Universal Phase Separators are fitted with a selectively permeable insert that separates aqueous phases from organic solvents under gravity; this can help remove an upper organic phase from a lower aqueous phase during a traditional liquid-liquid extraction process without creating additional process steps. The design allows the organic phase to pass through the internal frit wherever it is located, providing a universal approach to separating two liquid phases and enabling any volume under 80 mL to be processed in one step, or larger volumes by serial batches.