A device designed to perform dialysis in laboratory samples, a procedure that combines the separation of molecules with different characteristics through a semi-permeable membrane (diffusion) and the simultaneous movement of fluid through the membrane under imposed pressure gradients (ultrafiltration). The device typically consists of a container for the solution to be dialysed (e.g., serum, urine), a container for the solution that performs the dialysis (i.e., dialysate), and a semi-permeable membrane separating them. It is used in clinical laboratories for several procedures such as cerebrospinal fluid concentration, and electrophoresis and chromatography sample preparation.