An elastomeric cell is used as the disposable part of an apparatus for isoelectric focusing in free solution (without gels) in the 0.5 to 5 ml volume range. An inlet port is used for priming the cell and end-connectors for coupling with electrodes. A grid of parallel rods compresses the cell against a cold plate, thereby causing swelling of the skin of the cell between pairs of rods and forming contiguous fluid bubble-compartments for IEF separation. Before collection of separated fractions, the gap between the rods and the plate is further reduced so as to create distinct fluid compartments which now contain discrete products of separation. The separated fractions are collected by syringe-like devices by puncturing the elastomer skin. The plate, rods and deformable cell are capable of rotation or gentle rocking motion around the cell's main axis to avoid gravitational convection during the focusing process.