Automated immunochemical analyzer

Abstract: A small, inexpensive, and easy-to-use automated immunochemical analyzer comprises at least one disposable reaction plate (12) with a plurality of containers (14) formed as one body, a withdrawable table (10) for reaction plates, a withdrawable table (34) for specimen racks, a thermostat unit for reagents (44), a thermostat unit for the reaction containers (58), a reaction plate holder (90), means (66) for aspirating and discharging sample liquid, and an XY translator (70) on which the plate holder (90) and the means (66) are mounted. In use, the reaction plate is moved to the reaction thermostat (58) and sample and reagents are added to the containers from the specimen rack (36) & the reagent thermostat (44), using means (66) under control of the XY translator (70). The liquid in the reaction cups is kept at constant temperature and shaken to promote an antigen-antibody reaction. The reaction liquid is sampled subsequently by the means (66) and transferred to measuring means (118) to yield the results of the assay.

Description: BACKGROUND OF THE INVENTION The present invention relates to an automated immunochemical analyzer capable of quantitating antigens or antibodies by individually counting the number of particles of aggregates (agglutinated matter) of insoluble carriers produced by antigen-antibody reaction. The CIA method is known as the procedure of measuring trace tumor relates protein, such as alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA), promptly and at high sensitivity. Standing for counting immunoassay, the CIA method is to quantitate the target antigen (or antibody) in the specimen by mixing the specimen containing the target antigen (or antibody), and a reagent containing latex particles bonded with antibody (or antigen) specifically reacting with the antigen (or antibody) in the specimen, forming latex aggregates by antigen-antibody reaction, measuring the particles of the aggregates, calculating the degree of aggregation from the unaggregated particle count and aggregated particle count, and converting into the concentration of antigen (or antibody). An automated immunochemical analyzer by the CIA method has been disclosed, for example, in the Published Unexamined Japanese Patent Application Hei. 1-259257. In the conventional automated immunochemical analyzer, aspiration and discharge means were individually installed for the specimen, reagent and reaction liquid, and aspiration, discharge and cleaning (rinsing) were performed by rotating the arm furnished with a pipet, and moving the pipet in the arc direction. Besides, for aspiration and discharge of a plurality of specimens, reagents and reaction liquids, it is necessary to move the object container during circulation motion of the pipet, and it is realized by rotating the tables mounting the plurality of specimen containers, at least one reagent container and at least one reaction container. The reaction containers are cleaned in the apparatus by cleaning means after use. Therefore, the apparatus is complicated, and the wide space for turntables is necessary, and the apparatus becomes larger in size and higher in price. During reaction or measurement, the turntables and aspiration and discharge means cooperate, and it has been difficult to add the specimens to be measured or to be squeezed by emergency specimens. Besides, depending on the measuring items, the contamination problem has been caused even after cleaning the reaction container. From EP-A-0 449 321 there is known an automated immunochemical analyzer comprising at least one reaction plate on which a plurality of reaction containers are formed integrally and a table for the reaction plate(s) that can be drawn out and on which the reaction plate(s) before use is (are) disposed. In this known analyzer a plurality of aspiration and discharge means are arranged along a long straight reaction line on which the reaction plate is moved linearly on belts so that this analyzer is widely similar to the above-mentioned other conventional automated immunochemical analyzer with the main difference that the moving paths are different, namely circular on the one hand and straight on the other hand. Therefore, in the analyzer according to EP-A-0 449 321 a wide space for the long straight reaction line is necessary so that this analyzer is relatively large in size as the above-mentioned conventional analyzer. OBJECT AND SUMMARY OF THE INVENTION It is hence a primary object of the invention to provide an automated immunochemical analyzer of high precision that is small in size, low in price, and easy to use, by solving the above problems. To achieve the above object, referring to the drawings, the invention provides an automated immunochemical analyzer comprising: at least one reaction plate 12 on which a plurality of reaction containers 14 are formed integrally, a table 10 for one or more reaction plates that can be drawn out on which the reaction plate before use and the reaction plate after use are disposed, a table 34 for specimen racks that can be drawn out on which a plurality of specimen racks 36 are disposed, a reagent thermostatic unit 44 for keeping reagents in thermostatic (constant temperature) state, a reaction thermostatic unit 58 for shaking the reaction plate 12 while holding (keeping) in thermostatic (constant temperature) state, a reaction plate holding part 90 for holding and lifting the reaction plate 12, means 66 for aspirating and discharging sample liquid for aspirating and discharging a specific amount of specimen and reagent from a pipet 82, and a single X-Y moving part 70 on which are mounted both the means 66 for aspirating and dispensing liquid and the reaction plate holding part 90. The reaction plate 12 is of disposable type, and is discarded (dumped) after use without being cleaned. First, by the X-Y moving part 70, the holding part 90 is moved from the table 10 for reaction plate up to the reaction thermostatic unit 58 while holding the reaction plate before use. Consequently, by the X-Y moving part 70, the means 66 for aspirating and discharging sample liquid is moved reciprocally among the specimen rack 36, reagent thermostatic unit 44 and reaction thermostatic unit 58, and distributes specimen and reagent in the reaction plate. The distributed liquid is kept thermostatically (in constant temperature), shaken, and agitated, and the antigen-antibody reaction is promoted. The reaction liquid is sampled by the means 66 for aspirating and discharging sample liquid, and is measured. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory plan view showing an embodiment of an automated immunochemical analyzer of the invention. Fig. 2 is a perspective view showing an example of a reaction plate used in the apparatus of the invention. Fig. 3 is an explanatory diagram showing the drawn state of the table for reaction plate as seen from the direction of arrow B in Fig. 1 (a side explanatory diagram around the table for reaction plate). Fig. 4 is an explanatory diagram showing a drawn state of the table for specimen rack as seen from the direction of arrow B in Fig. 1 (a side explanatory diagram around the table for specimen rack). Fig. 5 is a front explanatory diagram of the means for aspirating and discharging sample liquid (as seen from direction of arrow C in Fig. 1). Fig. 6 is a side explanatory view of the reaction plate holding part (as seen from direction of arrow D in Fig. 5). Fig. 7 is a flow chart showing a display method of display means. Fig. 8 is a flow chart showing reservation/cancellation of table draw-out. Fig. 9 is a flow chart showing the processing of drawing of table. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, some of the preferred embodiments of the invention are described in detail below. Fig. 1 is a plan view of an embodiment of an automated immunochemical analyzer of the invention. The basic construction of the reaction system and measurement system is same as the apparatus disclosed in the Published Unexamined Japanese Patent Application No. Hei.1-259257. The apparatus of the invention is downsized in order to reduce the cost of that conventional apparatus. A principal difference is the use of disposable reaction plates. As a result, the cleaning device is not needed. Besides, using only one means for aspirating and discharging liquid, the means is moved two-dimensionally,and the move of other units is eliminated, and the means is provided with a function for holding the reaction plate, so that the effective use of space and saving of cost are realized. By reference to Fig. 1, a general construction of the automated immunochemical analyzer of the invention is described below. Numeral 10 is a table for reaction plate for disposing reaction plates 12. Numeral 34 is a table for specimen rack for disposing specimen racks 36. Numeral 44 is a reagent thermostatic unit for keeping reagents in a thermostatic (constant temperature) state. Numeral 58 is a reaction thermostatic unit for keeping in a thermostatic state while shaking and agitating a reaction liquid (a mixed liquid of specimen and reagents). Numeral 66 is a means for aspirating and discharging sample liquid. Numeral 90 is a holding part for holding reaction plates 12. The means 66 for aspirating and discharging sample liquid and the holding part 90 are mounted on a same XY moving part 70, and are moved back and forth, right and left. Numeral 2 denotes an operation panel for setting and entering data. Numeral 4 is a printer, and 6 is a display unit. The construction of each part is described in further detail below. Fig. 2 is a perspective view of an example of a reaction plate 12 used in the apparatus of the invention. The reaction plate 12 is made of synthetic resin, and one plate holds, for example, a total of 25 reaction containers 14 in 5 rows by 5 lines, and these containers 14 are linked with each other by a base plate 16, and all are formed in one body. The inside diameter and height of the containers 14 are, for example, about 8 mm and about 24 mm, respectively. As seen from the top, the reaction plate 12 has a square shape of one side of, for example, about 70 mm. At both sides of the reaction plate 12, handles 18, 20 for holding the reaction plate are attached. At both sides of the handles 18, 20, moreover, since protrusions 22, 24 for holding are provided downward, so that holding of the reaction plate is much easier, while the positional deviation of the reaction plate when moving is prevented. The detail is described below. The upper end and outer frame of each container 14 are located higher than the position of the base plate 16 (for example, 6 mm), and the liquid in the containers hardly splashes out, and the liquid spilling over the base plate 16 hardly gets into the containers 14, structurally. A corner 26 of the reaction plate 12 is partly cut for positioning purpose. In the bottom of each container 14, a recess 28 is formed, and stable dimensions are obtained in manufacture, and it is possible to install in the apparatus securely. The reaction plate should be preferably made of a transparent body entirely. Back to Fig. 1, the explanation continues. The table 10 for reaction plate for mounting the reaction plates 12 is partitioned by, for example, three partition members 30, so that four reaction plates may be disposed. The places of disposition are supposed to be, from the nearest side (the lowest side in Fig. 1), first place 32a, second place 32b, third place 32c, and fourth place 32d. The first and second places 32a, 32b are the spaces for placing the reaction plates 12a, 12b before use. The third and fourth places 32c, 32d are spaces for placing the reaction plates after use, and the third and fourth places 32c, 32d are empty (open) before use. When the measurement ends, the reaction plates 12a, 12b are used as the measurement starts, they are put in the places 32c, 32d. The table 10 can be drawn out in the direction of arrow A in Fig. 1. Fig.3 is a view from the direction of arrow B in Fig. 1, showing the state of the table 10 being drawn out. By drawing out the table 10, the reaction plate can be placed and taken out easily. On the table 34 for specimen rack, for example, up to eight specimen racks 36 can be mounted. One specimen rack can hold, for example, five specimen containers 38. The specimens are human serum, plasma or urine. Each specimen is aspirated and sampled through a penetration hole 42 of a chassis 40. The table 34 for specimen rack can be also drawn out in the direction of arrow A, same as the table 10 for reaction plate. Fig. 4 is a view from the direction of arrow B in Fig. 1, showing the state of the table 34 being drawn out. A mounting table 37 of specimen rack comprising a front panel 33 and a bottom plate 35 can be drawn out. The specimen rack is placed or taken out by drawing out or removing the table 34. Usually, the places for six racks on the left side are used, and the places for two racks on the right side are kept open for emergency specimens. On the back side of the reagent thermostatic unit 44, a cooler (not shown) is provided, and the reagents are kept at about 15°C or less. On the top of the reagent thermostatic unit 44, recesses 46, 48, 50 are provided, and buffer solution container 52, latex reagent container 54, and diluent liquid container 56 are put in the recesses. The reaction plate 12 is put on the reaction thermostatic unit 58, and the reaction liquid which is a mixed liquid of specimen and reagents is kept around 45°C by a heater (not shown) attached to the back side of the reaction thermostatic unit 58. Furthermore, the entire reaction thermostatic unit 58 makes shaking motions. The radius of rotation of shaking motions is, for example, 1.5 mm, and the rotating speed is 600 rpm. On the top of the reaction thermostatic unit 58, there are a plurality of recesses 60 in which the container portions of the reaction plate settle home. The reaction thermostatic unit 58 consists of first place 58a and second place 58b, and two reaction plates are put in these places, so that they can be kept thermostatically (in constant temperature), shaken and agitated simultaneously. Numerals 62, 64 are holding members for grasping and holding the reaction plate from both sides. The automated immunochemical analyzer of the present invention is provided with only one means for aspirating and discharging the liquid sample. The means 66 for aspirating and discharging the sample liquid moves vertically for aspirating and discharging liquid. The means 66 for aspirating and discharging sample liquid is furnished with the holding part 90 for holding and lifting the reaction plate 12. The means 66 for aspirating and discharging sample liquid having a holding part 90 is mounted on the XY moving part 70 which can move two-dimensionally on the automated immunochemical analyzer. Accordingly, the means 66 for aspirating and discharging sample liquid 66 can discharge the liquid aspirated at one position to other position, and move the reaction plate from one place to other place. Fig. 5 is a front view of the portion of the means 66 for aspirating and discharging the sample liquid (a view from the direction of arrow C in Fig. 1). A guide rail 74 is mounted on a base plate 72. A slider 76 moves only vertically along the guide rail 74. An arm 80 is attached to the slider 76 through a mounting member 78. As aspiration pipet 82 is drooping from the arm 80. A tube 84 is connected to the aspiration pipet 82. Another guide rail 86 is mounted on the base plate 72 parallel to the guide plate 74, and a slider 88 moves only vertically along the guide rail 86. The slider 88 is combined with the holding part 90 for holding the reaction plate 12 through mounting members 92, 94, 93, 96. The holding part 90 comprises the mounting member 96 having the ends bent inward, that is, in a shape of notching (cutting) the middle portion of the lower side of a square, and an inside member 98 provided inside of the mounting member 96. The reaction plate 12 is held as handles 18, 20 of the reaction plate 12 are fitted in bent parts 100, 102 of the holding part 90. Numeral 103 is a positioning sensor attached to a vertical member 104. Fig. 6 is a view of the holding part 90 as seen from its side (a view from direction of arrow D in Fig. 5). Since protrusions 22, 24 for holding provided in the lower part at both ends of the handle 18 of the reaction plate 12 are located so as to grasp the bent part 100 from both sides, and the reaction plate 12 is lifted up while maintaining the specific position, and is not hence deviated in position. Furthermore, the base plate 72 is provided with a columnar member 106 with round ends through the vertical member 104, and the columnar member 106 is designed to be fitted into one container of the reaction plate 12 when the reaction plate 12 is held and lifted by the holding part 90. Hence, the reaction plate 12 is fixed firmly, and is not deviated or loosened in spite of longitudinal or lateral movement. The base plate 72 is rotatably provided with a pair of pulleys 108, 110, and a belt 112 is applied on the pulleys 108, 110. One pulley 108 is coupled with the rotary shaft of a motor 114, and the belt 112 can rotate both normally and reversely. The mounting member 78 is connected to one side of the belt 112, while the mounting member 92 is connected to the another side of the belt 112. Hence, the arm 80 and holding part 90 move mutually in reverse directions. That is, when the arm 80 ascends, the holding part 90 descends, and when the arm 80 descends, the holding part 90 ascends. Comparing the frequency of aspirating and discharging action of liquid and holding action of reaction plate, the frequency of liquid aspiration and discharge is higher by far, and it is not necessary to do the both actions simultaneously, there is no problem by moving the arm 80 and holding part 90 up and down alternately by one motor 114. When the holding part 90 is lowered in order to hold the reaction plate (or released the held reaction plate), the pipet 82 goes up, and hence there is no obstacle for holding (or releasing) of the reaction plate. When the pipet 82 is lowered for aspiration or distribution of the liquid, the holding part 90 goes up, and there is no problem for aspirating and discharging action. The actual operation is described below while referring to Fig. 1. The means 66 for aspirating and discharging sample liquid provided with the holding part 90 of the reaction plate moves to above the first place 32a on the table 10, where the holding part 90 descends, and the reaction plate 12a is held. After holding the reaction plate, it goes up, and moves to above the first reaction part 58a of the reaction thermostatic unit 58, and places the held reaction plate 12a. The reaction plate 12b is similarly moved from the second place 32b on the table 10 to above the second reaction part 58b. Next, by the means 66 for aspirating and discharging sample liquid, the specimen, buffer solution and latex reagent are sequentially aspirated by specific volumes, and sequentially discharged into empty containers 14 of the reaction plate placed on the reaction thermostatic unit 58. For example, 100 µl of reaction liquid composed of 10 µl of specimen, 80 µl of buffer solution and 10 µl of latex reagent is held thermostatically and shaken and agitated, and the agglutination reaction of latex particles by the antigen-antibody reaction is promoted. Until the time of measurement, the reaction liquid is prepared for each specimen one after another. Numeral 116 is a cleaning tank for cleaning (rinsing) the pipet 82. If necessary, the specimen is preliminarily diluted by adding a diluent liquid. When reaction for specific time is over, the reaction liquid is sampled in the means 66 for aspirating and discharging sample liquid, and distributed in a measuring chamber 118, and is transferred to a measuring unit (not shown) and measured. A practical example of measuring unit is disclosed, for instance, in the Published Japanese Laid-open Patent Hei. 1-259257. When all containers of the reaction plates are used up, the used reaction plates are moved to the places 32c, 32d on the table 10. Herein, the table 10 is drawn out, and the used reaction plates are discarded (dumped), and new reaction plates are put in places 32a, 32b. These placing and removing actions of reaction plates can be done also while the apparatus is in action. It is the same for placing and removing of specimen racks. Near the tables 10, 34, display means showing possible/impossible to draw out is provided, for example, the green lamp means (displays) possible and red lamp impossible, and according to the display the drawing action can be done. Even in impossible state, by entering the draw-out reserve, it can be set in possible state for drawing out by changing the sequence (however, the important sequence such as the reaction condition that may affect the result of measurement is not changed). Fig. 7 is a flow chart showing the display method of the display means. To display in the table for specimen rack, it is judged and displayed possible/impossible to draw out depending on whether the means 66 for aspirating and discharging sample liquid moves to the table 34 for specimen rack or not. It is the same in the case of table 10 for reaction plate. Fig. 8 is a flow chart showing the reserve/cancel of table drawing out. When reserved, the sequence for enabling to draw out the table is effected. That is, while continuing the reaction sequence or measurement sequence of specimens, the means 66 for aspirating and discharging sample liquid is prevented from accessing the table. In the draw-out sequence, as shown in Fig. 7, the display turns to green, and it is ready to draw out. After closing, when the reserve key is entered again, the operation returns to the routine sequence. Fig. 9 is a flow chart showing the processing of drawing out the table. When already reserved or during drawing sequence, the drawing sequence starts or continues. If not reserved, when set in drawing state, it is reserved. Not in drawing state, together with an alarm, the pipet of the means 66 for aspirating and discharging sample liquid is immediately lifted to escape, and stopped, and the error processing is done (conducted). It is more preferable to provide with means for locking the table drawing to actuate the locking means while the table drawing is disabled so that the table cannot be drawn out. In the table drawing state, the locking means is invalidated, that is, the locking means does not act. Such locking means may be realized by the known art. Being thus constructed, the invention brings about the following effects. (1) The reaction plate is of disposable type, and the cleaning (rinsing) mechanism is not needed, and carry-over is eliminated, so that the precision may be enhanced. (2) Since the means for aspirating and discharging sample liquid and reaction plate holding part can be moved by the XY moving part, individual rotary mechanisms used in the conventional apparatus are not needed, and only one drive mechanism is enough, so that the structure of the apparatus may be extremely simplified. (3) It is not necessary to dispose a plurality of specimen containers, reagent containers and reaction containers on the circumference of each turntable, and they can be laid out in rows, so that the apparatus size may be significantly reduced. (4) By downsizing and simplifying of the apparatus, an apparatus of high reliability and low price may be provided. (5) The specimen containers, reagent containers, and reaction containers are fixed in position, and by considering only the XY moving part which is the only one drive mechanism, addition of specimens to be measured or interruption (squeezing) with emergency specimens may be easily enabled, so that an easy-to-use apparatus is realized. Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims: An automated immunochemical analyzer comprising: at least one reaction plate (12) on which a plurality of reaction containers (14) are formed integrally, a table (10) for one or more reaction plates that can be drawn out on which the reaction plate before use and the reaction plate after use are disposed, a table (34) for specimen racks that can be drawn out on which a plurality of specimen racks (36) are disposed, a reagent thermostatic unit (44) for keeping reagents in thermostatic state, a reaction thermostatic unit (58) for shaking the reaction plate (12) while keeping in thermostatic state, a reaction plate holding part (90) for holding and lifting the reaction plate (12), means (66) for aspirating and discharging sample liquid for aspirating and discharging a specific amount of specimen and reagent from a pipet (82), and a single X-Y moving part (70) on which are mounted both the means (66) for aspirating and dispensing liquid and the reaction plate holding part (90). An automated immunochemical analyzer according to claim 1, characterized in that the reaction plate (12) is disposable.

Inventors: IZUMI TAKAYOSHI, OOTANI TOSHIHIRO, IZUMI, TAKAYOSHI, OOTANI, TOSHIHIRO
Applicants: TOA MEDICAL ELECTRONICS, TOA MEDICAL ELECTRONICS CO., LTD.
Application year: 1993
Main classification: G01N35
IPC codes: B01L3, G01N33, G01N35