Means providing separation of exterior sheath of liquid on dispensing tip

Claim 1

In apparatus for aspirating liquid into a dispensing container having a dispensing tip and aperture, and means for moving said container and dispensing tip first into the liquid to permit aspiration, and then away from the liquid to permit dispensing of a prescribed volume, said dispensing tip comprising an end surface through which said dispensing aperture extends, said end surface terminating at an edge, said extending tip further including an exterior surface extending from said end surface edge, said exterior surface being subjected to residual liquid which can form a sheath thereon when said tip is immersed in the liquid during aspiration and then removed from the liquid; the improvement wherein said apparatus further includes means separate from said tip for separating said sheath into at least two parts, without detaching residual liquid physically from said exterior surface, said two parts being separated along the axis of said tip by a dry annular portion of said exterior surface having a width effective to keep dispensed liquid from joining both parts, said separating means being disposed so that the separated liquid part closest to said platform edge contacts a surface area on said tip that holds only a volume that is negligible compared to said prescribed volume, said separating means being spaced from said tip a distance effective to prevent contact with either said dispensing tip or said sheath of liquid.