JPH0731184B2 - Method and device for automatic analysis of acid value and saponification value of oil - Google Patents

Description

TECHNICAL FIELD The present invention relates to an oil for automatically analyzing at least one of the acid value and the saponification value of fats and oils such as rolling oil used in the production of thin plates. The present invention relates to an automatic analysis method and an automatic analyzer for acid value and saponification value.

[Prior Art] For example, when a thin plate is manufactured in the steel industry, oil is emulsified with an emulsifier and water, and this is used as rolling oil.
There are two types of rolling oil, oil-fat acid type and ester type, and the quality control of this rolling oil requires regular measurement because its defects affect the stabilization of operation and the improvement of product quality. .

In other words, quality deterioration of rolling oil is caused by mixing and deterioration of different types of oil.
It is caused by the mixing of iron, etc., and the cause of the deterioration of product quality due to the influence is considered to be thermal volatility deterioration, carbon polymerization acceleration, and iron oxide generation acceleration. Then, oil baking occurs on the steel sheet due to poor thermal volatility, and carbon edges are projected on the steel sheet due to acceleration of carbon polymerization,
Further, rust-like stains are produced on the steel sheet due to the acceleration of iron oxide production.

For early detection and prediction of such defects, it is necessary to analyze the deterioration status of rolling oil. This analysis includes iron concentration, acid value (how many grams of alkali react per gram of oil) and saponification value (what is bound to the ester in the oil and acid value). (How much total amount of fatty acids corresponding to is there)), and the most important of these are the acid number and the saponification number.

The iron concentration serves as an indicator of rolling oil deterioration and the cleanliness of the steel sheet surface, the acid value serves as an indicator of the amount of COOH groups per unit weight (fatty acid type oil) lubricity and deterioration, and the saponification value serves as a unit weight per unit weight. It is an index of COO-group content (ester type oil) and lubricity. The higher the iron content is, the worse it is, and the worse the oil is, the higher the acid value and the lower the saponification value are.

Regarding the measurement of acid value and saponification value of oil in rolling oil, JIS-K
There are regulations in 2501, JIS-K2502, and JIS-K2503. Here, after extracting the oil content from the rolling oil, a certain amount of the oil content is measured by alkali titration in an organic solvent to measure the acid value. Next, an excess amount of alkali is added and reacted on a water bath, and unreacted alkali is measured by acid titration. The end point of each titration is determined visually with a PH (pH) indicator.

Conventionally, when performing such an analysis, a skilled worker manually performed the analysis. The specific method will be described below.

[Iron concentration analysis] concentration of Fe ³⁺ of ... oil ^{Fe 3+ + 6SCN - → Fe (} SCN) 6 3+ ( slightly yellow) (colorless) (red florid) In other words, SCN ^- added, Fe ^{3 The} concentration is determined by utilizing the property that ⁺ (iron ion) reacts with thiocyanate ion to produce red blood color. In this case, a comparative analysis method is used in which the degree of color due to coloring is compared with a standard color facilitated by density.

[Acid number analysis] --- COOH concentration in oil [Saponification number analysis] --- COOR concentration in oil For these analyzes, KOH (phenol Titrate potassium hydroxide), and when all -COOH is replaced with -COOK, it is neutralized and the acid value is judged when the phenolphthalene is colored red. In addition, titrate KOH further, and after heating, add HCl
Is titrated, and the saponification value is determined by seeing that KOH is decolorized from red to transparent when neutralized with HCl (hydrochloric acid).

[Problems to be Solved by the Invention] However, in the above-described conventional technique, since analysis is performed depending on the intuition and naked eyes of an expert, when the end of the titration is determined, a long time is required for the analysis. There is a problem in that the measurement results are time-constrained and individual differences occur depending on the person who performs the analysis, and the measurement results vary or are biased.

Further, depending on the operating conditions, analysis work outside the normal working hours is forced, and there is a risk of inhaling vapors of harmful organic solvents, which is a health problem.

An object of the present invention is to provide an automatic analysis method for an acid value and a saponification value and an automatic analyzer capable of automatically analyzing an acid value and a saponification value in oil.

[Means for Solving the Problems] In order to achieve the above object, the present invention introduces a sample to which a trace amount of a PH indicator has been added into a reaction vessel equipped with a heating means and a mixing means, and then the sample in the reaction vessel. Is circulated and supplied to an absorptiometer, alkali titration is performed while detecting the absorbance by the absorptiometer, and the acid value in the sample is calculated based on the alkali titer and the absorbance detection value. .

The acid value calculation is performed by averaging the absorbance data at several points before and after each measurement point to obtain the absorbance data at that point for each point, while the data after one at each titration point of the titration is performed. This can be obtained by subtracting the previous data from the above to perform differentiation and performing the titration amount at the derivative maximum value as the end point of titration. Further, the saponification value of the oil, a sample to which a trace amount of PH indicator was added is introduced into a reaction vessel equipped with heating means and mixing means,
Then, an excess amount of alkali is added to the sample in the reaction vessel, this is heated and reacted for a certain period of time, then allowed to cool, and the unreacted alkali is titrated with an acid to measure the saponification value in the sample. be able to.

The saponification value calculation is performed by averaging the absorbance data at several points before and after each measurement point to obtain the absorbance data at that point for each point, and the previous data at each titration point of the titration is performed. It is possible to obtain the value by subtracting the next data from the above, performing differentiation, and performing the titration amount at the derivative maximum value as the end point of the titration.

Furthermore, the acid value and the saponification value are determined by adding an excess amount of alkali to the sample in the reaction vessel after measuring the acid value described above, allowing this to heat-react for a certain period of time and then allowing to cool, and further reacting the unreacted alkali with acid. It can be determined by titrating and measuring the saponification value in the sample.

On the other hand, the automatic analyzer is a reaction container, an absorptiometer for measuring the absorbance at a specific wavelength, a solution circulating means for circulating the solution in the reaction container to the absorptiometer, and the absorptiometer. A first titration means for titrating the alkali into the reaction container little by little at the time of measurement, an acid value measurement means for measuring an acid value based on the absorbance measurement value by the absorptiometer and the alkali titration amount, and the inside of the reaction container Second titration means for supplying an excess amount of alkali to the sample, mixing means for mixing and stirring the solution in the reaction vessel after titration by the means, and heating the reaction vessel in parallel with the mixing process by the means. A heater, a third titration means for titrating the acid after heating by the heater, and a saponification value measuring means for calculating a saponification value based on the titration quantity by the means and the absorbance measurement value by the absorptiometer. It can be constructed by including.

[Operation] According to the above-mentioned means, the absorbance is detected by the absorptiometer while performing the alkali titration, and when all the acid components in the sample are neutralized by the alkali, the PH value rapidly increases,
The coloring of the sample at that time is detected by the absorptiometer as a change in absorbance, and the acid value is calculated when the rate of change in absorbance is maximized. Therefore, the acid value can be automatically obtained without relying on intuition or experience.

Following the acid value, an excess amount of alkali is supplied, and the mixture is heated and mixed, allowed to cool, and back-titrated with an acid, and the saponification value is calculated when the rate of change in absorbance by an absorptiometer at that time is maximized.
With this, similarly to the case of the acid value, the saponification value can be automatically obtained without depending on the intuition or experience.

By performing the above-mentioned acid value calculation means in advance and supplying an excess amount of alkali following the acid value treatment, it is possible to perform the above-mentioned saponification value means after the acid value calculation means. As a result, the acid value and the saponification value, which are most important for the evaluation of deterioration in rolling oil, can be performed at the same time.

In the automatic analyzer, the solution in the reaction container is circulated to the absorptiometer while the alkali is titrated by the first titration means by the automatic titration device into the reaction container in which the sample is introduced to neutralize the solution. By circulating the circulating fluid, the change in the absorbance of the circulating liquid is obtained, and the acid value is calculated by the acid value measuring means based on the absorbance at that time. Further, excess alkali is supplied into the reaction vessel by the second titration means, the mixture is heated by the heater while being mixed by the mixing means and then allowed to cool, and the back titration of the acid is carried out by the third titration means. The saponification value is determined by the saponification value measuring means based on the absorbance of the absorptiometer at that time. As a result, it becomes possible to automatically measure the acid value and the saponification value, the measurement accuracy and reliability are improved, and it is possible to eliminate the need for a dedicated measurement staff.

Then, the neutralization reaction by titration is clearly identified by using the measurement wavelength of the absorptiometer as the coloring wavelength of the PH indicator to be used. Therefore, analysis accuracy and reproducibility can be improved.

[Examples] FIG. 1 is a system diagram showing an automatic analyzer for acid value and saponification value according to the present invention. Fig. 2 shows 0.5N KOH at acid value titration.
FIG. 6 is a characteristic diagram showing the relationship between the titer (N is a specified concentration) and the absorbance, and FIG. 6 is a characteristic diagram showing the relationship between the 0.5N HCl titer and the absorbance at the saponification value.

Container 2 filled with titrant 1 (0.5N KOH / ethanol)
Is connected in parallel with an automatic titrator 3 (first and second titration means), and its connecting pipe is connected to the reaction container 4. Further, an automatic titration device 7 (third titration means) is connected in parallel to a container 6 filled with a titration liquid (0.5N HCl / ethanol) 5, and its connecting pipe is connected to a mixer 4 as a mixing means. ing. Further, a heater 8 using a heater is arranged so as to surround the reaction container 4, and a mixer 9 is arranged below the reaction container 4 and the heater 8.

A circulation pump 10 (a solution circulation means and an absorptiometer 11 are connected in series to the reaction container 4 and electromagnetic valves 12, 13,
Each of 14 and 15 is connected. A beaker 18 in which a cleaning liquid (for example, methanol) 17 is enclosed is connected to the solenoid valve 12, and a nozzle 19 is connected to the solenoid valve 13. nozzle
A beaker 21 containing the sample 20 is arranged on the sample table 22 below the sample 19. The nozzle 19 is supported by a lifter 23 that can be raised and lowered so that the tip of the nozzle 19 can be inserted into the sample 20.

On the other hand, the solenoid valves 14 and 15 are connected to a waste liquid container 25 containing a waste liquid 24, and the waste liquid container 25 is connected to a solenoid valve 16 and a decompression pump 26.

Automatic titrators 3, 7, heater 8, mixer 9, solenoid valve 12 ~
16, each of the circulation pump 10, the absorptiometer 11, the sample stage 22 and the decompression pump 26 is connected to a computer 27, and data is sent to the computer 27,
The equipment is driven and controlled. The computer 27 has a keyboard 28 for inputting various data and parameters, a display 29 for displaying data and analysis results,
And a printer that prints out data and analysis results 30
Are each connected. In the case of the present embodiment, the piping for communicating each device has an inner diameter of 2 mmφ and an outer diameter of 3 mmφ.
Teflon tube was used.

The operation method and operation of the above configuration will be described.

[Acid Value Measurement] First, acid value titration is performed. First of all, the oil containing beef tallow as the main component.
Weigh 1 g with an electronic balance and transfer this to beaker 21 (eg 50 ml wide-mouth beaker). To this oil, add 1 ml of 1% ethanol solution of phenolphthalene, add 50 ml of xylene and stir well to completely dissolve the oil.
20, and the beaker 21 is placed on the sample table 22. Up to this point, the operator manually performs the process, but the subsequent process is automatically performed by the computer 27 controlling each device.

A nozzle 19 is set by the lifter 23 for the set sample 20.
Descends, and the lifter 23 stops when its tip reaches the bottom of the beaker 21. Then, the decompression pump 26 and the electromagnetic valve 14 are operated to generate a negative pressure in the reaction container 4, and the electromagnetic valve 13 is driven to open the valve, so that the sample 20 is sucked into the reaction container 4.

Upon completion of the suction, the decompression pump 26 and the solenoid valves 13 and 14 are stopped, the solenoid valve 16 is operated for several seconds (for example, 10 seconds), and the inside of the waste liquid container 25 is opened to the atmospheric pressure. Then, the circulation pump 10 is operated, the solution in the reaction container 4 is sent to the absorptiometer 11 at a predetermined speed (for example, 25 ml / min), analysis is performed, and the used solution is collected in the reaction container 4. To do. The absorptiometer 11 has, for example, a measurement wavelength of 570 nm and an optical path length of 5 mm, and its absorbance (indicating the degree of absorption of light of a specific wavelength, the absorbance "1" is when 90% of light of a specific wavelength is absorbed). Is detected, and the detection result is sent to the computer 27. The reason why the solution is circulated in the absorptiometer 11 using the circulation pump 10 is necessary because the absorptiometer 11 cannot be arranged in the reaction container 4.

Then, the mixer 9 is operated to stir the solution in the reaction container 4. After this, the titration solution 1 (0.5N
For example, 0.01 ml of KOH dissolved in ethanol is titrated, the absorbance is read multiple times (for example, 10 times), and the average value is stored in the computer 27 as absorbance data at this time and titrated to 15 ml. After that, the circulation pump 10 is stopped. During the titration, the data before 0.01 ml and the present data are compared by the computer 27, and the next titration time is controlled in proportion to the difference.

FIG. 3 is a flowchart showing an example of the averaging process by the computer 27 (S represents a step in the figure).
Further, FIG. 4 is an explanatory view showing the concept of the automatic change processing of the titration time.

First, as shown in FIG. 3, a small amount of 0.01 ml is titrated (S31), and the absorbance (Dn) given by the following equation is determined (S31).
32).

Next, the amount of change between adjacent points of the absorbance data, that is, the difference ΔD _n = (D _n −D _n-1 ) is obtained (S33). After this, the waiting time to secure the titration reaction time near the end point
t _{n + 1} = t _{n + 1} = ΔD _n × a + b (where a and b are constants)
Is calculated (S34), the process is returned to step 31 at the time when it is determined that the calculated time is exceeded (S35), and the subsequent processes are repeatedly executed.

On the other hand, after step 31, the integration process of the titer amount together with the absorbance is performed (S36), and when it is determined that the prescribed amount of 15 ml is reached, the integration process ends (S37).

As a result, the titration result as shown in the characteristic A of FIG. 2 was obtained. The 0.5N KOH solution, the titration amount, and the absorbance data are processed by the computer 27 to calculate the acid value. The result is stored in the memory in the computer 27. In this case, the averaging process and the differential process are used.

The averaging process is the sum of the absorbance data for every 0.01 ml, excluding the first two and the last two, and the total of five data before and after each point, and dividing the total by "5". Perform the calculation with the data of that point. For example, 0.03ml to 1
Perform on data up to 4.98 ml. This result is second
The characteristic B shown in the figure has been modified to reduce small noise-like changes.

Next, differential processing is performed. This is the averaged data
Data for each point corresponding to 0.03 ml to 14.98 ml (alkaline is in excess at this level near 15 ml) The value obtained by subtracting the previous data from the data after each point is the data for that point Is the process of This means that the characteristic B of FIG. 2 is differentiated, and it is possible to convert the data into only the amount of change shown in the characteristic C of FIG. The peak position of the characteristic C means a point where the fatty acid is lost and the product is colored red. In this example, the position of ml when the maximum value is given in this differential processing data is the end point EP1 [ml] of the titration reaction. By performing such a series of data processing, a highly reproducible result can be obtained.

FIG. 5 is a flowchart showing the processing for obtaining the end point EP1 of the titration reaction.

First, after the averaging process (S51) by the means described above, the waveform is differentiated (the characteristic B is differentiated) (S52), and the maximum differential value is selected (S53). Further, a process for displaying the differential value characteristic of the characteristic C in FIG. 2 is performed (S54). After the process of step 53 is executed, the acid value is calculated by the formula shown below.
Also, the saponification value, which will be described later, is calculated (S55).

Acid value [KOHmg / g] = 28 × EP1 [ml] / Amount of sampled oil [g] The calculated acid value is stored in the memory of the computer 27 and displayed on the display 29.
Printed out by 30.

[Saponification number measurement] Next, the saponification number analysis will be described.

First, while the mixer 9 is operated to mix the solution in the reaction container 4, the heater 8 is energized for a predetermined time (for example, at 100 ° C. for about 30 minutes and not at a high temperature). A temperature sensor (not shown) is attached to the heater 8, and the computer 27 controls the temperature of the heater 8 to maintain a constant value (for example, 115 ° C.) based on the detected value. The reason for heating in this way is that the ester cannot be decomposed at room temperature. By heating and adding alkali, the ester is decomposed and the alkali reacts.

The temperature of the solution in the reaction vessel 4 was 1: 1 with the solvent xylene.
-Propanol solution, the boiling point of which is 115 ° C, so it does not rise further. At this point, the heater 8 is stopped, and cooling is performed for a fixed time (for example, 10 minutes).
Then, while the mixer 9 is still operating, the automatic titrator 7 is operated while moving the circulation pump 10, and the titrant 5 (0.5N
Titrate with 0.01 ml of HCl ethanol solution. Also in this case, the absorbance data is read n times (10 times in the present example) every time 0.01 ml titration is performed as in the acid value titration, and the average value is used as the absorbance data at this time. Further, the data before 0.01 ml is compared with the present data, and titration is performed while controlling the next titration time in proportion to the difference value of the absorbance. The titration amount and the absorbance data at that time are stored in the computer 27.

After the end of the titration, the circulation pump 10 and the mixer 9 are stopped, and then the decompression pump 26 and the electromagnetic valves 13 and 15 are operated to drain the solution in the reaction container 4 to the waste liquid container 25 and further wash.

For the cleaning, the decompression pump 26 and the solenoid valves 12 and 14 are operated to absorb the cleaning liquid 17 with methanol into the empty reaction container 4. Further, after the decompression pump 26 and the solenoid valves 12 and 14 are stopped, the mixer 9 and the circulation pump 10 are operated to remove the solution in the circulation pump 10, the absorptiometer 11 and the attached pipe,
Replace with wash solution. Then, the mixer 9 and the circulation pump 10
Is stopped and the solenoid valves 13 and 15 are operated to discharge the cleaning liquid in the reaction container 4 to the waste liquid container 25. After this cleaning process, the decompression pump 26 and the electromagnetic valves 13 and 15 are stopped, and the reaction container 4 and the waste liquid container 25 are opened to the atmospheric pressure. By the above, all the washing operations are completed. After that, data processing for determining the saponification value is executed. This data processing method is performed using the same method as in the case of acid value.

FIG. 6 shows the absorption characteristics of saponification number, in which characteristic D is specific data, characteristic E is averaging processing data, and characteristic F is differentiating processing data. This differential processing uses the method of calculating by subtracting the data after one from the data before one of each point, and the titer at which the maximum value of the differential data is obtained is determined by the end point EP2 [ml] of the titration. Determined to be At this time, when observed with the naked eye, it can be seen that the color of the solution changes from red to transparent. The saponification value is calculated by the following formula.

Saponification number [KOHmg / ml] = 28 x (15-EP2 [ml] / sample oil collection amount [g] The saponification number obtained according to this formula is stored in the memory of the computer 27 and displayed on the display 29. ,
Further, it is printed out from the printer 30.

The series of operations described above are displayed on the display 29 one by one, and the operator can grasp the progress of the analysis. The keyboard 28
It is configured to be able to input from.

As described above, the analysis for one sample is completed. If you still need to analyze the next sample,
Control of each device, driving, and data processing are performed by the above-described procedure, and the acid value and saponification value are automatically calculated.

That is, when the analysis of one sample is completed, the sample table 22 is automatically rotated by one sample, and the second sample analysis is executed.

In the above examples, 1-propanol, xylene, and ethanol are used as the sample solvent.
In addition, methanol, methyl ethyl ketone, benzene and the like can be used.

[Effects of the Invention] Since the present invention is configured as described above, it has the effects described below.

In the automatic analysis method of acid value and saponification value in oil according to claim (1), a sample to which a trace amount of PH indicator is added is introduced into a reaction vessel equipped with heating means and mixing means, and then in the reaction vessel. The sample was circulated and supplied to the absorptiometer, alkali titration was performed while detecting the absorbance by the absorptiometer, and the acid value in the sample was calculated based on the alkali titer and the absorbance detection value. Therefore, the acid value can be automatically calculated without relying on intuition or experience.In addition, the averaging process is performed by averaging the absorbance data at several points before and after each measurement point to obtain the absorbance data at that point. Then, subtract the previous data from the subsequent data at each titration point to perform differentiation, and calculate the acid value with the titration amount at the maximum differential value as the end point of the titration. By performing, it is possible to determine the end point of the titration precisely.

In the automatic analysis method for oil and saponification value according to claim (2),
A sample to which a PH indicator was differentially added was introduced into a reaction vessel equipped with a heating means and a mixing means, and then an excess amount of alkali was added to the sample in the reaction vessel, which was allowed to cool for a certain period of time and then allowed to cool, Furthermore, since the unreacted alkali was titrated with an acid to measure the saponification value in the sample, the saponification value can be automatically determined without relying on intuition or experience,
In addition, averaging the absorbance data of several points before and after each measurement point to obtain the absorbance data of that point is averaged for each point, and one from the previous data at each titration point of the titration The end point of the titration can be accurately determined by subtracting the subsequent data and performing the differentiation, and performing the saponification value calculation using the titration amount at the maximum value of the differentiation as the end point of the titration.

In the automatic analyzer for acid value and saponification value in oil according to claim (3), a reaction container, an absorptiometer for absorbing a specific wavelength, and a sample introduced into the reaction container are circulated and supplied to the absorptiometer. A solution circulating means, a first titration means for titrating the alkali into the reaction container in small amounts at the time of measurement by the absorptiometer, and an absorbance measurement value by the absorptiometer and the alkali titer of each measurement point An averaging process is performed for each point by averaging the absorbance data of the above-mentioned several points to obtain the absorbance data of that point, and 1 is obtained from the data after one at each titration point of the titration.
Acid value measuring means for performing the differentiation by subtracting the immediately preceding data, and titrating the titration amount at the differential maximum value as the end point of the titration; and second titration means for supplying an excess alkali to the sample in the reaction container, Mixing means for mixing and stirring the solution in the reaction vessel after titration by the means, a heater for heating the reaction vessel in parallel with the mixing process by the means, and titration of the acid after heating by the heater 3 titration means,
Averaging processing is performed for each point by averaging the absorbance data at several points before and after each measurement point in the sample based on the titration amount by the means and the absorbance measurement value by the absorptiometer. On the other hand, a saponification value measuring means for performing differentiation by subtracting the data after one from the data before one at each titration point of the titration and performing the titration at the differential maximum value as the end point of the titration is provided. Therefore, the acid value and the saponification value can be automatically measured, the measurement accuracy and reliability can be improved, the exclusive use of staff is unnecessary, and the safety can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram showing an automatic analyzer for acid value and saponification value according to the present invention, FIG. 2 is a characteristic diagram showing a relationship between titration amount and absorbance at the time of acid value titration according to the present invention, and FIG. FIG. 4 is a flow chart showing an example of averaging processing, FIG. 4 is an explanatory view showing the concept of automatic change processing of the titration time accompanying the processing of FIG. 3, and FIG. 5 is a flow chart showing processing of obtaining the end point EP1 of the titration reaction. FIG. 6 is an absorbance characteristic diagram of saponification value according to the present invention. In the figure. 1,5: Titrant 2,6,18: Vessel 3,7: Automatic titrator 4: Reaction vessel, 8: Heater 9: Mixer, 10: Circulating pump 11: Absorptiometer 12 to 16: Solenoid valve 17 : Washing liquid, 19: Nozzle 20: Sample, 21: Beaker 22: Sample stand, 23: Lifter 24: Waste liquid, 25: Waste liquid container 26: Decompression pump, 27: Computer 28: Keyboard, 29: Display 30: Printer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideaki Hyakutake, Inventor Hideki Hyakutake, 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Stock (72) Inventor, Katsu Eguchi 1-Kimizu, Kimitsu, Chiba Nippon Steel Corp. Company Kimitsu Works (72) Inventor Takatoshi Hayashi 3-4-3 Yamato, Kisarazu-shi, Chiba Terada Sangyo Co., Ltd. Kimitsu Branch (72) Inventor Masahiro Midorikawa 9-15-203 Mizobata, Sakado, Saitama Prefecture (56) References JP-A-63-314447 (JP, A) JP-A-2-52239 (JP, A) JP-A-2-52240 (JP, A) JP-B-55-31899 (JP, B2)

Claims (3)

[Claims] 1. A sample to which a trace amount of a PH indicator has been added is introduced into a reaction vessel equipped with heating means and mixing means, and then the sample in the reaction vessel is circulated and supplied to an absorptiometer, and the absorbance is measured by the absorptiometer. Performing alkali titration while detecting, when calculating the acid value in the sample based on the alkali titer and the absorbance detection value, the absorbance data of the several points of each measurement point are averaged to obtain the absorbance at that point. Data is averaged for each point, and the previous data at each titration point is subtracted from the previous data to perform differentiation, and the titration amount at the maximum derivative value is used as the end point of the titration. An acid value automatic analysis method, characterized in that 2. A sample to which a trace amount of a PH indicator has been added is introduced into a reaction vessel equipped with heating means and mixing means, and then an excess amount of alkali is added to the sample in the reaction vessel, and this is heated and reacted for a certain period of time. After cooling, the unreacted alkali is titrated with an acid, and the absorbance data at several points before and after each measurement point of the saponification value in the sample are averaged to obtain the absorbance data at that point. About
On the other hand, the automatic saponification value of oil is characterized in that the data after one is subtracted from the data before one at each titration point of the titration to perform differentiation, and the titration amount at the differential maximum value is used as the end point of the titration. Analysis method. 3. A reaction container, an absorptiometer for measuring the absorbance at a specific wavelength, a solution circulating means for circulating and supplying the solution in the reaction container to the absorptiometer, and at the time of measurement by the absorptiometer. A first titration means for titrating the alkali into the reaction container little by little, and based on the absorbance measurement value by the absorptiometer and the alkali titration amount, the absorbance data at the several points of each measurement point are averaged to obtain the point. Perform the averaging process to obtain the absorbance data for each point, and subtract the previous data from the one after the data at each titration point of the titration to perform differentiation, and titrate the titer at the maximum derivative value. Acid value measuring means performed as an end point of the reaction, a second titration means for supplying an excess alkali to the sample in the reaction vessel, and a dissolution in the reaction vessel after titration by the means. Mixing means for mixing and stirring, a heater for heating the reaction vessel in parallel with the mixing treatment by the means, a third titration means for performing acid titration after heating by the heater, and a titration by the means. Based on the amount and the absorbance measurement value by the absorptance, the averaging process is performed for each point by averaging the absorbance data at several points before and after each measurement point in the sample to obtain the absorbance data at that point, for which, And a saponification value measuring means for performing a differentiation by subtracting the data after one from the data before one at each titration point of the titration and performing the titration at the differential maximum value as the end point of the titration. Automatic analyzer for oil acid value and saponification value.