The invention relates to a closure for a reagent container (7) with a screw-cap or lid (6), comprising a conical insert (4), reaching in the direction of the contents. The conical insert (4) is cut at least once, such that said insert may be bent apart in the lower region thereof and further comprises, for example, an annular step (3) in the middle region thereof. In the rest state the cone completely seals the reagent container. For the removal of liquid, a pipette with a release sleeve (2), in other words, a broadening (2) at a particular separation from the needle end (1), is introduced. The release sleeve contacts the step of the conical insert (3) and produces a separation of the divided walls of the cone. The pipette needle enters the container without making contact with the cone, in other words with the closure. As the pipette needle, complete with release sleeve (2), is withdrawn, the walls of the cone close back together, as the release sleeve (2) is no longer pressing on the step (3).