Abstract: Embodiments of the present invention relate to a filtration device for use in filtration of a liquid, and disclose: a liquid receptacle having an open end and a closed end; a plunger body moveable at least partially within the liquid receptacle along an axis said axis extending between the open and closed ends, said plunger including a filtrate chamber in fluid communication with the liquid receptacle via a fluid filtering path and a filter disposed in the filtering path, and the device further including a slidable seal for inhibiting or preventing fluid flow across the seal during said plunger movement; wherein said seal includes a first skirt depending from the plunger at one end of the first skirt, said first skirt having an outer surface which in use slidably and sealingly abuts the vial, and having, at least in an uncompressed state, a generally annular separation between the skirt and the plunger body, which separation extends generally parallel to the axis.