Target compounds are extracted from an aqueous sample, through a µL-volume of organic solvent sustained as a thin supported liquid membrane (SLM) in the pores in the wall of a porous hollow fiber, and into an acceptor solution inside the lumen of the hollow fiber. Extraction is based on electrokinetic migration in an electrical field sustained across the SLM. The volume of the acceptor solution is typically 5-25 µL. The acceptor solution is an aqueous solution, and can be analyzed by liquid chromatography (LC) or capillary electrophoresis (CE).