A vacuum filter device is disclosed which includes a filter body (11) which is adapted to receive in fluid-tight, sealed relationship a pair of closed containers (15,16) for solutions to be filtered by means of a membrane filter positioned within the filter body. A vacuum port (23) in the filter body (11) communicates with the downstream side of the membrane and a vent passageway (60;70) also located in the filter body (11) communicates with the closed sample container to serve as a vent to atmospheric pressure. The vent passageway is sealed by an air permeable hydrophobic filter to prevent the sample solutions from leaking out of the device during normal use.