Abstract: A multichannel air-displacement pipette liquid-end assembly having a modular construction, which enables individual components to be easily replaced when they become contaminated or worn. The modular liquid-end assembly also enables selected piston and cylinder components to be selectively removed so that any one of a number of predetermined multichannel pipetting configurations can be employed. Additionally, the modular liquid-end assembly preferably comprises an ejector for providing low-friction mechanical advantage in order to facilitate dislodging spent tips.

Abstract: A disposable pipette tip member having three inner coaxial annular sealing bands spaced axially from an open proximal end for receiving a conical pipette tip mounting shaft. The first two sealing bands and adjacent valley regions of the tip member are relatively resilient and are shaped such that the two sealing bands simultaneously engage, guide and laterally support the pipette shaft as it enters the tip member to form annular fluid-tight seals with the shaft. The third band is relatively rigid and upon engagement with the shaft, forms a third annular fluid-tight seal and a controllable stop for the shaft such that the tip member is seated on the shaft adjacent the pipette tip ejector mechanism.