JP3464703B2 - Method and apparatus for automatically injecting a small amount of liquid chromatograph sample - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for automatically injecting a small amount of sample in a liquid chromatograph, and more particularly to a device for automatically injecting a small amount of sample into an injector provided in the liquid chromatograph using a microsyringe.

[0002]

2. Description of the Related Art In recent years, liquid chromatographic analysis has the advantages of cost reduction and environmental pollution without the need for a small amount of eluent, and that even a valuable sample can be analyzed because it requires a small amount of sample. For the same sample amount, it has moved to the analytical size column (internal diameter 3 to 12 mm) ↓ semi-micro size column (internal diameter 1 to 3 mm) ↓ micro size column (internal diameter 1 mm or less) because it has higher sensitivity than the analytical size column. .

However, the peak width (W) of the normal component peak
Is expressed by a formula of W ² = WC ² + WE ² WC: spread within the column WE: spread other than the column (injection part, detector flow cell, other piping), so even if the inner diameter of the column becomes micronized, The influence of the spread outside the column increases, and a sharp peak is often not obtained. That is, it is necessary to pay attention to the spread outside the column as the column inner diameter becomes smaller.

Conventionally, when introducing a sample into a liquid chromatograph, an injector is provided and the sample is manually injected by a microsyringe. However,
Due to the increase in the number of samples and the diversification of samples to be handled, and due to the handling of toxic substances and radioactive substances, automation without human labor is required.

In the conventional autosampler, the diluter system shown in FIG. 8 uses a flow path switching valve 64 for injecting a sample and uses a column 68 in an oven 67.
Was injecting the sample into.

However, in this method, the pipe 62 between the cylinder 65 and the flow path switching valve 64 is lengthened to increase the dead volume, which promotes the waste and diffusion of the sample. Since the cylinder 65 is used for measuring a large volume of the cleaning liquid in addition to the sample, the capacity of the cylinder 65 is inevitably large, and the measuring accuracy is reduced accordingly, and an injection error is likely to occur, resulting in good reproducibility. There was a problem that I could not get the data.

In particular, when a microcolumn or the like which requires a minute amount of injection is used, the injection amount becomes 1 μl or less,
It has been very difficult to obtain the absolute amount of injection and the reproducibility.

Further, since the flow path switching valve 64 is outside the oven 67, the pipe 61 up to the column 68 becomes long, resulting in diffusion of the sample. In addition, since the flow path switching valve 64 is cold and the column 68 is warm, a thermal gradient can be formed between the flow path switching valve 64 and the column 68 and inside the column 68, thereby promoting diffusion of the sample. There will also be a problem.

Therefore, the flow path switching valve 64 is the oven 6
Must be in or in contact with 7.

For the above reasons, the conventional diluter system cannot support semi-micro and micro LC.

In order to cope with the above situation, there has been proposed a sample injection device which automates the conventional manual operation of measuring with a microsyringe and injecting a sample. (JP-A-5-188048)

In the apparatus, when the rotor rotates, the movable plate holding the injector main body is moved by the drive mechanism at the same time, and the rotation of the rotor is offset by the movement of the movable plate, and the absolute position of the sample injection port with respect to the fixed base is adjusted. The rotor is rotated around the sample inlet without turning the sample inlet without changing.

Normally, a plurality of flow paths are formed in the injector body, and normally six pipes are formed so that the circuit can be switched to a liquid chromatograph or the like. When the injector main body rotates and rotates each time the valve is switched as in the present invention, the piping itself naturally moves at the same time.

[0014]

However, the pipes move,
Alternatively, having to move means making the tubing more tolerant and lengthening the tubing connected to the column in the oven. The longer the pipe, the larger the diffusion of the sample, so it cannot be used for semi-micro and micro LC.

Therefore, in order to support semi-micro and micro-LC, it is necessary to scale down the flow rate, the pipe diameter, the detection cell capacity, etc. Therefore, it is necessary to maintain the sample at a low diffusion and reproducibility of the injection amount. It is required that the injection valve can be easily installed inside the thermostatic chamber, the temperature of the sample can be controlled, and a series of operations can be automated.

To this end, the sampler is an autosampler which moves between the sample storage container and the injector and sucks and injects the sample, and the piping is short, so that the diffusion of the sample can be suppressed.
Moreover, the valve must be placed in a constant temperature bath. Then, as a configuration that satisfies these configurations, it is necessary to make the microsyringe correspond to the injection valve.

[0017]

[Means for Solving the Problems] Therefore, in order to satisfy the general requirements, the present invention firstly uses an injection valve having an eccentric port, and after inserting a microsyringe directly into the injection valve, the injection valve is switched. At the same time, the microsyringe holder is swung following the switching operation to introduce the tip of the microsyringe into the sample supply section .
A system with a syringe holder that holds a black syringe
The fringe carriage can be moved up and down, and the micro cylinder
Insert into injection valve with eccentric port
Freely and support the syringe carriage on the fixed plate.
Acceptable and rotatable, injection valve rotating machine
Interlocked with the injection valve that is rotated through the structure
Rotate the syringe holder provided on the syringe carriage.
The microsyringe held in the syringe holder
It is characterized in that the tip of the can be freely introduced into the sample supply section .

[0018]

The present invention will be described below with reference to the drawings showing the embodiments. A syringe carriage block 1 is movable in the X-axis 2 and Y-axis 3 directions. That is, the syringe carriage block 1 is provided with the rotating wheels 4 and 4 extending from the syringe carriage block 1.
Is placed on a guide 6 provided on a base 5 in the Y-axis 3 direction, and a Y-axis belt 8 suspended on pulleys 7, 7 provided on the base 5
It is supported by a belt fixing tool 9, one end of which is fixed.

A motor 10 is provided on the Y-axis block 11, and the Y-axis block 11 has the base 5 fixed thereto, and is mounted or straddled on the X-axis guide 12 so as to run freely. Thirteen
Is a belt which is passed between the pulleys 14 and 14 and fixes the Y-axis block 11. The pulley 14 is rotatable by a motor shaft 15 of a motor (not shown).

Reference numeral 16 denotes a chassis of the syringe carriage block 1 , which is formed in a substantially U shape, and can be rotated by a follow-up shaft 18A, 18A via bearings 18, 18 above and below a fixed plate 17 formed in the same manner. Is pivoted to.

A shaft 19 is provided at one end of the fixed plate 17, and a syringe carriage 20 is rotatably supported on the outer shaft 19. On the other hand, the other end of the syringe carriage 20 is engaged with the timing belt 22 by the pulling metal fitting 21 fixed thereto.

The timing belt 22 is suspended between pulleys 25, 25 supported by shafts 23, 23 provided on the chassis 16 via bearings 24, 24. Axis 2
One of the elements 3 is connected to the Z-axis motor 52 to drive the timing belt 22.

Therefore, the syringe carriage 20 has a shaft 19
It is possible to move within a range where the timing belt 22 is loosened around. In addition, the syringe carriage 20 has a shaft 27 in which an insertion portion 26 provided in a part thereof is provided in the fixed plate 17.
It is inserted through.

Reference numeral 28 denotes a syringe holder, which is constructed so as to project to one side of the syringe carriage 20 and hold a syringe 29. As an example of such a structure, one in which the upper edge of the syringe 29 is inserted between two plate bodies and an insertion hole for holding the cylindrical portion of the syringe 29 is formed below the plate body is used.

Reference numeral 30 denotes a plunger which can be inserted and supported by a plunger holder 31. The plunger holder 31 is fixed to a timing belt 34 suspended between pulleys 32 and 33 provided on the syringe carriage 20 , and the pulley 32 is connected to a plunger drive motor 35 such as a stepping motor. Further, the timing belt 34 is provided with a projecting piece 37 that comes into contact with a detector 36 such as a limit switch. Plunger holder 31,
A timing belt 34, a pulley 32 for suspending it,
32, the plunger operation by the plunger drive motor 35
It constitutes the dynamic mechanism .

Reference numeral 38 denotes an injection valve, and a valve shaft 40 formed in the valve body 39 is provided with a rotor 42 having a needle port 41 in contact with the ceramic stator 43. Reference numeral 44 denotes an arm, and one end of a link 46 is fitted and inserted into a link pin 45 provided on the arm. The rotor 42 and the ceramic stator 43 form a sample supply unit.

Further, a hooking pin 47 is provided on the arm 44 so as to project therefrom, and the hooking pin 47 is arranged at a position where the hooking plate 48 hangs from the syringe carriage 20 . The other end of the link 46 is pivotally supported 51 on a plate 50 fixed to a rotating shaft of a motor 49.

Next, the operation will be described. The syringe carriage 20 is moved by moving the syringe carriage block 1 in the X-axis 2 and Y-axis 3 directions. That is, the syringe carriage block 1 rotates the belt 13 by the drive of the motor shaft 15 and the X-axis guide 1 via the base 5.
2, while the Y-axis motor 10 rotates to rotate the Y-axis 3 via the belt fixture 9 provided on the Y-axis belt 8.
It can be moved in the direction.

The syringe carriage 20 on the syringe carriage block 1 also moves at the same time, and the syringe 2
9 moves. By this operation, a large number of syringes 29 are moved on a sample bottle or the like installed below, and when a desired sample is selected, it can be positioned on the sample.

Then, when the Z-axis motor 52 is started, the timing belt 22 is driven via the shaft 23 and the bearing 24. At this time, the tow metal fitting 21 is lowered to insert the insertion portion 2
6 is guided by the shaft 27 and the syringe carriage 20
Goes down.

The syringe 29 held by the syringe holder 28 provided on the syringe carriage 20 also descends, and the needle 53 provided at the tip thereof descends and enters the sample.

Then, when the plunger drive motor 35 is driven, the belt 34 is rotated via the pulley 32,
Raise the plunger holder 31. Therefore, when the plunger holder 31 is pulled up, the needle 53
As a result, the sample is sucked into the syringe 29.

After the suction is completed, the Z-axis motor 52 is rotated to pull up the syringe carriage 20 by the timing belt 22, and the needle 53 at the tip of the syringe 29 is pulled up out of the sample. Next, the syringe carriage block 1 is moved by the operation reverse to the above, and the injection valve 3
Bring on 8 .

The needle 53 is inserted into the valve shaft 40 by lowering the syringe carriage 20 . This insertion is stopped by the upper end of the needle 53 hitting the upper end of the valve shaft 40, and the tip of the needle 53 reaches the needle port 41 at that time. At this time, there is a case where the needle port 41 and the loop (not shown) are electrically connected and a case where they are not electrically connected, and it is considered that air is not mixed in the case where they are not electrically connected.

When the valve rotation motor 49 is rotated, the plate 50 rotates as the valve rotation motor shaft rotates, and the arm 44 is pivoted by the pivotal support 51 via the link 46.
pull. This arm 44 rotates the valve shaft 40 by 60 degrees.

At this time, the hook 44 is rotated by the rotation of the arm 44.
7 also rotates and presses the catch plate 48. When the syringe carriage 20 is pressed through the hook plate 48, the follower shaft 1
It is rotated at the same time as the fixed plate 17 around 8A and 18A, and approximately follows the rotation locus of the eccentric port 54.

At this time, the syringe carriage 20 facilitates the rotational displacement by utilizing the flexibility of the timing belt 22 connected with an appropriate tension.

The rotation of the valve shaft 40 is required to be exactly 60 degrees, but the stopper built into the injection valve 38 is used as it is, and the load exceeding the required torque for switching is released by using the torque limiter. It is as a structure.

[0039]

According to the present invention as described above, firstly, an injection valve having an eccentric port is used, a microsyringe is directly inserted into the injection valve, and then the injection valve is switched, and at the same time, the switching operation is performed. Syringe holder that holds the second microsyringe by rotating the microsyringe holder and introducing the tip of the microsyringe into the sample supply unit.
The syringe carriage with the
An injection bar with an eccentric port
Tube and the syringe carriage
It is supported on a fixed plate and can be rotated, and the injection bar
Injection valve that is rotated via the rotary mechanism
The syringe holder installed on the syringe carriage
Microphone that is held by the syringe holder
(B) The tip of the syringe can be freely introduced into the sample supply section.
At, the sample can be injected into the sample loop by inserting the microsyringe directly into the injection valve.

It can be introduced with a low diffusion flowing into the column connected with the shortest flow path, micro injection with micro-syringe and stepping motor drive can be more thoroughly injected, the needle tip is in complete contact with the stator part of the injection valve, and dead volume is very small. The sample can be introduced into the sample loop, and the reproducibility of the injection amount is extremely good.

Further, since the flow path switching valve can be arranged in the oven or in contact therewith, sample diffusion can be prevented.

After the injection valve of the needle is inserted, when the injection valve is switched, the needle port portion automatically follows the eccentric rotation, so that it is not necessary to rotate the injector, which is problematic, and the movement of the pipe or the You don't have to worry about your dead volume.

As a result, an analysis with a sample injection amount of 50 μl or less became possible, and the solvent consumption amount was greatly improved. Of course,
With this device, complete automation of sample analysis could be achieved.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an embodiment of the present invention.

FIG. 2 is a side view of the main part of the same.

FIG. 3 is a partial explanatory view of the same as above.

FIG. 4 is an explanatory plan view of a main part of the same.

FIG. 5 is an enlarged partial plan view of the same as above.

FIG. 6 is a partially enlarged explanatory view of the same as above.

FIG. 7 is a partially enlarged vertical side view of the same.

FIG. 8 Conventional autosampler

[Description of Reference Signs] 1 Syringe carriage block 5 Base 10 Motor 16 Chassis 17 Fixing plate 20 Syringe carriage 22 Timing belt 28 Syringe holder 30 Plunger 34 Timing belt 38 Injection valve 42 Rotor 43 Ceramic stator 44 Arm

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 30/00-30/95

Claims (2)

(57) [Claims] 1. An injection valve having an eccentric port is used, and after inserting the microsyringe directly into the injection valve, the injection valve is switched, and at the same time, the microsyringe holder is swung by the switching operation to follow the tip of the microsyringe. Is introduced into the sample supply section.
Rough trace sample automatic injection method . 2. A syringe ho which holds a microsyringe.
A syringe carriage equipped with a rudder can be moved up and down.
Inject the microsyringe with an eccentric port
It can be inserted freely into the
The ridge is supported by a fixed plate, and it can be rotated and
Injector rotated via the rotation valve rotation mechanism
Series installed on the syringe carriage in conjunction with the valve.
Rotate the syringe holder to hold it in the syringe holder.
The tip of a microsyringe can be freely introduced into the sample supply section
And microinjected sample automatic injection system for a liquid chromatograph, characterized in that the.