JPH0136905B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a separation member in a separation tube for centrifuging a liquid containing at least two components.

[Conventional technology]

Such a separating member has a top surface and a bottom surface and is made of a non-elastic material, in particular a non-elastic plastic material, with a specific gravity intermediate to that of the components to be separated from each other, and which, when the separating tube is at rest, is located inside the separating tube. Seal the cross section.

Such separation tubes are
It is already known from No. 2711336. In that patent application, a substantially cylindrical polystyrene separation member is placed within a plastic separation tube. During the centrifugation process, the diameter of the separation tube is slightly enlarged due to compression, but the separation element made of hard plastic does not change its shape. Therefore, an annular gap is created between the separation member and the inner wall of the separation tube, and the separation member moves toward the bottom of the separation tube due to the action of centrifugal force. The lighter component passes through the annular gap and the separating member is carried by the heavier component. Once the centrifugation process is complete,
the inner wall of the separation tube and the separation member are closely engaged again;
The annular gap is closed. As a result, complete separation of the two components is achieved and maintained.

[Problem to be solved by the invention]

A disadvantage of the known separation tubes is that glass tubes cannot be used as separation tubes, since materials that cannot expand radially during the centrifugation process cannot be used as the material for the separation tubes.

It is an object of the invention to improve the known separation element in such a way that a gap is formed between the separation element and the separation tube wall during centrifugation, whether the separation tube is made of glass or of plastic material. It is to be.

[Means to solve the problem]

According to the present invention, the object is to provide a separation member disposed in a separation tube for centrifuging a liquid containing at least two types of components having different specific gravity from each other, the specific gravity of which is lower than the specific gravity of each of the two types of components. made of a material of intermediate value and whose stiffness is comparable to that of glass, and having a cross section that is the same shape and size as the inner cross section of the separation tube in its rest state; and is arranged within the separation tube such that the cross section is oriented perpendicular to the longitudinal central axis of the separation tube to occupy the inner cross section in the resting state, and the center of gravity is located along the longitudinal axis in the resting state. an outer shape that is eccentric from a central axis and that allows the separation member to tilt about an axis perpendicular to the longitudinal central axis due to acceleration applied along the longitudinal central axis during centrifugation of the separation tube, This is achieved by the separating member having an outer shape whose projected shape with respect to the longitudinal center axis is smaller than the cross section after the separating member is tilted.

[Effect]

The separation member of the present invention has a specific gravity of 2 to be centrifuged.
It is made of a material that has a value intermediate between the specific gravity of each component of the seed and has a stiffness comparable to that of glass, and has a cross section that is the same shape and size as the inner cross section of the separation tube in its resting state. The cross section is arranged perpendicular to the longitudinal center axis of the separation tube so as to occupy the inner cross section of the separation tube in the stationary state, and the center of gravity is located perpendicular to the longitudinal center axis of the separation tube in the stationary state. It is eccentric and has an external shape that can be tilted about an axis perpendicular to the longitudinal central axis of the separation tube during centrifugation and after tilting, the projected shape with respect to the longitudinal central axis of the separation tube is smaller than the cross section. Therefore, whether the separation tube is made of glass or of plastic material, the separation member can simply tilt during centrifugation, forming a gap between the inner wall of the separation tube and the separation member; The lighter of the two components can be moved from below to above the separation member.

That is, during centrifugation, the separating member is tilted such that its center of gravity moves towards axis M. When the separation tube is made of glass, the separation member contacts the inner wall of the separation tube at two opposite points on the diameter of its cross section and is inclined, forming two crescent-shaped gaps through which the components to be separated pass. . When the separating tube is made of plastic material, in addition to the conventional gap caused by the radial expansion of the separating tube, the separating member is interrupted at two opposing points on or slightly offset from the diameter of the cross section. The two crescent-shaped gaps are tilted in contact with each other to form two crescent-shaped gaps.

The preferred external shape of the separating member of the present invention is an oblique truncated cone. In this case, the top surface of the oblique truncated cone provides the above-mentioned cross section, and the maximum diameter D ₁ at the top surface is equal to the oblique truncated cone. It is twice as large as the minimum diameter D ₂ at the bottom surface, and these top and bottom surfaces are
Preferred are oblique truncated cones connected by generatrixes perpendicular to both their top and bottom surfaces. The outline of such a separation member including the generatrix when viewed from the side is trapezoidal, so that the aforementioned cross section is aligned with respect to the longitudinal central axis M of the separation tube in order to occupy the inner cross section of the separation tube in a stationary state. When placed vertically, the center of gravity is the axis M
eccentric to

Therefore, during centrifugation, the center of gravity of this separating member is aligned with the axis M.
The separation member moves in the separation tube with an inclination toward , but when the inclination reaches a certain angle, one point on the bottom comes into contact with the separation tube wall, thereby preventing the separation member from overturning.

The external shape of the separation member of the present invention includes, in addition to the oblique conical truncated cone, a disk top portion having a circular top surface, and a disk top portion that is integrally connected to the disk top portion on the opposite side of the circular top surface. a columnar section extending perpendicularly to the column and having a cross section smaller than the circular top surface to allow the separation member to tilt; A preferred shape is a partition wall portion integrally connected to both the circular top portion and the columnar portion on the opposite side of the top surface and extending along the columnar portion. Therefore, in this separation member, the circular top surface is the above-mentioned cross section, and during centrifugation, this separation member moves in the separation tube with an inclination such that the center of gravity moves toward the axis M, but the inclination is When a certain angle is reached, one point of the partition wall comes into contact with the separation tube wall, thereby preventing the separation member from overturning. In this case, the surface of the disk top opposite to the circular top surface is preferably sloped toward the bottom surface of the column, so that no air is trapped below the disk top.

In addition to the external shape described above, the separating member of the present invention preferably has a conical shape with a spherical bottom surface. In this case, the height of the cone engaged with the base of the spherical crown is more preferably smaller than 1/2 of the diameter of the cross section defined by the outer circumference of the base of the spherical crown, so that the apex of the cone during centrifugation is When it is facing upward, the center of gravity is located above the cross section of the separating member, and the centrifugal separation is unstable, so it rotates.
The apex of the cone will point downwards.

The separation member of the present invention is preferably formed at the tip of the piston rod extending in a direction perpendicular to the cross section through a predetermined cutting point. In this case, the separation member can be used as a syringe plunger prior to the centrifugation process.

It is preferable that the separation member of the present invention has at least one buoyancy chamber arranged eccentrically with respect to the axis M when the separation tube is at rest, and that the buoyancy chamber is filled with air before the centrifugation process. The encapsulation facilitates tilting of the separation member. In this case, the buoyancy chamber is more preferably arranged in a region symmetrical to the center of gravity about the axis M, so that the buoyancy force promotes the action of the centrifugal force acting during the rotation of the separating member. Furthermore, the gradient of the walls of the buoyancy chamber is such that the air enclosed in the separation tube in its static state is completely discharged from the buoyancy chamber by the tilting of the separation member during centrifugation, and after the centrifugation process, it enters the region of the boundary layer between the two components. Preferably, it is selected so that no air remains. Such residual air will reduce the efficiency of centrifugation.

As the material for the separation member of the present invention, inelastic plastic materials are preferred, and more specifically polystyrene is preferred.

〔Concrete example〕

The invention will be explained in more detail below on the basis of non-limiting embodiments shown in the accompanying drawings, in which: FIG.

1 to 3 show the state of the separation member 6 at each stage of the centrifugation process. In these figures the separation tube 2 is shown in the horizontal position often used in centrifugation processes. The separation tube 2 is made of plastic material or glass, for example, and is initially fitted with a stopper 4.
is blocked off. A separating member 6 in the shape of an oblique truncated cone having an eccentric center of gravity S is attached to the lower surface of the stopper 4 via a connecting member 8 . The two components or pairs to be separated are indicated by short lines and dots, respectively, where the short lines indicate the liquid phase and the dots indicate a heavier phase, such as a solid phase dispersed in the liquid phase. The connecting member 8 is, for example, an adhesive layer, and the separating member 6 is separated from this adhesive layer by the action of centrifugal force. Separation member 6 in FIGS. 1 to 9
are a top surface 7 and a bottom surface 5 which are parallel to each other and both are circular.
and has. Outer diameter of the circular top surface 7 as a cross section
D ₁ is equal to the inner diameter of the separation tube 2, and the diameter of the bottom surface 5 D ₂
is 1/2 of the top diameter _D1 . Bottom surface 5 and top surface 7
The distance between them corresponds to the height of the separating member, which has a right trapezoidal cross section. In the resting state of FIG. 1, one generatrix of the separation member 6 is located along the wall of the separation tube 2, and is diametrically opposed to the generatrix and has a top surface 7.
A generatrix connecting the bottom surface 5 and the bottom surface 5 reaches the longitudinal center axis M of the separation tube from the inner wall of the separation tube 2. In this state, the top surface 7 therefore occupies the inner cross section of the separation tube 2. Since the separating member 6 has the shape shown below, the center of gravity S is not located within the axis M, but is eccentric to the axis M by an amount e.

The separation member of FIG. 1 further has at least one buoyancy chamber 10 in the half facing the center of gravity S, and in the resting state of FIG. 1, the chamber 10 is filled with air L.

FIG. 2 shows the state after centrifugal force has been applied for a predetermined period of time. The separating member 6 has separated from the connecting member 8, and due to the inclination of the separating member, the two sets are slightly separated through a gap f created between the separating member 6 and the pipe wall. This tilting or rotation of the separating member 6 occurs because the centrifugal force acting at the center of gravity S causes the separating member 6 to rotate in the axis M. At the same time, the buoyant force exerted in the buoyancy chamber acts in the opposite direction of the centrifugal force action, so that a pair of torques is formed, which promote the rotational movement of the separating member 6 in the direction of arrow A. When the separation tube 2 is made of glass, the separation member 6 is supported by the inner wall of the separation tube 2 at two diametrically opposed points on the top surface 7 during tilting or rotation. These points are the intersections of the normal plane passing through the axis M on the cross section of the figure and the circumference of the top surface 7. In addition, when the separating tube 2 is made of plastic material, the separating tube 2 expands slightly during tilting or rotation, so the separating member 6 has two opposing points on the diameter of the top surface 7 or slightly deviated from the diameter. It is intermittently supported by the inner wall of the separation tube 2. In this case, the gap f becomes slightly larger than when the separation tube 2 is made of glass.

As the centrifugation process further progresses, the lighter phase passes through the separating member 6 sliding towards the bottom of the tube and eventually floats on top of the heavier phase as shown in FIG. When the separation member 6 is immersed in the heavier phase, it is subjected to buoyancy, so
By rotating in the opposite direction and returning to the initial position, the bottom surface 7, which is a cross section, occupies the inner cross section of the separation tube 2, thereby sealing the inner cross section of the separation tube 2. The air L that was enclosed in the buoyancy chamber 10 before the centrifugation process is completely exhausted during the centrifugation process, so that no restoring buoyancy force acts on the heavy phase in the final position of FIG. Furthermore, no air is enclosed in the buoyancy chamber 10, which would have an adverse effect on the heavy phase.

The separating member 6 can be made of any material, in particular a plastic material, whose stiffness is comparable to that of glass. The member may be solid or hollow and may be filled with a weighted material. The buoyancy chamber 10 is a separation member 6
It can open toward the circumference. According to another construction, the buoyancy chamber is sealed and a granular material is accommodated as an additional float element. For blood separation it is preferred to use a lightweight plastic material with the hardness of glass, such as polystyrene. The specific gravity of this material is ~
1.045, lighter than the red blood cell layer, which has a specific gravity of ~1.09.
Slightly heavier than blood or serum layer with specific gravity <1.04 to 1.045.

FIG. 4 shows the operation and position of the buoyancy chamber 10 by means of five positions of the separation member 6 during the centrifugation process. For ease of understanding, five positions are shown in a vertical line within one separation tube 2. In the figure, N is the normal to the separation tube 2 and/or the axis M. The inclination angle of the buoyancy chamber wall with respect to the normal N is α _I - _V , and the inclination angle of the top surface is β _I - _V
Indicated by

Figure 4○

Claims (1)

[Scope of Claims] 1. A separation member disposed in a separation tube for centrifuging a liquid containing at least two components having different specific gravities, the specific gravity of which is between the specific gravities of the two components. is made of a material whose value and stiffness are comparable to that of glass, and has a cross section that is the same shape and size as the inner cross section of the separation tube in its rest state; In the resting state, the cross section is arranged in the separation tube so as to occupy the inner cross section and is oriented perpendicularly to the longitudinal central axis of the separation tube, and the center of gravity is perpendicular to the longitudinal central axis in the resting state. an outer shape that allows the separation member to tilt about an axis perpendicular to the longitudinal center axis due to acceleration applied along the longitudinal center axis during centrifugation of the separation tube; A separation member characterized in that the separation member has an outer shape whose projected shape with respect to the longitudinal center axis is smaller than the cross section after the member is tilted. 2. The separation member according to claim 1, wherein the outer shape is a truncated oblique cone, and the cross section is a top surface of the truncated oblique cone. 3. The diameter of the top surface is twice the diameter of the bottom surface of the truncated cone, and the top surface and the bottom surface are connected by a generating line perpendicular to both the top surface and the bottom surface. The separation member according to claim 2, characterized in that: 4. A disk top having a circular top surface as the cross section, and integrally connected to the disk top on the opposite side of the circular top surface and extending in a direction perpendicular to the circular top surface, and a columnar portion having a cross section smaller than the cross section to allow the separation member to tilt; and a disk top portion on the opposite side to prevent overturning of the separation member during centrifugation of the separation tube. 2. The separating member according to claim 1, further comprising a partition wall part integrally connected to both the columnar part and extending along the columnar part. 5. The separation member according to claim 4, wherein the opposite side is inclined toward the bottom surface of the columnar part. 6. The separation member according to claim 1, wherein the outer shape is a cone with a spherical bottom surface. 7. The separating member according to any one of claims 1 to 3, having a conical top surface. 8. Claims 1 to 7, characterized in that the piston rod is formed through a predetermined cutting point at the tip of the piston rod extending in a direction perpendicular to the cross section.
The separation member according to any one of paragraphs. 9 The cross section has a flat top surface,
9. A separating member according to claim 8, wherein the predetermined cutting point is provided on the flat top surface. 10. The separating member according to claim 8, wherein the separating member has a conical top surface, and the predetermined cutting point is provided at the tip of the conical top surface. 11. The separation member according to claim 8, wherein the separation member has a spherical bottom surface, and the predetermined cutting point is provided on the bottom surface. 12. Claims 1 to 1, characterized in that they have at least one eccentrically arranged buoyancy chamber.
The separation member according to any one of Item 1. 13. A separating member according to any one of claims 1 to 12, characterized in that the material is an inelastic plastic material. 14. A separation member according to claim 13, wherein said inelastic plastic material is polystyrene.