Dielectrophoresis (DEP) of single DNA (about 40 kbp) labeled with a fluorophore was successfully observed in a planar quadrupole electrode cell whose working area was 65 mum in radius. The DEP behavior depended on frequency (f) of alternating current: positive DEP at lower f and negative DEP at higher f: The combination of the DEP force and a laminar flow in a capillary (82.5 mum in inner radius) with a quadrupole electrode controlled the elution of DNA from the capillary as a function off.