JPH0418629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to volumetric analysis such as concentration measurement.

[Prior art]

FIG. 1 is a diagram showing a conventional titration apparatus. The titration operation will be explained below. Sample 2 to be analyzed first
Accurately measure the specified volume (V ₁ ) and put it into beaker 1. When the start switch of the control section 3 is turned on, the piston pump 4 is activated to suck the titrant 6 through the tube 7. The piston pump 4 then turns into a pumping action and sends the titrant 6 through the tube 8 into the beaker 1 . The control unit 3 detects that the reaction has reached its end point based on a signal from a sensor 9 such as a PH meter, and stops the operation of the piston pump 4. The piston pump 4 is provided with a sliding resistor whose resistance value changes according to the movement of the piston, and the control unit 3 measures this resistance value at the end point and determines the volume V of the titrant 6 required for titration. Calculate ₂ .
Here, since the concentration N of the titrant 6 is known and the volume V ₁ of the sample 2 has also been measured, the concentration NX of the sample 2 is given by the following equation.

NX=N·V ₂ /V ₁ The control unit 3 calculates and displays the concentration of the sample 2 based on this equation.

However, it had the following drawbacks. That is,
The first drawback is that both the piston pump 4 and the sliding resistor require high accuracy because it is necessary to accurately know the volume of titrant liquid required for titration. A second drawback is that even if the piston pump 4 or the sliding resistor is of high precision, if the precision deteriorates with use of the device, accurate measurements will no longer be possible. A third drawback is that the measurement of the sample 2 is carried out by a human, which is inconvenient especially when titration is to be carried out continuously, and titration cannot be carried out unattended.

In order to solve the first and second drawbacks, it is conceivable to use a squeezing type pump instead of the piston pump 4. Here, the ladder pump refers to a pump that squeezes the tube with a roller or the like to push out a minute amount of liquid.

If a squeeze-type pump is used, the amount of displacement can be detected by measuring the number of times the pump is squeezed, thereby eliminating the need for a sliding resistor and solving the problem of increasing the accuracy of the sliding resistor and preventing deterioration. However, since the tube is squeezed, the amount of extrusion changes depending on the type of tube, the duration of use, etc., and a fourth drawback arises: accurate titration is impossible without constant complicated correction. Ta.

In order to solve the third drawback, there is also an apparatus in which the sample 2 is further fed into the beaker using another piston pump. However, these additionally provided piston pumps and sliding resistors are also required to have high precision and high durability, creating new problems and making the device larger and more complex.

[Structure of the invention]

This invention was made for the purpose of solving the above-mentioned drawbacks, and uses a switching valve to push out the sample and the titrant liquid with the same pump, and determines the concentration etc. based on the ratio of the sample and the titrant liquid required for titration This paper proposes a method and apparatus for performing the analysis.

FIG. 2 is an overall configuration diagram for clearly showing the configuration of the present invention. The valve means 200 allows one of the sample, cleaning liquid, or titration liquid to pass through the flow path 25, and performs a switching operation in response to a signal from the valve control signal generating means. A pump 210 provided in the flow path 25 sends out a sample and the like to the nozzle 22 . The nozzle control signal generating means gives a signal to the nozzle switching means to change the position of the tip of the nozzle 22 to switch whether or not to introduce the sample, etc. into the reaction tank 23. Upon receiving the signal from the sensor 9, the end point signal generating means detects the end point of the reaction, provides the end point signal to the pump control signal generating means, and stops the pump 210. The counting means for counting the operation of the pump 210 provides a count signal to the quantitative signal generating means and the calculating means. The calculation means receives the end point signal and performs capacity analysis.

〔Example〕

Examples thereof will be described below based on the drawings.

In FIG. 3, tubes 60 to 62 are a water tank 35, which is a first cleaning liquid, a titrant liquid tank 36, and a second water tank 35, which is a first cleaning liquid.
A flow path connected to a cleaning liquid tank 37 and a sample tank 38 is formed. Each tank 35-38 is 3
It is connected to a nozzle 40 via directional valves 20, 30-32 and a straining pump 21. As another embodiment, a piston pump or the like may be used instead of the squeezing pump 21. Reaction tank 2
A sensor 9 such as a PH meter and an electrometer is provided inside the reaction tank 3, and a discharge tank 26 is provided outside the reaction tank 23. The nozzle 40 is driven by a nozzle drive motor 29
medial position (position indicated by solid line in the figure)
Or it can be switched to the outer position (the position indicated by the dashed line). A discharge port 28 and a valve 34 are provided at the bottom of the reaction tank 23.
is provided. The water tank 35 is also connected to the nozzle 42 via a tube 63 and a valve 33. The electronic circuit 100 controls each part, and will be described below using a microcomputer, but in other embodiments,
It is also possible to configure the system without using a microcomputer.

Next, the configuration of the electronic circuit 100 using a microcomputer will be explained with reference to FIG.

The pulse generating circuit 56 generates pulses in response to the operation of the straining pump 21. Counter 57 counts these pulses and provides them to microcomputer 50. It is also possible to have the microcomputer 50 perform this function without providing a special counter 57. Output port 5
5 selectively gives the output of the CPU 53 to each valve, etc. Note that the use of an A/D converter and a D/A converter is a matter of course for those skilled in the art, and therefore illustration thereof is omitted.

Next, the program written in the ROM 54 is shown in a flowchart as shown in FIG. The operation of the titration device will be explained below according to this flowchart.

When the program starts, the microcomputer 50 first applies a port designation signal to the output port 55 via the signal line 59, selectively outputs an output signal, and opens the valve 34. In this way, the water that was filled in the reaction tank 23 to protect the sensor 9 is discharged. Thereafter, valve 34 is closed (step 70). Next, a signal is sent to the nozzle drive motor 29 to move the nozzle 40 to the position shown by the dotted line in FIG. 8, that is, to the outer position (step 7l). Then, the squeezing pump 21 is rotated enough to fill the tube 62 and nozzle 40 with the sample (steps 72 and 78). The number of rotations of the pump 21 to complete filling is fixed and known in advance. Therefore, the CPU 53 checks the output of the counter 57 so that it rotates a little more. At this time, the excess sample is discharged through the discharge port 27 of the discharge tank 26. In another embodiment, the microcomputer 50 may play the role of the counter 57. In still other embodiments, the nozzle 4
It is also possible to determine filling by providing a sensor that reacts to the sample at the tip of the zero.

Next, the nozzle 40 is placed in the inner position, and the straining pump 21 is rotated a predetermined number of times (hereinafter referred to as A).
The sample is sent to the reaction tank 23 (steps 74 and 75).

After that, repeat the same operation as above to send the titrant solution to the reaction tank and start titration (step 76~
82). However, before sending the titrant to tube 62,
If the tube 62 is not cleaned, a reaction will occur between the remaining sample and the tube, making accurate measurements impossible. Therefore, in this embodiment, the tube 6
2. The nozzle 40 is washed with water (step 78).

The titration is completed by the microcomputer 50 checking the signal from the sensor 9 (step
83). When the end point is reached, the straining pump 21 is stopped and the number of revolutions of the counter 57 (hereinafter referred to as B) is stored (steps 84, 85).

The amount of discharge per revolution of the pump changes depending on the age and thickness of the tube, but the change is so small that it can be ignored within a single measurement period. Therefore, the concentration NX of the sample is given by the following formula, where N is the concentration of the titrant. The concentration NX is calculated based on this calculation formula and displayed (steps 86 and 87).

NX=N*(B/A) Step 88 and below are reaction tank 23, tube 62,
This is to clean the valve 40 (step 88).
~91). In this embodiment, in addition to water, a second cleaning liquid is also used as the cleaning liquid (step 90). For example, when the sample is a phosphoric acid coating treatment solution, it is desirable to use H ₂ SO ₄ as the second cleaning solution to prevent the sample from adhering to the inside of the tube due to a drop in temperature or the like.
Note that depending on the type of titrant and sample, washing with water may be sufficient, and in such cases, the second washing liquid is not necessary.

Finally, the reaction tank 23 is filled with water and the process ends (step 92).

In addition, in the apparatus and method according to this example, the sample and the titrant were sent to the reaction tank 23 in this order.
In other embodiments, the titrant and the sample can be sent to the reaction tank in this order.

When a straining type pump is used for a long period of time, the flexibility of the tube changes and the amount delivered per pump operation changes. However, even if such a change occurs, it has no effect because the delivered amounts of both sample and titrant fluid change in the same proportional relationship. That is, there is no influence on the measurement results in this invention obtained from the ratio of the number of rotations of the pump.

Next, an embodiment of the concentration control device according to the present invention will be described with reference to FIGS. 6 to 8.

FIG. 6 is a diagram showing the configuration of the concentration control device.
In the figure, a titration apparatus 200 is shown in FIG. 8, and a water tank 35 is connected to tap water through a water pressure regulating valve 110 and a valve 111. Processing tank 1
The concentration control object (for example, phosphate coating treatment liquid, etc.) in the chamber 19 is processed as a sample by a three-way valve 118 → sample transfer pump 112 → sample tank 38 → intermediate tank 117 → sample return pump 115 → treatment tank 119
The sample tank 38 is constantly supplied with new samples. three-way valve 1
An air pump 114 is also connected to 18.
This pump 114 is for preventing clogging of the intake port 150. The chemical liquid injection pump 116 sends the chemical liquid in the chemical liquid tank 118 to the processing tank 119.

FIG. 7 is a diagram showing the configuration of an electronic circuit within the titration apparatus 200. The basic configuration is the same as that shown in FIG. 4, but each pump 112, 115, 116 shown in FIG. 6 is connected to the output port 55, and each pump is controlled by the CPU.

The program written in the ROM of the microcomputer 50 will be explained according to the flowchart of FIG. At a specified time (for example, every 30 minutes)
Pump 112 is operated to send the sample to the sample tank (steps 131, 132, 133). Determine the concentration of the sample and print the time and concentration (step 134,
135). Here, the details of step 134 are the same as the flowchart shown in FIG. Next, target concentration NE
and the measured concentration NX, and if the concentration is insufficient, the chemical solution is injected based on the concentration difference (steps 136 and 137).
Thereafter, the process waits until the next measurement time, and when the measurement time arrives, the above operations are repeated (step 131). In this way, according to this embodiment, the density can be adjusted and recorded at predetermined time intervals.

In this embodiment, no treatment is performed in case of overconcentration, but in other embodiments, it is also possible to inject another chemical solution to lower the concentration.

〔Effect of the invention〕

This invention uses a switching valve and sends out the sample and the titrant using the same pump, so it has the following effects.

(b) Since the same pump is used, the volume ratio of the titrant and sample can be calculated from the pump rotation speed, etc., without having to measure the volumes of the titrant and sample. Therefore, volumetric analysis can be performed with high accuracy without using a high-precision pump that can accurately determine the delivered amount.

(b) In addition, in conventional methods and devices, even if a high-precision pump is used, the amount of pumping changes due to deterioration of the pump, deterioration of the tube, etc. with repeated use, so adjustment is necessary. However, according to the present invention, since the same pump is used and calculations are made based on the ratio of both liquids, such adjustment is not necessary even if the delivery amount changes.

(c) That is, according to the present invention, highly accurate volumetric analysis can be performed even when a simple squeezing type pump is used.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a conventional measuring device, Fig. 2 is an overall configuration diagram to clarify the structure of the present invention, and Fig. 3
4 is a block diagram showing the configuration of the electronic circuit of the capacitance analyzer shown in FIG. 3, and FIG. 5 is a diagram showing the configuration of the electronic circuit of the capacitance analyzer shown in FIG. A flowchart of a program written in the ROM, FIG. 6 is a diagram showing a concentration control device as an embodiment of the present invention, FIG. 7 is a block diagram showing the configuration of an electronic circuit of the concentration control device shown in FIG. FIG. 8 is a flowchart of a program written in the ROM of the electronic circuit shown in FIG. 9...Sensor, 21...Stretching type pump, 2
0... Three-way valve, 30, 31, 32... Three-way valve, 22... Nozzle, 23... Reaction tank, 2
5... Channel, 26... Discharge tank. In the figure, the same reference numerals are given to the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A sample sending step in which a sample is introduced into a flow path by a switching valve, and a predetermined amount of the sample is sent to a reaction tank by a pump provided in the flow path; and a cleaning liquid is introduced into the flow path by the switching valve. a cleaning step of directing the tip of the flow path to the outside of the reaction tank and discharging the cleaning liquid to the outside of the reaction tank to clean the flow path; passing the titrant liquid through the flow path with the switching valve; a titrant sending step of sending the titrant to the reaction tank by the pump until the reaction between the sample and the titrant reaches an end point; a predetermined amount of the sample sent in the sample sending step; and a titrant A volumetric analysis method in which volumetric analysis is performed based on the ratio to the amount of the titrant solution sent in the delivery stage. 2. The ratio between the predetermined amount of the sample in the sample delivery stage and the amount of the titrant in the titrant delivery stage is determined by the ratio of the rotational speed or operating time of the pump in the sample delivery stage and the titrant delivery stage. 2. The volumetric analysis method according to claim 1, wherein the volumetric analysis method is calculated by: 3. a reaction tank, a flow path, a valve means for communicating any one of the sample, cleaning liquid, and titration liquid to the flow path, a pump provided in the flow path, and a pump provided at the tip of the flow path. a nozzle; a nozzle switching means for switching whether the nozzle is directed into or out of the reaction tank; a sensor provided in the reaction tank; and detecting the end point of the reaction based on the output of the sensor. end point signal generating means; counting means for measuring the operation of the pump; quantitative signal generating means for detecting a predetermined amount based on the output of the counting means; and a valve for controlling switching of the valve based on the quantitative signal. a control signal generating means; a pump control signal generating means for controlling the operation of the pump based on the end point signal and the quantitative signal; and a filling detection means for detecting that the flow path and the nozzle are filled with a sample and a titrant. a signal generating means; a nozzle control signal generating means for controlling the position of the nozzle based on the quantitative signal and the filling detection signal; a calculating means for performing a calculation based on the end point signal and the output of the counting means; A capacity analyzer characterized by comprising: 4. The volumetric analyzer according to claim 8, wherein the reaction tank has a discharge tank. 5. The volumetric analyzer according to claim 4, wherein the reaction tank is cylindrical, and the discharge tank is arranged concentrically outside the reaction tank.