phase; the analyte is either neutral or charged; the applied electric field has a significant component substantially aligned with said gradient and in a direction such that the resulting electrophoretic motion of the ionic pseudostationary phase is substantially aligned in a direction from a region of high retention factor to a region of low retention factor; and the applied bulk solution flow has a significant component substantially aligned in a direction opposite the direction of the electrophoretic motion of the ionic pseudostationary phase.