Abstract: A pipetting apparatus is provided with clot detection. The pipetting apparatus comprises a nozzle for aspirating a sample. A pressure sensor is connected with the nozzle for measuring pressure in said nozzle. A plurality of pressure difference calculating circuits are operatively connected with the pressure sensor, each for inputting an output of said pressure sensor and obtaining a pressure difference at a different pressure calculation period, respectively. A plurality of discriminating circuits each having a different discrimination threshold value determined according to each of the pressure calculation periods are provided. An alarm circuit is included for outputting a clot detection alarm signal when at least one of said discriminating circuits discriminates that the obtained pressure difference exceeds the discrimination threshold value.

Abstract: The present invention aims to shorten an aspiration time, when aspirating a red blood cell component of a liquid sample having high viscosity. When aspirating the red blood cell component of a blood sample through a nozzle tip, a piston is pulled at its maximum to produce a maximum aspirating force, and starts aspiration. When a pressure in an aspirating system becomes equal to a predetermined value .alpha., the piston is returned to a position in which only a necessary aspiration volume of the liquid sample can be aspirated. Since the maximum aspirating force of the pump is utilized during the aspiration, the aspirating operation can be carried out more quickly.

Abstract: The presence of air bubbles is detected during a dispensing of samples for determining if the volume of the sample dispensed is insufficient.The characteristic of a presence-of-bubbles curve (101) has a difference in a pressure inside a nozzle from the characteristic of a curve (100) under a normal condition in which no bubbles exist, at the time just before the dispensing of the sample is completed. Accordingly, it is possible to determine whether or not bubbles exist by detecting the pressure inside the nozzle at the determination time (105) and comparing the detected value with an established threshold value, and it is determined that an insufficient volume of sample has been dispensed, thereby a warning is generated.

Abstract: In pipetting a blood plasma component and a red blood cell component separated vertically in a blood sample by a centrifugation, the red blood cell component having a high viscosity is aspirated as quickly as possible. A nozzle 32 is composed of a nozzle base 35 and a disposable tip 36, and is transferred upwardly and downwardly and to the right and left by an XYZ robot 34. At first the blood plasma component in the blood sample put in a test tube 62 is pipetted by a nozzle 32, and then an inner wall of the disposable tip 36 is coated with the blood plasma component, and thereafter the red blood component is pipetted.