JP2001046915A - Precipitation tube for centrifugal separation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constantly and surely suck a lower layer liquid to a dispensing nozzle from a two-liquid phase system separated into an upper layer liquid and the lower layer liquid by centrifugal force. SOLUTION: This precipitation tube is provided with a bottomed tubular vessel body 10 opened at the upper face, an inner tube 12 having smaller outside diameter than the inside diameter of the vessel body, formed tubular and inserted into the inside of the vessel body so that the lower end is located near the bottom surface of the vessel body, a restricting plug 28 engaged freely detachably with the lower end part of the inner tube to plug liquid tightly the lower end port of the inner tube and easily falling off from the lower end part of the inner tube by downward pressure and a cap 14 formed between the inner peripheral surface of the vessel body and the outer peripheral surface of the inner tube and for tightly closing a centrifugal separation chamber. In such a case, the lower surface side of the restricting plug is controlled to fall down to either of left or right when the restricting plug falls off from the lower end part of the inner tube and reaches the inner bottom surface of the vessel body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal sedimentation tube used for separating a liquid mixture that can be separated into two or more liquid phases by using a centrifugal force due to a difference in specific gravity. (Hereinafter referred to as “centrifuge tube”).

[0002]

2. Description of the Related Art For example, when measuring the concentration of a drug contained in serum, the drug in the serum is extracted with chloroform. In this case, a buffer is added to the serum, and chloroform is further added. After sufficiently shaking the mixed solution, the mixed solution is immediately separated into an aqueous phase (upper liquid) and a chloroform phase (lower liquid) using a centrifuge, and a predetermined amount of the chloroform phase is weighed. Like that. As described above, when a mixed solution that can be separated into two liquid phases using a centrifugal separator, for example, a mixed solution of water and an organic solvent is separated into an upper liquid and a lower liquid by a difference in specific gravity, the distance is large. A sink tube is used. A conventional centrifuge tube is composed of a tubular container body having an open upper surface, and a cap for closing the upper surface opening of the container liquid-tightly. To separate the mixed solution into an upper layer solution and a lower layer solution using the centrifuge tube, pour the mixture solution into the container body, fit the cap tightly into the upper opening of the container body, and then centrifuge the centrifuge. To Thereby, the mixed solution in the centrifuge tube is separated into an upper layer solution and a lower layer solution by a difference in specific gravity. To separate the lower layer liquid from the upper layer liquid and the lower layer liquid separated in the centrifuge tube by centrifugal force, use a syringe,
The entire upper liquid is sucked through the suction nozzle and discharged from the container body.Or, if manual operation is performed, the boundary between the upper liquid and the lower liquid is visually checked using a hole pipettor or pipettor. It is a common practice to remove all of the upper liquid from the container body while leaving only the lower liquid in the container body.

However, in the method in which the upper liquid is sucked through the suction nozzle by a syringe to remove the entire upper liquid from the container body, a liquid flow is generated when the upper liquid is sucked by the suction nozzle, so that a part of the upper liquid is generated. Are mixed with the lower layer liquid, making it difficult to remove only the upper layer liquid.
There is such a problem. In addition, in the manual method using a hole pipettor or the like, when the upper liquid is removed to near the boundary surface of the lower liquid, depending on the type of liquid, a part of the upper liquid easily mixes with the lower liquid, so only the upper liquid is used. However, there is a problem that considerable skill is required to remove from the container body.

Japanese Patent Laid-Open Publication No. Hei 9-285740 discloses a centrifugal tube that solves the above-mentioned problems, as shown in a vertical sectional view of FIG. There is disclosed a centrifugal tube in which a cap 2 for closing a top opening of a container body 1 in a liquid-tight manner is formed by a sealing plug portion 3, an inner cylinder 4, and a closing plug 5. Sealing part 3 of this centrifuge tube
Is inserted into the upper end of the container body 1 and the outer peripheral surface is closely fitted, and a through hole 6 is formed in the center. The inner cylinder 4 has an outer diameter smaller than the inner diameter of the container body 1, and has a cylindrical shape with a lower part gradually formed in a smaller diameter. And is integrated with the sealing part 3. The inner cylinder 4 is formed to have a length such that the lower end is located near the inner bottom surface of the container main body 1 when the sealing plug 3 is closely fitted to the upper end of the container main body 1. The closing plug 5 is inserted upward into the lower end of the inner cylinder 4 to close the lower end of the inner cylinder 4 in a liquid-tight manner. The closing plug 5 is easily dropped off by a downward pressing force, that is, a force pressed downward by the lower end of the dispensing nozzle or the pipettor.

In the centrifuge tube shown in FIG. 4, after a liquid to be separated by centrifugal force is injected into the container body 1, the inner cylinder 4 of the cap 2 is inserted deeply into the container body 1 and inserted into the liquid. Then, the hermetic plug portion 3 is tightly fitted to the upper end portion of the container main body 1, and is then centrifuged in this state. Thereby, the liquid in the centrifuge tube is separated into the upper liquid 7 and the lower liquid 8 by a difference in specific gravity (see FIG. 5). At this time,
Since the inner cylinder 4 of the cap 2 is inserted into the liquid in the container body 1 and its lower end is located near the inner bottom surface of the container body 1, the lower end of the inner cylinder 4 is liquid-tightly closed and the upper layer is closed. It is located below the boundary surface between the liquid 7 and the lower liquid 8, and the vicinity of the lower end of the inner cylinder 4 is in a state of being inserted into the lower liquid 8. To extract only the lower layer liquid 8 from the centrifuge tube in such a state, FIG.
Dispensing nozzle (or disposable tip (disposable tip) forming the lower end of dispensing nozzle) as shown in
Or pipettor (hereinafter referred to as "dispensing nozzle 9")
Is inserted deeply into the inner cylinder 4 through the through-hole 6 of the sealing plug 3 of the cap 2, and the lower end of the dispensing nozzle 9 presses the closing plug 5 at the lower end of the inner cylinder 4 downward. This allows
The closing plug 5 closing the lower end of the inner cylinder 4 falls off, and the lower end of the dispensing nozzle 9 is inserted into the lower liquid 8. Thereafter, when the syringe is driven to suck the liquid into the dispensing nozzle 9,
Since the lower end of the dispensing nozzle 9 is inserted into the lower liquid 8, only the lower liquid 8 is sucked into the dispensing nozzle 9.

[0006]

However, in a centrifuge tube as shown in FIG. 4, after the liquid is separated into an upper liquid 7 and a lower liquid 8, the lower end of the dispensing nozzle 9 is used to lower the lower end of the inner cylinder 4. When the closing plug 5 closing the lower end of the inner cylinder 4 is dropped by pressing the closing plug 5 downward, as shown in FIG. 5, the bottom surface of the closing plug 5 is flat. Therefore, it is settled immediately below the lower end of the inner cylinder 4 and is placed on the inner bottom surface of the container body 1 in the same posture. Therefore, when the dispensing nozzle 9 is inserted until its lower end is close to the inner bottom surface of the container body 1, the lower end surface of the dispensing nozzle 9 comes into close contact with the upper surface of the closing plug 5,
For example, the lower end of the dispensing nozzle 9 is completely closed by the stopper plug 5. As a result, the liquid is not sucked into the dispensing nozzle 9. In particular, the dispensing nozzle 9
This is a significant problem when the operation of sucking the liquid into the dispensing nozzle 9 is automated by driving the pump up and down.

Further, before the centrifuge is applied to the centrifuge, the liquid is injected into the container body 1 and then the inner cylinder 4 is inserted deeply into the container body by inserting the inner cylinder 4 deeply into the liquid. The liquid flows such that the liquid is pushed away by the lower surface of the obturator plug 5 inserted into the lower end of the container. In this case, if the lower surface of the plug 5 is flat as shown in FIG. 4, for example, the boundary surface between the aqueous phase and the chloroform phase (the mixed solution may have a certain degree of two phases even before centrifugation due to a difference in specific gravity. When the lower end of the inner tube 4 passes through the lower end of the inner plug 4, the lower surface of the plug 5 comes into contact with impurities on the boundary surface, and the liquid is centrifuged while the impurities are attached to the lower surface of the plug 5. . When the lower liquid 8 separated by centrifugation contacts the lower surface of the plug 5, the impurities attached to the lower surface of the plug 5 diffuse into the lower liquid to be extracted and analyzed. This happens. For this reason, it has an adverse effect on the instrument analysis.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an inner cylinder having a smaller diameter and a lower end provided inside a container body having a bottomed cylindrical shape having an open upper surface. Separated by centrifugal force in a sealed centrifugal chamber formed between the inner peripheral surface of the container body and the outer peripheral surface of the inner cylinder, having a configuration inserted and held so as to be located near the inner bottom surface of the main body. From the two liquid phase systems or more liquid phase systems, the stopper plug fitted to the lower end of the inner cylinder is pressed downward with the lower end of the dispensing nozzle or pipettor to drop it, and only the lower layer liquid is removed. In the centrifuge tube that enables extraction of the liquid, the lower layer liquid can always be reliably sucked into the dispensing nozzle or pipettor, and after the liquid is injected into the container main body, the inner cylinder is inserted deeply into the container main body. Impurities adhere to the lower surface of the plug during insertion into the liquid , It is an object to be able to prevent such.

[0009]

The invention according to claim 1 is
A container body having a bottomed cylindrical shape with an open upper surface, and a cylindrical shape having an outer diameter smaller than the inner diameter of the container body, the lower end being inserted near the inner bottom surface of the container body near the inner bottom surface of the container body. An inner cylinder held so as to be positioned and a lower end of the inner cylinder is removably fitted to the lower end of the inner cylinder to close the lower end of the inner cylinder in a liquid-tight manner. In a centrifugal tube provided with an obturator plug that falls off to the container, and a sealing unit that seals a centrifugal separation chamber formed between the inner peripheral surface of the container body and the outer peripheral surface of the inner cylinder, To
It is characterized in that the obstruction plug is formed into a shape that falls down to the left or right from the drop position when the stopper plug drops from the lower end of the inner cylinder and reaches the inner bottom surface of the container body.

According to a second aspect of the present invention, in the centrifuge tube according to the first aspect, the lower surface side of the obstruction plug is formed in a conical shape.

According to a third aspect of the present invention, in the centrifuge tube according to the first or second aspect, a liquid-tight member is interposed at the upper end of the inner cylinder at the upper end of the container body or directly. A screw portion is formed on an outer peripheral surface of an upper end portion of the container main body, and the sealing means is mounted on an upper end portion of the container main body and screwed to the screw portion. And a cap formed with a through-hole at the center of the upper surface, and screwing the cap onto the upper end of the container body to form between the inner peripheral surface of the container body and the outer peripheral surface of the inner cylinder. The centrifugal separation chamber is hermetically sealed, and the cap is loosened so that the centrifugal separation chamber communicates with the outside air.

In the centrifuge tube according to the first aspect of the present invention, after the liquid to be separated by centrifugal force is injected into the container body, the inner cylinder is inserted deep into the container body and inserted into the liquid. The centrifugal separation chamber formed between the inner peripheral surface of the inner cylinder and the outer peripheral surface of the inner cylinder is sealed by a sealing means. The centrifuge tube is centrifuged in this state. The liquid in the centrifuge tube is separated into an upper layer liquid and a lower layer liquid by a difference in specific gravity by the centrifuge. At this time, since the lower end of the inner cylinder is inserted into the liquid in the container body and its lower end is located near the inner bottom surface of the container main body, the lower end of the inner cylinder is closed in a liquid-tight manner, and the upper and lower liquids are closed. And the lower end of the inner cylinder is inserted into the lower liquid. In order to extract only the lower layer liquid from the centrifuge tube in such a state, the lower end of a dispensing nozzle (a pipetter or the like when manually operated. In the following, an example in which a dispensing nozzle is used will be described). The plug is inserted deep into the inner cylinder, and the lower end of the dispensing nozzle presses the plug at the lower end of the inner cylinder downward. As a result, the closing plug that has closed the lower end of the inner cylinder falls off, and the lower end of the dispensing nozzle is inserted into the lower liquid. The obstruction plug that has fallen from the lower end of the inner cylinder sinks just below the lower end of the inner cylinder. And the obstruction plug that reached the inner bottom surface of the container body is
Fall to the right. For this reason, even if the lower end of the dispensing nozzle is inserted until it is close to the inner bottom surface of the container body, the lower end of the dispensing nozzle is in close contact with the closing plug and the entire lower end port is closed by the closing plug. Does not happen. Therefore, the lower layer liquid is reliably sucked into the dispensing nozzle.

In the centrifugal tube according to the second aspect of the present invention, the obstruction plug that has fallen from the lower end of the inner cylinder and has reached the inner bottom surface of the container body has a conical bottom surface, so that the left and right sides are conical. Fall down to either. For this reason, even if the lower end of the dispensing nozzle is inserted until it is close to the inner bottom surface of the container body, the lower end of the dispensing nozzle is in close contact with the closing plug and the entire lower end port is closed by the closing plug. Does not happen.

Further, after the liquid is injected into the container body, the inner cylinder is inserted deeply into the container body and inserted into the liquid.
Although the liquid flows so as to be pushed away by the lower surface side of the obstruction plug inserted into the lower end opening of the inner cylinder, since the lower surface side of the obstruction plug is formed in a conical shape, for example, the boundary surface between the aqueous phase and the chloroform phase is formed. When the lower end of the inner cylinder passes through, even if the lower surface of the obturator plug comes into contact with impurities, the impurity flows upward along with the conical lower surface side of the obturator plug together with the liquid, and the impurity flows on the lower surface side of the obturator plug. Does not adhere. Therefore, diffusion of impurities adhering to the lower surface side of the obstruction plug into the lower layer liquid separated by centrifugation is prevented.

In the centrifuge tube according to the third aspect of the present invention, when the liquid is to be centrifuged by the centrifugal separator, the liquid is injected into the container main body with the inner cylinder pulled out from the container main body, The inner cylinder is inserted into the container main body, and then the upper end of the container main body is covered with a cap and screwed. As a result, the flange at the upper end of the inner cylinder is pressed directly or directly against the upper edge of the container body by the peripheral edge of the through hole on the upper surface of the cap with the liquid-tight member interposed therebetween, and the flange of the inner cylinder and the upper end of the container main body The edge is in close contact, and the centrifugal separation chamber formed between the inner peripheral surface of the container body and the outer peripheral surface of the inner cylinder is hermetically and liquid-tightly sealed. When extracting the lower layer liquid from the centrifuge tube after centrifugation, the cap placed on the upper end of the container body is loosened. Thereby, the close state between the flange portion of the inner cylinder and the upper edge of the container body is released, and the gap between the inner peripheral surface of the upper portion of the container body and the outer peripheral surface of the upper portion of the inner cylinder and the flange portion of the inner cylinder are removed. The centrifuge chamber communicates with the outside air through a gap between the upper edge of the container body. Therefore, when the lower end of the dispensing nozzle successively pushes the stopper at the lower end of the inner cylinder downward to drop it off, the lower layer liquid flows into the inner cylinder vigorously due to the gas pressure of the gas phase. The interface between the upper liquid and the lower liquid is disturbed, and a part of the upper liquid mixes into the lower liquid and flows into the inner cylinder together with the lower liquid.
There is no worry about such things happening.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS.

1 and 2 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a centrifuge tube, and FIG. 2 is a perspective view showing the centrifuge tube separated into components. FIG.

The centrifugal tube has a bottomed cylindrical container body 10 with an open upper surface, an inner cylinder 12 inserted into the container body 10, and a cap 14 attached to the upper end of the container body 10. It is configured with such as. A screw portion 16 is formed on an outer peripheral surface of an upper end portion of the container body 10, and a screw portion 18 that is screwed with the screw portion 16 of the container body 10 is formed on an inner peripheral surface of the cap 14. I have. The cap 14 has a through hole 20 formed in the center of the upper surface.
The cap 14 and the inner cylinder 12 are connected to each other and integrated by a connection ring 21 inserted inside the cap 14.

The inner cylinder 12 has an outer diameter smaller than the inner diameter of the container main body 10, and has a lower part formed in a gradually smaller diameter. A flange 22 is formed at the upper end of the inner cylinder 12. When the inner cylinder 12 is inserted into the container main body 10, the flange 22 is connected to the container main body with a liquid-tight member such as an O-ring 24 interposed therebetween. 10 is engaged with the upper end edge thereof so as to be appropriately in close contact. Note that the O-ring 24 does not need to be particularly inserted as long as the flange portion 22 can be in close contact with the upper end edge of the container body 10 as appropriate. By inserting the inner cylinder 12 into the container main body 10, a centrifugal separation chamber 26 is formed between the inner peripheral surface of the container main body 10 and the outer peripheral surface of the inner cylinder 16. Also, inner cylinder 1
2 is inserted into the container body 10, the inner cylinder 12
There is a very small gap between the upper outer peripheral surface of the container body 10 and the upper inner peripheral surface of the container body 10 to the extent that ventilation is possible. The length of the inner cylinder 12 is such that the lower end is positioned near the inner bottom surface of the container main body 10 when the inner cylinder 12 is inserted to the innermost part of the container main body 10.

At the lower end of the inner cylinder 12, a closing plug 28 is inserted upward at the lower end thereof, and the lower end of the inner cylinder 12 is liquid-tightly closed. The closing plug 28 is easily dropped by a downward pressing force, that is, a force pressed downward by a lower end of a dispensing nozzle, a pipettor, or the like. The obturator plug 28 has a conical or pyramidal pyramid on the lower surface.

Next, the operation of extracting the lower layer liquid by centrifuging the liquid using the centrifuge tube having the above configuration will be described with reference to FIG.

First, a mixed liquid to be separated by centrifugal force is poured into the main body container 10 in a state where the cap 14 is removed from the container main body 10 and the inner cylinder 12 is pulled out. For example, when extracting the drug contained in serum with chloroform,
For example, 0.5 cc of serum, 0.5 cc of buffer, and 3.5 cc of chloroform are sequentially injected into the container body 10. Next, after the inner cylinder 12 is inserted deeply into the container body 10 and inserted into the liquid, the cap 14 is put on the upper end of the container body 10 and screwed to the end. Thereby, the inner cylinder 1
2 is formed with a through-hole 20 on the upper surface of the cap 14.
O-ring 24 is provided on the upper edge of container body 10 by the peripheral edge of
It is pressed with interposition. Then, the flange 22 of the inner cylinder 12 and the upper end edge of the container body 10 come into close contact with each other, and the container body 1
The centrifugal separation chamber 26 formed between the inner peripheral surface of the inner cylinder 12 and the outer peripheral surface of the inner cylinder 12 is hermetically and liquid-tightly sealed. The centrifuge tube in this state is shaken to transfer the drug in the serum into chloroform, and then centrifuged. As a result, FIG.
As shown in (a), the liquid contained in the centrifugal separation chamber 26 is separated into an upper liquid (aqueous layer) 30 and a lower liquid (chloroform) 32 due to a difference in specific gravity. At this time, as shown in FIG. 3A, since the lower end of the inner cylinder 12 is located near the inner bottom surface of the container main body 10, the lower end of the inner cylinder 12 has the upper liquid 30 and the lower liquid. 32 is located below the boundary surface 34. Therefore, the vicinity of the lower end of the inner cylinder 12 is in a state of being inserted into the lower liquid 32.

When the centrifugation operation is completed, the centrifuge tube is taken out of the centrifuge, and only the lower layer liquid is extracted from the centrifuge tube by an automatic pipetting device (not shown). For this, first, the cap 14 placed on the upper end of the container body 10 is twisted and loosened. Thereby, the flange 22 of the inner cylinder 12 and the container body 10
The close state between the upper edge of the container body 10 is released, the gap between the inner peripheral surface of the upper part of the container body 10 and the outer peripheral surface of the upper part of the inner cylinder 12 and the flange 22 of the inner cylinder 12 and the upper edge of the container body 10 are removed. The centrifuge chamber 26 communicates with the outside air through the gap between the two. Then, the centrifuge tube in this state is fixed to the mounting portion of the automatic dispensing device.
Subsequently, the dispensing nozzle is lowered by the nozzle drive mechanism,
As shown in FIG. 1, a disposable tip (hereinafter, referred to as “disposal tip”) 36 forming the lower end of the dispensing nozzle is passed through the through-hole 20 of the cap 12 of the centrifugal tube and into the inner cylinder 12. Into the box. Then, as shown in FIG. 3A, the lower end of the disposable tip 36 presses the closing plug 28 at the lower end of the inner cylinder 12 downward, and as shown in FIG. The inner cylinder 12
And the lower end of the disposable chip 36 is inserted into the lower layer liquid 32. At this time, since the centrifugal separation chamber 26 is in communication with the outside air as described above, even if the plug 28 is dropped from the lower end of the inner cylinder 12, the liquid flows into the inner cylinder 12 due to the gas pressure of the gas phase. There is no such thing as a vigorous influx.

The closure plug 28 which has fallen from the lower end of the inner cylinder 12
Is settled immediately below the lower end of the inner cylinder 12 and the stopper plug 28 that has reached the inner bottom surface of the container body 10 falls down to the left or right because the lower surface side is formed in a conical shape. For this reason, as shown in FIG. 3C, even if the lower end of the disposable chip 36 is inserted until it comes close to the inner bottom surface of the container body 10, the closing plug 28 is pushed away by the lower end of the disposable chip 36, or the disposable chip 36 is displaced. When only a part of the lower end surface of the tip 36 comes into contact with the plug 28, the disposable tip 3
It does not occur that the lower end surface of 6 is in close contact with the closure plug 28 and the entire lower end port is closed by the closure plug 28.

Since the lower end of the disposable chip 36 is inserted into the lower layer liquid 32, the syringe connected to the dispensing nozzle is thereafter driven, so that the lower end of the disposable chip 36 passes through the lower end opening of the disposable chip 36. The lower liquid 32 is sucked into the inside. At this time, since the lower end of the disposable chip 36 is not closed by the closing plug 28 as described above, the lower layer liquid 32 is reliably sucked into the disposable chip 36. At this time, the lower end of the disposable chip 36 is located at the boundary 3 between the upper liquid 30 and the lower liquid 32.
4, the upper liquid 30 is not mixed with the lower liquid 32 to cause contamination.

In the above-described embodiment, the inner cylinder 12 and the cap 14 are separated, but the inner cylinder and the cap may be integrated or formed integrally as shown in FIG. Further, in the above description based on FIG. 3, only the lower layer liquid is extracted from the centrifuge tube by the automatic pipetting device, but only the lower layer liquid is extracted manually from the centrifuge tube using a hole pipettor or the like. Of course, it is also possible.

In the above embodiment, the obstruction plug 28
The lower surface side of the stopper plug is formed in a conical shape, but the shape of the lower surface side of the stopper plug is either left or right from the falling position when the stopper plug comes off from the lower end of the inner cylinder and reaches the inner bottom surface of the container body. If it falls down, a shape other than a cone may be used, for example, a bar-shaped projection may be formed at the center of the lower surface of the obturator.

[0028]

When the centrifuge tube according to the first aspect of the present invention is used, a lower layer liquid is dispensed from a two liquid phase system or more liquid phase systems separated into an upper liquid and a lower liquid by centrifugal force. Thus, it is possible to always reliably suck the liquid into the pipette or the pipette, thereby preventing an operation error particularly when the dispensing nozzle is driven up and down to automate the operation of sucking the liquid into the dispensing nozzle.

In the centrifuge tube according to the second aspect of the present invention, since the lower surface side of the stopper plug is formed in a conical shape, the stopper plug that has fallen from the lower end of the inner cylinder and has reached the inner bottom surface of the container body is: Surely fall left or right. Therefore, the above effect of the invention according to claim 1 can be reliably obtained. In addition, in the process of inserting the inner cylinder deeply into the container body after injecting the liquid into the container body and inserting the inner cylinder into the liquid, impurities adhere to the lower surface of the obstruction plug, and into the lower layer liquid to be extracted and analyzed. The diffusion of impurities can be prevented, and the reliability of the instrument analysis result can be improved.

In the centrifuge tube according to the third aspect of the present invention, when the obstruction plug at the lower end of the inner cylinder is pressed downward by the lower end of the dispensing nozzle, pipettor, or the like, and drops off, the lower layer liquid enters the inner cylinder. To surely prevent the influx of vigorous flow, disturb the interface between the upper liquid and the lower liquid, and a part of the upper liquid mixing into the lower liquid side and flowing into the inner cylinder together with the lower liquid. Can be
Only the lower layer liquid can be reliably extracted without causing contamination with the upper layer liquid.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a centrifuge tube according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which the centrifuge tube shown in FIG. 1 is separated into components.

FIG. 3 is a partial vertical cross-sectional view for explaining an operation of separating a mixed liquid into an upper liquid and a lower liquid and extracting only a lower liquid by using the centrifuge tube shown in FIGS. 1 and 2;

FIG. 4 is a longitudinal sectional view showing an example of the configuration of a conventional centrifuge tube.

FIG. 5 is a vertical cross-sectional view for explaining a problem in extracting a lower layer liquid using a conventional centrifuge tube.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Container main body 12 Inner cylinder 14 Cap 16 Screw part of container main body 18 Screw part of cap 20 Through hole of cap 21 Connection ring 22 Flange of inner cylinder 24 O-ring 26 Centrifugal separation chamber 28 Stopper 30 Upper liquid 32 Lower liquid 34 Boundary surface between upper and lower liquids 36 Disposable tip forming lower end of dispensing nozzle

Continuation of front page (72) Inventor Shintaro Nishimura 4-3-34-517 Tsuruno, Settsu-shi, Osaka F-term (reference) 4D057 AA03 AB03 AC01 AC05 AD01 AE11 BA15

Claims (3)

[Claims] 1. A container body having a bottomed cylindrical shape having an open upper surface, a cylindrical shape having an outer diameter smaller than the inner diameter of the container body, and a lower end inserted into the container body and having a lower end. An inner cylinder which is held near the inner bottom surface of the inner cylinder; a lower end of the inner cylinder which is removably fitted to the lower end of the inner cylinder so as to close the lower end of the inner cylinder in a liquid-tight manner; Centrifugal sedimentation tube, comprising: a stopper plug that easily falls off from the lower end of the container; and sealing means that seals a centrifugal separation chamber formed between the inner peripheral surface of the container body and the outer peripheral surface of the inner cylinder. In the above, the lower surface side of the plug is formed in a shape that falls to the left or right from the drop position when the plug falls from the lower end of the inner cylinder and reaches the inner bottom surface of the container body. Centrifuge settling tube. 2. The centrifugal sedimentation tube according to claim 1, wherein the lower surface side of the plug is formed in a conical shape. 3. An upper end portion of the inner cylinder is formed with a flange portion which is in close contact with the upper end edge of the container main body with a liquid-tight member interposed or directly engaged with the upper end portion, and an outer peripheral surface of an upper end portion of the container main body. A screw portion is formed, the sealing means is constituted by a cap having a screw portion which is screwed to the screw portion and is mounted on the upper end portion of the container main body, and a through hole is formed in the center of the upper surface, By screwing the cap onto the upper end of the container main body, the centrifugal separation chamber formed between the inner peripheral surface of the container main body and the outer peripheral surface of the inner cylinder is airtightly sealed, and the centrifugal separation is performed by loosening the cap. 3. The centrifugal sedimentation tube according to claim 1, wherein the chamber is communicated with outside air.