Apparatus and process for taking up and letting out a liquid

摘要

The accuracy of measurement of an apparatus for taking up and letting out liquid is improved by eliminating the influence of changes in atmospheric pressure and of the internal pressure on the volume of an amount of liquid taken up or let out. A pipetting apparatus (1) sucks in a specified amount of liquid into a tip section (10) or lets a specified amount of liquid out of the tip section (10) by controlling the internal pressure of a cylinder section having a cylinder (11) and a piston (12). A preset control value, for the volume of liquid to be taken up or let out, from a command section (5) and information from an atmospheric pressure-measuring section (3) and a pressure sensor (17) for determining the internal pressure of the cylinder (11) are passed to a correction calculation section (4) which in turn performs a correction calculation based on the measured data for the atmospheric and internal pressure and on the data for the shapes of the cylinder (11) and the tip section (10) in order to obtain the distance through which the piston (12) must move so that the preset control value from the command section (2) is attained. A control region (5) controls a motor as a drive device for the piston (12) in accordance with information, concerning the path through which the piston (12) must travel, from the correction calculation section (4). <IMAGE>