Abstract: An apparatus producing a vacuum in several cavities configured in a microtitration filter plate, each cavity having an upper sample liquid input aperture and a lower aperture fitted with a filter covering the aperture cross-section. The apparatus includes a device that produces a vacuum and that can be connected to the lower apertures such that, upon connection, a vacuum can be applied to the apertures and such that, during the vacuum stage, the sample liquid in the cavities is aspirated through the filters. A flexible plate is mounted in planar contact at the side of the upper cavity apertures on the microtitration filter plate. The flexible plate, when mounted on the microtitration plate and when the vacuum is applied, hermetically seals the upper apertures of unfilled cavities.

Abstract: Apparatus producing a vacuum in several cavities configured in a microtitration filter plate, each cavity comprising an upper sample liquid input aperture and a lower aperture fitted with a filter covering the aperture cross-section, said apparatus including a device which produces a vacuum and which can be connected to the lower apertures in such manner that upon connection a vacuum can be applied to the apertures and that during the vacuum stage the sample liquid in the cavities shall be aspirated through the filters, said apparatus being characterized in that a flexible plate can be mounted to make planar contact at the side of the upper cavity apertures on the microtitration filter plate, and in that said plate, when mounted on the microtitration plate and when the vacuum is applied, shall hermetically seal the upper apertures of unfilled cavities.