Patent ID: 8551788

Claim:
A method of selecting pipetting parameters of a pipetting device for a dispense of a specific volume of a liquid sample drawn in during aspiration, wherein the pipetting device comprises a fluid chamber which is pneumatically connected to a measuring chamber, a fluid column being situated in the fluid chamber, wherein the internal pressure of said measuring chamber is monitored using a pressure transducer, and wherein at least a first part of the fluid chamber is brought into fluid connection with a sample of the liquid by immersion of a pipette tip, the method comprising: a) setting the fluid column into oscillation by a sudden movement in relation to the liquid sample at the beginning of the aspiration, b) monitoring pressure with the pressure transducer in the measuring chamber, which is pneumatically connected to the fluid chamber, during the aspiration, wherein pressure changes generated during the aspiration are recorded and converted into measuring signals, c) said measuring signals being processed by a computer or micro-processor and reproduced as a pressure curve, d) said pressure curve being characterized by the pressure course during the transient oscillation of the fluid column at the beginning of the aspiration, and during the aspiration, e) comparing the measured pressure curve, which is characteristic for the fluid column with the aspirated liquid sample, with known pressure curves, f) based on the comparison of step e), selecting pipetting parameters of the pipetting device for the dispense of the specific volume of the liquid sample drawn in during the aspiration, wherein selectable pipetting parameters comprise at least a speed of a movement of a pump piston of the pipetting device, and g) dispensing the specific volume of the liquid sample drawn in during the aspiration using the pipetting device with the selected pipetting parameters of step f).