Abstract: To collect from an electrophoresis capillary tube containing a liquid separating medium, a sample cup has two wells containing electrolyte. The bottoms of the wells are covered with clamped-on semipermeable membrane assemblies to permit the flow of buffer ions but not the migration of separated sample. Electrical continuity for the electrophoretic migration taking place in capillary tubes is provided through the electrolyte in wells, the assembled semipermeable membranes, electrolyte buffer residing the carrier, the electrode and a conductor leading to electrical ground. Separated zones are detected, electrophoretically eluted or electrosmotically discharged from the capillary tube into the electrolyte in well where they are trapped by the semipermeable membrane in assembly.