JPH0658882A - Automatic titrator - Google Patents

Abstract

PURPOSE:To obtain an automatic titrator with high accuracy. CONSTITUTION:An automatic titrator 1 for titrating caustic soda by a caustic soda injection system 1 is provided with a CCD camera 61 which detects coloring information of phenolphthalein in a beaker filled with a sample solution containing phenolphthalein to convert it to a video information and an image processor to detect the changes of coloring condition of phenolphthalein based on the video information of the camera 61. The camera 61 can detect the coloring conditions at a plurality of points and the expansion of coloring area by the image processor, thereby detecting the completion of titrating securely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic titrator suitable for measuring acidity of vinegar and the like.

[0002]

2. Description of the Related Art Conventionally, as a sensor for measuring the acidity, there is a near infrared sensor and a sensor using a PH electrode in titration ("Quantitative analysis" by Toyosuke Tanaka). Of these sensors, the near-infrared sensor is capable of instantaneously measuring multi-component acids, but is expensive and requires a calibration curve for each product type. Further, the PH electrode is characterized in that it is easily affected by foreign matters and the measurement error is large depending on the product type. On the other hand, in the production of vinegar, an accuracy of up to 1/100% is required for the target acidity, so in the acidity control of the produced vinegar, the titrant is added to the sample solution containing the titration indicator. The present situation is that the acidity of vinegar is measured on the basis of neutralization titration by dripping and visually confirming the change of the titration indicator by a person to find a neutralization point.

[0003]

In recent years, even in the process of producing vinegar, there is a demand for complete automation. For that purpose, the acidity of vinegar after blending is measured quickly and accurately to obtain a target acidity. There is a need for advanced techniques such as the need to correct the blending amount when different. However, the conventional acidity sensor cannot obtain sufficient accuracy, and there has been no apparatus that performs rapid and highly accurate titration in place of these. Therefore, it is necessary to rely on human measurement, which is an obstacle in automating the production of vinegar, and an automatic titrator that can be used in a vinegar production line is desired.

An object of the present invention is to provide an automatic titrator capable of automatically performing high-precision and rapid titration.

[0005]

The present invention provides an automatic titrator for titrating the sample solution by dropping the titrant solution into the container containing the sample solution containing the titration indicator by means of the dropping means. The technical means includes: a camera for detecting a change in color information and converting it into video information; and an image processing means for detecting a change in the coloring state of the titration indicator based on the video information of the camera. Further, the image processing means,
It is preferable to include a correction unit that corrects the reference value for determining the change in the coloring state of the titration indicator according to the brightness of the sample liquid. Further, the dropping means may change the dropping speed in accordance with a change in the coloring state of the titration indicator detected by the image processing means. The camera has a CC
It is preferable to use a D camera or a MOS type image pickup camera. The camera may be provided with an optical filter that is a complementary color to the color developed by the titration indicator. Further, it is preferable to include a weight measuring means for measuring the weight of the sample solution, dilution water for diluting the sample solution, the titration indicator, the titrant solution, and the container into which all of these solutions are charged. Further, a stirrer for stirring the solution in the container is provided in a non-contact manner with the container, and the weight of the container due to the buoyancy and surface tension of the stirrer with respect to the solution in the container. It is preferable to provide a correction means for correcting the error. In an automatic titrator that titrates the sample solution by dropping the titrant into the container containing the sample solution containing the titration indicator by a dropping means, a floodlight having a light source of the same color as the titration indicator or a complementary color of the titration indicator It is a technical means to have an optical sensor having a section. In an automatic titrator that titrates the sample liquid by dropping a titration liquid into a container containing a sample liquid containing a titration indicator, the same color as the titration indicator or a floodlight having a filter of a complementary color of the titration indicator It is a technical means to have an optical sensor having a section.

[0006]

In the automatic titration device according to the first aspect, the color development information of the titration indicator is converted into video information by the camera, and the video information is image-processed by the image processing means. Therefore,
Even if the color is partially developed in the sample solution, it can be easily detected by image processing and the spread state of the color development range can be reliably detected, so when the end point of the titration is reached, the titration solution is dropped. Can be reliably controlled. In the automatic titration device according to claim 8, since the sample liquid is illuminated by a light source of a color similar to or complementary to that of the titration indicator, when the titration indicator develops color, a marked change in the brightness of the sample liquid appears. It can be easily detected. In the automatic titration device according to the ninth aspect, since the light source has a filter having a color similar to or complementary to the titration indicator, the light emitted by the light source has a color similar to or complementary to the titration indicator. Therefore, when the titration indicator develops color, the change in the brightness of the sample solution remarkably appears, and the end point of the titration can be easily detected.

[0007]

According to the first aspect of the present invention, even when the titrant is dropped onto the sample liquid and the color is partially developed by the titration indicator, the change is caused by image processing of the image information of the camera. It can be reliably detected by means.
Therefore, by accurately controlling the dropping state of the titrant based on the change, accurate titration can be performed. According to the second aspect of the present invention, the reference value for determining whether or not color has developed in the sample liquid is corrected in accordance with the lightness of the sample liquid, so that in the case of the sample liquid having a large degree of coloration and suspension. Even if there is, there is no error in determining whether or not color has developed. According to the third aspect of the invention, when it is detected that the color partially develops in the sample solution, the dropping speed is changed to increase the dropping speed until the color is detected. After color development is detected, the time required for titration can be shortened by slowing down the dropping speed, and accurate titration becomes easy. According to the invention of claim 4, the image processing in the image processing means is facilitated by using the CCD camera or the MOS type image pickup camera. According to the invention of claim 5, since the camera is provided with an optical filter which is a complementary color to the color of the titration indicator, it is easy to detect the color-developed portion. Can be easily detected. According to the invention of claim 6, the weight of each liquid actually put in the container can be surely detected by measuring the container into which each liquid is put by the weight measuring device. Even if there is an error in the titrant due to the error, the titration can be performed based on the correct value. According to the invention of claim 7, by stirring the liquid in the container by the stirring means, diffusion of the dropped liquid is promoted, and the influence of the measurement error that the stirring means gives to the weight measuring means is eliminated, so that it is quick and accurate. Titration can be performed automatically. In the invention of claim 8, the color change due to the titration indicator remarkably appears, so that the detection by the optical sensor becomes easy and the burden of the detection accuracy of the optical sensor is reduced.
Also in the ninth aspect of the invention, since the color change due to the titration indicator appears remarkably, the detection by the optical sensor becomes easy, and the burden of the detection accuracy of the optical sensor is reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on the embodiments shown in the drawings. FIG. 1 is a neutralization titration apparatus 1 in which an automated process for neutralization titration of an acidic sample solution such as vinegar using an aqueous caustic soda (sodium hydroxide) solution as a titration solution using phenolphthalein as a titration indicator is performed. 1 shows a schematic configuration for injecting and draining a beaker 10 provided as a container for performing the above.

As a liquid injection system for injecting a liquid required for neutralization titration into the sample liquid in the beaker 10, a dilution water injection system 20 and a caustic soda injection system 3 are used.
0, a phenolphthalein injection system 40 is provided. The dilution water injection system 20 has a low brightness of the sample solution (dark).
In this case, the concentration of the sample liquid is lowered and the concentration of the sample liquid is changed to a concentration that facilitates titration. The dilution water injection system 20 includes a dilution water for storing distilled water as dilution water. Tank 21, dilution water measuring pinch valve 22 for measuring dilution water and dilution water measuring pipe 23, beaker 10
Dilution water injection pinch valve 24 for controlling injection against
Is provided.

The caustic soda injection system 30 is a dropping means for dropping caustic soda (sodium hydroxide) for neutralizing the sample liquid. The caustic soda injection system 30 has the caustic soda tank 31 and the caustic soda measuring pinch as described above. A valve 32, a caustic soda measuring pipe 33, and a caustic soda injection pinch valve 34 are provided. Similarly, in the phenolphthalein injection system 40 for injecting phenolphthalein as a titration indicator, the phenolphthalein tank 4
1, a phenolphthalein metering pinch valve 42, a phenolphthalein metering pipe 43, and a phenolphthalein injection pinch valve 44 are provided respectively.

Each liquid injection system has an injection pinch valve 24, 3
Injection tubes 25, 3 provided on the downstream side of 4, 44
Each solution is injected into the beaker 10 through 5, 45 respectively. In each liquid injection system, each tank 21, 31,
41 is located above each measuring pipe 23, 33, 43,
Further, each of the measuring tubes 23, 33, 43 is located above the beaker 10. Therefore, each tank 21, 31, 41
The liquid in each metering pinch valve 22, 32, 42 is supplied to each metering pipe 23, 33, 43 by natural fall when each metering pinch valve 22, 32, 42 is opened. When the pinch valves 24, 34, 44 are opened, the pinch valves 24, 34, 44 are naturally dropped to beaker 10. In addition, each measuring pipe 2
3, 33, 43, each liquid is a measuring pipe 23, 33, 43
In order to detect that the above conditions are satisfied, the diluting water measuring float switch 26, the caustic soda measuring float switch 36, and the phenolphthalein measuring float switch 4 respectively.
6 is provided.

On the other hand, a sample solution injection system 50 for injecting the sample solution into the beaker 10 is provided with a sample measuring pipe 51 and a sample injection pinch valve 52, like the above-mentioned injection systems, and further. A suction pump 55 is connected to the sample measuring pipe 51 via a sample liquid measuring solenoid valve 53 and a waste liquid suction / discharge solenoid valve 54. Further, a sample supply source 56 is separately connected to the sample measuring pipe 51 via a switching electromagnetic valve 57, and the sample liquid of the sample supply source 56 is supplied to the sample measuring pipe 51.
In the case of introducing into the inside, the sample liquid measuring solenoid valve 53 and the waste liquid suction / discharging solenoid valve 54 connect the sample measuring pipe 51 and the suction pump 55, and when the suction pump 55 operates, the sample liquid of the sample supply source 56 is Sample measuring tube 5 via switching solenoid valve 57
It is sucked into 1.

Further, a waste liquid tank 58 is provided between the waste liquid suction / discharge electromagnetic valve 54 and the beaker 10. When the waste liquid suction / discharge electromagnetic valve 54 is switched to connect the waste liquid tank 58 and the suction pump 55, The titrated solution or the like in the beaker 10 can be sucked and discharged to the waste liquid tank 58. The switching electromagnetic valve 57 is used to switch between the cleaning liquid for cleaning the sample measuring pipe 51 and the like and the sample liquid of the sample supply source 56, and the blowback pump 59 provided in the sample liquid measuring electromagnetic valve 53 is It is used to empty the inside of the sample measuring tube 51 by sending air into the sample measuring tube 51 to raise the atmospheric pressure and causing the sample solution or the cleaning solution in the sample measuring tube 51 to flow backward. In the figure, 10a is a beaker full alarm electrode, 51a is a sample liquid full alarm electrode, 58a.
Is a waste liquid full alarm float switch, and 58b is a waste liquid pinch valve.

In addition to the above-described injection and drainage automatic titration apparatus 1, in addition to each injection tube 25,3.
Tube set block 11 for fixing 5 and 45 to beaker 10 without touching, and beaker 10
An agitator 12 for agitating the liquid injected therein is provided, and titration control is performed by the sequence control circuit 60 shown in FIG. In addition, an electronic balance 2 capable of measuring the weight of each beaker 10 together with the beaker 10 in order to measure the weight of each liquid injected into the beaker 10 is provided in the unit of 0.001 gram, and the sequencer is further provided. A personal computer for calculating the weight of each liquid injected into the beaker 10 from the control signal of the control circuit 60 and the measurement signal from the electronic balance 2, and for calculating the acidity of the sample liquid according to the end of the neutralization titration. A (personal computer) 3 is provided.

The sequence control circuit 60 includes a CCD camera 61 for monitoring the color change in the beaker 10 and phenolphthalein as a titration indicator from the image signal of the CCD camera 61 in order to perform a quick and accurate titration control. Image processing device 6 for performing image processing for detecting color development of
2 and.

The sequence control circuit 60 performs titration control in a predetermined sequence in accordance with the switch operation of the operation switch group 63, which is separately provided, and opens each of the metering pinch valves 22, 32 and 42 described above to release each liquid. Each measuring tube 2
3, 33, 43, and each float switch 26, 3
In accordance with the detection signals of 6, 46, the respective measuring pinch valves 22, 3,
2, 42 are closed, supply of the liquid is stopped, each liquid is measured by a predetermined amount, and the suction pump 55 is operated,
A predetermined amount (for example, 20-30
ml) and weigh it into the beaker 10. After that, the motor 13 of the stirrer 12 is energized, and the stirrer 14 fixed to the tip of the output shaft 13a is moved to the beaker 10
Each injection pinch valve 24, 34, 44 while rotating within
Is controlled to be opened and closed to inject a liquid from each of the injection systems 20, 30, and 40, and neutralization titration is performed as follows.

In the neutralization titration, the apparent color difference of the phenolphthalein of the image processing device 62 is affected by the apparent lightness and darkness which varies depending on the concentration of the sample solution.
First, the sample solution is diluted with the diluent until the apparent density of the sample solution does not affect the determination of the titration of the image processing device 62. Next, 0.05 g of phenolphthalein is injected. Then, in order to neutralize the sample solution, caustic soda aqueous solution is injected until phenolphthalein develops color. This caustic soda injection process is the most important process in the neutralization titration, and it is required to be swift without excessive injection.

In this example, neutralization titration is carried out to measure the acidity of vinegar. The purpose is to measure the acidity of vinegar mixed with various organic acids and amino acids as the standard for vinegar. Since it is performed to check whether the acidity is within the allowable range, the approximate acidity is known in advance. Therefore, in order to quickly perform the neutralization titration, it is possible to continuously open the caustic soda injection pinch valve 34 to neutralize 95% of the standard acidity regardless of the color development reaction of phenolphthalein. As much caustic soda as possible is quickly injected, and then the caustic soda injection pinch valve 34 is opened and closed according to the determination result by the image processing device 62 to prevent excessive injection of caustic soda.

Whether or not the end point has been reached is determined by whether or not the time for red color change has continued for 5 seconds and has been determined by the image processing device 62. When the end point of neutralization titration approaches, one drop of caustic soda is obtained. Each time it is injected, the phenolphthalein in the beaker 1 turns red and then becomes transparent again. Therefore, the caustic soda injection pinch valve 34, which controls the interval of caustic soda injection, repeatedly opens and closes so that continuous injection can be performed until the inside of the beaker 10 changes to red, and once the change to red is detected. In this case, the caustic soda injection pinch valve 34 is closed, and the duration of the red state is measured to determine whether or not to continue for 5 seconds. Then, the caustic soda injection pinch valve 34 is opened and closed to promptly restart the caustic soda injection. That is, the rate of caustic soda dropping was increased until the color developed to red, and once the color developed to red, the next drop was performed as soon as the red state disappeared, thus shortening the titration time until the end point was reached. Therefore, rapid titration can be performed.

The CCD camera 61 is a black-and-white dedicated camera which is arranged so that the sample liquid in the beaker 10 is oriented so as not to be affected by the stirrer 14 and the like. A green optical filter 64, which is a complementary color to red, is provided so that the change can be easily detected when the liquid in the beaker 10 changes color to red due to rain. As a result, when the sample liquid develops red color, the colored portion reaches the CCD camera 61 through the optical filter 64, and thus appears as a dark shadow image.

The image processing device 62 determines that the lightness of the dark shadow image of the image signal obtained from the CCD camera 61 is
The sample solution is binarized depending on whether it is darker than the predetermined standard lightness or not, and based on the value, it is determined whether the phenolphthalein in the beaker 10 has developed color. To do. However, when the brightness of the sample solution itself is originally dark, even if the phenolphthalein in the sample solution does not turn red, the brightness becomes darker than the standard brightness for binarization. Therefore, when the sample solution is injected into the beaker 10, its brightness is once detected, and a value binarized based on the brightness indicates that the sample solution is in a transparent state. Standard brightness for thresholding (threshold value)
The correction is performed, and after the correction, the titration is started.

Further, in the image processing device 62, a window for judging the binarized value of only the pixel of 2 cm ^{2 is set} for the image obtained from the CCD camera 61, and the sample corresponding to the window is set. Only the color change for the liquid is detected. As described above, in the image processing device 62 that corrects the reference lightness, in the initial stage of titration, it is determined whether or not the proportion of the area of the portion that is determined to have developed color within the window has reached 50%. When the coloring portion in the window reaches 50%, a signal indicating that the end point of the titration is approaching is emitted, and the sequence control circuit 60 causes the caustic soda injection pinch valve 3
The drip rate of 4 is slowed.

When a color change is detected for all 100% in the window, it is determined whether or not the color development state continues for 5 seconds as described above. When the color development state continues for 5 seconds, the titration is completed. To judge. In addition, CCD
As a light source for detecting a color change in the beaker 10 by the camera 61, a white or daylight high-frequency fluorescent lamp (frequency: several tens of kHz) 65 is provided, and the high-frequency fluorescent lamp 65 emits light from the beaker 10. Transparent,
It is arranged so as to reach the CCD camera 61.

The personal computer 3 inputs the measured weight value of the electronic balance 2 at the end of the injection of the sample solution, the end of the injection of phenolphthalein, and the end of the injection of the diluting water by the control signal from the sequence control circuit 60. In addition to calculating the weight of each liquid by arithmetic processing, input the measured weight value of the electronic balance 2 at the time when the titration of caustic soda is completed,
The amount of caustic soda used is calculated, and the acidity of the sample solution is calculated based on the calculated value. Here, since the stirrer 15 applies surface tension or buoyancy to the solution in the beaker 10 according to the total amount of each liquid in the beaker 10, the weight measured by the electronic balance 2 is not the actual weight. Will have different values. For this reason, in the PC 3, the beaker 1
Based on the amount of each solution in 0, the measurement error of the weight generated by the stirrer 15 is corrected to calculate the accurate values of the sample liquid amount and the caustic soda aqueous solution amount, and the acidity of the sample liquid is calculated based on the values. Calculate The sequence control circuit 60 is provided with a display lamp for displaying the state of titration control and an alarm buzzer for issuing a full water alarm for the beaker 10 and other measuring tubes.

The automatic titrator 1 of the present embodiment having the above construction operates as follows. The weight of the beaker 10 is preliminarily measured by the electronic balance 2 according to the operation of the operation switch group 63, and the value is input to the personal computer 3. With each injection pinch valve 24, 34, 44 closed, each metering pinch valve 22, 32, 42 opened and each tank 21,
When the solutions in 31, 41 are supplied into the respective measuring pipes 23, 33, 43 and detected by the respective measuring float switches 26, 36, 46, the respective measuring pinch valves 22, 32, 42 are closed.

On the other hand, when the suction pump 56 is driven with the sample injection pinch valve 52 closed, the sample supply source 53
The sample solution inside is supplied to the sample measuring pipe 51, and then the sample injection pinch valve 52 is opened to inject the measured sample solution into the beaker 10. Here, the weight of the sample solution is measured together with the beaker 10 by the electronic balance 2, and the value is input to the personal computer 3. At this point, the CCD camera 6
The threshold value of the image processing device 62 is corrected according to the brightness of the sample liquid so that the value binarized based on the video signal of 1 indicates that the sample liquid is transparent.

The phenolphthalein injection pinch valve 44 is opened and closed, 0.05 g of phenolphthalein is injected into the beaker 10, and driving of the stirrer 12 is also started. The caustic soda injection pinch valve 34 is opened to inject into the beaker 10 enough caustic soda to neutralize 95% of the acid in the sample solution in the beaker 10, and then drop caustic soda drop by drop in response to the signal of the image processing device 62. Is injected. When it was detected that phenolphthalein in the sample solution partially turned red due to the injection of caustic soda and reached 50% of the window of the image processing device 62, it was determined that the titration end point was approaching. , The caustic soda injection pinch valve 34 is closed, and then the stirrer 1
When the determination result of the image processing device 62 does not detect the color development of phenolphthalein due to the stirring of 2, caustic soda is dropped one drop at a time.

When it is determined that the color development of phenolphthalein has continued for 5 seconds, it is determined that the end point of titration has been reached, and the determination weight and the measured weight of the electronic balance 2 at that time are input to the personal computer 3. To be done. On PC 3,
Based on the input measured value of the electronic balance 2, the stirring bar 14
The acidity of the sample liquid is calculated based on each weight in which the error due to the surface tension and the buoyancy is corrected.

The results of the acidity measurement according to this example are shown for the case of using a typical commercial grain vinegar having a high lightness and the case of using a typical brown rice vinegar having a low lightness as a sample.
They are shown in Table 1 and Table 2, respectively.

[0030]

[Table 1]

[0031]

[Table 2]

Further, in order to compare the accuracy of the acidity measurement according to the present example with the conventional method, the results measured by a skilled analyst were used as a sample when using commercially available grain vinegar and when using commercially available brown rice vinegar. The cases are shown in Table 3 and Table 4, respectively, and a PH type automatic acidity measuring instrument (manufactured by Hiranuma Sangyo Co., Ltd.)
The results of measurement according to 500) are shown in Table 5 and Table 6 for the case of using commercially available grain vinegar and the case of using commercially available brown rice vinegar, respectively.

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

As is clear from the above-mentioned tables, the measurement results of the automatic titrator of the present example almost match the measurement values by a trained analyst, and are very accurate, while the PH-type automatic When measured with an acidity measuring device, the grain vinegar has a low acidity of 0.05%, and the brown rice vinegar has a acidity of 0.
The 04% acidity is low, and it can be seen that the automatic titrator of this example is superior in accuracy to the PH type automatic acidity measuring device. Further, the results of analysis using an acetic acid solution prepared by dissolving glacial acetic acid as a reagent in distilled water also revealed that the automatic titrator of the present invention is superior in accuracy.

Further, the measurement time in the automatic titrator of this embodiment is set to the measurement time by the above-mentioned expert analyst and PH.
The results are shown in Table 7 in comparison with the measurement time by the automatic acidity meter.

[0039]

[Table 7]

As is clear from this table, in this embodiment, when 20 ml was used as the sample solution, about 200
The sample solution can be titrated, the acidity can be measured, and the cleaning can be performed in seconds, and in the present embodiment, the measurement can be performed in a shorter time than other measurements.

As described above, in the present invention, the color change of the phenolphthalein in the beaker 10 is detected by the image processing of the image of the CCD camera 61 by the image processing device 62, so that the partial color change is detected. Can be easily detected, and as a result, it can be reliably detected that the end point of the titration is approaching. Therefore, the end point can be accurately detected, and accurate acidity can be measured.

In the above embodiment, the white or daylight high-frequency fluorescent lamp was used as it was as a light source. However, the color of the titration indicator was changed by using a red filter which emits the color of the titration indicator or a green filter which is a complementary color thereof. It is also possible to irradiate the red color or the complementary green color. Also,
The beaker used may be colored green to have a filtering effect. Alternatively, the irradiation light of the fluorescent lamp itself may be a red color emitted by the titration indicator or its complementary color. By using these light sources, the state of red color change of phenolphthalein appears remarkably,
The threshold values of the image processing apparatus can be set with ease, and the range of correction depending on the brightness of the sample liquid can be reduced.
The operator of the automatic titration device 1 can directly inject an arbitrary amount of the sample liquid into the beaker 10.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an automatic titrator according to an embodiment of the present invention.

FIG. 2 is a block diagram relating to a sequence control circuit of an automatic titration apparatus showing an embodiment of the present invention.

[Explanation of symbols]

 1 Automatic Titrator 2 Electronic Balance (Weight Measuring Means) 10 Beaker (Container) 12 Stirrer (Stirring Means) 14 Stirrer 30 Caustic Soda Injection System (Dripping Means) 61 CCD Camera (Camera) 62 Image Processor (Image Processing Means) 64 Optical filter 65 High-frequency fluorescent lamp (light source)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiro Funato 2-119, Kamesu-cho, Handa-shi, Aichi Rainbow No. 401 Handa No. 401 (72) Inventor, Chisato Ito 2-105, Toyonari, Taketoyo-cho, Chita-gun, Aichi

Claims (9)

[Claims] 1. An automatic titrator that titrates a sample solution by dropping the titrant solution into a container containing a sample solution containing a titration indicator by means of a dropping means to detect color development information of the titration indicator and convert it into image information. And an image processing unit for detecting a change in the coloring state of the titration indicator based on the image information of the camera. 2. The image processing means comprises a correction means for correcting a reference value for judging a change in the color development state of the titration indicator in accordance with the lightness of the sample liquid. The automatic titrator described in. 3. The dropping means changes the dropping speed in accordance with a change in a coloring state of the titration indicator detected by the image processing means.
The automatic titrator according to any one of 1. 4. The camera is a CCD camera or a MOS
4. A type image pickup camera as claimed in claim 1, wherein
The automatic titrator according to any one of 1. 5. The automatic titration device according to claim 1, wherein the camera includes an optical filter that is a complementary color to the color development of the titration indicator. 6. The sample solution, dilution water for diluting the sample solution, the titration indicator, the titrant solution, and a weight measuring means for measuring the weight of the container into which all of these solutions are charged. The automatic titrator according to any one of claims 1 to 5, wherein 7. An agitator for agitating the solution in the container is provided in a non-contact manner with the agitator, and the agitator for the solution in the container is caused by buoyancy and surface tension of the agitator. The automatic titration device according to claim 6, further comprising a correction unit that corrects a weight error of the container. 8. An automatic titrator for titrating the sample solution by dropping the titrant solution into a container containing a sample solution containing the titration indicator by a dropping means, wherein a color similar to that of the titration indicator or a color complementary to the titration indicator is used. An automatic titrator having an optical sensor having a light projecting portion having a light source. 9. An automatic titrator that titrates the sample solution by dropping the titrant into a container containing the sample solution containing the titration indicator by a dropping means, wherein the color is similar to the titration indicator or a complementary color of the titration indicator. An automatic titrator having an optical sensor having a light projecting portion having a filter.