Abstract: A vacuum manifold for solid phase extraction of a plurality of liquid samples from reagent tubes removably connected by valves to a vacuum chamber through a removable vacuum tight cover closing. A plurality of parallel flow paths are provided through the cover for the flow of liquid samples into the vacuum chamber, through a plurality of valves rotatable about an axis parallel to the general direction of flow through the cover to provide flow adjustment and closing of the valves. A valve is also provided for attaching the vacuum chamber to a vacuum source to create a vacuum therein. An optional attachment is provided permitting treatment of materials with nitrogen or other gases using a manifold plate attached to a source of gas and providing a plurality of valve control means axially aligned to couple with the rotatable valves for passage of liquid into the vacuum chamber.