The invention provides apparatus for separation of particles and methods for using the apparatus. In an embodiment, the apparatus includes three arms extending radially from a central reservoir, each arm being associated with a separation electrode. At least one on the arms includes a separation medium. Using a sequence of driving and mobility-changing voltages, target particles can be separated from closely related particles within a sample. For example, single point mutations can be resolved from a sample containing predominantly wild type nucleic acids.
