A vacuum filter device is disclosed which includes a filter body which is adapted to receive in fluid-tight, sealed relationship a pair of closed containers for solutions to be filtered by a membrane filter positioned within the filter body. A vacuum port in the filter body communicates with the downstream side of the membrane and a venting passageway also located in the filter body communicates with the closed sample container to serve as a vent to atmospheric pressure. The venting passageway is made of an air permeable hydrophobic filter or preferably a small enough opening to prevent the sample solutions from leaking out of the device during normal use.