A method of detecting aspiration pressure during aspiration of a liquid (107R, 108S), comprising: attempting to aspirate a volume of a liquid (107R, 108S) into a probe wherein the attempted aspiration generates an aspiration frequency over an aspiration cycle and the total aspirated volume is less than 10 μL; measuring an aspiration pressure associated with the attempted aspiration of the liquid (107R, 108S) and providing a measured pressure signal; characterized in that the method further comprises: determining the aspiration frequency in the measured pressure signal and a dominant resonant frequency in the measured signal, filtering the measured pressure signal with a filter (136, 132) having a passband containing the aspiration frequency and attenuating frequencies of the disturbance causing noise in the measured pressure signal by setting a cutoff frequency between the aspiration frequency and the dominant resonant frequency wherein the passband contains frequencies in the range of 1Hz to 20Hz, to obtain a filtered pressure signal; and verifying at an evaluation point (355, 572, 678, 782) of the filtered pressure signal the effectiveness of the aspiration by comparing the filtered pressure signal to a pre-established threshold value at the evaluation point. attempting to aspirate a volume of a liquid (107R, 108S) into a probe wherein the attempted aspiration generates an aspiration frequency over an aspiration cycle and the total aspirated volume is less than 10 μL; measuring an aspiration pressure associated with the attempted aspiration of the liquid (107R, 108S) and providing a measured pressure signal; characterized in that the method further comprises: determining the aspiration frequency in the measured pressure signal and a dominant resonant frequency in the measured signal, filtering the measured pressure signal with a filter (136, 132) having a passband containing the aspiration frequency and attenuating frequencies of the disturbance causing noise in the measured pressure signal by setting a cutoff frequency between the aspiration frequency and the dominant resonant frequency wherein the passband contains frequencies in the range of 1Hz to 20Hz, to obtain a filtered pressure signal; and verifying at an evaluation point (355, 572, 678, 782) of the filtered pressure signal the effectiveness of the aspiration by comparing the filtered pressure signal to a pre-established threshold value at the evaluation point. determining the aspiration frequency in the measured pressure signal and a dominant resonant frequency in the measured signal, filtering the measured pressure signal with a filter (136, 132) having a passband containing the aspiration frequency and attenuating frequencies of the disturbance causing noise in the measured pressure signal by setting a cutoff frequency between the aspiration frequency and the dominant resonant frequency wherein the passband contains frequencies in the range of 1Hz to 20Hz, to obtain a filtered pressure signal; and verifying at an evaluation point (355, 572, 678, 782) of the filtered pressure signal the effectiveness of the aspiration by comparing the filtered pressure signal to a pre-established threshold value at the evaluation point.