Abstract: An apparatus for wiping the tip of a sample dispensing tube. The apparatus includes means such as a pair of arms for locating the tip portion of a dip tube and for guiding the tube for movement between a first operative position in which the tube aspirates a charge of liquid from a sample container and a second position in which said tube will discharge said liquid into a reaction vessel such as a transfer disc. The wiper includes means for receiving a supply of absorbent wiping material in ribbon form, and a spool for taking up the ribbon, as well as means defining a path along which said ribbon will move between the supply means and the takeup spool. A pair of pins or the like are spaced closely apart from said tip and adapted to urge said ribbon into wiping contact with said tip. The takeup spool is driven in response to movement of the locating and guiding arms.

Abstract: A variable volume, positive displacement pump apparatus for withdrawing samples of liquid from a reservoir and discharging them into a sample analyzer. In the preferred form of pump, two syringe assemblies are provided, each one having a movable plunger assembly and a valve unit associated therewith. The plunger assemblies are reciprocated by engagement thereof by a motor driven, reciprocable carriage assembly which includes a cross member for pushing selected metering rods upwardly against the plungers. The carriage also includes a pair of yokes to engage the plungers and pull them downwardly to aspirate the specimens. Valve movement is achieved by a gear drive which moves the valve between one position which enables the syringe to be filled and another position enabling the syringe contents to be discharged. The volume displaced with each stroke is determined by the length of the metering rod inserted between the carriage and the syringe plunger.