Automatic analysis device

Abstract

In order to provide a compact and inexpensive automatic analysis device that makes it possible to secure predetermined dispensing accuracy without including a deaeration module, the present invention has the following configuration.　Provided is an automatic analysis device comprising: a dispensing probe for dispensing a liquid; a syringe for generating a pressure for drawing the liquid into the dispensing probe; and a flow passage connecting the dispensing probe and the syringe. The flow passage is routed so as to pass through a point A, which is a location higher than the syringe, and a point B, which is a location lower than the dispensing probe, and has a bubble retention part between the point A and the point B for temporarily retaining bubbles generated in the syringe.

Description

automatic analyzer

[0001] The present invention relates to an automatic analyzer.

[0002] An automated analyzer is a device that reacts a sample, such as blood, with a target component in the sample and an analytical reagent, and analyzes this reaction using an optical method, automatically performing the entire process from detecting the target component to outputting the results. Such an automated analyzer has a step of aspirating the sample using a dispensing probe (also called a dispensing nozzle).

[0003] The dispensing probe is connected to a pump called a syringe via a flow path, and the liquid to be dispensed is sucked into the dispensing probe by driving the syringe to create a negative pressure in the flow path. Such a dispensing probe structure is shown in, for example, Figure 2 of Patent Document 1.

[0004] International Publication No. 2020 / 066523

[0005] As shown in Figure 2 of Patent Document 1, the flow path between the dispensing probe and the syringe is generally connected to a syringe installed in an analyzer through the rotation axis of an arm that moves the dispensing probe up and down and rotates. The flow path is filled with water (also called system water) as a pressure transmission medium, and operation of the syringe causes the system water to move through the flow path, generating negative and positive pressures in the dispensing nozzle at the tip of the probe, allowing liquid to be sucked into and discharged from the nozzle.

[0006] Because system water is a pressure transmission medium, if there are air bubbles in the liquid, they will temporarily collapse and act as a cushion, making it impossible to accurately control the amount of liquid dispensed into / discharged into the probe.For this reason, in general automatic analyzers, pure water produced in a pure water production machine is passed through a degassing module (vacuum degassing is common) to remove air bubbles from the water before being supplied to the probe flow path.

[0007] However, the degassing module requires a vacuum pump and degassing piping for degassing, and therefore requires a considerable amount of space for installation inside the automatic analyzer, which can be an obstacle to miniaturization, especially in small instruments.In addition, the degassing module adds cost, making it difficult to apply to small automatic analyzers, which are required to be inexpensive.

[0008] An object of the present invention is to provide a small, inexpensive automatic analyzer that can ensure a predetermined dispensing accuracy without providing a degassing module.

[0009] The present invention achieves the above object in the following manner: An automatic analyzer includes a dispensing probe that dispenses liquid, a syringe that generates pressure to draw the liquid into the dispensing probe, and a flow path that connects the dispensing probe and the syringe, the flow path being arranged to pass through point A, which is higher than the syringe, and point B, which is lower than the dispensing probe, and having an air bubble retention section between points A and B for temporarily retaining air bubbles generated in the syringe.

[0010] According to the present invention, a predetermined dispensing accuracy can be ensured without providing a degassing module, and a small, inexpensive automatic analyzer can be provided.

[0011] 5 is a schematic diagram of an automatic analyzer. A schematic diagram of a dispensing mechanism of an automatic analyzer. A diagram showing a general configuration of a dispensing mechanism flow path of an automatic analyzer. A diagram showing pressure fluctuations when continuous dispensing is performed to the liquid dispensing mechanism flow path of FIG. 3. A diagram showing the configuration of a liquid dispensing mechanism flow path according to Example 1. A diagram explaining the behavior of bubbles in the flow path shown in FIG. 5. A diagram explaining the behavior of bubbles in the flow path shown in FIG. 5. A diagram showing pressure fluctuations when continuous dispensing is performed to the liquid dispensing mechanism flow path of FIG. 5. A diagram showing the configuration of a liquid dispensing mechanism flow path according to Example 2. A diagram showing the configuration of a liquid dispensing mechanism flow path according to Example 3. A diagram showing the configuration of a liquid dispensing mechanism flow path according to Example 4. A diagram showing the configuration of a liquid dispensing mechanism flow path according to Example 5.

[0012] Hereinafter, examples of the present invention will be described with reference to the drawings. It should be noted that the following are examples and the present invention is not limited to these examples.

[0013] FIG. 1 is a diagram showing an example of the configuration of an automatic analyzer.

[0014] Sample containers 103 can be placed in a ring shape on a sample disk 102 inside an automatic analyzer 101. When dispensing a sample, the disk rotates clockwise and counterclockwise, moving the sample containers 103 to an access position of a sample dispensing mechanism 104.

[0015] To simplify sample management, an identification barcode may be attached to the sample container 103. The barcode records information linked to the sample ID and information related to the sample type (e.g., serum, urine, etc.). The barcode attached to the sample container 103 is read by a barcode reader 120.

[0016] The sample dispensing mechanism 104 is composed of a rotation drive mechanism, a vertical drive mechanism, and a dispensing probe. The rotation drive mechanism and the vertical drive mechanism move the sample dispensing mechanism between a sample suction position and a sample dispensing position.

[0017] The reagent storage cabinet 105 has a reagent disk 106 and reagent container holders 107. Reagent storage cabinets generally have a cooling function to prevent reagents from deteriorating over time. The reagent container holders 107 are arranged in a double ring on the reagent disk 106 and are designed to hold multiple reagent bottles. The reagent disk 106 has a rotation drive mechanism, and by rotation, each reagent bottle is moved to a predetermined position on the circumference.

[0018] The reagent dispensing mechanism 108 is composed of a rotation drive mechanism, a vertical drive mechanism, and a dispensing probe. The reagent dispensing mechanism rotates and descends to the position of a predetermined type of reagent bottle on the reagent disk 106, and aspirates a predetermined amount of reagent. After aspirating the reagent, the dispensing mechanism ascends. Next, it rotates and descends to the reagent ejection destination (a predetermined reaction cell on the reaction disk 109), and ejects the reagent.

[0019] The flow of biochemical analysis will be explained in the order of processing (sample dispensing, reagent dispensing, reaction, and detection).

[0020] First, the specimen dispensing mechanism 104 dispenses a predetermined amount of specimen into a predetermined reaction cell on the reaction disk 109. Then, the reaction disk 109 rotates, and moves the reaction cell into which the specimen has been dispensed to an access position of the reagent dispensing mechanism 108.

[0021] The reagent dispensing mechanism 108 dispenses a predetermined amount of reagent into the reaction cell into which the sample has been discharged. Next, the reaction disk 109 rotates, and moves the reaction cell into which the sample and reagent have been discharged to a position where the mixing unit 110 is installed. The sample and reagent are then mixed by the mixing unit 110. The reaction disk 109 is kept at an appropriate temperature to promote the reaction between the sample and the reagent.

[0022] When the reaction process between the sample and the reagent on the reaction disk 109 is completed, the reaction disk 109 rotates and moves the reaction cell containing the reaction solution after the reaction to the installation position of the biochemical detection unit 111. Then, the reaction signal is measured by the detection unit in the biochemical detection unit 111. After the signal measurement, the reaction solution is discharged from the reaction cell by the reaction cell washing mechanism 112.

[0023] The above-described mechanism of the automatic analyzer is referred to as the “analysis operation unit.” In addition to the analysis operation unit, the automatic analyzer further includes a control unit 113 and an operation unit 114 that control the overall operation of the automatic analyzer.

[0024] The control unit 113 is composed of, for example, a hardware board and a computer, and is connected to a storage device 115 such as a hard disk. The operation unit 114 is composed of a display unit 117 which is a display equipped with a touch panel, and input devices such as a mouse 118 and a keyboard 119. The storage device 115 stores, for example, analysis items for samples registered by the user. The control unit 113 may be composed of hardware such as a dedicated circuit board, or may be composed of software executed on a computer.

[0025] When configured using hardware, it can be realized by integrating multiple arithmetic units that execute the processing on a wiring board, or in a semiconductor chip or package. When configured using software, it can be realized by installing a high-speed general-purpose CPU in a computer and running a program that executes the desired arithmetic processing. It is also possible to upgrade existing devices using a recording medium on which this program is recorded. Furthermore, these devices, circuits, and computers are connected via a wired or wireless network, and data is sent and received as appropriate.

[0026] The operation of the sample dispensing mechanism in the automatic analyzer is described below. The reagent dispensing mechanism also has a similar configuration, and liquid dispensing abnormality detection can be performed. To avoid duplication, a description of the reagent dispensing mechanism will be omitted.

[0027] 2 is a schematic diagram of the sample dispensing mechanism. A sample probe (also referred to as a sample dispensing probe or dispensing probe) 201 is connected to a sample syringe (also simply referred to as a "syringe") 203 via a flow path 202, and the insides of these are filled with liquid.

[0028] The specimen syringe 203 is composed of a cylinder 203a and a plunger 203b, and the plunger 203b is connected to a syringe driving means 204. The syringe driving means 204 drives the plunger 203b up and down relative to the cylinder 203a to aspirate and discharge the specimen.

[0029] A motor is connected to the sample probe 201 as a sample probe driving means 205, which moves the sample probe up and down and in a rotational direction to a predetermined position. The syringe driving means 204 and the sample probe driving means 205 are controlled by a sample probe control unit 206 (denoted as "control unit" in FIG. 2).

[0030] When aspirating a specimen 208 in a container (also called a specimen container) 207, prior to the aspirating operation, a predetermined amount of air (called segmented air) is aspirated into the specimen probe 201 to prevent the specimen 208 from mixing with the liquid filled in the specimen probe 201.

[0031] Thereafter, the specimen probe driving means 205 lowers the specimen probe 201 until it reaches the specimen 208, and then performs a suction operation.

[0032] At this time, the sample probe is lowered by monitoring the amount of change in capacitance caused by the sample probe 201 reaching the liquid surface of the sample 208, and the sample probe control unit 206 controls the sample probe driving means 205 to determine the amount of lowering of the sample probe.

[0033] When the sample aspirating operation is completed, the sample syringe 203 performs a backlash discharging operation to correct the sample discharging amount in the next discharging operation. Thereafter, the sample probe 201 moves to the sample discharging position, and the sample syringe 203 performs a discharging operation.

[0034] After the discharge, cleaning water 211 in a water supply tank 210 is sprayed out at high pressure by a water supply pump 209, thereby cleaning the inner surface of the sample probe 201 (this is called probe internal cleaning, or "internal cleaning" for short, and the water used for internal cleaning is called "internal cleaning water"). The flow path to the water supply tank is opened and closed by a solenoid valve 212. The solenoid valve 212 is controlled by the sample probe control unit 206.

[0035] Pressure sensor 213 for measuring the pressure inside flow path 202 is connected to a flow path system including sample probe 201, flow path 202, and sample syringe 203 via branch block 214. Here, pressure sensor 213 is desirably installed as close to sample probe 201 as possible in order to measure pressure fluctuations in sample probe 201 with good sensitivity.

[0036] The output value of pressure sensor 213 is amplified by signal amplifier 215 and converted into a digital signal by A / D converter 216. The digitally converted signal is sent to calculation unit 218, which calculates a judgment index for judging whether the aspirating was successful (determining whether dry aspirating occurred or whether the sample probe is clogged with fibrin or the like) using the method described below. Judgment unit 219 compares the judgment index calculated by calculation unit 218 with a threshold value to determine whether the sample was aspirated successfully.

[0037] In the above dispensing operation, the operation timing of each mechanism is defined within a predetermined time cycle, and continuous dispensing is performed by repeating this cycle.

[0038] The automated analyzer is not limited to a biochemical analyzer, but may be an analyzer capable of measuring different analysis items, such as an immunoanalyzer. Furthermore, the automated analyzer is not limited to a configuration with a single analysis module, but may be configured with two or more analysis modules capable of measuring various identical or different analysis items or pretreatment modules that perform pretreatment, connected by a transport device.

[0039] Next, the flow path connecting the dispensing probe and syringe of the above-mentioned automatic analyzer will be described. The flow path 202 is a tube connecting the syringe 203 and the dispensing probe 201, and the inside of the flow path 202 is filled with water (system water). The syringe 203 generates a pressure change in the flow path 202, and generally has a rod-shaped piston inside an outer tube (cylinder), and by moving the piston in the longitudinal direction of the cylinder, the internal volume of the cylinder is changed and pressure is generated. Note that well-known pumps other than syringes, such as peristaltic pumps, can also be used as long as they generate a pressure change.

[0040] The dispensing probe 201 has the function of aspirating a predetermined amount of a liquid such as a reagent or specimen from a container containing the liquid, using pressure changes generated by a syringe 203, and dispensing the predetermined amount into another container such as a reaction container. The tip of the dispensing probe 201 is provided with a dispensing nozzle that is immersed in the liquid to be aspirated. Depending on the context, the entire dispensing probe including the dispensing nozzle may be referred to as the dispensing probe, or simply as the probe. For example, the expression "immersing the tip of the dispensing probe in the liquid" may be used.

[0041] The dispensing probe 201 is attached to approximately the tip of an arm that rotates in an arc around a rotation axis as shown in Figure 1, and as this arm rotates and moves up and down, the tip of the probe is immersed in the reagent or sample in a reagent container or sample container at a predetermined position, a predetermined amount of reagent or sample is aspirated, and then the probe is pulled up and the arm is rotated to dispense the predetermined amount of reagent, sample, etc. into another container to which the reagent or sample is to be dispensed. Note that the liquid to be aspirated can be various other liquids such as cleaning liquid, water, etc. in addition to reagents and samples.

[0042] 3, the flow path closest to the syringe 203 is at the highest position (point A), then passes through the lowest position (point B), passes through a higher position (point C) again near the dispensing probe (often a point extending horizontally within the arm), and connects to the dispensing nozzle. The reason for passing through the lowest position (point B) is, for example, to avoid a reaction disk 109 equipped with a thermostatic chamber, which is often provided in the center of the device.

[0043] In particular, in small-sized automatic analyzers, various devices are arranged densely within the device, and therefore, the flow path 202 may have to be arranged to fill the gaps between these various devices, and such an arrangement may be unavoidable. Furthermore, in large-sized automatic analyzers that have relatively ample space within the device, the syringe 203 is generally provided at the bottom front of the device, but in small-sized automatic analyzers, particularly tabletop automatic analyzers, it may be provided at the top of the device from the perspective of ease of maintenance, and naturally, the flow path closest to the syringe 203 may be at the highest position (point A) as shown in Figure 3.

[0044] Here, the area connecting point A and point B will be called area A, and the area connecting point B and dispensing probe 201 will be called area B. In this type of flow path configuration, if plunger 203b of syringe 203 moves (moves) at high speed in the water (sometimes called system water) filled in flow path 202, causing the air dissolved in the system water to evaporate and generate bubbles, the generated bubbles will float up due to differences in specific gravity and remain at the highest position (point A) in flow path 202, and small bubbles may coalesce to form larger bubbles that remain.

[0045] As mentioned above, in order to clean the inner surface of the sample probe 201, an internal wash is performed inside the flow path 202 by using the water supply pump 209 to spray cleaning water 211 from the water supply tank 210 at high pressure.Therefore, small air bubbles inside the flow path 202 are pushed downstream by the internal wash water and are pushed out from the tip of the dispensing probe 201 together with the system water.

[0046] However, bubbles that have accumulated at the highest point (point A) and grown large may not be able to pass through to the lowest point (point B) even if interior wash water is flowed at high pressure. The liquid (system water) in flow path 202 acts as a pressure transmission medium, but if bubbles form in the liquid, even when pressure is generated by a syringe and the liquid is sucked into the probe tip, the pressure is used to crush the bubbles, making accurate dispensing control difficult. This is a phenomenon similar to vapor lock, in which the brake fluid in an automobile becomes hot due to continuous use of the brakes, causing the brake fluid to boil and form bubbles, making the brakes less effective.

[0047] Although the generation of bubbles can be suppressed to some extent by moving the syringe 203 slowly, it is practically difficult to move the syringe 203 slowly because an automatic analyzer is required to have a predetermined analysis throughput.

[0048] Figure 4 shows the pressure change in the flow channel 202 when dispensing is repeated using the dispensing mechanism having the flow channel 202 shown in Figure 3. During the first dispensing, the change in pressure in the flow channel is sharp, but as the number of dispensings increases, such as the 15th and 45th dispensings, the pressure change becomes more gradual. This is evidence that air bubbles are acting as a cushion. If this occurs, for example, even if plunger 203b is operated to aspirate 50 μL of liquid, which is the initial design value, only about 45 μL may actually be aspirated, which may result in an inaccurate analysis result.

[0049] 5 shows the flow channel configuration according to Example 1. In order to temporarily hold bubbles midway through the flow channel 202, multiple vertically looped portions of the flow channel 202 are provided. "Looped vertically" can also be expressed as meaning that the central axis of the looped flow channel is set in a substantially horizontal direction.

[0050] As mentioned above, bubbles that have accumulated at the highest position (point A) and grown large may not be able to pass through to the lowest position (point B) even if internal washing water is flowed at high pressure, but by providing a bubble accumulation section (which can also be expressed as a bubble trap that traps bubbles, or a bubble storage section) that temporarily accumulates bubbles between points A and B, it is possible to gradually move the bubbles that have accumulated at point A downward. Therefore, the force of the internal washing water makes it easier for the generated bubbles to flow through the flow path 202 and be expelled from the tip of the dispensing probe 201.

[0051] The movement of bubbles will be described in detail with reference to Figures 6A and 6B. (1) Internal Wash 1: Bubbles generated in the syringe flow in. (2) After Internal Wash 1 is completed, step 1: Bubbles rise due to buoyancy. (3) After Internal Wash 1 is completed, step 2: Bubbles that exceed point 1-1 in loop 1 move due to buoyancy to point 1-2. (4) Internal Wash 2: Bubbles that reach point 1-2 move to loop 2. (5) After Internal Wash 2 is completed, step 1: Bubbles rise due to buoyancy. (6) After Internal Wash 2 is completed, step 2: Bubbles that exceed point 2-1 in loop 2 move due to buoyancy to point 2-2. In other words, by providing a region between points A and B where bubbles temporarily remain and gradually moving the bubbles remaining at point A to a region closer to point B, bubbles can be removed from flow path 202, allowing dispensing to continue without affecting pressure propagation.

[0052] The diameter of the loop depends on the level of bubbles generated, but for example, if the height (vertical length) from point B to point A is about 60 cm, the loop diameter is preferably about 6 cm. Depending on the tube that makes up the flow path, it may be difficult to bend and form a loop with a small diameter, so the diameter of the loop shape is preferably 6 cm to 12 cm, that is, about 1 / 5 to 1 / 10 of the difference in altitude between points A and B.

[0053] Of course, the loop diameter does not depend only on the difference in altitude between points A and B, but also on the inner diameter of the flow path 202, so it is not possible to uniquely determine the optimal loop diameter. Ultimately, it is desirable to determine the loop diameter and the number of loops to be installed by conducting experiments to determine whether the bubbles retained at point A are pushed out by the internal wash water. While a single loop is shown in Figure 5, if a large number of bubbles are generated, a double or triple loop can be used to increase the amount of bubbles that can be trapped. The number of loop-shaped flow paths to be installed may be two to four or more, depending on the amount of bubbles generated, the water pressure of the internal wash water, the inner diameter of the flow path, etc.

[0054] Figure 7 shows the pressure change when dispensing is repeated using a dispensing mechanism having the flow path shown in Figure 5. Compared to Figure 4, it can be seen that the pressure change remains almost the same even when the number of dispensing operations increases, from the 1st dispensing to the 15th dispensing and the 45th dispensing.

[0055] FIG. 8 shows a dispensing mechanism according to Example 2. It differs from FIG. 5 in that the loop is arranged horizontally rather than vertically (this arrangement can be described as "a loop-shaped flow path with its central axis arranged substantially vertically"). The effect of gradually pushing out air is the same as the dispensing mechanism shown in FIG. 5, but it differs from the flow path of FIG. 5 in that bubbles accumulate in a horizontal region, resulting in a larger area (volume) where bubbles are trapped, unlike the flow path of FIG. 5, which has a vertical loop structure. Therefore, even if a large number of bubbles are generated at once, it is expected that the bubbles will be pushed away beyond point B. This configuration is effective when bubbles grow quickly due to the syringe operation and the liquid filling the flow path, and the bubbles cannot be expelled quickly enough in Example 1.

[0056] Figure 9 shows a dispensing mechanism according to Example 3. A bubble retention section consisting of multiple combined U-shapes is provided midway along the flow path. This configuration also has the effect of gradually pushing out air, similar to Examples 1 and 2. This configuration is effective when the flow path material is hard and it is difficult to form a loop structure for the flow path, or when the diameter must be so large that it cannot be accommodated within the layout inside the automatic analyzer.

[0057] Figure 10 shows a dispensing mechanism according to Example 4. A flow path that prevents air bubbles from floating up is provided midway along the flow path. Specifically, by providing continuous protrusions such as screw holes, air bubbles are trapped between the protrusions due to surface tension, which acts as an air bubble retention area similar to a looped flow path. This configuration also has the same effect of gradually pushing out air.

[0058] This configuration is effective when a loop structure cannot be created due to the material of the flow channel. Furthermore, the effect can be adjusted by changing the number and structure of the trap units. Since there is no need to make the flow channel as long as in a loop or U-shaped flow channel, the volume inside the flow channel can be reduced. This has the effect of enabling a more compact device design.

[0059] The obstruction structure must be such that it prevents the upward movement of bubbles due to buoyancy, and has enough resistance to push out the bubbles with the flow of in-house washing water. The obstruction structure can also be a valve-like structure.

[0060] Figure 11 shows a dispensing mechanism according to Example 5. A flow path with a processed inner surface was provided as a flow path to prevent air bubbles from floating up, as in Example 4. Specifically, by increasing the surface roughness of the inner surface of the tube that forms the flow path, it is expected that air bubbles will be trapped on the inner surface of the tube due to surface tension. Alternatively, a similar effect can be expected by providing a spiral groove on the inner surface of the tube. Alternatively, the effect of trapping air bubbles can be expected by attaching a cloth-like material to the inner surface of the tube. This configuration also has the same effect of gradually pushing out air.

[0061] This configuration is effective when a loop structure cannot be created due to the material of the channel. The effect can be adjusted by changing the number and structure of the trap units. Since there is no need to make the channel as long as in a loop or U-shaped channel, the volume inside the channel can be reduced. This has the effect of enabling a more compact device design.

[0062] The obstruction structure must be such that it prevents the upward movement of bubbles due to buoyancy, and yet has enough resistance to push out the bubbles with the flow of in-flush water.

[0063] <Others> The present invention is not limited to the above-described embodiments, and various modifications and applications are possible. The above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations.

[0064] 101: automatic analyzer, 102: sample disk, 103: sample container, 104: sample dispensing mechanism, 105: reagent storage, 106: reagent disk, 107: reagent container holder, 108: reagent dispensing mechanism, 109: reaction disk, 110: stirring unit, 111: biochemical detection unit, 112: reaction cell cleaning mechanism, 113: control unit, 114: operation unit, 115: storage device, 116: control device, 117: display unit, 118: mouse, 119: keyboard, 120: barcode reader, 201: sample dispensing processor 202: flow path, 203: specimen syringe, 203a: cylinder, 203b: plunger, 204: syringe drive means, 205: specimen probe drive means, 206: specimen probe control unit, 207: container, 208: specimen, 209: water supply pump, 210: water supply tank, 211: cleaning water, 212: solenoid valve, 213: pressure sensor, 214: branch block, 215: signal amplifier, 216: A / D converter, 217: specimen probe control unit, 218: calculation unit, 219: judgment unit, 220: suction volume calculation unit.

Claims

1. An automatic analyzer comprising: a dispensing probe that dispenses liquid; a syringe that generates pressure to draw liquid into the dispensing probe; and a flow path that connects the dispensing probe and the syringe, wherein the flow path is arranged to pass through point A, which is higher than the syringe, and point B, which is lower than the dispensing probe, and the automatic analyzer has an air bubble retention section between point A and point B for temporarily retaining air bubbles generated in the syringe.

2. An automatic analyzer according to claim 1, wherein the bubble retention portion is configured by forming a part of the flow path into a loop shape.

3. An automatic analyzer according to claim 2, wherein the loop-shaped flow path is arranged with its central axis in a substantially horizontal direction.

4. An automatic analyzer according to claim 2, wherein the loop-shaped flow path is arranged with its central axis in a substantially vertical direction.

5. An automatic analyzer according to claim 3 or 4, characterized in that a plurality of said loop-shaped flow paths are provided.

6. An automatic analyzer according to claim 3, wherein the diameter of the loop-shaped flow path is 1 / 5 to 1 / 10 of the height from point B to point A, and at least two loop-shaped flow paths are installed.

7. An automatic analyzer according to claim 1, wherein the bubble retention section is configured by forming a part of the flow path into a U-shape and combining a plurality of such U-shapes.

8. An automatic analyzer according to claim 1, wherein the bubble retention portion is a portion of the inner surface of the flow path having a surface shape that makes it difficult for bubbles in contact with the inner surface to flow.

9. An automatic analyzer according to claim 8, wherein the surface shape has a plurality of protrusions protruding from the inner surface.

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