A pipette nozzle that achieves a consistently high quality seal between the
nozzle and the interior surface of a replaceable pipette tip is provided.
In one aspect, the end portion of the nozzle is tapered. The tapered
nozzle aids pipette tip engagement in an automated system by relaxing the
tolerance on the co-location of the pipette tip and the syringe nozzle.
Additionally, the tapered end portion promotes tip sealing. In another
aspect of the invention, a small ridge is located on the tapered portion
of the nozzle. The ridge forms a seal with the interior surface of the
pipette tip. The ridge, in combination with the tapered portions of the
nozzle located on either side of the ridge, create three separate
interface regions.