Needle guide with centering for septum piercing

Abstract

A pipetting device () for removing fluid from a sample vessel () includes a pipetting needle () and an auxiliary cannula () for piercing a septum, designed to guide the pipetting needle axially through the auxiliary cannula. The pipetting device has a guide arm (), on the lower end () of which is arranged an end plate () that is axially displaceable along the guide arm against a resilient resistance. A centering device () inserts into the end plate of the guide arm, and at least three centering fingers () with conical bevels () are constructed on the radial outside of the centering device, distributed around the circumference thereof, and forming a holding-down device for the sample vessel. The disclosed construction makes possible to reliably pierce the septum of a sample vessel and to easily pull the pipetting needle out of the septum again even with thin pipetting needles.