JP6928275B2 - Analysis equipment - Google Patents

Description

The present invention relates to an analyzer. More specifically, the present invention relates to an analyzer that measures the absorbance of a liquid to be measured containing a component that is not suitable for draining into sewage or rivers as it is.

In order to measure the concentrations of total phosphorus, total nitrogen, total chromium, total copper, total nickel, total manganese, etc., the sample solution is thermally decomposed, and if necessary, a solution to which a color-developing reagent is added is used as the solution to be measured. As a result, an analyzer is used in which the sample cup of the reaction vessel is introduced into the flow cell of the absorptiometer and the absorbance is measured.
In these analyzers, the reagents contain components that are not suitable for draining into sewage, rivers, etc., so the liquid to be measured after measuring the absorbance is not drained into sewage, etc., but stored in a waste liquid tank. However, it is necessary to carry out appropriate wastewater treatment.

Since this waste liquid is the liquid to be measured after the absorbance has been measured, it is conceivable that the waste liquid is discharged into the waste liquid tank from the downstream side of the flow cell of the absorptiometer. However, in the analyzer of Non-Patent Document 1, the liquid to be measured after measuring the absorbance is once returned to the sample cup of the reaction tank and drained from the sample cup to the waste liquid tank without draining directly from the flow cell. There is.

The reason why the analyzer of Non-Patent Document 1 does not drain the liquid directly from the flow cell is that the pump for introducing the liquid to be measured into the flow cell is driven in the opposite direction (direction from the flow cell to the sample cup) for various purposes. Because that is being done.
When the waste liquid is discharged from the downstream side of the flow cell into the waste liquid tank, the waste liquid containing the reagents remaining in the piping and the pump on the downstream side of the flow cell flows back and mixes with the liquid in the sample cup when the pump is driven in the reverse direction. There is a concern.
In particular, in the case of a device that measures both the total nitrogen concentration and the total phosphorus concentration as in Non-Patent Document 1, the reagent for measuring the total phosphorus concentration is mixed in the liquid for measuring the total nitrogen concentration even if it is very small. Then, a big error is given.

One of the purposes of driving the pump in the opposite direction is to wash the flow cell together. Co-washing of the flow cell is required, especially when the amount of liquid to be measured in the sample cup is extremely small.
That is, recent analyzers have reduced the consumption of reagents to the utmost limit from the viewpoint of resource saving and environmental protection. Therefore, the amount of the liquid to be measured in the sample cup is as small as 4 to 5 mL, for example.

Since the flow cell is in a state of being wet with the washing water after the previous measurement, if a part of such a small amount of the liquid to be measured is introduced into the flow cell, it will be diluted with a small amount of washing water that wets the inside of the flow cell.
Therefore, in the analyzer of Non-Patent Document 1, the liquid to be measured once introduced into the flow cell is once returned to the sample cup to co-wash the inside of the flow cell, and then the absorbance of the liquid to be measured introduced into the flow cell is measured again. There is.
In order to perform this co-washing, it is necessary to return the liquid to be measured from the flow cell to the sample cup. Therefore, conventionally, there has been a concern that the waste liquid may flow back and contaminate the liquid to be measured when the liquid to be measured is returned to the sample cup.

Another purpose of driving the pump in the opposite direction is to measure the absorbance of the blank liquid.
The blank solution is a solution before the color-developing reagent is reacted, and the color-developing reagent means a reagent from which a color-developing solution to be measured for absorbance can be obtained by adding the reagent. The color-developing reagent may be a kind of compound or a combination of a plurality of compounds.

When the absorbance is measured with a flow cell using the blank liquid as the measurement target liquid, it is necessary to return the blank liquid to the sample cup and react it with the color-developing reagent without discarding it.
From this point as well, conventionally, there has been a concern that the waste liquid may flow back and contaminate the liquid to be measured when the blank liquid is returned to the sample cup.

Another purpose of driving the pump in the reverse direction is to prevent the liquid in the sample cup from entering the pipe provided with the flow cell except when measuring the absorbance.
In particular, the heat-decomposed liquid returned to the sample cup after heat-decomposing the sample liquid easily penetrates into the piping inserted in the sample cup because of the high temperature and high pressure.
By driving the pump in the opposite direction to send air into the sample cup, the liquid in the sample cup was prevented from entering the pipe provided with the flow cell.

Another purpose of driving the pump in the opposite direction is to stir the liquid in the sample cup at the time of dilution or introduction of the reagent to make it uniform.
For this purpose as well, the pump was driven in the opposite direction to pump air into the sample cup and agitate the liquid by bubbling.
In this way, even when the air is sent into the sample cup, there is a concern that the waste liquid may flow back and contaminate the liquid to be measured.
Due to the above concerns, the liquid to be measured after the absorbance measurement is not directly drained into the waste liquid tank, but is once returned to the sample cup in the reaction tank and then drained into the waste liquid tank.

On the other hand, the cleaning liquid such as a sample cup can be drained to sewage or the like as it is, except for the cleaning liquid containing the liquid to be measured at a high concentration. In addition, the surplus of the sample liquid introduced into the sample cup can usually be drained.
Therefore, in Non-Patent Document 1, a three-way valve is provided on the downstream side of the drainage pump in the drainage pipe, and either the pipe leading to the waste liquid tank or the pipe for draining the liquid as it is is selected.
Further, the drainage pipe inserted into the sample cup is branched into a pipe toward the waste liquid tank and a pipe for draining the liquid as it is on the downstream side, and a waste liquid pump is provided in the former and a drainage pump is provided in the latter.

"Instruction Manual Total Nitrogen / Total Phosphorus / COD Automatic Measuring Device NPW-160", DKK-TOA CORPORATION, July 7, 2016, p254

However, as in the analyzers of Non-Patent Documents 1 and 2, if the liquid is discharged after being returned from the flow cell to the sample cup of the reaction tank after the absorbance is measured, it takes more time than the liquid is directly discharged from the flow cell.
In addition, in order to distinguish the waste liquid returned to the sample cup from the drainage liquid that can be drained into sewage as it is, it is necessary to provide a three-way valve or use a dedicated pump for each, so the configuration of the entire analyzer is complicated. Become.
The present invention has been made in view of the above circumstances, and it is necessary to drive a pump for introducing the liquid to be measured into the flow cell in the opposite direction (direction from the flow cell to the sample cup) for various purposes. Even if there is a problem, it is an object of the present invention to provide an analyzer capable of quickly draining the liquid to be measured with a simple configuration without adversely affecting the next measurement or the like.

In order to achieve the above problems, the present invention has adopted the following configuration.
[1] A sample cup containing a liquid to be measured, a detection pipe whose upstream end is inserted into the sample cup, and a detection pipe whose downstream end is inserted to a position where the waste liquid tank is not immersed in the waste liquid. An absorbance detector, a buffer tank, and a pump, which are sequentially provided from the upstream side, are provided in the middle of the detection pipe.
The absorbance detection unit is an absorbance meter having a flow cell, and the flow cell is connected in the middle of the detection pipe.
The buffer tank has a portion formed so that the inner diameter gradually increases from the upstream side to the downstream side and then gradually decreases, and is connected in the middle of the detection pipe so that the upstream side is above the downstream side.
The pump is an analyzer characterized in that the liquid in the detection pipe can be sent in any of a forward direction from upstream to downstream and a reverse direction from downstream to upstream.

[2] The analyzer according to [1], which performs an operation including a step of driving the pump in the reverse direction.
[3] The pump is driven in the forward direction, a part of the liquid to be measured in the sample cup is sucked into the flow cell within a range where the liquid to be measured does not reach the buffer tank, and then the pump is sucked. The analyzer according to [2], wherein the analyzer is driven in the opposite direction to perform an operation including a step of returning the sucked liquid to be measured back into the sample cup.

a [4] The analyzer according to [1], wherein the following steps are sequentially performed.
Step D1: The pump is driven in the forward direction, and a part of the liquid to be measured in the sample cup is sucked into the flow cell within a range where the liquid to be measured does not reach the buffer tank.
Step D2: The pump is driven in the opposite direction to return the liquid to be measured sucked into the flow cell into the sample cup.
Step D3: The pump is driven in the forward direction to suck a part of the liquid to be measured in the sample cup into the flow cell.
Step D4: The absorbance of the liquid to be measured is measured by the absorbance detector.
Step D5: The pump is driven in the forward direction to drain the entire amount of the liquid to be measured in the sample cup into the waste liquid tank via the flow cell.

[5] The analyzer according to [4], wherein the following steps are sequentially performed following the step D5.
Step D6: Introduce wash water into the sample cup.
Step D7: The pump is driven in the forward direction to drain a part of the washing water in the sample cup into the waste liquid tank via the flow cell.
Step D8: The pump is driven in the reverse direction to return the washing water in the detection pipe to the sample cup, and then drain the washing water together with the washing water remaining in the sample cup.

[6] Further, a sample liquid pipe whose downstream end is arranged at a position where the sample liquid can be discharged into the sample cup, and one or more reagent discharges whose downstream end is arranged at a position where the reagent can be discharged into the sample cup. Equipped with piping
The liquid to be measured was obtained by reacting the sample liquid introduced into the sample cup by the sample liquid pipe with one or more reagents introduced into the sample cup by the one or more reagent discharge pipes. The analyzer according to any one of [1] to [5], which is a reaction solution.
[7] Color development obtained by reacting an L-ascorbic acid solution and an ammonium molybdate solution with a thermal decomposition solution obtained by adding a potassium persulfate solution to a sample solution and heat-decomposing the solution to be measured. The analyzer according to any one of [1] to [6], which is a liquid.
[8] The liquid to be measured is a liquid obtained by adding a potassium persulfate solution and a sodium hydroxide solution to a sample liquid and heat-decomposing the liquid, and adjusting the pH with hydrochloric acid. [1] to The analyzer according to any one of [6].

According to the analyzer of the present invention, even when the pump for introducing the liquid to be measured into the flow cell needs to be driven in the opposite direction (direction from the flow cell to the sample cup) for various purposes, the next measurement is performed. It is possible to quickly drain the liquid to be measured with a simple configuration without adversely affecting such factors.

It is a schematic block diagram of the analyzer which concerns on one Embodiment of this invention. It is a figure which shows an example of a buffer tank. It is a figure explaining step D1 by the analyzer of FIG. It is a figure explaining step D2 by the analyzer of FIG. It is a figure explaining steps D3 to D5 by the analyzer of FIG. It is a figure explaining steps D6, D7 by the analyzer of FIG. It is a schematic block diagram of the analyzer which concerns on one Example of this invention.

An analyzer according to an embodiment of the present invention will be described with reference to FIG. The size and dimensional ratio of each member in FIG. 1 are for convenience of explanation and are different from the actual ones.
The analyzer according to the embodiment of the present invention detects that the sample cup 11 containing the liquid to be measured and the upstream end are inserted into the sample cup 11 and the downstream end is inserted into the waste liquid tank. The pipe L1 and the absorbance detection unit 20, the buffer tank 15, and the detection pump P1 sequentially provided from the upstream side are provided in the middle of the detection pipe L1.
The downstream end of the detection pipe L1 is inserted to a position where it is not immersed in the waste liquid in the waste liquid tank. That is, the downstream end of the detection pipe L1 is open to the atmosphere.

The absorbance detection unit 20 is an absorbance meter having a flow cell 21.
The flow cell 21 is connected in the middle of the detection pipe L1 by a joint 14a on the upstream side and by a joint 14b on the downstream side. The flow cell 21 is arranged so that the flow path in the flow cell 21 becomes higher from the upstream to the downstream.
The reason why the flow path in the flow cell 21 is inclined in this way is to prevent a situation in which air bubbles stay in the flow cell 21 and interfere with the absorbance measurement.
Although only the flow cell 21 portion is shown in FIG. 1, the absorbance detection unit 20 includes a light source that irradiates the flow cell 21 with light, a light detection unit that detects the light transmitted through the flow cell, and a light source and a light detection unit. It is provided with an optical member such as a lens provided between the two.

The buffer tank 15 is connected to the downstream side of the flow cell 21 in the middle of the detection pipe L1 by the joint 14c on the upstream side and by the joint 14d on the downstream side. The buffer tank 15 is arranged so that the upstream side is above (higher position) than the downstream side. In the present embodiment, as shown in FIG. 1, the flow direction (direction from upstream to downstream) of the buffer tank 15 is arranged along the vertical direction. The flow direction of the buffer tank 15 may be inclined from the vertical direction as long as the upstream side is above (higher position) than the downstream side, but it is preferably closer to the vertical direction and most preferably along the vertical direction.

The buffer tank 15 has a portion formed so that the inner diameter gradually increases from the upstream to the downstream and then gradually decreases. That is, even when viewed from the downstream, it is formed so as to gradually increase from the downstream to the upstream and then gradually decrease.
By having a part that gradually increases from the downstream to the upstream, when a small amount of liquid flows back from the downstream side, the small amount of liquid that has become a liquid film becomes larger in area as it rises, so the film breaks in the middle. Will be done. Therefore, it is possible to prevent the liquid that has flowed back to the flow cell 21 side in the form of a liquid film from reaching.
Further, since there is a portion that gradually increases from the downstream to the upstream and then gradually decreases, it is possible to connect in the middle of the detection pipe L1.

As shown in FIG. 2, the buffer tank 15 of the present embodiment includes a tank main body 15a, an inlet portion 15b on the upstream side of the tank main body 15a, and an outlet portion 15c on the downstream side of the tank main body 15a. The tank body 15a is a portion formed so that the inner diameter gradually increases from the upstream to the downstream and then gradually decreases.

From the viewpoint of fully exerting the effect of breaking the liquid film, it is preferable that the inner diameter (maximum inner diameter) of the portion where the inner diameter of the buffer tank 15 is the largest is as large as possible. On the other hand, from the viewpoint of reducing the load of liquid movement by the detection pump P1, the volume of the buffer tank 15 is preferably small. Further, in order to facilitate connection in the middle of the detection pipe L1, it is preferable that the inner diameters of the upstream end and the downstream end are the same.

In consideration of the above points, it is preferable that the portion formed so that the inner diameter gradually increases from the upstream to the downstream and then gradually decreases has a spherical shape or a shape close to a spherical shape.
In the present embodiment, the inner surface of the tank body 15a is substantially spherical, and the outer surface is also substantially spherical along the inner surface.
Further, the connecting portion 15d between the tank body 15a and the inlet portion 15b and the connecting portion 15e between the tank body 15a and the outlet portion 15c are preferably formed as gently as possible so as not to cause a liquid pool, and between them. It is preferable that there are no steps, gaps, overlays, etc.

The detection pump P1 is connected to the downstream side of the buffer tank 15 in the middle of the detection pipe L1 by the joint 14e on the upstream side and the joint 14f on the downstream side. A joint 14g is further provided downstream of the joint 14f, and the curved pipe and the straight pipe are connected so that the downstream end side of the detection pipe L1 faces downward along the vertical direction.

The detection pump P1 is a pump capable of sending the liquid in the detection pipe L1 in either the forward direction from the upstream to the downstream and the reverse direction from the downstream to the upstream.
The detection pump P1 of the present embodiment is a peristal type pump. A peristal type pump is a pump that squeezes a soft tube with a roller to send liquid or air, and is also called a tube pump or a roller pump. By reversing the squeezing direction with a roller, the direction of liquid feeding or air feeding can be reversed. Perista pump (registered trademark) can be used as a commercially available product of the peristal type pump.
As the detection pump P1 provided in the detection pipe L1 of the present invention, a syringe pump provided with a flow path switching means such as a three-way valve on the discharge port side may be used.

The analyzer of the present embodiment performs an operation including a step of driving the detection pump P1 in the reverse direction (direction from downstream to upstream).
As an example of the process of driving in the reverse direction, the detection pump P1 is driven in the reverse direction when there is no liquid in the detection pipe L1, and the air drawn from the downstream end in the detection pipe L1 is drawn into the sample cup 11. There is an example of bubbling.

The bubbling is useful as a means for stirring the liquid in the sample cup 11 or as a means for preventing the liquid in the sample cup 11 from entering the detection pipe L1.
Even if some liquid remains on the downstream end side of the detection pipe L1 or in the buffer tank 15 during bubbling, the action of the buffer tank 15 can prevent the liquid from flowing back into the flow cell 21 or the sample cup 11.
Since bubbling is performed in a state where the detection pipe L1 is free of liquid, the detection pump P1 is driven in the forward direction (direction from upstream to downstream) in advance as necessary to be inside the detection pipe L1. Discharge the liquid in the waste liquid tank.

Further, before driving the detection pump P1 in the reverse direction, a part of the measurement target liquid in the sample cup 11 is sucked into the flow cell 21 within the range where the measurement target liquid does not reach the buffer tank 15, and then the detection is performed. It is also preferable to drive the pump P1 in the opposite direction to perform an operation including a step of returning the sucked liquid to be measured back into the sample cup.
Such an aspect is useful when co-washing the flow cell 21 and measuring the absorbance of the blank liquid.

The analyzer of the present embodiment sequentially performs the following steps when performing co-washing.
Step D1: The detection pump P1 is driven in the forward direction, and a part of the measurement target liquid R in the sample cup 11 is sucked into the flow cell 21 within a range where the measurement target liquid R does not reach the buffer tank 15.
Step D2: The detection pump P1 is driven in the opposite direction to return the liquid R to be measured sucked into the flow cell 21 into the sample cup 11.
Step D3: The detection pump P1 is driven in the positive direction to suck a part of the liquid to be measured R in the sample cup 11 into the flow cell.
Step D4: The absorbance of the liquid R to be measured is measured by the absorbance detection unit 20.
Step D5: The detection pump P1 is driven in the forward direction to drain the entire amount of the liquid to be measured in the sample cup 11 into the waste liquid tank via the flow cell 21.

In step D1, as shown in FIG. 3, the detection pump P1 is driven in the positive direction so that the liquid in the detection pipe L1 moves in the x direction, and a part of the liquid to be measured R in the sample cup 11 is flow cell. Suction into 21.
At this time, the amount of the liquid to be measured R sucked into the flow cell 21 is set to the minimum amount necessary for co-washing so as not to reach the buffer tank 15. The suction amount can be controlled by the driving time of the detection pump P1.

Next, in step D2, as shown in FIG. 4, the detection pump P1 is driven in the opposite direction so that the liquid in the detection pipe L1 moves in the y direction, and the measurement target liquid R sucked into the flow cell 21 is sampled. Return to 11.
At this time, the residual liquid such as the washing water after the previous measurement, which remains on the downstream side of the detection pipe L1, flows back as the waste liquid G, but the increase is stopped by the buffer tank 15 and the backflow to the flow cell 21 occurs. Be prevented.
However, if the detection pump P1 is driven in the opposite direction for too long, it may flow back beyond the buffer tank 15. Therefore, the drive time of the detection pump P1 is the drive time of the detection pump P1 in step D1. Equivalent or slightly longer than the drive time of the detection pump P1 in step D1.

Next, in step D3, as shown in FIG. 5, the detection pump P1 is driven in the positive direction so that the liquid in the detection pipe L1 moves in the x direction, and a part of the liquid to be measured R in the sample cup 11 is driven. Is sucked into the flow cell 21.
At this time, the amount of the liquid to be measured R sucked into the flow cell 21 may reach the buffer tank 15 to some extent. The amount to be filled. The suction amount can be controlled by the drive time of the detection pump P1 and is longer than the drive time of the detection pump P1 in step D1.

Then, in the state of FIG. 5, as step D4, the absorbance of the liquid to be measured R is measured by the absorbance detection unit 20.
Next, in step D5, the detection pump P1 is further driven in the positive direction to drain the entire amount of the measurement target liquid R in the sample cup 11 into the waste liquid tank as waste liquid G via the flow cell 21.

When performing blank measurement, the analyzer of the present embodiment sequentially performs the above steps D1 to D4. However, in step D3 when performing blank measurement, as in step D1, a part of the measurement target liquid R (blank liquid) is sucked into the flow cell 21 within a range where the measurement target liquid R does not reach the buffer tank 15. ..
After performing the above steps D1 to D4 in order to perform the blank measurement, the blank liquid is returned to the sample cup 11 in the same manner as in step D2. Then, a color-developing reagent may be added to the blank liquid in the sample cup 11 to obtain a color-developing liquid, and the above steps D1 to D5 may be sequentially performed using this color-developing liquid as the measurement target liquid R.

Further, when cleaning the detection pipe L1 after measuring the absorbance, the following steps are performed.
Step D6: The washing water W is introduced into the sample cup 11.
Step D7: The detection pump P1 is driven in the forward direction to drain a part of the washing water W in the sample cup 11 into the waste liquid tank via the flow cell 21.
Step D8: The detection pump P1 is driven in the reverse direction to return the cleaning water W in the detection pipe L1 to the sample cup 11, and then drain the cleaning water W together with the cleaning water W remaining in the sample cup 11.

After introducing the washing water W into the sample cup 11 in step D6, as step D7, as shown in FIG. 6, the detection pump P1 is driven in the positive direction to partially drive the washing water W in the sample cup 11. Is discharged as waste liquid G into the waste liquid tank via the flow cell 21.
The inside of the detection pipe L1 is cleaned to the extent that the next measurement is not hindered by flowing the cleaning water W to some extent. The cleaning water W remaining in the sufficiently cleaned detection pipe L1 is returned to the sample cup 11 as in step D8, and is drained together with the remaining cleaning water W in the sample cup 11 without being put in the waste liquid tank. Is preferable.
In step D7, the entire amount of the washing water W in the sample cup 11 may be drained into the waste liquid tank as the waste liquid G, but this is not preferable because the amount of the waste liquid G is unnecessarily increased.

Step D6 may be performed manually, but a pure water pipe (a pipe for washing water) is provided at a position where the washing water W can be discharged to the sample cup 11 at the downstream end, and the sample cup 11 is automatically washed by a pump or the like. It is preferable to introduce water W into the sample cup 11.
Although step D8 may be performed manually, it is preferable to provide a drainage pipe for draining the liquid in the sample cup 11 and automatically drain the washing water in the sample cup 11 by a pump or the like.

By performing the above steps, the inside of the flow cell 21 can be co-washed with the liquid to be measured R to perform accurate absorbance measurement or blank measurement without adversely affecting the next measurement or the like, which is unnecessary. The liquid R to be measured can be drained without returning to the sample cup 11.
Therefore, it is not necessary to waste the liquid after returning it to the sample cup, and quick measurement is possible.

Further, in the present embodiment, after the measurement target liquid R is drained, the washing water W is introduced, and the detection pipe L1 is washed with a part of the introduced washing water W to drain the liquid, but the rest is drained. In the present embodiment, since it is not necessary to drain the liquid from the sample cup 11, it is easy to drain the rest of the washing water W.
In addition, when using a drainage pipe, in order to distinguish the waste liquid returned to the sample cup from the drainage liquid, it is necessary to install a three-way valve in the pipe that also serves as the drainage liquid and the waste liquid, or to use a dedicated pump for each. Therefore, the configuration of the entire analyzer is not complicated.

The liquid to be measured R in the present embodiment is preferably a reaction liquid obtained by reacting the sample liquid with one or more kinds of reagents.
The sample liquid is preferably introduced into the sample cup 11 by a sample liquid pipe arranged at a position where the downstream end can discharge the sample liquid into the sample cup.
Further, it is preferable that one or more kinds of reagents are added to the sample liquid by one or more reagent discharge pipes whose downstream ends are arranged at positions where the reagents can be discharged into the sample cup 11.

FIG. 7 shows an analyzer for measuring total nitrogen concentration and total phosphorus concentration as an analyzer according to an embodiment of the present invention, but the analyzer of the present invention is not limited to this embodiment, and is specific. The configuration and operation procedure can be changed in various ways.
The analyzer of this embodiment includes a reaction tank 10, a heating tank 13, an absorbance detection unit 20, a pipe and a pump for moving the liquid, and a control unit 30 that controls the entire device.

The reaction tank 10 is composed of a sample cup 11 and a lid material 12 that covers the sample cup 11, penetrates the lid material 12, and penetrates the detection pipe L1, the sample liquid pipe L2, the first reagent discharge pipe L3, and the second reagent discharge pipe L4. , The third reagent discharge pipe L5, the total nitrogen decomposition pipe L6, the total nitrogen decomposition liquid discharge pipe L13, the total phosphorus decomposition pipe L7, the pure water pipe L8, and the drainage pipe L9 are inserted into the reaction tank 10.

As described with reference to FIG. 1, the detection pipe L1 has an upstream end inserted into the sample cup 11 and a downstream end inserted into the waste liquid tank T7. Further, in the middle of the detection pipe L1, an absorbance detection unit 20, a buffer tank 15, and a detection pump P1 are sequentially provided from the upstream side.
The upstream end of the sample liquid pipe L2 is connected to a sample liquid supply source such as a water receiving tank (not shown), and the downstream end is arranged at a position where the sample liquid can be discharged into the sample cup 11. A sample liquid pump P2 is provided in the middle of the sample liquid pipe L2.

The first reagent discharge pipe L3, the second reagent discharge pipe L4, and the third reagent discharge pipe L5 are all reagent discharge pipes, and their downstream ends are arranged at positions where liquid reagents can be discharged into the sample cup 11. Has been done.
On the other hand, a pressurizing pipe L10 is connected to the upstream end of each reagent discharge pipe, and an air pump P10 is provided in the pressurizing pipe L10. The air pump P10 has a structure that does not block the pressurizing pipe L10 when stopped, and the upstream end of the pressurizing pipe L10 is open to the atmosphere.

The first reagent discharge pipe L3 is provided with a fifth normally closed valve V5 on the upstream side connected to the pressurizing pipe L10, and pipe A, pipe B, and pipe C are connected to the downstream side in this order from the upstream side. Has been done.
The second reagent discharge pipe L4 is provided with a sixth normally closed valve V6 on the upstream side connected to the pressurizing pipe L10, and a pipe D is connected to the downstream side thereof.
The third reagent discharge pipe L5 is provided with a seventh normally closed valve V7 on the upstream side connected to the pressurizing pipe L10, and a pipe E is connected to the downstream side thereof.

The upstream end of the pipe A is inserted into the first reagent tank T1 containing the sodium hydroxide solution, the downstream end is connected to the first reagent discharge pipe L3 at the connection point a, and the first reagent pump is in the middle. P3 is provided.
The upstream end of the pipe B is inserted into the second reagent tank T2 containing the potassium persulfate solution, and the downstream end is connected to the first reagent discharge pipe L3 at the connection point b, and the second reagent is in the middle. A pump P4 is provided.
The upstream end of the pipe C is inserted into the third reagent tank T3 containing the L-ascorbic acid solution, and the downstream end is connected to the first reagent discharge pipe L3 at the connection point c, and the third reagent is in the middle. A pump P5 is provided.

The upstream end of the pipe D is inserted into the fourth reagent tank T4 containing the hydrochloric acid solution, the downstream end is connected to the second reagent discharge pipe L4 at the connection point d, and the fourth reagent pump P6 is in the middle. It is provided.
The upstream end of the pipe E is inserted into the fifth reagent tank T5 containing the ammonium molybdate solution, the downstream end is connected to the third reagent discharge pipe L5 at the connection point e, and the fifth reagent pump is in the middle. P7 is provided.

The pipe A, the pipe B, the pipe C, the pipe D, and the pipe E are all reagent supply pipes for supplying the liquid reagent to the reagent discharge pipe, and the reagent pump provided in each reagent supply pipe supplies the liquid reagent. It is a liquid feeding means to move.
By operating the first reagent pump P3, the reagent in the first reagent tank T1 is operated, by operating the second reagent pump P4, the reagent in the second reagent tank T2 is operated, and by operating the third reagent pump P5, the third reagent is operated. The reagent in the reagent tank T3 is connected to the reagent in the fourth reagent tank T4 by operating the fourth reagent pump P6, and the reagent in the fifth reagent tank T5 is connected by operating the fifth reagent pump P7. It is designed to be supplied to the piping.

The reagent pump provided in each reagent supply pipe closes the reagent supply pipe in an airtight manner at the position where the reagent pump is provided when stopped. As a result, the reagent can be held between the connection point between the reagent supply pipe and the reagent discharge pipe, which are provided for each, and the pump when the pump is stopped.
As the reagent pump provided in the reagent supply pipe, a syringe pump having a check valve or a peristal type pump can be preferably used.

In the present embodiment, in the standby state, the liquid reagents of each reagent supply pipe are filled from the upstream end of the reagent supply pipe to each connection point, and according to any of the following aspects, from any of the reagent supply pipes, It is configured so that the entire amount of the reagent supplied to any of the reagent discharge pipes beyond each connection point is discharged to the sample cup 11 of the reaction tank 10.
In addition, "the whole amount is discharged" in this specification means that substantially the whole amount is discharged, and even if a small amount of residual liquid inevitably adheres to the pipe and remains, "the whole amount is discharged". It corresponds to "being done".

In the first aspect, the normally closed valve V5, the sixth normally closed valve V6, and the seventh normally closed valve V7 are turned ON (open) while the air pump P10 is operated. Operate a reagent pump provided in any of the reagent supply lines connected to. Then, the entire amount of the reagent that has reached the reagent discharge pipe from the reagent supply pipe beyond the connection point can be ejected to the sample cup 11.
For example, when the fifth normally closed valve V5 is turned ON (open) and the first reagent pump P3 is operated while the air pump P10 is operated, the reagents in the first reagent tank T1 connect from the pipe A to the connection point a. The entire amount that exceeds the amount that reaches the first reagent discharge pipe L3 is immediately discharged to the sample cup 11 by air.

In the second aspect, the height position of the connection point is set higher than the height position of the downstream end of each reagent discharge pipe.
Then, with the 5th normally closed valve V5, the 6th normally closed valve V6, and the 7th normally closed valve V7 all turned OFF (closed) and the air pump P10 turned OFF, the reagent connected to any of the reagent supply pipes. When the pump is operated, a predetermined amount of liquid reagent moves toward the connection point of the reagent discharge pipe. The liquid reagent that has reached the reagent discharge pipe beyond the connection point enters the downstream side of the reagent discharge pipe because the upstream side is blocked by the normally closed valve.

After that, when the reagent pump is stopped and the normally closed valve provided in the reagent discharge pipe into which the liquid reagent is introduced is turned ON (open), the connection point is connected to the upstream end of the pressurizing pipe L10 in an open state to the atmosphere. Therefore, the entire amount of the liquid reagent supplied to the reagent discharge pipe beyond the connection point falls due to its own weight, and is discharged from the downstream end of the reagent discharge pipe toward the sample cup 11.
If there is a part higher than the connection point between the connection point and the downstream end, the liquid reagent is introduced to the part lower than the connection point (self-weight drop point) beyond the high part, and then the reagent pump. It is necessary to stop. If the liquid is not filled up to the drop point of its own weight, even if the connection point is open to the atmosphere, the drop due to its own weight does not occur.
After that, when the air pump P10 is operated with the ON (open) valve turned ON, a small amount of residual liquid remaining on the downstream side of each connection point of the reagent discharge pipe can be ejected to the sample cup 11.

For example, the reagent in the first reagent tank T1 is supplied to the sample cup 11 as follows. First, the first reagent pump P3 is operated with the fifth normally closed valve V5, the sixth normally closed valve V6, and the seventh normally closed valve V7 all turned off (closed) and the air pump P10 turned off, and the piping A A predetermined amount of the reagent in the first reagent tank T1 is moved from the to the connection point a. The reagent that has reached the first reagent discharge pipe L3 beyond the connection point a enters the downstream side of the first reagent discharge pipe L3 because the upstream side is blocked by the fifth normally closed valve V5.

After that, when the reagent pump is stopped and the normally closed valve provided in the reagent discharge pipe into which the liquid reagent is introduced is turned ON (open), the connection point a is connected to the upstream end of the pressurizing pipe L10 in an open state to the atmosphere. Therefore, the entire amount of the liquid reagent supplied to the first reagent discharge pipe L3 beyond the connection point a falls due to its own weight and is discharged from the downstream end of the first reagent discharge pipe L3 toward the sample cup 11. ..
Then, when the air pump P10 is operated with the fifth normally closed valve V5 turned ON (open), a small amount of residual liquid remaining on the downstream side of the connection point a can be ejected to the sample cup 11.

In either case, the entire amount of the reagent that reaches the reagent discharge pipe from the reagent supply pipe beyond the connection point can be introduced into the sample cup 11. Further, since the liquid in the sample cup 11 can be agitated by air, the introduced reagent and the sample liquid can be sufficiently mixed.
Further, after the reagent is introduced into the sample cup 11, the reagent is held in a state of being filled between the connection point of each reagent supply pipe and the reagent pump, so that it can be used for the next reagent supply.

Further, since the reagent discharge pipe is in a state where the reagent is not contained in the reagent discharge pipe after the reagent is introduced into the sample cup 11, it is possible to prevent the reagent from dropping from the tip of the reagent discharge pipe into the sample cup 11 at an unintended time. At the same time, it is possible to connect a plurality of reagent supply pipes to one reagent discharge pipe.

The total nitrogen decomposition pipe L6 and the total phosphorus decomposition pipe L7 each have a thermal decomposition section above the reaction vessel 10. The thermal decomposition section is a portion where the decomposition pipe L6 for total nitrogen and the decomposition pipe L7 for total phosphorus are covered with the heating tank 13.
The downstream ends of the total nitrogen decomposition pipe L6 and the total phosphorus decomposition pipe L7 are inserted to the bottom of the sample cup 11, respectively.

A first normally closed valve V1 is provided on the reaction tank 10 side of the thermal decomposition section of the total nitrogen decomposition pipe L6, and a second normally closed valve V2 is provided on the opposite side of the reaction tank 10.
Similarly, a third normally closed valve V3 is provided on the reaction tank 10 side of the thermal decomposition section of the whole phosphorus decomposition pipe L7, and a fourth normally closed valve V4 is provided on the opposite side of the reaction tank 10.
Further, the upstream end side of the total nitrogen decomposition liquid discharge pipe L13 is connected between the thermal decomposition part of the total nitrogen decomposition pipe L6 and the first normally closed valve V1, and the total nitrogen decomposition liquid discharge pipe L13 is connected to the total nitrogen decomposition liquid discharge pipe L13. The ninth normally closed valve V11 is provided.

The upstream ends of the total nitrogen disassembly pipe L6 and the total phosphorus disassembly pipe L7 are connected to the pressurization pipe L10 via the common pipe L12.
The eighth is between the part where the common pipe L12 of the pressurizing pipe L10 is connected and the part where the first reagent discharge pipe L3, the second reagent discharge pipe L4, and the third reagent discharge pipe L5 are connected. A normally closed valve V8 is provided.

Further, the upstream end of the pure water pipe L8 is inserted into the pure water tank T8, and the downstream end is arranged at a position where pure water can be discharged into the sample cup 11.
The pure water pipe L8 is provided with a first three-way valve V9 and a second three-way valve V10 in this order from the upstream side.

The discharge port of the pure water pump P8 is connected to the first three-way valve V9. In this embodiment, the pure water pump P8 is a syringe pump.
The first three-way valve V9 has a common port on the discharge port side of the pure water pump P8, a normally closed port on the pure water tank T8 side, and a normally open port on the second three-way valve V10 side.

Further, the upstream end of the heating tank cleaning pipe L11 is connected to the second three-way valve V10. The downstream end of the heating tank cleaning pipe L11 is connected to the connection point between the pressurizing pipe L10 and the common pipe L12.
The second three-way valve V10 has a common port on the first three-way valve V9 side, a normally closed port on the downstream end side of the pure water pipe L8, and a normally open port on the heating tank cleaning pipe L11 side.

The liquid in the sample cup 11 is sucked up to the thermal decomposition part by the suction operation of the pure water pump P8. The timing of suction to the thermal decomposition section in each of the total nitrogen decomposition pipe L6 and the total phosphorus decomposition pipe L7 is different.
Before the suction operation of the pure water pump P8 for sucking up to the heat decomposition section, the plunger of the pure water pump P8 is set to the discharge position.

The suction operation of the pure water pump P8 at the time of suction to the decomposition pipe L6 for all nitrogen is that the first normally closed valve V1 and the second normally closed valve V2 are ON (open), the third normally closed valve V3, and the fourth normally closed. Valve V4, 9th normally closed valve V11 is OFF (closed), 8th normally closed valve V8 is OFF (closed), 1st three-way valve V9 is OFF (T8 side is closed), 2nd three-way valve V10 is OFF (L11 side is OFF) It is done in the open) state.
The suction operation of the pure water pump P8 at the time of suction to the disassembly pipe L7 for total phosphorus is that the first normally closed valve V1, the second normally closed valve V2, and the ninth normally closed valve V11 are OFF (closed) and the third normally closed. Valve V3, 4th normally closed valve V4 is ON (open), 8th normally closed valve V8 is OFF (closed), 1st three-way valve V9 is OFF (T8 side is closed), 2nd three-way valve V10 is OFF (L11 side is OFF) It is done in the open) state.

The pressurization of the thermal decomposition part into which the liquid is introduced is performed by pressure feeding of air. The pressure feeding of air to the thermal decomposition section is performed by operating the air pump P10.
When pressurizing the heat decomposition part of the decomposition pipe L6 for total nitrogen, the first normally closed valve V1, the ninth normally closed valve V11, the third normally closed valve V3, and the fourth normally closed valve V4 are OFF (closed). The second normally closed valve V2 is ON (open), the eighth normally closed valve V8 is ON (open), and the second three-way valve V10 is ON (V8 side is closed).
When pressurizing the heat decomposition part of the decomposition pipe L7 for whole phosphorus, the first normally closed valve V1, the second normally closed valve V2, the ninth normally closed valve V11, and the third normally closed valve V3 are OFF (closed). The fourth normally closed valve V4 is ON (open), the eighth normally closed valve V8 is ON (open), and the second three-way valve V10 is ON (V8 side is closed).
Then, with the air pump P10 stopped and the first normally closed valves V1 to the fourth normally closed valves V4 and the first three-way valve V9 all turned off (closed), the heating decomposition section is heated by the heating tank 13. , The liquid introduced into each thermal decomposition section is thermally decomposed.

The temperature of the heating tank 13 is set to a preheated state of about 70 ° C. throughout the entire process except during thermal decomposition, and is set to 120 ° C. during thermal decomposition.
After that, the timings of depressurizing the heat-decomposed portion and returning the liquid (heat-decomposed liquid) to the sample cup 11 in each of the total nitrogen decomposition pipe L6 and the total phosphorus decomposition pipe L7 are different.

The pressure release of the thermal decomposition portion in the decomposition pipe L6 for total nitrogen is performed by turning on (opening) the ninth normally closed valve V11. Then, the heated decomposition liquid is returned to the sample cup 11 by turning on (opening) the ninth normally closed valve V11 and the second normally closed valve V2, so that the liquid is passed through the total nitrogen decomposition liquid discharge pipe L13 to the sample cup 11. By operating the air pump P10 with the 8th normally closed valve V8 ON (open) and the 2nd three-way valve V10 ON (V8 side closed), the residual liquid in the decomposition pipe L6 for total nitrogen is operated. It is done as if to drive out.
The reason why the heat-decomposed liquid for total nitrogen measurement is returned via the total nitrogen decomposition liquid discharge pipe L13 is that the unheated potassium persulfate solution remaining in the total nitrogen decomposition pipe L6 is mixed in the heat-decomposed liquid. This is to prevent. Unheated potassium persulfate solution is a hindrance to total nitrogen measurements.

The pressure release of the thermal decomposition portion in the decomposition pipe L7 for whole phosphorus is performed by turning on (opening) the third normally closed valve V3. Then, in order to return the heat-decomposed liquid to the sample cup 11, the liquid is dropped into the sample cup 11 by turning the third normally closed valve V3 and the fourth normally closed valve V4 ON (open), and then the eighth normal closing valve V4 is turned on. By operating the air pump P10 with the closed valve V8 ON (open) and the second three-way valve V10 ON (V8 side closed), the residual liquid in the whole phosphorus disassembly pipe L7 is expelled.

Cleaning of the thermal decomposition section is performed by flowing pure water through the thermal decomposition section. Specifically, any one of the first normally closed valve V1 and the second normally closed valve V2, the ninth normally closed valve V11 and the second normally closed valve V2, or the third normally closed valve V3 and the fourth normally closed valve V4. One or more sets are turned ON (open), and the pure water pump P8 starts to discharge while all of the 8th normally closed valve V8, the 1st three-way valve V9, and the 2nd three-way valve V10 are OFF. There is.

Further, in the work of directly introducing pure water into the sample cup 11 for cleaning and dilution, the eighth normally closed valve V8 is turned off (closed) and the first three-way valve V9 is turned off (the second three-way valve V10 side is open). , The pure water pump P8 is discharged in a state where the second three-way valve V10 is ON (the downstream end side of the pure water pipe L8 is opened).
Before the cleaning and dilution operations, the pure water pump P8 is sucked with the first three-way valve V9 turned on (the pure water tank T8 side is open), and the pure water pump P8 is filled with pure water. It is said that it is in a state of being.

The upstream end of the drainage pipe L9 is inserted to the bottom of the sample cup 11. The downstream end reaches the drainage port of the device because the drainage is drained to the outside of the device.
A drainage pump P9 is provided in the middle of the drainage pipe L9.

The total nitrogen concentration and the total phosphorus concentration are measured by the apparatus of this embodiment under the control of the control unit 30 according to the following procedure.
1. 1. Total nitrogen sample preparation First, a predetermined amount of sample liquid is introduced into the sample cup 11 by the sample liquid pipe L2. Here, if necessary, pure water is introduced into the sample cup 11 from the pure water pipe L8 to dilute the sample liquid. Next, the sodium hydroxide solution in the first reagent tank T1 and the potassium persulfate solution in the second reagent tank T2, which are thermal decomposition reagents for total nitrogen measurement, are introduced into the sample cup 11, and the sample liquid and the thermal decomposition reagent are mixed. Then, use the total nitrogen sample solution.
Then, the entire amount of the total nitrogen sample liquid is sucked up to the portion (heat decomposition part) housed in the heating tank 13 (preheated state) of the total nitrogen decomposition pipe L6, and the first normally closed valve V1 and the second normally closed valve are sucked. With V2 turned off (closed), it stands by while adjusting the total phosphorus sample.

2. After cleaning the inside of the whole phosphorus sample preparation sample cup 11, a predetermined amount of sample liquid is introduced into the sample cup 11 through the sample liquid pipe L2. Here, if necessary, pure water is introduced into the sample cup 11 from the pure water pipe L8 to dilute the sample liquid. Next, the potassium persulfate solution of the second reagent tank T2, which is a thermal decomposition reagent for measuring total phosphorus, is introduced into the sample cup 11, and the sample solution and the thermal decomposition reagent are mixed to obtain a total phosphorus sample solution.
Then, the entire amount of the total phosphorus sample liquid is sucked up to the portion (heat decomposition part) housed in the heating tank 13 (preheated state) of the total phosphorus decomposition pipe L7, and the third normally closed valve V3 and the fourth normally closed. The valve V4 is closed.

3. 3. Heat decomposition The heat decomposition part of the total nitrogen decomposition pipe L6 is pressurized, and then the heat decomposition part of the total phosphorus decomposition pipe L7 is pressurized.
Then, the temperature of the heating tank 13 is set to 120 ° C., and the total nitrogen sample solution of the total nitrogen decomposition pipe L6 and the total phosphorus sample solution of the total phosphorus decomposition pipe L7 are heat-decomposed for 30 minutes, and each is heated for total nitrogen measurement. The decomposition solution and the thermal decomposition solution for measuring total phosphorus are used.
By thermal decomposition, all nitrogen compounds in the sample solution are oxidized to nitrate ions. In addition, all the phosphorus compounds in the sample solution are oxidized to phosphate ions.
After thermal decomposition, depressurize each thermal decomposition part.

4. Total nitrogen measurement The heated decomposition liquid of the total nitrogen decomposition pipe L6 is depressurized and then returned to the sample cup 11 via the total nitrogen decomposition liquid discharge pipe L13. Hydrochloric acid in the fourth reagent tank T4 is introduced here to adjust the pH to 2 to 3, and a measurement target liquid R for total nitrogen measurement is obtained.
Next, the absorbance is measured by the absorbance detection unit 20 according to the procedure described with reference to FIGS. 3 to 5.

The absorbance is measured at a wavelength corresponding to the nitrate ion concentration and a wavelength corresponding to the amount of a turbid component or the like without absorption of nitrate ions. Then, the total nitrogen concentration of the sample solution is obtained based on the measurement results of both wavelengths and the calibration curve information obtained in advance.
For example, in Japan, Notification No. 64 of the Environment Agency (currently Ministry of the Environment) of 1974 and 45 of JIS K 0102: 2016, the wavelength corresponding to the nitrate ion concentration is 220 nm, and there is no absorption of nitrate ions, and the turbid component The total nitrogen concentration of the sample solution can be obtained by measuring the absorbance at each wavelength of 254 nm corresponding to the amount and converting the value obtained by subtracting the absorbance at 254 nm from the absorbance at 220 nm based on the calibration curve information obtained in advance. ..
In addition, according to the Chinese standards "HJ / T 102-2003" and "GB 11894-89", the wavelength is 220 nm, which corresponds to the nitrate ion concentration, and the wavelength is 275 nm, which does not absorb nitrate ions and corresponds to the amount of turbid components. The total nitrogen concentration of the sample solution can be obtained by measuring the absorbance at each wavelength and converting the value obtained by subtracting twice the absorbance at 275 nm from the absorbance at 220 nm based on the calibration curve information obtained in advance.

After the absorbance is measured, the liquid R to be measured in the sample cup 11 is drained into the waste liquid tank T7, and then the detection pipe L1 is washed according to the procedure described with reference to FIG. 6 if necessary. When cleaning the detection pipe L1, it is preferable to use pure water for cleaning the decomposition pipe L6 for total nitrogen and then the water discharged into the sample cup 11 as the cleaning water W.
As a result, all of the total nitrogen decomposition pipe L6, the sample cup 11, and the detection pipe L1 can be cleaned.
As described with reference to FIG. 6, after sufficiently cleaning the inside of the detection pipe L1, the cleaning water remaining in the buffer tank 15 or the like of the detection pipe L1 drives the detection pump P1 in the opposite direction to drive the sample cup. It is preferable to return the product to the inside of the sample cup 11 and drain the liquid from the drain pipe L9 together with the washing water remaining in the sample cup 11.

5. Total phosphorus measurement Return the thermal decomposition liquid of the total phosphorus decomposition pipe L7 to the sample cup 11. A blank liquid to which the L-ascorbic acid solution of the third reagent tank T3 is added is obtained as the measurement target liquid R.
Then, according to the procedure described with reference to FIGS. 3 to 5, the absorbance detection unit 20 measures the absorbance at the wavelength corresponding to molybdenum blue based on the phosphate ion of the blank solution (details will be described later).

After that, the blank liquid was returned to the sample cup 11 as shown in FIG. 4 without draining, and the ammonium molybdate solution of the fifth reagent tank T5 was introduced into the sample cup 11, and the color-developing liquid produced by molybdenum blue was used as the liquid to be measured. Obtained as R.
Then, according to the procedure described with reference to FIGS. 3 to 5, the absorbance detection unit 20 measures the absorbance at the wavelength corresponding to molybdenum blue based on the phosphate ion of the color-developing solution.
For example, Japan's 1974 Environmental Agency (currently Ministry of the Environment) Notification No. 64 and JIS K 0102: 2016 46.3 adopt a wavelength of 800 nm as the wavelength corresponding to molybdenum blue, so the wavelength is 800 nm. The total phosphorus concentration of the sample solution can be obtained by converting the value obtained by subtracting the absorbance of the blank solution from the absorbance of the color-developing solution in 1) based on the calibration curve information obtained in advance.
Further, in the Chinese standards "HJ / T 103-2003" and "GB 11893-89", the wavelength of 700 nm is adopted as the wavelength corresponding to molybdenum blue. The total phosphorus concentration of the sample solution can be obtained by converting the value obtained by subtracting the absorbance based on the calibration curve information obtained in advance.

If the temperature of the blank liquid returned to the sample cup 11 is too low due to the low ambient temperature, the blank liquid is decomposed by heating in the decomposition pipe L7 for total phosphorus before introducing the ammonium molybdate solution. It may be returned to and reheated by preheating. This promotes the reaction to produce molybdenum blue.
After the absorbance is measured, the liquid in the sample cup 11 is drained into the waste liquid tank T7, and then the detection pipe L1 is washed according to the procedure described with reference to FIG. As the washing water W, it is preferable to wash the decomposition pipe L7 for total phosphorus with pure water and then use the water discharged into the sample cup 11.
As a result, all of the disassembly pipe L7 for total phosphorus, the sample cup 11, and the detection pipe L1 can be cleaned.
As described with reference to FIG. 6, after sufficiently cleaning the inside of the detection pipe L1, the cleaning water remaining in the buffer tank 15 or the like of the detection pipe L1 drives the detection pump P1 in the opposite direction to drive the sample cup. It is preferable to return the product to the inside of the sample cup 11 and drain the liquid from the drain pipe L9 together with the washing water remaining in the sample cup 11.

10 Reaction tank 11 Sample cup 12 Cover material 13 Heating tank 15 Buffer tank 20 Absorption detection unit 21 Flow cell 30 Control unit L1 Detection pipe L2 Sample liquid pipe L3 First reagent discharge pipe L4 Second reagent discharge pipe L5 Third reagent discharge pipe L6 Total nitrogen decomposition pipe L7 Total phosphorus decomposition pipe L8 Pure water pipe L9 Drainage pipe L10 Pressurization pipe L11 Heating tank cleaning pipe L12 Common pipe L13 Total nitrogen decomposition liquid discharge pipe P1 Detection pump P2 Sample liquid pump P3 1st Reagent pump P4 2nd reagent pump P5 3rd reagent pump P6 4th reagent pump P7 5th reagent pump P8 Pure water pump P9 Drainage pump P10 Air pump

Claims (8)

A sample cup containing the liquid to be measured, a detection pipe whose upstream end is inserted into the sample cup, and a detection pipe whose downstream end is inserted to a position where it is not immersed in the waste liquid in the waste liquid tank of the waste liquid tank, and the detection pipe. On the way, an absorbance detector, a buffer tank, and a pump, which are sequentially provided from the upstream side, are provided.
The absorbance detection unit is an absorbance meter having a flow cell, and the flow cell is connected in the middle of the detection pipe.
The buffer tank has a portion formed so that the inner diameter gradually increases from the upstream side to the downstream side and then gradually decreases, and is connected in the middle of the detection pipe so that the upstream side is above the downstream side.
The pump is an analyzer characterized in that the liquid in the detection pipe can be sent in any of a forward direction from upstream to downstream and a reverse direction from downstream to upstream. The analyzer according to claim 1, wherein the analyzer performs an operation including a step of driving the pump in the reverse direction. The pump is driven in the forward direction to suck a part of the liquid to be measured in the sample cup into the flow cell within a range where the liquid to be measured does not reach the buffer tank, and then the pump is moved in the reverse direction. The analyzer according to claim 2, wherein the analyzer is driven to perform an operation including a step of returning the sucked liquid to be measured back into the sample cup. The analyzer according to claim 1, wherein the following steps are sequentially performed.
Step D1: The pump is driven in the forward direction, and a part of the liquid to be measured in the sample cup is sucked into the flow cell within a range where the liquid to be measured does not reach the buffer tank.
Step D2: The pump is driven in the opposite direction to return the liquid to be measured sucked into the flow cell into the sample cup.
Step D3: The pump is driven in the forward direction to suck a part of the liquid to be measured in the sample cup into the flow cell.
Step D4: The absorbance of the liquid to be measured is measured by the absorbance detector.
Step D5: The pump is driven in the forward direction to drain the entire amount of the liquid to be measured in the sample cup into the waste liquid tank via the flow cell. The analyzer according to claim 4, wherein the following steps are sequentially performed following the step D5.
Step D6: Introduce wash water into the sample cup.
Step D7: The pump is driven in the forward direction to drain a part of the washing water in the sample cup into the waste liquid tank via the flow cell.
Step D8: The pump is driven in the reverse direction to return the washing water in the detection pipe to the sample cup, and then drain the washing water together with the washing water remaining in the sample cup. Further, it is provided with a sample liquid pipe whose downstream end is arranged at a position where the sample liquid can be discharged into the sample cup, and one or more reagent discharge pipes whose downstream end is arranged at a position where the reagent can be discharged into the sample cup. ,
The liquid to be measured was obtained by reacting the sample liquid introduced into the sample cup by the sample liquid pipe with one or more reagents introduced into the sample cup by the one or more reagent discharge pipes. The analyzer according to any one of claims 1 to 5, which is a reaction solution. The liquid to be measured is a color-developing liquid obtained by reacting an L-ascorbic acid solution and an ammonium molybdate solution with a heat-decomposed liquid obtained by adding a potassium persulfate solution to a sample liquid and heat-decomposing it. , The analyzer according to any one of claims 1 to 6. Any of claims 1 to 6, wherein the liquid to be measured is a liquid obtained by adding a potassium peroxodisulfate solution and a sodium hydroxide solution to a sample liquid and heat-decomposing the liquid, and adjusting the pH with hydrochloric acid. The analyzer according to item 1.

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