Measuring and testing – Sampler – sample handling – etc. – Automatic control
Patent
1994-07-05
1996-02-06
Raevis, Robert
Measuring and testing
Sampler, sample handling, etc.
Automatic control
G01N 100
Patent
active
054888743
DESCRIPTION:
BRIEF SUMMARY
DETAILED DESCRIPTION OF THE INVENTION
Industrial Field of Utilization
The present invention relates to a liquid aspirating method and more particularly to a liquid aspirating method which is used in a pipetting apparatus for pipetting a high-viscosity liquid such as a red blood cell component or the like.
PRIOR ART
Various kinds of tests are conducted on a blood sample collected from a human body. For example, in a blood type test, as shown in FIG. 10, a collected blood sample 10 is put into a test tube 12 and is then separated into a blood plasma component 14 and a red blood cell component 16 by centrifuging it or leaving it as it is. Practically, a small quantity of white blood cell component 18 appears between the blood plasma component 14 and the red blood cell component 16. Since the white blood cell component 18 is not relevant to the following description of the present invention, it is not shown in other drawings.
A blood sample pipetting method which is carried out in a conventional pipetting apparatus generally comprises two processes, including a process of pipetting blood plasma and a process of pipetting red blood cells. In the blood plasma pipetting process, the blood plasma component 14 is aspirated through a nozzle tip 20, and then dispensed into a plurality of other recipient containers 22 in a predetermined volume, respectively. In the red blood cell pipetting process, the red blood cell component 16 is aspirated through the nozzle tip 20, and then transferred to a diluting container (not shown) to be mixed with a diluent. Thereafter, the diluted red blood cell component 16 is aspirated again through the nozzle tip 20 and then dispensed into each of a plurality of other recipient containers 24, respectively in a predetermined volume.
Blood type testing reagents (i.e., a reagent for the blood plasma component and a reagent for the red blood cell component) are introduced into the recipient containers 22, 24, respectively.
Then, these recipient containers 22, 24 are conveyed to an agglutination testing apparatus, where agglutination of the samples in the containers 22, 24 are measured optically or visually. On the basis of the results of the measurements, A type, B type, 0 type or AB type, or Rh type, or the like is determined.
FIG. 11 shows schematically a construction of an aspirating section of a conventional pipetting apparatus. To the nozzle tip 20, a pump 104 for producing an aspirating force and a dispensing force is connected via an air hose 102. The pump 104 includes a syringe 106 and a piston 108. By moving the piston 108 upwardly and downwardly, an inside volume of the syringe 106 varies, and this inside volume variation is transmitted to the nozzle tip 20 via the air hose 102 to generate the aspirating force or the dispensing force. The aspirating volume (or dispensing volume) is determined, depending on a moving amount of the piston 108.
FIG. 12 shows a general relationship between a time elapsed after starting of movement of the pump 104 and a pressure in an aspirating system detected by a pressure sensor 110.
As shown in FIG. 12, in case where the piston 108 has been moved by a predetermined distance within a pump moving time, characteristics of the pressure change depending on the viscosity of the blood sample to be aspirated. When a predetermined aspirating pressure is produced by the pump 104 to aspirate a predetermined volume of the blood sample, a waiting time becomes longer in accordance with increase of the viscosity of the liquid sample. As well known, the red blood cell component is a high-viscosity liquid (or a gel-like substance). So, when aspirating the red blood cell component through the nozzle tip 20, the aspiration volume does not follow the moving amount of the piston 108 quickly. After a predetermined time lapses after the aspiration starts, a predetermined volume of the liquid sample is aspirated. The predetermined time, i.e. the waiting time becomes longer with the increase of the liquid viscosity.
PROBLEMS TO BE SOLVED BY THE INVENTION
As aforem
REFERENCES:
patent: 4083363 (1978-04-01), Philpot, Jr.
patent: 4675301 (1987-06-01), Charneski et al.
patent: 4893515 (1990-01-01), Uchida
Bielarczyk Gregory A.
Katagi Hitomi
Kato Yuko
Kawanabe Junichi
Magee Rosie L.
Abbott Laboratories
Bach Mark C.
Raevis Robert
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