Patent ID: 7964160

Claim:
A method for accepting and rejecting a sample pipetted by a pipetting apparatus, comprising the following steps: a) providing a pipetting apparatus comprising: a pipette tip for aspirating and dispensing a liquid sample, a pump, connected to the pipette tip by a pump conduit, for generating negative pressure or positive pressure in the pipette tip, a fluid chamber defined by the pipette tip and/or the pump conduit, a pressure sensor functionally connected to the fluid chamber for measuring pressure changes in this fluid chamber during a pipetting process, and a device control system with a processor and an activatable computer program product, which, when activated, enables the control system to individually accept or reject pipetted liquid samples on the basis of the pressure changes measured; b) providing model parameters selected from a group comprising properties of liquid samples and instrument properties of the pipetting apparatus for generating a simulated curve using a mathematical model, wherein said model parameters are stored by the processor and are selectable and modifyable, c) selecting at least one model parameter from the group comprising: volume of fluid to be pipetted, and type of the pipette tip to be used, and entering the selected model parameter(s) in the processor: d) generating a simulated curve for a pipetting process by the activated computer program product using a mathematical model, said simulated curve simulating a pressure characteristic curve for a pipetting process as recordable by the pressure sensor, wherein the simulated curve is generated based on the model parameters as stored in the processor; e) storing the simulated curve by the processor; f) pipetting a liquid sample with the pipetting apparatus; g) measuring the pressure changes in the fluid chamber during the pipetting process using the pressure sensor; h) generating an actual measured pressure curve of the pipetting process by the processor; i) approximating the simulated curve to the actual measured pressure curve by systematically selecting and varying modifyable model parameters using the computer program product, thereby generating an iterative curve, wherein tolerance ranges for the model parameters are defined, within which these model parameters may vary; j) comparing the iterative curve with the actual measured pressure curve using the activated computer program product by analyzing deviating sections within the actual measured pressure curve that deviate from respective sections of the iterative curve; and k) accepting or rejecting the pipetting process based on the deviations in view of defined threshold values using the activated computer program product and the processor of the device control system, and thereby accepting or rejecting the pipetted liquid sample.