Automated analysis device and sample dispensing method therefor

Abstract

The purpose of the present invention is to provide an automatic analysis device capable of reducing carry-over between liquids and realizing high dispensing accuracy. To attain this purpose, the automated analysis device of the present invention comprises a dispensing mechanism for dispensing, into a reaction container, a sample accommodated in a sample container or a reagent accommodated in a reagent container by operating a syringe connected to a nozzle, and a control unit that controls the dispensing mechanism, the control unit performing a discharge operation of operating the syringe in a discharge direction after the sample or the reagent was sucked in by the dispensing mechanism but before it was discharged into the reaction vessel, wherein the discharge operation includes a first discharge operation performed in a state where the nozzle is at the position of the sample container or the reagent container, and a second discharge operation performed in the process of moving the nozzle from the position of the sample container or the reagent container to the position of the reaction container, and the operation amount of the syringe in the first discharge operation is smaller than the operation amount of the syringe in the second discharge operation.

Description

Automatic analyzer and dispensing method thereof

[0001] The present invention relates to an automatic analyzer and a dispensing method thereof.

[0002] An automated analyzer for analyzing biological samples such as blood and urine includes a dispensing mechanism for dispensing liquid containing a sample or reagent into a reaction vessel. The dispensing mechanism aspirates and dispenses liquid by operating a syringe connected to a nozzle. Because gaps (backlash) exist between the connecting parts of the mechanical components that make up the syringe, slight idle spin occurs due to the gaps when the syringe's operating direction is reversed. Therefore, for example, before the dispensing mechanism dispenses the aspirated liquid into a reaction vessel, a syringe operation (backlash removal operation) is required to eliminate the idle spin. For example, Patent Document 1 discloses that a sample probe descends at the position of a sample container to aspirate the sample from the sample container, and then a backlash removal operation is performed at the position of the sample container to dispense the sample from the sample probe (paragraph 0038, FIG. 6, etc.).

[0003] Japanese Patent Application Laid-Open No. 2019-174318

[0004] When the syringe is moved in the discharge direction as a backlash removal operation after the sample probe aspirates the sample, the syringe stops spinning and continues to move in the discharge direction, causing the sample inside the sample probe to be discharged. The sample being discharged contains not only the sample to be dispensed this time, but also a small amount of the previous sample from the previous dispensing operation. Therefore, as in the technology described in Patent Document 1, if the backlash removal operation after the sample probe aspirates the sample is performed only when the sample probe is positioned at the sample container, the previous sample that is discharged back into the sample container cannot be ignored. Furthermore, the previous sample is discharged back into the sample container and accumulates with each repeated dispensing, which may reduce dispensing accuracy.

[0005] The present invention has been made in view of the above problems, and its object is to provide an automatic analyzer and a dispensing method thereof that reduce carryover between liquids and achieve high dispensing accuracy.

[0006] In order to achieve the above-mentioned object, the present invention provides an automatic analyzer comprising a dispensing mechanism that dispenses a sample contained in a sample container or a reagent contained in a reagent container into a reaction container by operating a syringe connected to a nozzle, and a control unit that controls the dispensing mechanism, wherein after the dispensing mechanism has aspirated the sample or the reagent and before dispensing it into the reaction container, the control unit performs a dispensing operation by moving the syringe in a dispensing direction, wherein the dispensing operation includes a first dispensing operation that is performed when the nozzle is located at the position of the sample container or the reagent container, and a second dispensing operation that is performed while the nozzle is moving from the position of the sample container or the reagent container to the position of the reaction container, and the amount of movement of the syringe in the first dispensing operation is smaller than the amount of movement of the syringe in the second dispensing operation.

[0007] According to the present invention, it is possible to provide an automatic analyzer and a dispensing method thereof that reduce carryover between liquids and achieve high dispensing accuracy.

[0008] A perspective view schematically showing the overall configuration of an automatic analyzer. A top view schematically showing the main configuration of an automatic analyzer. A diagram schematically showing the flow path configuration of a sample dispensing mechanism. A diagram showing the operational sequence of sample dispensing in an automatic analyzer according to a comparative example. A diagram showing the mechanism of carry-over resulting from a previous specimen remaining inside the nozzle. A diagram showing the operational sequence of sample dispensing in an automatic analyzer according to Example 1. A table showing the values ​​of the first discharge operation amount and the second discharge operation amount set in the comparative example and Example 1. A graph showing the average inter-specimen carry-over rate in the comparative example and Example 1. A diagram showing the operational sequence of sample dispensing in an automatic analyzer according to Example 2. A diagram showing variations in the nozzle cleaning method.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (Overall Configuration of Automated Analyzer) An automated analyzer is an apparatus that dispenses a sample (specimen) such as blood or urine and a reagent into a reaction vessel 2, causes a reaction, and measures the reacted liquid. Fig. 1 is a perspective view that shows a schematic overall configuration of the automated analyzer, and Fig. 2 is a top view that shows a schematic main configuration of the automated analyzer. As shown in Figs. 1 and 2, the automated analyzer is composed of a sample transport mechanism 8, a reagent disk 3, a reaction disk 1, a sample dispensing mechanism 9, reagent dispensing mechanisms 11 and 13, stirring mechanisms 17 and 18, a spectrophotometer 16 (measurement unit), a cleaning mechanism 15, a control unit 24, etc.

[0011] Reaction vessels 2 are arranged circumferentially on the reaction disk 1. The reaction vessels 2 are containers for containing a mixed liquid obtained by mixing a sample and a reagent, and a plurality of reaction vessels 2 are arranged on the reaction disk 1. A sample transport mechanism 8 is arranged near the reaction disk 1, which transports a sample rack 7 loaded with a plurality of sample vessels 6 containing samples to be analyzed. The reaction vessels 2 are immersed in a reaction tank 5 (see FIG. 2 ) filled with a thermally conductive medium (e.g., constant temperature water) whose temperature is controlled at, for example, 37°C, and the temperature of the reaction vessels 2 is constantly maintained at 37°C by circulating the constant temperature water within the reaction tank 5.

[0012] The reagent disk 3 can accommodate a plurality of reagent bottles 4 (reagent containers) containing reagents used in analysis on its circumference, and also functions as a refrigerator that keeps the reagent bottles 4 cool.

[0013] A sample dispensing mechanism 9 is disposed between the reaction disk 1 and the sample transport mechanism 8 for dispensing a sample from a sample container 6 to a reaction container 2. The sample dispensing mechanism 9 is capable of horizontal rotation and vertical movement and has a sample nozzle 10 whose tip faces downward. A washing tank 19 for washing the sample nozzle 10 with washing water is disposed within the operating range of the sample dispensing mechanism 9. Reagent dispensing mechanisms 11 and 13 are also disposed between the reaction disk 1 and the reagent disk 3 for dispensing a reagent from a reagent bottle 4 to a reaction container 2. The reagent dispensing mechanisms 11 and 13 are capable of horizontal rotation and vertical movement and have reagent nozzles 12 and 14 whose tips face downward. Washing tanks 20 and 21 for washing the reagent nozzles 12 and 14 with washing water are disposed within the operating range of the reagent dispensing mechanisms 11 and 13.

[0014] Around the reaction disk 1, there are arranged stirring mechanisms 17, 18, a spectrophotometer 16 (see Figure 2) that measures the absorbance of the reaction solution by measuring the transmitted light obtained from a light source (not shown) through the reaction solution in the reaction vessel 2, and a cleaning mechanism 15 that cleans used reaction vessels 2.

[0015] The stirring mechanisms 17, 18 are capable of rotating horizontally and moving vertically, and stir the mixture of sample and reagent (reaction solution) by being inserted into the reaction vessel 2. Washing tanks 22, 23 for washing the stirring mechanisms 17, 18 with wash water are disposed within the operating range of the stirring mechanisms 17, 18.

[0016] The control unit 24 is composed of a computer or the like, and controls the operation of each mechanism that constitutes the automatic analyzer, and performs calculations to determine the concentration of a predetermined component in a sample. Note that, in Fig. 1, for simplicity of illustration, the connections between each mechanism that constitutes the automatic analyzer and the control unit 24 are omitted.

[0017] In the automated analyzer configured as described above, the analytical process generally proceeds as follows. First, the control unit 24 causes the sample nozzle 10 of the sample dispensing mechanism 9 to dispense a sample from a sample container 6 on the sample rack 7, which has been transported near the reaction disk 1 by the sample transport mechanism 8, into a reaction container 2 on the reaction disk 1. The control unit 24 then cleans the sample nozzle 10 in the cleaning tank 19. Next, the control unit 24 causes the reagent nozzles 12 and 14 of the reagent dispensing mechanisms 11 and 13 to dispense a reagent from a reagent bottle 4 on the reagent disk 3 into the reaction container 2 into which the sample was previously dispensed. The control unit 24 then cleans the reagent nozzles 12 and 14 in the cleaning tanks 20 and 21. Next, the control unit 24 uses the stirring mechanisms 17 and 18 to stir the mixture of sample and reagent in the reaction container 2. The control unit 24 then transmits light generated from the light source through the reaction container 2 containing the mixture, and measures the luminous intensity of the transmitted light using the spectrophotometer 16. The light intensity information measured by the spectrophotometer 16 is transmitted to the control unit 24 via an A / D converter and an interface. The control unit 24 then calculates the concentration of a predetermined component of the analysis item based on the received light intensity information, and displays the calculation result on a display unit (not shown) or stores it in a memory unit (not shown).

[0018] (Configuration of Dispensing Mechanism) Next, the configuration of the dispensing mechanism will be specifically described with reference to FIG. 3 . The following description will be given using the sample dispensing mechanism 9 as an example, but the same can be applied to the reagent dispensing mechanisms 11 and 13. FIG. 3 is a diagram schematically illustrating the flow path configuration of the sample dispensing mechanism. The sample dispensing mechanism 9 mainly includes a sample nozzle 10 and a syringe 28. By operating the syringe 28 connected to the sample nozzle 10, the sample in the sample container 6 is dispensed into the reaction container 2. The syringe 28 is provided with a plunger 30, which is connected to a motor 31. The motor 31 drives the plunger 30 to aspirate and discharge the sample to be dispensed from the sample nozzle 10.

[0019] A flow path from the sample nozzle 10 to the water supply pump 25 via a syringe 28, an electromagnetic valve 29, and a liquid feed pump 26 is formed by a tube 27, and the flow path is filled with system water. System water is water used for pressure transmission, and is generally purified water such as ion-exchanged water. When the inside of the sample nozzle 10 is to be cleaned, the electromagnetic valve 29 opens, and the system water (cleaning water) supplied from the water supply pump 25 is discharged from the tip of the sample nozzle 10.

[0020] When the sample dispensing mechanism 9 dispenses a sample, first, while the solenoid valve 29 remains closed, the sample nozzle 10 moves to a position where it aspirates the sample from the sample container 6 (sample aspirating position). Next, with the tip of the sample nozzle 10 reaching the liquid surface of the sample, the plunger 30 is driven in the aspirating direction to draw the sample into the sample nozzle 10. After that, the sample nozzle 10 moves to a position where it ejects the sample into the reaction container 2 (sample ejecting position), and in this state, the plunger 30 is driven in the ejecting direction to eject the sample into the reaction container 2. After the sample dispensing mechanism 9 dispenses the sample, the sample nozzle 10 moves to the washing tank 19, where the inside and outside of the sample nozzle 10 are washed.

[0021] Next, the operation of the sample dispensing mechanism 9 will be described in detail.

[0022] (Dispensing Method According to Comparative Example) First, as a comparative example, a sample dispensing method in a conventional automatic analyzer will be described with reference to Fig. 4. Fig. 4 is a diagram showing the operational sequence of sample dispensing in the automatic analyzer according to the comparative example.

[0023] First, in step S1, with the sample nozzle 10 positioned at the washing tank 19, the control unit 24 causes the liquid supply pump 26 to supply system water to wash the inside and outside of the sample nozzle 10.

[0024] Next, in step S2, while the sample nozzle 10 is moving from the position of the washing tank 19 to the position of the sample container 6 (sample aspirating position), the control unit 24 operates the syringe 28 in the aspirating direction to aspirate segmented air. The segmented air is air that separates the system water and the sample, and serves as an air layer that prevents the sample from coming into contact with the system water during sample aspirating, thereby diluting the sample concentration.

[0025] Next, the sample nozzle 10 descends to the sample suction position, and in step S3, with the sample nozzle 10 immersed in the liquid surface in the sample container 6, the control unit 24 operates the syringe 28 in the suction direction to aspirate a predetermined amount of sample. The suction operation amount of the syringe 28 in step S3 is the required measurement amount a + dummy amount b + sufficient backlash removal amount c. The required measurement amount a refers to the amount of sample required for measurement in the measurement item in question. The dummy amount b refers to the amount of sample that is aspirated in excess to reduce the effect of dilution by system water in the sample nozzle 10. The sufficient backlash removal amount c refers to the syringe operation amount sufficient to remove backlash from the syringe 28.

[0026] Note that backlash refers to gaps that exist at the connection points between the mechanical parts that make up the syringe, and the backlash removal operation is an operation to eliminate the minute idling that occurs due to these gaps when the syringe's operating direction is reversed. However, the amount of backlash that a syringe actually has (hereinafter simply referred to as the "actual backlash amount") c' varies from syringe to syringe and does not necessarily match the theoretical amount of backlash estimated from the syringe's design values. For this reason, the sufficient backlash removal amount c is set to a margin added to the theoretical amount of backlash, for example, an amount approximately twice the theoretical value.

[0027] Next, immediately after step S3, in step S4, the control unit 24 operates the syringe 28 in the discharge direction while the sample nozzle 10 is immersed in the liquid surface in the sample container 6. The discharge amount of the syringe 28 in step S4 is a sufficient amount c for removing backlash, which is larger than the actual backlash amount c', and therefore backlash of the syringe 28 can be reliably removed. Therefore, in step S4, after all backlash has been removed, a portion of the sample aspirated in step S3 (specifically, an amount equivalent to c-c') is expelled back into the sample container 6.

[0028] Next, after the sample nozzle 10 has risen, it moves to the position of the washing tank 19, and in step S5, the control unit 24 supplies system water using the liquid supply pump 26 to wash the outside of the sample nozzle 10. Note that this step S5 may be omitted.

[0029] Next, when the sample nozzle 10 moves to the position of the reaction vessel 2 and the tip of the sample nozzle descends to the bottom of the reaction vessel 2, in step S6, the control unit 24 again operates the syringe 28 in the discharge direction. The discharge amount of the syringe 28 in step S6 is the required measurement amount a. Note that the operating direction of the syringe 28 in step S6 is the same as the previous operating direction, i.e., the discharge direction in step S4, so there is no need to consider backlash.

[0030] Next, after the sample nozzle 10 has moved to the cleaning tank 19, if there are no other measurement requests for the sample, in step S7, the control unit 24 discharges a dummy amount of sample from the sample nozzle 10 and returns to step S1.

[0031] (Mechanism of carryover between liquids) Here, the mechanism of carryover between liquids, in which a previously dispensed liquid is carried over into the next liquid, will be described. Below, we will use an example where the liquid is a sample, but the same applies when the liquid is a reagent. Carryover between samples can be thought of as occurring for two main reasons. The first reason is that a portion of the previous sample adhering to the outside of the nozzle remains without being washed away even after the nozzle has been cleaned, resulting in contamination of the next liquid. The second reason is that a portion of the previous sample adhering to the inside of the nozzle remains without being washed away even after the nozzle has been cleaned, resulting in contamination of the next sample. The second reason will be described in detail below with reference to FIG. 5.

[0032] Figure 5 illustrates the mechanism of carryover resulting from the previous sample remaining inside the nozzle. As shown in Figure 5, once dispensing of the previous sample is completed, the dummy amount of the previous sample that was inside the nozzle is discharged in the washing tank, and the inside of the nozzle is washed with washing water. However, because a small amount of the previous sample remains inside the nozzle without being completely washed away, when the next sample is aspirated, the inside of the nozzle contains not only the next sample but also a small amount of the previous sample. If a backlash removal operation is performed in this state, the previous sample is spit back into the sample container containing the next sample along with the next sample. Even if the amount of the previous sample spit back into the sample container during one backlash removal operation is small, as dispensing is repeated and the number of backlash removal operations increases, the previous sample spit back into the sample container accumulates, which can have a significant impact on dispensing accuracy.

[0033] One possible method for suppressing carryover of the preceding sample is to improve the cleaning effect by extending the cleaning time or increasing the amount of cleaning water (per unit time). However, extending the cleaning time may reduce the processing capacity of the automated analyzer, and increasing the water pressure to increase the amount of cleaning water is not easy due to the device's configuration. Furthermore, performing special cleaning using detergents, which differs from the normal cleaning using system water, requires additional steps, which may also reduce the processing capacity of the automated analyzer. Another possible method for suppressing carryover of the preceding sample is to reduce the area where the sample adheres (the contaminated area). However, the contaminated area inside the nozzle is determined by the amount of sample aspirated, making it difficult to uniformly reduce the area regardless of the measurement item.

[0034] Therefore, in this embodiment, in order to suppress carryover from the previous sample remaining inside the nozzle, the sample is discharged while the nozzle is moving from the position of the sample container to the position of the reaction container, thereby reducing the amount of sample that is discharged back into the sample container. Below, two examples will be given to explain the specific details of the dispensing method.

[0035] In Example 1, similar to the comparative example, after the dispensing mechanism aspirates a sample and before dispensing it into a reaction vessel, a syringe dispensing operation including a backlash removal operation is performed. However, unlike the comparative example, this dispensing operation is performed in two steps. Figure 6 is a diagram showing the operational sequence of sample dispensing in the automatic analyzer according to Example 1.

[0036] Steps S11, S12, S13, S16, and S17 are similar to steps S1, S2, S3, S6, and S7 of the comparative example, respectively.

[0037] Step S14 is a first dispensing operation performed with the sample nozzle 10 positioned at the sample container 6. In this step S14, similar to step S4 in the comparative example, the controller 24 operates the syringe 28 in the dispensing direction with the sample nozzle 10 immersed in the liquid surface in the sample container 6. However, unlike the comparative example, the dispensing amount of the syringe 28 in step S14 is the first dispensing amount d1, which is less than the amount c sufficient to remove backlash. This makes it possible to reduce the amount of liquid actually discharged back into the sample container 6, and also to reduce the amount of analyte contained in that liquid.

[0038] Next, step S15 is the second dispensing operation, which is performed while the sample nozzle 10 is positioned in the washing tank 19. The dispensing volume of the syringe 28 in step S15 is the second dispensing volume d2, which is set so that the sum of the first dispensing volume d1 and the second dispensing volume d2 is the aforementioned sufficient volume c for removing backlash. Therefore, by the time the second dispensing operation in step S15 is completed, backlash from the syringe 28 is reliably removed. Furthermore, in step S15, the external cleaning of the sample nozzle 10 is also performed in parallel with the second dispensing operation. However, the external cleaning time is longer than the second dispensing operation, and the cleaning water remains in contact with the sample nozzle 10 from the start to the end of sample dispensing in the second dispensing operation. If the sample is dispensed without the cleaning water hitting the tip of the sample nozzle 10, the sample may splash. To further prevent sample splashing, it is desirable for the sample nozzle 10 to be stopped during the second dispensing operation.

[0039] In this embodiment, the carryover suppression effect is enhanced by making the first dispensing operation volume d1 smaller than the second dispensing operation volume d2. Furthermore, if only the carryover suppression effect is considered, the proportion of the first dispensing operation volume d1 can be reduced and the proportion of the second dispensing operation volume d2 can be increased. Here, the sample nozzle 10 stops at the washing tank 19 while moving from the sample container 6 to the reaction container 2, and performs the second dispensing operation. However, to maintain the processing capacity of the automated analyzer, the time allowed for the stop at the washing tank 19 is limited. For example, if the time allowed for stopping at the washing tank 19 is 60 ms, taking into account factors such as the pressure response delay of the syringe 28, the time allocated for the second dispensing operation is 40 ms or less. Therefore, if the proportion of the second dispensing operation volume d2 is too large, it may be difficult to complete the second dispensing operation and external cleaning within 40 ms. In this case, it is necessary to complete a certain amount of discharging in the first discharging operation, and depending on the magnitude of the first discharging operation amount d1, the backlash that the syringe 28 actually has is removed by the time the first discharging operation is completed, and a portion (d1-c') of the sample is discharged back into the sample container 6. However, since the amount of sample discharged back into the sample container 6 can be reduced compared to the comparative example, this leads to the suppression of carryover.

[0040] One possible method for completing the second dispensing operation within the limited time that the sample nozzle 10 is positioned in the washing tank 19 is to operate the syringe 28 at high speed during the second dispensing operation. However, operating the syringe 28 too quickly can result in pressure pulsations, potentially dispensing more sample than intended, thereby affecting dispensing accuracy. Therefore, it is desirable to operate the syringe 28 at the slowest speed during the entire dispensing operation (equivalent to the speed used when aspirating the segmented air in step S12). For example, if the syringe 28 dispenses sample at a speed of 1,000 pulses / second with a resolution of 0.02 μL / pulse, the second dispensing operation volume d2 that can be performed in 40 ms is 0.8 μL.

[0041] On the other hand, if there is sufficient time for the sample nozzle 10 to stop at the washing tank 19 in step S15, the first dispensing operation amount d1 can be made smaller. Therefore, by setting the first dispensing operation amount d1 to an amount less than the theoretical value of the backlash amount estimated from the syringe design values ​​(or the lower limit if there is a range in the theoretical value due to individual differences), backlash from the syringe 28 can be retained even at the end of the first dispensing operation. This effectively reduces the amount of backlash spit back into the sample container 6 during the first dispensing operation, further reducing carryover. In this case, backlash removal is completed during the second dispensing operation, and the sample is then dispensed from the sample nozzle 10.

[0042] Next, the effects of Example 1 will be described with reference to FIGS. 7A and 7B. FIG. 7A is a table showing the values ​​of the first and second dispensing operation amounts set in the comparative example and Example 1, and FIG. 7B is a graph showing the average inter-analyte carry-over rates in the comparative example and Example 1. Note that in the comparative example, the syringe dispensing operation, including the backlash removal operation performed before dispensing into the reaction vessel, is performed once. However, for convenience, this is divided into the first and second dispensing operations, and the second dispensing operation amount is set to zero. Furthermore, the inter-analyte carry-over rate indicates the proportion of target components from sample A that are carried over into sample B when the previous sample is a high-concentration contaminated sample, sample A, and the next sample is a low-concentration contaminated sample, sample B.

[0043] As shown in FIG. 7A , if the first dispensing operation amount in the comparative example is X, then in Example 1, the first dispensing operation amount is X / 7 and the second dispensing operation amount is 6X / 7. That is, in Example 1, the first dispensing operation amount is reduced to one-seventh of that in the comparative example. As a result, as shown in FIG. 7B , it can be seen that in Example 1, the inter-analyte carry-over rate can be reduced by 65% ​​compared to the comparative example. Note that the reduction rate of inter-analyte carry-over varies depending on conditions such as the initial concentration and viscosity of the contaminating sample, the temperature of the measurement environment, and other factors. Thus, according to Example 1, the amount of sample discharged back into the sample container can be reduced, thereby reducing carry-over resulting from sample remaining inside the nozzle, making it possible to realize an automated analyzer with high dispensing accuracy.

[0044] Example 2 Example 2 is an example in which the first discharge operation amount in Example 1 is set to zero. Fig. 8 is a diagram showing the sample dispensing operation sequence in an automatic analyzer according to Example 2.

[0045] Steps S21, S22, S23, S26, and S27 are similar to steps S11, S12, S13, S16, and S17 in the first embodiment, respectively.

[0046] In step S24, the first ejection operation amount d1' is zero, so the first ejection operation is not performed.

[0047] Next, in step S25, the second discharge operation is performed. The second discharge operation amount d2' in the second embodiment is larger than the second discharge operation amount d2 in the first embodiment and is equal to the sufficient backlash removal amount c.

[0048] According to the second embodiment, the sample is not discharged back into the sample container, so carryover from the sample remaining inside the nozzle can be substantially reduced to zero, and an automatic analyzer with higher dispensing accuracy can be realized. However, in the second embodiment, the amount of the second dispensing operation is large, so this is only possible when there is sufficient time for the sample nozzle 10 to stop at the washing tank 19.

[0049] (Note) The present invention is not limited to the above-described embodiments, but includes various modifications and combinations. For example, although the embodiments are directed to suppressing carryover when dispensing a sample, they can also be applied when dispensing a reagent.

[0050] In each example, the outside of the sample nozzle 10 was washed with cleaning water in parallel with the second dispensing operation, but this washing may be performed by other methods. Figure 9 shows variations in the nozzle washing method. As shown in Figure 9, washing methods other than using cleaning water include a method using air blowing and a method using vacuum suction.

[0051] Furthermore, in each embodiment, the second dispensing operation was performed at the position of the washing tank 19, but it may also be performed at a position other than the washing tank 19 as long as the sample nozzle 10 is in the middle of moving from the position of the sample container 6 to the position of the reaction container 2. The second dispensing operation may also be comprised of multiple operations performed when the nozzle is in different positions. For example, the first half of the second dispensing operation may involve cleaning the nozzle tip with cleaning water at the position of the washing tank 19, then moving the nozzle to the air blow position, and the second half of the second dispensing operation may involve removing residual cleaning water adhering to the nozzle by vacuum suction. In this way, combining multiple cleaning methods makes it possible to further stabilize dispensing accuracy.

[0052] 1... reaction disk, 2... reaction container, 3... reagent disk, 4... reagent bottle, 6... sample container, 7... sample rack, 8... sample transport mechanism, 9... sample dispensing mechanism, 10... sample nozzle, 11, 13... reagent dispensing mechanism, 12, 14... reagent nozzle, 15... cleaning mechanism, 17, 18... stirring mechanism, 19... cleaning tank, 20, 21... cleaning tank, 22, 23... cleaning tank, 24... control unit, 25... water supply pump, 26... liquid delivery pump, 27... tube, 28... syringe, 29... solenoid valve, 30... plunger, 31... motor

Claims

1. An automatic analyzer comprising a dispensing mechanism which dispenses a sample contained in a sample container or a reagent contained in a reagent container into a reaction container by operating a syringe connected to a nozzle, and a control unit which controls the dispensing mechanism, wherein after the dispensing mechanism has aspirated the sample or reagent and before dispensing it into the reaction container, the control unit performs a dispensing operation by moving the syringe in a dispensing direction, wherein the dispensing operation comprises: a first dispensing operation which is performed while the nozzle is in the position of the sample container or the reagent container; and a second dispensing operation which is performed while the nozzle is moving from the position of the sample container or the reagent container to the position of the reaction container, and wherein the amount of movement of the syringe in the first dispensing operation is smaller than the amount of movement of the syringe in the second dispensing operation.

2. The automatic analyzer according to claim 1, wherein at least in the second ejection operation, the sample or the reagent is ejected from the nozzle.

3. An automatic analyzer as described in claim 1, characterized in that backlash of the syringe is removed by the end of the first ejection operation, and the sample or reagent is ejected from the nozzle from the start of the second ejection operation.

4. An automatic analyzer as described in claim 1, characterized in that at the end of the first ejection operation, backlash remains in the syringe, and during the second ejection operation, the backlash is removed and the sample or reagent is ejected from the nozzle.

5. The automatic analyzer according to claim 1, wherein the amount of movement of the syringe in the first discharge operation is zero.

6. An automatic analyzer according to claim 1, further comprising a cleaning tank for cleaning the outside of the nozzle, and the second ejection operation is performed with the nozzle positioned at the cleaning tank.

7. An automatic analyzer according to claim 6, wherein in the second ejection operation, cleaning water is in contact with the nozzle from the start of ejection of the sample or reagent to the end of ejection.

8. The automatic analyzer according to claim 6, wherein the nozzle is stopped during the second ejection operation.

9. An automatic analyzer according to claim 1, wherein the second ejection operation is made up of a plurality of operations that are performed when the nozzle is in different positions.

10. A dispensing method for dispensing a sample contained in a sample container or a reagent contained in a reagent container into a reaction container using an automatic analyzer equipped with a dispensing mechanism having a nozzle and a syringe, and a control unit for controlling the dispensing mechanism, comprising: a liquid suction step in which the control unit operates the syringe in the suction direction while the nozzle is in the position of the sample container or the reagent container; a first discharge step in which the control unit operates the syringe in the discharge direction while the nozzle is in the position of the sample container or the reagent container; a second discharge step in which the control unit operates the syringe in the discharge direction while the nozzle is moving from the position of the sample container or the reagent container to the position of the reaction container; and a liquid discharge step in which the control unit operates the syringe in the discharge direction while the nozzle is in the position of the reaction container, wherein the amount of movement of the syringe in the first discharge step is smaller than the amount of movement of the syringe in the second discharge step.

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