Liquid purification or separation – With drip – overflow or content draining feature
Reexamination Certificate
2000-01-19
2001-08-28
Smith, Duane (Department: 1724)
Liquid purification or separation
With drip, overflow or content draining feature
C210S445000, C210S451000, C210S477000, C210S489000, C210S503000, C073S863230, C422S105000
Reexamination Certificate
active
06280621
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a blood filter cartridge for the preparation of a plasma or serum sample from whole blood.
The type or concentration of blood components, such as metabolites, proteins, lipids, electrolytes, enzymes, antigens, and antibodies, is measured, in general, using a plasma or serum sample obtained by centrifuging whole blood. However, centrifuging takes labor and time. Particularly, centrifuging is unsuitable for an urgent case of measuring a small number of samples promptly and in site inspection, because of requiring a centrifuge and electricity. Thereupon, it has been investigated to separate serum from whole blood by filtration.
Several filtration methods using glass fiber filter have been developed wherein whole blood is charged into the glass fiber put in a column from one side of the column, and pressurized or evacuated to obtain plasma or serum from the other side (Japanese Patent KOKOKU Nos. 44-14673, 5-52463, Japanese Patent KOKAI Nos. 2-208565, 4-208856).
However, practical filtration methods capable of obtaining an amount of plasma or serum from whole blood necessary for measuring by an automatic analyzer have not been developed except a part of items, such as blood sugar.
On the other hand, the inventors developed a blood filter cartridge composed of a filter holder and a syringe. The filter holder is composed of a holder body which contains filter material and a cap which is screwed on the holder body. The filter material consists of, e.g. two sheets of glass fiber filter, one sheet of cellulose filter and one sheet of polysulfone microporous membrane (FIG. 1 of EP 785430 A1)
Another blood filter cartridge composed of a holder body and a cap was also developed. The holder body consists of a filtrate receiver located on the upper side and a filter chamber located on the underside. The filter material put in the filter chamber is composed of six sheets of glass fiber filter and one sheet of polysulfone microporous membrane (Example 1 of EP 785012A1).
The inventors further developed various blood filter cartridges, and their patent applications were made (Japanese Patent KOKAI 10-227788, 10-185909, 10-185780, etc.)
SUMMARY OF THE INVENTION
Incidentally, the inventors conceived to use the filtrate receiver of the above blood filter cartridges as a sample cup of analyzers. They found that, when the filtrate receiver of the blood filter cartridge was used as the sample cup, the volume drawn by a suction nozzle of the analyzer varied by sucking bubbles together with the filtrate in the receiver. That is, the space in the blood filtering material, filtrate passages, and the like are filled with air. Upon filtering blood, the air is entrapped in the filtrate, and enters the filtrate receiver as bubbles. The bubbles are stable, and are not extinguished for a considerably long period. Then, the bubbles are sucked together with the filtrate by the analyzer, and cause the short volume of plasma samples.
An object of the invention is to provide a simple and inexpensive means for removing the suction of bubbles contained in the plasma or serum upon sucking a sample for analysis from the filtrate receiver of a blood filter cartridge which filters blood to receive the filtrate which is plasma or serum in the receiver which can be used as a sample cup for an analyzer.
The inventors investigated eagerly in order to solve the above bubble suction problem, and developed a means for collecting bubbles on the periphery by forming a meniscus in the filtrate receiver, or providing a difference in height on the upper end of the filtrate receiver to render the highest position of liquid level on the upper end of the receiver, and thereby, succeeded in avoiding the suction of bubbles.
Thus, the present invention provides a blood filter cartridge which comprises a blood filtering material, a holder containing the blood filtering material and having a blood inlet and a filtrate outlet, and a filtrate receiver for receiving filtrate discharged from the filtrate outlet, has a volume greater than a designed volume of the filtrate, the filtrate receiver has an upper end having a difference in height, or which has a structure for returning the filtrate from the upper end of the filtrate receiver to the filtrate outlet.
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Arai Takaki
Seshimoto Osamu
Yazawa Kenichiro
Fuji Photo Film Co. , Ltd.
Prince Fred
Reed Smith LLP
Smith Duane
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