Device for charging separation buffer liquid to microchip, and microchip processing device equipped with the charging device, electrophoresis method in capillary channel and its microchip processing device

In a separation buffer solution filling device, a microchip is arranged such reservoirs are opened on a surface on respective ends of channels including at least a main separation channel in which analysis is performed while a solution moves inside a plate-like member, and the reservoirs face upward. The filling device fills separation buffer solution into the channels by supplying air from an air supply port which is pushed while maintaining air-tightness onto a top of the reservoir filled with the separation buffer solution on either end of said channels. The air supply port is an opening on a front end of an air cylinder, and has a seal part on that opening. The filling device is pushed onto the reservoir while maintaining air-tightness by that seal part.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a microchip processing apparatus for performing analysis by a microchip electrophoresis method or micro liquid chromatography, or the like, in fields such as chemistry and life science, and a device for filling separation buffer solution into a microchip in such a microchip processing apparatus. Also, the present invention relates to a capillary electrophoresis method for separating and analyzing samples, and a microchip processing apparatus for realizing such a capillary electrophoresis method.

In microchip electrophoresis, a sample such as DNA, RNA or protein introduced on one side of a main separation channel, is electrophoretically separated toward the other end of that channel by a voltage applied between both ends of that channel.

In microchip electrophoresis, an apparatus that automatically performs filling of buffer solution, dispensing of samples, electrophoresis, and detection of separated sample components by repeatedly using a single microchip having one electrophoresis channel has been developed (see Patent Document 1).

Electrophoresis apparatus having plural channels in order to raise operating efficiency of analysis also have been proposed. One of these apparatus has 12 channels, and after manually filling of the separation buffer solution and dispensing of the samples, it electrophoretically separates them sequentially from the 12 channels and obtains data (see Non-Patent Document 1).

Another device has 12 channels using capillaries, and it is made so as to automatically perform: filling of separation buffer solution, dispensing of samples, electrophoretic separation, and data acquisition (see Non-Patent Document 2).

In micro liquid chromatography, the microchip has a liquid delivery channel including a separation column in the form of a main channel, and separates and analyzes a sample introduced to one side of the separation column by moving it toward the other end of that separation column (see Non-Patent Document 3).Patent Document 1: Publication of Japanese Unexamined Patent No. H10-246721Non-Patent Document 1: “Bunseki” (“Analytical Sciences”), No. 5, pp. 267-270 (2002)Non-Patent Document 2: Electrophoresis 2003, 24, 93-95Non-Patent Document 3: Anal. Chem., 70, 3790 (1998)

A microchip having reservoirs opened on the surface on the respective ends of the channels is used, and the microchip is held in a manner such that the reservoirs face upward when installing on the microchip processing apparatus. At that time, when filling separation buffer solution into the channels, or when exchanging the separation buffer solution of the channels of the microchip having finished analysis, the separation buffer solution is supplied to one reservoir by a separation buffer solution filling device. The separation buffer solution is pushed into the channels by pushing an air supply port onto that reservoir and supplying air, and the separation buffer solution overflowing from the other reservoirs, is drawn off by a suction nozzle.

At this time, because it is common that the mechanism for pushing the air supply port onto the reservoir and the driving mechanism for supplying air are separate mechanisms, the apparatus tends to become bulky. Also, it is not good that the separation buffer solution which is supposed to be drawn from the reservoirs by the suction nozzle and discharged, remains in the reservoirs, and in particular when, due to repeated used of the microchip, contamination from the analytical sample of the previous time occurs and the analytical precision is lowered.

Also, in capillary electrophoresis, after the separation buffer solution is filled into the channels and the sample is injected into the channels, it is determined as to whether the phoresis operation is being performed normally or whether it will be performed normally. The method for that is a method in which the electrical current value in the sample phoresis is compared with a threshold value after starting electrophoresis of the sample, or a test current value by application of a voltage lower than the electrophoresis voltage is compared with a threshold value. In either case the normality or abnormality of phoresis is determined according to the electrified state after sample introduction. Further, the electrophoresis process is discontinued when it is determined not to be normal.

However, with the method that determines whether phoresis is normal or not after injecting the sample into the channels, because the sample submitted to analysis is already lost when it is determined not to be normal, it is difficult to measure it again in the case of a sample that can be obtained only in a small quantity.

Therefore, the first purpose of the present invention is to provide a compact and inexpensive separation buffer solution filling device by simplifying the mechanism for pushing the air supply port onto the reservoir and supplying air.

The second purpose of the present invention is to provide a separation buffer solution filling device that makes it easier to draw the separation buffer solution to be discharged from the reservoirs when filling the separation buffer solution into the channels of the microchip.

The third purpose of the present invention is to provide a microchip processing apparatus using such a separation buffer solution filling device.

The fourth purpose of the present invention is to make it such that it can be determined as to whether the filling of the separation buffer solution into the channels has been performed normally even without introducing the sample into the channels.

SUMMARY OF THE INVENTION

The separation buffer solution filling device of the present invention for achieving the first purpose, is a separation buffer solution filling device for a microchip having reservoirs opened on the surface on the respective ends of channels including at least a main separation channel in which analysis is performed while a solution moves inside a plate-like member which is placed in a manner such that the reservoirs face upward, for filling separation buffer solution into the channels by supplying air from an air supply port which is pushed while maintaining air-tightness onto the top of a reservoir filled with separation buffer solution on either end of the channels.

This air supply port is an opening on the front end of an air cylinder, and has a seal part on that opening which is pushed onto the reservoir to maintain an air-tightness. An air cylinder moving/driving mechanism for moving the air cylinder in the vertical direction and operating a plunger thereof, comprises an air cylinder holding member for holding the air cylinder, a plunger holding member for holding the plunger above the air cylinder holding member, a guide for supporting the air cylinder holding member and plunger holding member so as to be capable of sliding, an elastic member placed between the air cylinder holding member and plunger holding member, a driving mechanism for moving the plunger holding member in the vertical direction, and a stopper for defining a top dead center of the plunger holding member. The elastic member is set in a manner such that, in the process of the descent of the plunger holding member accompanying the operation of the driving mechanism, the air cylinder holding member is pushed downward by the elastic member until the air supply port contacts the microchip, and the plunger is pushed to supply air from the air supply port after the air supply port contacts with the microchip.

The separation buffer solution filling device of the present invention for achieving the second purpose, is for a microchip having reservoirs opened on the surface on the respective ends of channels including at least a main separation channel in which analysis is performed while a solution moves inside a plate-like member which is placed in a manner such that the reservoirs face upward, for filling separation buffer solution into the channels. This device has an air supply port which is pushed while maintaining air-tightness, onto the top of a reservoir filled with separation buffer solution, on either end of a channel of the microchip. Suction nozzles which are inserted from above into all of the remaining other reservoirs and draw separation buffer solution overflowing into the reservoirs from the channels when separation buffer solution is pushed into the channels by air being blown from the air supply port. These suction nozzles are supported so as to be capable of sliding via a nozzle holding member which moves in the vertical direction, and are forced downward by a forcing means, whereby they assume a state, forced by the forcing means, wherein they are pushed against the bottoms of the reservoirs.

Of the reservoirs, the reservoir for sample supply may have the separation buffer solution removed or be washed. In order to respond to such a situation, in a preferred embodiment, it is attached in a manner such that, in the state before the suction nozzles are inserted into the reservoirs, the length by which the suction nozzle inserted into the sample supply reservoir among the suction nozzles, projects downward from the nozzle holding member, compared with the length by which the other suction nozzles project downward from the nozzle holding member, is longer than the amount of depth of the liquid present in the reservoirs into which the other suction nozzles are inserted.

In a more preferred embodiment, the outer diameter of the front end of the suction nozzle is smaller than the size of the bottom of the reservoir into which it is inserted, and it is made such that the front end of the suction nozzle is pushed against a side wall part on the bottom of the reservoir when the suction nozzle imbibes liquid from the reservoir.

In a more preferred embodiment, the air supply port is an opening on the front end of an air cylinder, and has a seal part on that opening so that it can be pushed onto the reservoir while maintaining air-tightness by that seal part.

In a more preferred embodiment, an air cylinder moving/driving mechanism for moving the air cylinder in the vertical direction and operating a plunger thereof comprises an air cylinder holding member for holding the air cylinder, a plunger holding member for holding the plunger above the air cylinder holding member, a guide for supporting the air cylinder holding member and plunger holding member to be capable of sliding, an elastic member placed between the air cylinder holding member and plunger holding member, a driving mechanism for moving the plunger holding member in the vertical direction, and a stopper for defining a top dead center of the plunger holding member. The elastic member is set in a manner such that in the process of descending of the plunger holding member accompanying operation of the driving mechanism, the air cylinder holding member is pushed downward by the elastic member until the air supply port contacts the microchip, and the plunger is pushed to supply air from the air supply port after the air supply port contacts with the microchip.

In a more preferred embodiment, the air cylinder holding member is integrated with the nozzle holding member.

The microchip processing apparatus to which the present invention is applied is not limited in particular. However, a preferred example is a microchip processing apparatus, comprising at least a holding part for holding a microchip having at least a main separation channel in which analysis is performed while a solution moves inside a plate-like member, a separation buffer solution filling device for filling separation buffer solution into a channel of the microchip, a dispensing probe which is inserted from above into a sample container or a reagent container for imbibing a sample or a reagent and injecting it to a prescribed position on a microchip held on the holding part, and a dispensing probe driving mechanism for moving the dispensing probe between prescribed positions of the microchip, sample container, and reagent container. A separation buffer solution filling device of the present invention is used as that separation buffer solution filling device.

In a preferred example of such a microchip processing apparatus, the holding part holds a microchip in a manner such that the number of main channels becomes plural, a control part is provided in order to control a preprocessing process and an analysis process in the main channels, and the dispensing probe is used commonly by the plural main channels, and performs the preprocessing process in advance of the analysis process in those main channels. This control part controls so that the preprocessing process is performed independently for each main channel such that it moves to the preprocessing process of the next main channel when the preprocessing process in one main channel is finished, and the analysis process is performed in parallel in plural main channels having finished the preprocessing process.

The electrophoresis method of the present invention for achieving the fourth purpose is an electrophoresis method, in which a separation buffer solution is filled into a capillary channel and then a sample is injected and the sample components are electrophoretically separated from one end toward the other end of the capillary channel, and includes a process in which, after filling separation buffer solution into the capillary channel and before injecting the sample, a voltage is applied to the capillary channel to determine whether the filling of the separation buffer solution is normal or not from the electrified state at that time.

One example of a capillary channel is one that is formed inside a plate-like member constituting a microchip, and that microchip has reservoirs opened on the surface of the plate-like member on the respective ends of the capillary channel. In this case, this electrophoresis method injects a sample into one reservoir after filling the separation buffer solution into the capillary channel.

The microchip processing apparatus to which the electrophoresis method of the present invention for achieving the fourth purpose is applied, is not specifically limited, and for example, it can take the form of a microchip processing apparatus, comprising a holding part for holding a microchip having channels including a main separation channel in which analysis is performed while a solution moves inside a plate-like member, a separation buffer solution filling device for filling separation buffer solution into the microchip, a sample injection device for injecting a sample into the microchip, a power supply device for applying electrophoresis voltage to the main channel, and a control part for controlling filling of separation buffer solution into the channel, introduction of samples, and electrophoretic separation. In this case, it is arranged that the control part also includes a function by which, after filling separation buffer solution into the channel and before injecting the sample into the channel, a voltage is applied to the channel by the power supply device and the electrified state at that time is monitored, and it is determined from that electrified state as to whether the filling of the buffer solution is normal or not.

As for the case when the filling of the separation buffer solution is not normal, mixing of dirt and bubbles into the separation buffer solution can be mentioned. When such foreign matter is mixed in and a voltage is applied to the channel, the electrical current value expected from that applied voltage value does not occur. Therefore, it can be determined as to whether the filling of the separation buffer solution is normal or not even before introduction of the sample to the channel.

One embodiment of the electrified state used for determining the state of filling of the separation buffer solution is the size of the electrical current value. In that case, it is determined to be normal when a current value in a predetermined range flows when a predetermined voltage is applied.

The voltage value applied to the channel for determining the electrified state may be the phoresis voltage for performing electrophoresis to analyze samples, but it also may be set to a value different from the phoresis voltage. Also, it can be arranged such that refilling of separation buffer solution is performed when the filling of the separation buffer solution is not judged to be normal according to the electrified state.

In a preferred example of the electrophoresis method of the present invention, the capillary channels are prepared in a manner such that there are plural capillary channels serving as main separation channels in which samples are analyzed while moving, and a common separation buffer solution filling device and a common sample injection device are prepared for the capillary channels including those plural main channels. An electrophoresis power supply device is prepared for each main channel, and when the separation buffer solution filling process concerning one main channel is finished, a voltage is applied in the capillary channels including the main channel to determine whether the filling of the separation buffer solution is normal or not from the electrified state at that time. If it is normal, a sample is injected into the capillary channels including the main channel, and then the process moves to the separation buffer solution filling process of the capillary channels including the next main channel. In such manner the process from filling of separation buffer solution to sample injection is performed sequentially for each main channel, and the process of analysis by electrophoresis after sample injection is performed independently while partially overlapping in plural main channels.

In a preferred example of the microchip processing apparatus of the present invention, the holding part places the microchip in a manner such that the number of main channels becomes plural, the separation buffer solution filling device and sample injection device are common to the channels including those plural main channels, a power supply device is provided for each main channel, and the control part controls as follows. When the separation buffer solution filling process concerning one main channel is finished, a voltage is applied in the channels including that main channel to determine whether the filling of the separation buffer solution is normal or not from the electrified state at that time. If it is normal, a sample is injected into the channels including that main channel, and then it moves to the separation buffer solution filling process of the channels including the next main channel. In such manner the process from filling of separation buffer solution to sample injection is performed sequentially for each main channel, and the process of analysis by electrophoresis after sample injection is performed independently while partially overlapping in plural main channels.

In the separation buffer solution filling device, if the air supply port for supplying air to push the separation buffer solution into the channels is made as a hole on the front end of the air cylinder, there is no need to separately provide an air supply means so the device becomes compact.

Also, as an air cylinder moving/driving mechanism for moving that air cylinder in the vertical direction and operating the plunger thereof, the air cylinder holding member and plunger holding member are supported to be capable of sliding by a guide, and an elastic member is placed between the air cylinder holding member and plunger holding member. If it is made such that the air cylinder holding member is pushed downward by the elastic member until the air supply port contacts with the microchip, and the plunger is pushed to supply air from the air supply port after the air supply port contacts with the microchip, the movement of the air cylinder in the vertical direction and the driving of the plunger can be realized with one driving source. Therefore, the air cylinder moving/driving mechanism becomes simple, and the separation buffer solution filling device becomes compact and inexpensive.

Also, in the separation buffer solution filling device, if it is made such that the suction nozzles which are pushed into the channels and draw separation buffer solution overflowing from the other reservoirs are supported to be capable of sliding by a nozzle holding member which moves in the vertical direction, and they are forced downward by a forcing means to be pushed against the bottoms of the reservoirs, it becomes possible to draw the separation buffer solution to be discharged from the reservoir without leaving any.

The length by which the suction nozzle inserted into the sample supply reservoir among the suction nozzles projects downward from the nozzle holding member, compared with the length by which the other suction nozzles project downward from the nozzle holding member, is made longer than the amount of depth of the liquid present in the reservoirs into which those other suction nozzles are inserted. By this, because it becomes possible to draw only the liquid of the sample supply reservoir, it becomes possible to remove the separation buffer solution or perform washing of only the sample supply reservoir.

If it is made such that the front end of the suction nozzle is pushed against a side wall part on the bottom of the reservoir when imbibing liquid from the reservoir, it becomes possible to draw up to the liquid remaining at the peripheral part of the bottom of the reservoir. As a result, in the case when repeatedly using the microchip, there is less contamination (carry-over) from the sample measured the previous time. Also, it becomes sufficient with less quantity of wash liquid when washing the reservoirs, and the washing time can be shortened, and consequently it is connected to shortening of the analysis time.

If the air cylinder holding member and the nozzle holding member are integrated, the separation buffer solution filling device becomes even more compact and inexpensive. Also, if a separation buffer solution filling device of the present invention is mounted on the microchip processing apparatus, it becomes easier to discharge superfluous separation buffer solution and wash liquid from the reservoirs so the analytical precision can be increased.

In the electrophoresis method and microchip processing apparatus of the present invention, because a voltage is applied to the capillary channel to determine whether the filling of the separation buffer solution is normal from the electrified state at that time after filling the separation buffer solution into the capillary channel and before injecting the sample, even if it was determined that the filling of the separation buffer solution is not normal, there is no loss of sample because the sample has not been injected at that time.

If it is made so as to determine whether the filling of the separation buffer solution is normal or not according to the size of the electrical current value, the determination can be performed by a simple means. If the voltage for determining the electrified state is set greater than the phoresis voltage, the electrified state can be determined with high sensitivity. Conversely, if the voltage for determining the electrified state is set smaller than the phoresis voltage, even if there were bubbles, it is possible to prevent damage to the capillary due to concentration of electrical field in the bubble part.

If the voltage applied to the channel for determining the electrified state is made smaller than the phoresis voltage, it is possible to control the power consumption. Also, if it is made such that refilling of separation buffer solution is performed when it is not judged that the filling of the separation buffer solution is normal, it is not necessary to perform a worthless electrophoresis process, and the operating efficiency is improved.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1is a block drawing summarily showing the part related to the control part in one example in which the present invention is applied to a microchip electrophoresis apparatus.

2is a dispensing part, which includes a dispensing probe driving mechanism having a dispensing probe. The dispensing probe of the dispensing part2imbibes a separation buffer solution or a sample by a syringe pump4and injects it to one end of the electrophoresis channel of the microchip, and it is provided commonly for plural electrophoresis channels.16is a separation buffer solution filling device in which separation buffer solution injected into one end of the electrophoresis channel is filled by air pressure into the electrophoresis channel and superfluous separation buffer solution is discharged by a vacuum pump part23, and the separation buffer solution filling device16also is provided commonly for the plural electrophoresis channels to perform processing.26is a high-voltage electrophoresis power supply part which applies phoresis voltage independently to the respective electrophoresis channels.31is a fluorescence measurement part as one example of a detection part which detects sample components separated in the electrophoresis channels.38is a control part, and it controls the operation of the dispensing part2so as to move to separation buffer solution filling and sample injection into the next electrophoresis channel when separation buffer solution filling and sample injection into one electrophoresis channel is finished, and controls the operation of the high-voltage electrophoresis power supply part26so as to apply phoresis voltage to cause electrophoresis in the electrophoresis channel in which sample injection was finished, and controls the operation of detection by the fluorescence measurement part31.40is a personal computer as an external control device for instructing the operations of this microchip electrophoresis apparatus and taking in and processing data obtained by the fluorescence measurement part31.

FIG. 2summarily shows the essential parts of a microchip electrophoresis apparatus in one working example. Four microchips5-1˜5-4are held by a holding part (not illustrated). The microchips5-1˜5-4, as explained in detail later, each have formed one electrophoresis channel for processing one sample

In order to dispense separation buffer solution and samples to those microchips5-1˜5-4, the dispensing part2has a syringe pump4for performing suction and ejection, a dispensing probe8having a dispensing nozzle, and a wash solution container10, and the dispensing probe8and the wash solution container10are connected to the syringe pump4by means of a three-way electromagnetic valve6. The separation buffer solution and samples are respectively received in holes on a micro titer plate12, and they are dispensed to the microchips5-1˜5-4by the dispensing part2. The separation buffer solution also may be contained in a dedicated container and placed near the micro titer plate12.14is a washing part for washing the dispensing probe8, and it is overflowing with wash solution.

The dispensing part2draws separation buffer solution or sample into the dispensing probe8with the three-way electromagnetic valve6connected in the direction where the dispensing probe8and the syringe pump4are connected, and ejects it by the syringe pump4into any electrophoresis channel of the microchips5-1˜5-4. When washing the dispensing probe8, washing is performed by switching the three-way electromagnetic valve6to the direction for connecting the syringe pump4and the wash solution container10, and drawing the wash solution into the syringe pump4, then flooding the dispensing probe8with wash solution of the washing part14, switching the three-way electromagnetic valve6to the side connecting the syringe pump4and the dispensing probe8, and ejecting the wash solution from inside of the dispensing probe8.

The separation buffer solution filling device16is provided commonly for the four microchips5-1˜5-4, in order to fill into the channels the separation buffer solution dispensed into the reservoirs on one end of the electrophoresis channels of the microchips5-1˜5-4. The separation buffer solution filling device16pushes an air supply port18against the reservoir on one end of any electrophoresis channel of the microchips5-1˜5-4maintaining air-tightness, and inserts suction nozzles22into the other reservoirs, and blows air from the air supply port18to push the separation buffer solution into the electrophoresis channel, and also draws the separation buffer solution overflowing from the other reservoirs by the vacuum pump from the nozzles22to discharge it to the outside.

A high-voltage electrophoresis power supply26(26-1˜26-4) independent for each microchip5-1˜5-4is provided in order to apply phoresis voltage independently to the electrophoresis channel of each microchip5-1˜5-4.

The fluorescence measurement part31for detecting the sample component electrophoretically separated in the separation channel55of the microchip5-1˜5-4comprises: LEDs (light-emitting diodes)30-1˜30-4which are provided for each microchip5-1˜5-4and radiate excited light on a part of the respective electrophoresis channels; optical fibers32-1˜32-4which receive fluorescent light generated by excitation of sample components moving in the electrophoresis channels by excited light from the LEDs30-1˜30-4; and a photoelectric amplification tube36which receives the fluorescent light by means of a filter34which removes the excited light component from the fluorescent light from those optical fibers32-1˜32-4and allows only the fluorescent light portion to pass. By causing the LEDs30-1˜30-4to emit light with the times mutually shifted, it is possible to identify and detect the fluorescent light from four microchips5-1˜5-4with one photoelectric amplification tube36. The light source of the excited light is not limited to LEDs, and LDs (laser diodes) also may be used.

FIG. 3(A)-3(C)andFIG. 4show one example of the microchip in this working example. The microchip in the present invention indicates such an electrophoresis apparatus having an electrophoresis channel formed inside the substrate, and does not necessarily imply being limited to one having a small size.

As shown inFIG. 3(A)-3(C), this microchip5consists of a pair of transparent substrates (quartz glass or other glass substrates or resin substrates)51and52, and on the surface of one substrate52, as shown inFIG. 3(B), mutually intersecting capillary electrophoresis grooves54and55are formed, and on the other substrate51, as shown inFIG. 3(C), reservoirs53are provided as through-holes in positions corresponding to the ends of those grooves54and55. The two substrates51and52are overlaid and bonded together as shown inFIG. 3(C), and the capillary grooves54and55are used as a separation channel55for electrophoretic separation of samples and a sample introduction channel54for introducing samples into that separation channel.

The microchip5is basically that which is shown inFIG. 3(A)-3(C), but in order to make handling easier, as shown inFIG. 4, one having electrode terminals for applying a voltage formed in advance on the chip is used.FIG. 4shows a plan view of this microchip5. The four reservoirs53are also ports for applying a voltage to the channels54and55. Ports #1and #2are ports positioned on both ends of the sample introduction channel54, and ports #3and #4are ports positioned on both ends of the separation channel55. In order to apply a voltage to each port, electrode patterns61˜64formed on the surface of this chip5are formed extending from the respective ports to the side end parts of the microchip5, and they are formed so as to be connected to the high-voltage electrophoresis power supply parts26-1˜26-4.

FIG. 5summarily shows the state of connection between the air supply port18on the buffer filling/discharging part16and the microchip5. An O-ring20is provided on the front end of the air supply port18, and by pushing the air supply port18onto one reservoir of the microchip5, the air supply port18can be attached to the electrophoresis channel of the microchip5maintaining air-tightness, and air can be pressurized and sent into the channel from the air supply port18. The nozzles22are connected to the other reservoirs, and the superfluous separation buffer solution overflowing from the channels is imbibed and discharged.

FIG. 6(A)-FIG.6(B) show in detail the operations in one working example. Here, that which has one electrophoresis channel formed on one microchip is used. Accordingly, in this case, moving of processing from one microchip to the next microchip is the same meaning as moving of processing from one electrophoresis channel to the next electrophoresis channel.

FIG. 6(A)shows the operation of the working example in which a preprocessing process and the electrophoresis/light-measurement process are performed sequentially while partially in parallel on four microchips.

Each process is set in time, the preprocessing process is set to 40 seconds and the electrophoresis/light-measurement process to 120 seconds, and one cycle for one microchip is 160 seconds.

When the preprocessing process for one microchip is finished, it moves to the preprocessing process of the next microchip without waiting for the end of the electrophoresis/light measurement process on the former microchip. That is, electrophoresis is started accompanying the end of the preprocessing process on the first microchip, and light measurement also is started, and in addition, the preprocessing process on the second microchip is started. When the preprocessing process on the second microchip is finished, electrophoresis on the second microchip is started, and light measurement also is started, and in addition, the preprocessing process on the third microchip is started. Thus, the preprocessing process goes on to be performed sequentially for each microchip, and separately from that, on a microchip having finished the preprocessing process, electrophoresis and light measurement go on to be started sequentially, and as a result electrophoresis and light measurement are performed in parallel on plural microchips. When the preprocessing process is performed up to the fourth microchip, because the analysis is finished on the first microchip, the first microchip is reused and the same kind of processing goes on to be repeated.

In the electrophoresis process, application of a voltage in order to lead the sample from the sample introduction channel to the position of intersection with the separation channel is performed, and the next electrophoretic separation by application of a voltage in the separation channel is performed. Along with this, light radiation from the LED is performed in the detection position, and fluorescence measurement is started.

The preprocessing process is shown in detail inFIG. 6(B).

The uppermost numbers represent the time (seconds). The “microchip” fields indicate the contents of the processing in one microchip. The “dispensing part” fields indicate the operations of drawing and ejecting of separation buffer solution and sample from the dispensing probe8performed by the syringe pump4.

The “separation buffer solution filling device” fields indicate the filling operation of pushing the separation buffer solution dispensed to the microchip into the channel and the operation of performing the drawing process of drawing and discharging the overflowing separation buffer solution by the suction pump.

In the “microchip” fields, the first separation buffer solution drawing (B drawing) is the process of drawing and discharging the separation buffer solution used in the first analysis. In the next “W4B dispensing” operation, the separation buffer solution is dispensed to the fourth reservoir, and in the next “filling/drawing” process, pressurized air is supplied from the separation buffer solution filling device and that separation buffer solution is pushed into the electrophoresis channel, and also the superfluous separation buffer solution is drawn in and discharged from the other reservoirs whereby the channels are washed with new separation buffer solution.

By the next “W1B dispensing” process, new separation buffer solution is dispensed into the first reservoir in order to wash the first reservoir, and in the next “filling/drawing” process, pressurized air is supplied to the fourth reservoir from the separation buffer solution filling device and that separation buffer solution is pushed into the electrophoresis channel, and also the superfluous separation buffer solution is drawn in and discharged from the other reservoirs whereby the separation buffer solution is filled into the channels. After that, by the next “W2, 3, 4 buffer dispensing” processes, the separation buffer solution is dispensed also from the other second, third, and fourth reservoirs. With this, filling of separation buffer solution into the electrophoresis channel is completed.

Next, the sample is drawn into the dispensing probe of the dispensing part for dispensing of the sample, and by the “W1S dispensing” process, sample dispensing is performed by ejection of that sample in the first reservoir. After sample dispensing, the dispensing probe of the dispensing part is washed, and then it prepares for imbibing the separation buffer solution for the next sample. With this, the preprocessing process in the electrophoresis channel of that microchip is finished.

In the microchip of the working example, an electrophoresis channel by cross injection method is used, but it is not limited to this, and it also may be a microchip with only a separation channel.

Also, in the microchip of the working example, that which has only one electrophoresis channel on one microchip is used, it also may have plural electrophoresis channels formed on one microchip, and in that case, the present invention should be applied with the electrophoresis channels as a unit.

That which measures fluorescence was used as a detection part, but in addition to measuring fluorescence, it is possible also to measure light absorption or use a detection method using chemical light emission or biological light emission. Regarding the detection part, even if it is not one which radiates excited light independently for each microchip, it also may be a method in which a light measurement system used commonly by all microchips is prepared, and that optical system scans in a manner so as to be moved among the detection positions of all of the microchips.

Next the dispensing part2is explained in detail.

As shown in enlargement inFIG. 7, the dispensing probe8is hollow and the tip is needle-like, and imbibing and ejecting of liquid are performed from a hole on the tip. The dispensing probe8is used commonly by samples and reagents (in this working example separation buffer solution).FIG. 7shows the state in which the tip of the dispensing probe8was inserted into the sample container90. The sample container90, as shown inFIG. 7, is installed in this microchip processing apparatus in a state having the upper opening closed by a seal material90asuch as a septum that can be penetrated by the needle of the dispensing probe8. On the other hand, the reagent container containing the separation buffer solution is installed in this microchip processing apparatus in a state having the upper opening opened by removal of the outer lid. During the sample dispensing operation, the needle of the dispensing probe8is inserted into the sample container90penetrating the seal material90aand imbibing of the sample is performed, and during reagent dispensing, the needle of the dispensing probe8is inserted into the opened reagent container and imbibing of the reagent is performed.

The dispensing probe8has a groove8bon its side surface. That groove8bfor example has both a width and a height of 50 μm˜0.6 mm, and its position is the position where the inside of the sample container90and the atmosphere communicate when the tip of the dispensing probe8is inserted into the sample container90to imbibe the sample, that is, the position where it is penetrating the seal material90a. By this, because the atmosphere flows into the container90through the groove8beven when the sample inside the container90is imbibed by the dispensing probe8, it is possible to prevent the inside of the container90from being negatively pressurized, and the liquid can be drawn with good precision.

The dispensing probe8is made of metal, and it serves as an electrostatic capacitance type liquid surface sensor by detection of the electrostatic capacitance at its tip part. The electrostatic capacitance detects the liquid surface by changing when the tip part of the dispensing probe8is inserted into the sample container or the reagent container and contacts with the liquid inside the container. The liquid surface sensor, as indicated by symbol92inFIG. 1, is connected to the control part38, and by regularly monitoring the electrostatic capacitance, the position of the liquid surface inside the sample container or the reagent container is sensed.

The control part38calculates the remaining liquid quantity inside the sample container or inside the reagent container based on the output of this liquid surface sensor, and performs a display as shown inFIG. 8with the personal computer (PC)40as the remaining liquid quantity display part.

It also may be made such that in the event that the remaining liquid quantity based on the output of this liquid surface sensor was insufficient before the start of analysis, the control part38makes that known with the personal computer40as a warning means.

It also may be made such that in the event that the remaining liquid quantity based on the output of this liquid surface sensor became insufficient, the control part38makes that known at that time with the personal computer40as a warning means.

FIG. 9(A)-9(C)show an example in which the dispensing probe driving mechanism in the dispensing part2has on the lower end a restraining lever86as a restraining mechanism having a horizontal restraining member86bwhich forces downward so that the sample container90does not come up when the dispensing probe8is driven in the Z direction (vertical direction) and the dispensing probe8is pulled out from the sample container90.

The restraining lever86is attached to be capable of sliding on a probe holder80for holding the dispensing probe8and moving in the vertical direction, and it has a spring87as a forcing means for forcing the restraining lever86downward against the probe holder80, and a stopper86afor restricting the restraining lever86bfrom moving further downward from the stopping position (position in the state inFIG. 9(A)) of the lower end of the dispensing probe8against the probe holder80. The stopper86ais fixed on the restraining lever86above the probe holder80, and due to contact with the upper surface of the probe holder80, the restraining lever86is prevented from moving further downward. The spring87is a tension spring. This spring is hung above the probe holder80between the upper end of the restraining lever86and the probe holder80.

The restraining lever86and the dispensing probe8are driven by a single-axis drive system for moving the probe holder80in the vertical direction. Explaining this mechanism in further detail, the driving part70for driving the dispensing probe8has a fixed shaft72which is fixed to a driving mechanism (not illustrated) for moving this driving part70in the X direction and Y direction on a horizontal plane. A vertical linear guide82is fixed on the fixed shaft72, and the probe holder80is guided by the linear guide82, and it is supported to be capable of sliding in the vertical direction. A ball screw76is fitted on the probe holder80, and the movement of the probe holder80in the vertical direction is driven by rotation of the ball screw76. Also, a stepping motor as a drive motor74, is attached on the fixed shaft72, and the rotating shaft of the drive motor74and the ball screw76are linked by a timing belt78, whereby the rotation of the drive motor74is transmitted to the ball screw76.

The operation of imbibing a sample with the dispensing probe8by the dispensing part inFIG. 9(A)-9(C)is explained.

The position inFIG. 9(A)is the waiting position, and in the waiting position, the probe holder80is raised to the uppermost position, and the restraining lever86has become in the state most descended against the probe holder80with the stopper86aof the restraining lever86in contact with the upper surface of the probe holder80. In this waiting state, the restraining member86bat the lower end of the restraining lever86has come further downward from the tip of the dispensing probe8.

(Descent for Sample Imbibing)

FIG. 9(B)shows the state when the dispensing probe8descends. The rotation of the drive motor74is transmitted to the ball screw76by means of the timing belt78, and the ball screw76rotates whereby the probe holder80descends. Because the dispensing probe8is fixed to the probe holder80, it descends together with the probe holder80. Also, because the restraining lever86is forced downward against the probe holder80by the spring87, the restraining lever86also descends together with the probe holder80. The descent of the restraining lever86stops when the restraining member86bat the lower end of the restraining lever86contacts with the upper surface of the sample container90.

The probe holder80continues to descend further from the state inFIG. 9(B). The restraining lever86cannot descend further because the restraining member86bon its lower end is in contact with the sample container, and the restraining lever86slides against the probe holder80accompanying descent of the probe holder80, and only the probe holder80continues to descend and the spring87goes on to stretch. The dispensing probe8descends together with the probe holder80, and its tip is inserted into the sample container90penetrating the shield material90aof the sample container90. Because the tip of the dispensing probe8serves as a liquid surface sensor, when the liquid surface sensor senses the liquid surface inside the sample container90, by that, the driving of the drive motor74is stopped at the place where it has intruded into the sample by a prescribed depth, and the descent of the probe holder80is stopped. That state is the state shown inFIG. 9(C), and in that state a prescribed quantity of sample is imbibed by the dispensing probe8.

Next, the drive motor74rotates in the reverse direction, and the probe holder80starts to ascend. The dispensing probe8starts to ascend accompanying the ascent of the probe holder80, and it is pulled out from the sample container90. At this time, because the restraining lever86is being forced downward against the probe holder80by the spring87, the restraining lever86stops at the position inFIG. 9(C)even though the probe holder80is starting to ascend. By this, although a force in the direction of pulling upward works on the sample container90by friction between the dispensing probe8and the seal material90awhen the dispensing probe8is pulled out from the seal material90aof the sample container90, the sample container90is prevented from coming up because the restraining member86bis fixed in the position inFIG. 9(C).

Soon, when the probe holder80ascends up to the position inFIG. 9(B), the stopper86aattached to the restraining lever86contacts with the upper surface of the probe holder80, and after that when the probe holder80ascends further, the restraining lever86ascends together with the probe holder80. When the probe holder80ascends up to the position inFIG. 9(A), the sample imbibing operation is finished.

After that, the entire driving part70is moved up to a prescribed position of the microchip, and the dispensing probe8is inserted into a prescribed reservoir of the microchip and the sample is injected.

The dispensing probe8is used not only for dispensing of samples, but also for dispensing of reagents. Although the reagent in this working example is separation buffer solution, it is the same even in the case when using other reagents. For the reagent container, one that is larger than the sample container is used in order to contain a reagent that is repeatedly dispensed to the microchip, and it is installed in this microchip processing apparatus in a state having the lid on the open part removed. The dispensing probe8has been manufactured with a view that it will be inserted into a reagent container with the lid removed. The lid of the reagent container for example is made of metal, or the like, and it is harder compared with the seal material90aof the sample container90, and there is a concern that if it is installed in the microchip processing apparatus with the lid of the reagent container attached, the tip of the dispensing probe8may be damaged by being pushed against the lid of the reagent container. As a working example for preventing such a situation,FIG. 10(A)-10(C)shows one in which it has a means for sensing that the dispensing probe8hit the lid of the reagent container.

When compared with the driving part70inFIG. 9(A)-9(C), the driving part70ashown inFIG. 10(A)-10(C)differs from the one inFIG. 9in the point that the mechanism for holding the dispensing probe8against the probe holder80is different, and it is provided with a sensor for sensing that the tip of the dispensing probe8hit the lid.

In the driving part70ainFIG. 10(A)-10(C), the dispensing probe8is held to be capable of sliding against the probe holder80. The probe holder80integrally has an L-shaped spring restraining part80awhich extends upward. The dispensing probe8is supported to be capable of sliding running through the probe holder80and the spring restraining part80a, and a compression spring84is inserted on the lower side of the spring restraining part80aand forces the dispensing probe8downward against the probe holder80.

In order to detect that the dispensing probe8was displaced against the probe holder80, the dispensing probe8is provided with a protruding piece8aon the side above the probe holder80. A position sensor88such as a photosensor is provided on the probe holder80in order to detect that protruding piece8a. The positions of both the protruding piece8aand the position sensor88are defined such that the position sensor88turns on when the dispensing probe8is displaced upward against the probe holder80by a prescribed amount.

The operation of sensing that the tip of the dispensing probe8hit the lid of the reagent container in the working example inFIG. 10(A)-10(C)is explained.

Although the reagent container91should be installed in a state having the lid91aremoved, it is supposed that it was installed in this microchip processing apparatus erroneously with the lid91aattached.

FIG. 10(A)is the waiting state, and from that state as explained withFIG. 9(A), the probe holder80descends, and when the restraining member86bat the lower end of the restraining lever86contacts with the upper surface of the reagent container91as inFIG. 10(B), the descent of the restraining lever86stops, but the probe holder80continues to descend further whereby the tip of the dispensing probe8contacts with the lid91aof the reagent container91.

The probe holder80continues to descend further even after that, but because the dispensing probe8cannot penetrate the lid91a, the dispensing probe8stops, and the probe holder80continues to descend further sliding against the dispensing probe8. Because the position sensor88is fixed on the probe holder80, it descends along with the probe holder80, and soon as shown inFIG. 10(C)the position sensor88turns on at the place where the position sensor88comes up to the protruding piece8a, and it is sensed that the tip of the dispensing probe8contacts a hard object. In this state the descent of the probe holder80is stopped, and the dispensing operation is stopped.

The processing procedure in the case when the microchip is repeatedly used in this microchip processing apparatus is shown inFIG. 11(A)toFIG. 14(U), and it is explained using the flow chart inFIG. 15. The symbols (A-U) in the flow chart inFIG. 15stand for the symbols of the processes inFIG. 11(A)-FIG.14(U). The processing performed here is a series of processes in which the microchip used in the previous round of analysis is washed, separation buffer solution is filled into the channel, a phoresis test is performed as to whether or not the current flows normally in the channel in a state when separation buffer solution is filled into all reservoirs, and after that a sample is dispensed and phoresis is started, and the dispensing probe and the suction nozzle are washed.

FIG. 11(A)shows the microchip5. The microchip5is the one shown inFIG. 3(A)andFIG. 4, it has the separation channel55and the sample introduction channel54provided in an intersecting manner, and has reservoirs53formed on the ends of each channel54and55. The reservoirs from first to fourth inFIG. 4are indicated here with the symbols53-1˜53-4.

FIG. 11(B)is the state when analysis of the previous sample was finished, and separation buffer solution is remaining in the channels and each reservoir, and separated sample also is remaining in that separation buffer solution.

InFIG. 11(C), first, in order to wash the sample injection reservoir53-1, only the suction nozzle22-1is inserted into the reservoir53-1. The suction nozzle22-2and the suction nozzle22-3also move vertically simultaneously with the suction nozzle22-1, but because the length of the suction nozzle22-1is longer than that of the other suction nozzles22-2and22-3, only the suction nozzle22-1is inserted into the reservoir53-1to become in a state being pushed against the bottom part of that reservoir53-1, but the other suction nozzles22-2and22-3are not inserted into the respectively corresponding reservoirs53-2and53-3. In that state the separation buffer solution inside the reservoir53-1is drawn and removed by being drawn from the suction nozzle22-1.

InFIG. 11(D), wash liquid is supplied into the reservoir53-1from the dispensing probe8.

InFIG. 11(E), again the suction nozzle22-1is inserted into the reservoir53-1, and the wash liquid is drawn and discharged.

InFIG. 12(F), wash liquid is supplied again into the reservoir53-1from the dispensing probe8.

InFIG. 12(G), next, the suction nozzles22-1˜22-3are inserted respectively into the reservoirs53-1˜53-3. At this time, the three suction nozzles22-1˜22-3are inserted into the respective reservoirs53-1˜53-3, and they contact with the bottoms of the respective reservoirs by being pushed against them. The liquid is drawn simultaneously by those three suction nozzles22-1˜22-3and is removed. The dispensing probe8is inserted into a rinse port100and the entirety of the wash liquid inside the dispensing probe8is ejected, and also the inside and outside of the dispensing probe8are washed.

InFIG. 12(H), the fourth suction nozzle22-4is inserted into the other one reservoir53-4. This suction nozzle22-4is provided separately from the three suction nozzles22-1˜22-3, and it is placed near a cylinder for air supply port shown inFIG. 15explained later. The suction nozzle22-4also contacts the bottom of the reservoir53-4by being pushed against it. The separation buffer solution inside the reservoir53-4is drawn by the suction nozzle22-4and is removed. The dispensing probe8draws the separation buffer solution from the reagent container91containing buffer solution.

InFIG. 12(I), the dispensing probe8is moved to the reservoir53-4, and it dispenses the separation buffer solution.

InFIG. 12(J), the air supply port18is pushed onto the reservoir53-4maintaining air-tightness, and air is supplied into the channel from the reservoir53-4by driving of the cylinder shown inFIG. 15later. The suction nozzles22-1˜22-3are inserted respectively into the other reservoirs53-1˜53-3, and the separation buffer solution overflowing into the respective reservoirs53-1˜53-3from the channel is drawn and removed.

InFIG. 12(K), the suction nozzle22-4is inserted into the reservoir53-4, and the separation buffer solution in that reservoir53-4is drawn and removed. By this it assumes a state in which the separation buffer solution remains only in the channel.

In FIG.13(L)˜(O), the separation buffer solution is dispensed sequentially into the reservoirs53-1˜53-4by the dispensing probe8.

InFIG. 13(P), electrodes are inserted into the respective reservoirs, and a phoresis test is performed. Here, it is confirmed as to whether or not dirt or bubbles are mixed in the channel by detecting the current value between the electrodes. The voltage applied to the channel here may be the same as the phoresis voltage for separating samples, but it also may be voltage lower than that.

The dispensing probe8having dispensed the separation buffer solution is inserted into the rinse port100, and the separation buffer solution inside the dispensing probe8is entirely ejected and also the inside and outside of the dispensing probe8are washed.

When it was determined that filling of separation buffer into the channel was performed normally in this phoresis test process, the flow advances to the next processFIG. 13(Q)for injecting the sample and performing analysis, but when it was not determined that filling of separation buffer into the channel was performed normally, the flow returns to the processFIG. 11(B)for refilling of separation buffer solution into the channel.

The number of times (N) that refilling of separation buffer solution into the channel is allowed is set in advance, and when it is not determined that filling of separation buffer solution into the channel was performed normally even when refilling of separation buffer solution was performed that number of times, the flow returns to the process (B) after exchanging with another microchip. The number of times N that refilling of separation buffer solution is allowed is not particularly limited, but for example 2 or 3 is suitable.

InFIG. 13(Q), the suction nozzle22-1is inserted only in the sample supply reservoir53-1, and the separation buffer solution in that reservoir53-1is drawn and removed.

InFIG. 14(R), a sample is injected into that reservoir53-1from the dispensing probe8.

InFIG. 14(S), electrodes are inserted into the respective reservoirs53-1˜53-3and voltage for sample introduction is applied, and the sample is led to the position of intersection of the channels54and55.

InFIG. 14(T), the applied voltage is switched to a voltage for phoresis separation, and the sample is electrophoretically separated toward the reservoir53-4in the separation channel55.

InFIG. 14(U), after the end of analysis, each suction nozzle22-1˜22-4is inserted into a rinse pool102and the wash liquid is drawn, and the insides and outsides of the nozzles are washed, and also the probe8is inserted into the rinse port100and the inside and outside are washed.

Next, one working example of a separation buffer solution filling device is explained according toFIG. 16(A)-16(C)and FIG.17.

The three suction nozzles22-1˜22-3are held to be capable of sliding on a nozzle holding member104, and as shown in enlargement inFIG. 17, the range of movement in the vertical direction is restricted by upper and lower stoppers105and107, and they are forced downward from the nozzle holding member104by a spring106. These suction nozzles22-1˜22-3can be moved upward in opposition to the spring106by being pushed against the reservoirs.

As shown inFIG. 16(A), in the state before the suction nozzles are inserted into the reservoirs, the length by which the suction nozzle22-1projects downward from the nozzle holding member104is set longer than the amount of depth of the liquid present in the reservoir compared with the other suction nozzles22-2and22-3. This means that at the point when the tip of the suction nozzle22-1contacts the bottom of the reservoir53-1in the state projecting downward, the suction nozzles22-2and22-3do not yet reach the liquid surfaces inside the reservoirs53-2and53-3. When the needle holding member104is moved further downward, all of the suction nozzles22-1˜22-3contact with the bottoms of the reservoirs.

In this working example, the nozzle holding member104doubles as an air cylinder holding member, and a cylinder108is fixed to the nozzle holding member104. A seal part110is provided on an open part on the front end of the cylinder108, and the opening having that seal part serves as the air supply port18. The cylinder108has a plunger112on its upper side, and air is ejected from the cylinder by vertical movement of the plunger112. The plunger112is fixed to a plunger holding member114.

The nozzle holding member (air cylinder holding member)104and the plunger holding member114are supported to be capable of sliding on a linear guide116, and a coil spring118is inserted between the nozzle holding member104and the plunger holding member114. A stopper120which extends upward from the nozzle holding member104is provided, and the stopper120forms the top dead center of the plunger holding member114.

This separation buffer solution filling device is fixed to a support body122, and the support body122is attached to a horizontal directional movement mechanism, whereby this separation buffer solution filling device becomes capable of movement in the horizontal direction. As a mechanism for moving the nozzle holding member104and the plunger holding member114in the vertical direction, a stepping motor is attached as a drive motor124to the support body122, and a ball screw126is fitted on the plunger holding member114. A timing belt128is hung between the motor124and the ball screw126, and the rotation of the motor124is transmitted to the ball screw126by means of the timing belt128. The plunger holding member114is moved in the vertical direction by the rotation of the ball screw126. In this working example, because the nozzle holding member104doubles as an air cylinder holding member, the mechanisms for driving of the suction nozzles22-1˜22-3and moving and driving of the air cylinder108can be driven by one drive motor124.

InFIG. 16(A)-16(C), an embodiment in which the nozzle holding member104does not have suction nozzles22-1˜22-3, that is, an embodiment in which the member104functions simply as an air cylinder holding member without performing the function of a nozzle holding member, also becomes one working example of the present invention.

Next, the operation of filling separation buffer solution into the microchip5is explained according toFIG. 16(A)-16(C). This operation corresponds to the processes after the separation buffer solution was supplied to the reservoir53-4inFIG. 12(I), and up to when the separation buffer solution is pressed in by supply of air from the air supply port18inFIG. 12(J), and also the separation buffer solution overflowing from the channel is drawn by the suction nozzles22-1˜22-3and discharged.

(A):FIG. 16(A)is the waiting state, and the plunger holding member114is at the top dead center. In this state the separation buffer solution has already been supplied to the reservoir53-4of the microchip.

(B): The ball screw126rotates and the plunger holding member114goes down, and the nozzle holding member104is pushed down by means of the coil spring118. As shown inFIG. 16(B), the seal part110of the cylinder108is made to contact onto the reservoir53-4maintaining air-tightness, and simultaneously the three suction nozzles22-1˜22-3are inserted into the respective reservoirs53-1˜53-3and become in a state being pushed against the bottoms of the reservoirs.

(C): When the plunger holding member114is caused to descend by further rotation of the ball screw126, further descent of the nozzle holding member104is restricted by the lower end of the cylinder108contacting with the microchip5, but as shown inFIG. 16(C), the plunger holding member114separates from the stopper120by contraction of the coil spring118and descends further, and it pushes the plunger112to supply air from the air supply port18. By this, the separation buffer solution inside the reservoir53-4is pressed into the channel, and the separation buffer solution overflowing from the channel into the reservoirs53-1˜53-3is drawn by the respective suction nozzles22-1˜22-3and is removed.

After the separation buffer solution was pressed into the channel in the state inFIG. 16(C), the ball screw126rotates in the reverse direction, and it returns to the state inFIG. 16(B). After that, when the ball screw126further rotates in the reverse direction, the plunger holding member114hits the stopper120whereby the nozzle holding member104is pulled up, and it returns to the waiting state inFIG. 16(A).

In the separation buffer solution filling device inFIG. 16(A)-16(C), when the rotation of the ball screw126stops at the point when the tip of the suction nozzle22-1has contacted the bottom surface of the reservoir53-1, only the suction nozzle22-1is inserted into the reservoir53-1, and the other suction nozzles22-2and22-3come to stop at a position not reaching the liquid surfaces of the respective reservoirs53-2and53-3. This state is the state used inFIG. 11(E)andFIG. 13(Q).

Although it is not shown inFIG. 16(A)-16(C), another suction nozzle22-4is provided near the cylinder108, and it is forced downward by a spring just as the other suction nozzles22-1˜22-3. Because the support body122is moving in the horizontal direction when that suction nozzle22-4is inserted into the reservoir53-4, the other suction nozzles22-1˜22-3are not inserted into the respectively corresponding reservoirs53-1˜53-3.

FIG. 18(A)-18(C)show the state of drawing and removal of the liquid inside the reservoir in the case that the suction nozzle22(22-1˜22-4) contacted a place other than the peripheral part of the bottom surface of the reservoir53(53-1˜53-3), for example the center part.

The outer diameter of the tip of the suction nozzle22is smaller than the size of the bottom of the reservoir53, and the tip of the suction nozzle22is cut diagonally, and it draws liquid from a gap between the bottom surface of the reservoir and the tip of the suction nozzle. When the suction nozzle22contacts a place other than the side wall part of the bottom of the reservoir, for example, the center part, the liquid130remains in a donut shape at the peripheral part of the bottom of the reservoir. Particularly in the case when this reservoir53is a reservoir for sample supply, if it is not cleaned sufficiently, it will become a cause of carry-over to the next analysis. Therefore, in the case when liquid remains at the peripheral part of the bottom of the reservoir, the quantity of liquid for washing the reservoir must be made greater or the number of times of washing must be increased, and the washing time becomes longer, and as a result the overall analysis time becomes longer.

Therefore, as a preferred working example, as shown inFIG. 19, the suction nozzle22is inserted so as to be pushed against the perimeter wall part of the bottom of the reservoir53. By adjusting the position of the suction nozzle22in this manner, it is possible to draw and remove the liquid without leaving any in the reservoir53. As a result, the carry-over becomes smaller, and it becomes sufficient with less wash liquid, and the washing time becomes shorter, and as a result the analysis time can be shortened. Also, if under the same washing conditions, the analytical precision is improved by the fact that the carry-over becomes smaller,

Reference is made here to matters disclosed in Japanese Patent Application No. 2005-296478, filed on Oct. 11, 2005, and Japanese Patent Application No. 2005-296459, filed on Oct. 11, 2005, and they are to be incorporated into the present application.

Although the present invention was explained up to here based on specific working examples, the above explanation is for the purpose of showing examples, and the present invention is limited only by the claims.