A method for controlling the dispensation of a liquid volume sample when metering amounts of liquid by sucking into a tube, probe or tip a volume of a liquid to be displaced and ejecting the sample to a different vessel. According to the method the metering act is performed normally and the liquid to be metered is, displaced thereafter in a desired vessel. During the metering act and after a desired amount of liquid is sucked into the metering line, a supplementary suction step is performed wherefrom the success of the metering act can be deduced. The pressure function of the supplementary suction step is measured and this function is compared with a calibration function.