Device and method for determining the quality of pulsed dispensing of liquid according to the air displacement principle

A pipetting device, comprising:

• a pipetting channel extending along a channel path and filled at least in part with a compressible working gas,
• a pipetting piston accommodated movably in the pipetting channel along the channel path,
• a piston drive, configured for impelling the pipetting piston to move along the channel path in order to modify the pressure of the working gas in the pipetting channel by means of piston motion,
• a control device, configured for actuating the piston drive,
• a data memory linked with the control device so as to allow signal transmission,
• a pressure sensor that acquires the pressure of the working gas and that is linked with the control device so as to allow signal transmission,
• a piston position sensor that acquires a position of the pipetting piston and that is linked with the control device so as to allow signal transmission,
• where the control device is configured for impelling the pipetting piston to a pulsed dispensing motion for single-volume dispensing of a single volume of not more than 1 μl, where through the dispensing motion for single-volume dispensing, which dispensing motion for each single-volume dispensing comprises two motion sections in opposite directions along the channel path, an overpressure pulse is generated in the working gas for a duration not exceeding 50 ms,
• wherein the control device is configured to determine for a specified dosing liquid a quality of a dispensing sequence, which comprises at least one pulsed single-volume dispensing run, on the basis of
• a target residual quantity value, which represents a target residual quantity of dosing liquid remaining in the pipetting channel at the end of the dispensing sequence,
• a working gas pressure after the end of the dispensing sequence, and
• an end position of the pipetting piston after the end of the dispensing sequence and to output the determined quality discernibly.