JPH0450747A - Method and device for wet oxidizing decompostion - Google Patents

Abstract

PURPOSE:To enable easy and speedy decomposing operation with good reproducibility by inputting data on various conditions corresponding to a sample, outputting control signals for holding temperature, temperature rising speed, oxidizing agent, and purging gas flow rate contorl, and controlling reaction. CONSTITUTION:A liquid oxidizing agent supply means 3 consists of a liquid oxidizing agent storage tank 31 where a liquid oxidizing agent 11 is reservoired and a gas pressure feeding means 4. Further, various conditions corresponding to the sample are inputted to a program temperature control means 5, control signals for the holding temperature and temperature rising speed are outputted to a heating means 2, control signal for the oxidizing agent 11 is outputted to the means 3, and control signals for flow rate adjustment is outputted to a purging gas flow rate control means 22 to control the decomposition reaction. Then when specific temperature is reached, the means 4 and a solenoid valve 23 are put in operation to send air to raise the pressure in the storage tank 31, so the oxidizing agent 11 is extruded, properly supplied into a reaction container 1, and mixed with the sample 6, so that the sample 6 is oxidized and decomposed in a short time. Thus, the easy, efficient, and speedy decomposing operation with the good reproducibility is preformed and the use of the oxidizing agent 11 is minimized.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a wet oxidative decomposition method and a wet oxidative decomposition apparatus, and particularly to a wet oxidative decomposition method and a wet oxidative decomposition apparatus, and particularly a method for oxidatively decomposing organic substances containing metal elements by efficiently utilizing a liquid oxidizing agent. The present invention relates to a method and apparatus for easily preparing samples for analysis of ash content and metal elements.

<Prior art> When quantifying trace amounts of metal elements contained in organic matter using an analytical device such as an atomic absorption spectrometer, an 8-coupled plasma emission spectrometer, or an absorption spectrometer, it is necessary to Wet oxidative decomposition is a method for pre-treating organic substances and preparing samples to be compatible with the analytical equipment used. This wet oxidative decomposition method is a method of oxidatively decomposing organic substances containing trace amounts of metal elements with a liquid oxidizing agent such as nitric acid, perchloric acid, sulfuric acid, or hydrogen peroxide while heating.

By the way, the liquid oxidizing agent usually contains trace amounts of metal elements on the order of 10-9 g/g, and the amount of liquid oxidizing agent used is necessary in order to suppress the contamination of the sample with this metal element. It is desirable to keep it to a minimum.

In addition, in the wet oxidative decomposition method, the temperature at which the liquid oxidant is added, the speed at which the liquid oxidant is added,
The conditions for oxidative decomposition must be appropriately adjusted depending on the addition time, the heating method used, the type of liquid oxidizing agent, etc. For example, in a wet oxidative decomposition method using microwave heating, even if heated with the same microwave, if different liquid oxidants are used, the organic matter will be heated to different temperatures, and the reaction temperature for oxidative decomposition will be adjusted to the optimum temperature. It becomes difficult to control. Furthermore, when quantifying metal elements in a sample using a carbon furnace atomic absorption spectrometer, if sulfuric acid is present, it is necessary to adjust the analysis conditions, such as lengthening the ashing time or raising the ashing temperature. arise. Therefore, when a sample is prepared using sulfuric acid as a liquid oxidizing agent, it is desirable to remove the sulfuric acid after oxidative decomposition of the sample before subjecting it to analysis. However, with microwave heating, the output is insufficient and the temperature is not high enough to evaporate the sulfuric acid, making it difficult to remove the sulfuric acid. In addition, conventionally, the liquid oxidant and the sample are placed in a container and heated at the same time, so the liquid oxidant is lost by evaporation due to heating, and it is necessary to prepare an excess amount of liquid oxidant to account for this evaporation loss. .

Furthermore, some organic substances that undergo oxidative decomposition are thermally stable, and a combination of sulfuric acid and another oxidizing agent may be used as a liquid oxidizing agent.

In that case, if you combine sulfuric acid and an oxidizing agent with a boiling point lower than sulfuric acid and heat it together with the organic sample as in the past, the oxidizing agent with the boiling point evaporates and takes away the heat of vaporization, so the optimum temperature for oxidative decomposition cannot be reached. , the time required for decomposition becomes longer and the amount of oxidizing agent used increases.

In addition, if sulfuric acid and other oxidizing agents are charged at the same time and the temperature is raised, depending on the sample, oxidative decomposition may begin rapidly when the temperature exceeds a certain level, resulting in bumping and causing a big danger, or the decomposed sample may scatter. It may be lost.

If you simply want to automate the wet oxidative decomposition operation using a liquid oxidant, you can place the sample in a digestion vessel, heat it, and pump the liquid oxidant, or charge the sample and liquid oxidation agent into the digestion vessel at the same time. , wet oxidative decomposition may be performed while heating. However, when performing wet oxidative decomposition using such a method, a large amount of liquid oxidizing agent is used.

<Problems to be Solved by the Invention> Conventionally, in order to efficiently oxidize and decompose an organic sample using the minimum amount of liquid oxidant, a skilled person was always present, monitoring the progress of the reaction, and performing liquid oxidation. Work is being done to adjust the supply amount of the agent and add liquid oxidizing agent in a refreshing manner.

Therefore, the purpose of the present invention is to enable anyone to perform wet oxidative decomposition treatment simply, efficiently, quickly, and with good reproducibility, and to perform oxidative decomposition using a minimum amount of liquid oxidizing agent. Therefore, it is an object of the present invention to provide a wet oxidative decomposition method and apparatus that can minimize contamination from reagents.

Means for Solving the Problems> In order to solve the above problems, the present invention provides a method for wet oxidative decomposition of a sample, which comprises a reaction vessel for oxidative decomposition of the sample, a means for heating the sample, and a reaction vessel. A liquid oxidant supply means that continuously or intermittently pumps a liquid oxidizer into a container using pressurized gas, and a flow rate of purge gas supplied in the middle of a liquid oxidant supply path connecting the reaction container and the liquid oxidizer supply means. A wet oxidation decomposition apparatus is used, which has a purge gas flow rate control means and a program temperature control means, and the program temperature control means has a temperature for oxidation decomposition, a heating rate, and a liquid oxidant depending on the sample to be oxidized and decomposed. The operating conditions of the liquid oxidant supply means for supplying the liquid oxidant to the reaction vessel and the operation/stop conditions of the purge gas flow rate adjustment means are input, and based on this data, the program temperature adjustment means controls the heating means to maintain and increase the holding temperature. A control signal related to the temperature rate is sent, a control signal related to the liquid oxidant is sent to the liquid oxidant supply means, a control signal for adjusting the flow rate of the purge gas is sent to the purge gas flow rate adjustment means, and the sample The present invention provides a wet oxidative decomposition method in which the oxidative decomposition reaction is controlled.

The present invention also provides an apparatus for carrying out the method described above, which includes a reaction vessel for oxidatively decomposing the sample, a means for heating the sample, and a liquid oxidizing agent in the reaction vessel. Purge gas flow rate adjustment that adjusts the flow rate of purge gas supplied in the middle of the liquid oxidant supply path connecting the reaction container and the liquid oxidant supply means and a programmed temperature regulating means, the programmed temperature regulating means including, depending on the sample to be oxidatively decomposed,
Data on the oxidation decomposition temperature, temperature increase rate, operating conditions of the liquid oxidant supply means for supplying the liquid oxidant to the reaction vessel, and activation/stop conditions of the purge gas flow rate adjustment means are input, and the program temperature adjustment is performed using the data. A control signal related to the holding temperature and temperature increase rate is sent to the heating device, a control signal related to the liquid oxidizer is sent to the liquid oxidizer supply device, and a purge gas flow rate adjustment device adjusts the flow rate of the purge gas. The object of the present invention is to provide a wet oxidative decomposition apparatus in which a control signal is sent to control the oxidative decomposition reaction of a sample.

Hereinafter, the method and apparatus of the present invention will be explained in detail based on a preferred embodiment of the apparatus of the present invention shown in FIG.

In FIG. 1, 1 is a reaction vessel, 2 is a heating means for heating a sample in the reaction vessel 1, and 3 is a liquid oxidant supply means.

In this apparatus, a reaction vessel 1 is placed within a heating means 2, into which a sample 6 is charged. Rice reaction container 1
is provided with a liquid oxidant lower part and a gas outlet 8,
A liquid oxidant is supplied to the liquid oxidant lower portion from a liquid oxidant storage tank 31 via a liquid oxidant supply path 9 . In addition, from the gas outlet 8, water vapor generated in the reaction vessel 1,
Carbon dioxide gas, other acidic gases, and excess liquid oxidant not consumed in the oxidative decomposition reaction are discharged as gas.

The heating means 2 heats the sample 6 charged in the reaction vessel 1, and the heating temperature is adjusted according to the control signal 10 from the program temperature adjustment means 5. A specific example of this heating means is an aluminum block heater.

The liquid oxidant supply means 3 includes a liquid oxidant storage tank 31 and a gas pressure feeding means 4. The liquid oxidizing agent storage tank 31 stores a liquid oxidizing agent 11 such as sulfuric acid, nitric acid, perchloric acid, hydrogen peroxide, etc., and the internal space 3a is is pressurized.

Due to the pressure of this pressurized gas, the liquid oxidizing agent 11 is pushed 6 from the liquid oxidizing agent outlet 3b disposed in the liquid, and is supplied to the reaction vessel 1 via the liquid oxidizing agent supply path 9.
The liquid oxidant storage tank 31 and the liquid oxidant supply path 9 may be of any type as long as they are not corroded by the stored or supplied liquid oxidant and can accommodate the required supply amount of the liquid oxidant.

For example, the liquid oxidant storage tank may be made of glass or a fluororesin such as trifluoride resin or tetrafluoride resin, and the liquid oxidizer sub-supply route may have a diameter of 0.5 m.
For example, a tube made of trifluoride resin or tetrafluoride resin with a size of about 100 m is used.

The gas pressure feeding means 4 is for pressurizing gas as needed according to the control signal 13 from the program temperature controller 5 and supplying the liquid oxidizing agent to the reaction vessel, and is, for example, a beristaltic bomb (straining pump). That's fine.

Further, gas components including water vapor, carbon dioxide gas, acid gas, and evaporated gas of excess liquid oxidant generated as a result of oxidative decomposition of the sample in the reaction vessel 111 are discharged from the gas specific gravity 8 of the reaction vessel 1. The gas is introduced into a gas cooler 15 via a path 14 and cooled by cooling water 16 .
Examples of this cooler include a glass condenser.

The liquid separated from the gas component by cooling in the cooler 15 is collected in the liquid collecting means 17. Furthermore, after the liquid component has been collected, the gas component is collected by a gas collecting means 1 containing an alkaline aqueous solution 18 such as potassium hydroxide.
9 and a gas collecting means 21 containing an aqueous potassium permanganate solution 20, carbon dioxide gas, acidic gas, nitrogen oxides, etc. are absorbed and removed and discharged from the system. Providing such waste gas and waste liquid collection means such as the liquid collection means 17 and the gas collection means 19 and 21 is preferable since it is possible to prevent air and water pollution from being caused by waste gas and waste liquid.

Program temperature ll! The regulating means 5 is for adjusting the heating temperature of the sample, the supply amount and supply timing of the liquid oxidizing agent, and the like. This program temperature control means 5 is
In order to heat the sample to a predetermined temperature, a temperature control signal 10 is sent to the heating means 2 according to a preset program.
send. Further, the gas pressure feeding means 4 is controlled to adjust the amount and timing of supply of the liquid oxidant to the reaction vessel. Furthermore, in this program temperature iJ1w5 means 5, a control signal 32 is sent to the solenoid valve 23 of the purge gas flow rate adjustment means 22,
This solenoid valve 23 is controlled to adjust the flow rate of a purge gas 24 such as nitrogen gas. The purge gas 24 is filtered by a filter 25 to remove fine particles, etc. from the gas, and is then supplied to the liquid oxidant supply path 9 via the distribution path 26, where the liquid oxidant is pumped from the liquid oxidant storage tank 31. This helps in adjusting the amount and timing of supply to the reaction vessel. filter 2
Examples of the material 5 include those made of trifluoride resin and tetrafluoride resin.

Next, in the apparatus of this preferred embodiment, as the heating means,
Using an aluminum block heater as a means of compressed gas delivery,
Taking as an example an apparatus using a straining pump, a method for wet oxidative decomposition of a sample using the apparatus of the present invention will be explained in more detail.

In this device, first, a sample is placed in a reaction vessel, and if necessary, sulfuric acid is also added at the same time, and the sample is placed in an aluminum block heater. Conditions such as the target temperature, temperature increase rate, time during which the straining pump stops operating, and time during which the solenoid valve of the purge gas consumption control means stops operating are input into the program temperature control means in advance, and the program temperature control means Activate.

When the target temperature is reached, the squeezing pump and solenoid valve are activated by a signal from the program temperature control means, operated for a predetermined period of time, and then stopped.

A straining pump pumps air to increase the pressure of a tank containing liquid oxidizer. This straining pump usually has Q,
The flow rate of air to be pumped can be controlled in the range of i to 10 mu/mtn. In the pressurized tank, liquid oxidant is forced out and fed dropwise into the reaction vessel. The liquid oxidant supplied to the reaction vessel is mixed with the sample, and the sample is oxidized and decomposed within a short time.

Acid gas, water, and excess liquid oxidant not used in the decomposition that are generated during oxidative decomposition of the sample are cooled in a condenser, and then water and liquid oxidant are removed in a liquid trap, which is a liquid collection means. , carbon dioxide gas, acidic gas, and nitrogen oxides are absorbed and removed by gas collection means 19 and 21 filled with an alkaline aqueous solution and a potassium permanganate aqueous solution, respectively.

By doing this, the liquid oxidant can be delivered to the maximum decomposition temperature depending on the type of sample, and
Each operation can be performed automatically. Then, the pressurized gas is used to control the amount of liquid oxidizer sent, for example, by turning on and off a solenoid valve, but the operation of the solenoid valve or air pump depends on the temperature of the block heater, which is the heat source for decomposition. By turning on and off according to the signal from the temperature regulator used for control, it is possible to feed the necessary minimum amount of liquid oxidant at the optimum temperature.

<Example> As a preferred example of the present invention, terephthalic acid (hereinafter referred to as r
A method for wet oxidative decomposition of TAJ) will be specifically explained.

An apparatus having the same configuration as that shown in FIG. 1 was used. In order to increase the pressure inside the liquid oxidant storage tank (hereinafter referred to as "tank"), a straining bong:j (Verystar pump) was used as a means for pumping gas.

Pour approximately 20 ml of 63% nitric acid as a liquid oxidizing agent into the tank and weigh it. Charge TALg into a reaction vessel, add 5 ml of 98% sulfuric acid, and set the reaction vessel on an aluminum block heater. Cooling water is passed through a condenser, which is a gas cooling means, and one acid trap and two waste gas absorption bottles are connected in series, and about 50 ml of water is charged into the acid trap.

Add 50ml of 5% potassium hydroxide aqueous solution to the gas absorption bottle.
．． Fill the gas absorption bottle at the end with 50ml of 5% potassium permanganate aqueous solution.

In the program temperature control means, the heating temperature of the sample, the opening/closing timing of the solenoid valve, and the ON/OFF timing of the straining pump were set in five stages as shown in FIG. That is, (1) In the first step, the temperature is raised to 250° C. over 30 minutes.

■ In the second stage, maintain the temperature at 250°C for 30 minutes.

■ In the third stage, the temperature is raised from 250°C to 350°C over 10 minutes.

■ The fourth stage is to hold the temperature at 350°C for 60 minutes.

■ In the fifth stage, the heater is stopped and the product is allowed to cool naturally.

Also, at the same time as entering the second stage, a current flows from the program temperature control means to operate the solenoid valve, the solenoid valve opens, and the purge gas passes through a 0.2 micron tetrafluoride resin filter. , into the reaction vessel.

Leave the solenoid valve open until the end of the 5th stage.

TA completely dissolved in sulfuric acid in 10 minutes after the temperature reached 250°C. Therefore, 10 minutes after the second stage of gluing is started, a current flows through the programmed temperature control means to operate the straining pump, and air is sent from the straining pump into the tank containing nitric acid.

Since the straining pump has a structure that allows the flow rate to be controlled, the flow rate was set in advance at 0.5 ml/min. A tank pressurized with air is
Nitric acid is quantitatively extruded and completely filled into the reaction vessel through a Teflon tube with an inner diameter of 1 mm. Every time a drop of nitric acid enters, an amount of TA corresponding to the amount of nitric acid is instantaneously oxidized and decomposed into water, carbon dioxide gas, and nitrogen oxides. I had set the program temperature control means to stop the squeezing pump once every 20 minutes, so the squeezing pump only started operating 2 times.
It stopped after 0 minutes.

In the third stage, the temperature is raised to 350°C, and in the fourth stage, 350°C is maintained for 60 minutes. Sulfuric acid began to distill out about 10 minutes after the temperature reached 350°C. At this time, undecomposed TA adhering to the wall surface is partially washed off to the bottom of the reaction vessel with condensed sulfuric acid. Therefore, 10 minutes after the fourth stage, the straining pump was set to operate again for 10 minutes, and during this time, nitric acid was fed again to completely oxidize and decompose the TA. Thereafter, the sulfuric acid was completely distilled off, and at the fifth stage, the heater was stopped and natural cooling was performed.

The amount of nitric acid used during the entire operation was 15 ml, the wet oxidative decomposition time was 2 hours and 10 minutes, and the actual manual work time was 20 minutes.

(Comparative Example 1) TALg, 5 ml of 98% sulfuric acid, and 2 ml of 63% nitric acid were charged into a reaction vessel, and the temperature was raised at a temperature increase rate of 5° C./min.
When the temperature reached 190°C, decomposition occurred rapidly, foaming occurred, and the sample was scattered.

(Comparative Example 2) Automatic wet decomposition equipment using microwaves (MIC
ROI) IGEST 300), TALg, 9
8% sulfuric acid (10ml) and 63% nitric acid (5ml) were charged into a reaction vessel, the output of the microwave was increased, and nitric acid was added intermittently.

After 90 minutes, the inside of the reaction container became a transparent pale yellow liquid, and HaboTA was decomposed. However, even at the highest microwave output, the sulfuric acid could not be removed by evaporation.

(Comparative Example 3) TALg, 5 ml of 98% sulfuric acid, and 2 ml of 63% nitric acid were charged into a reaction container, and the container was set in a block heater. Third
Oxidative decomposition treatment was performed as follows according to the steps shown in the figure.

First, the block heater was heated to 250° C. over 30 minutes. When the temperature reaches 190℃, rapid decomposition occurs,
It foamed and the sample was scattered. Furthermore, TA was not completely dissolved in sulfuric acid at this temperature, and a portion of it sublimated and scattered together with the sulfuric acid and water vapor.

Continued decomposition operation, and after reaching 250℃, 63%
Add plenty of nitric acid with a pipette. Thereafter, 60 minutes, 90 minutes, and 120 minutes after starting the 63% nitric acid decomposition equipment.
After 1 minute, each was added with a 5 ml pipette.

The temperature of the block heater was maintained at 250° C. from 30 minutes to 60 minutes after starting the decomposition operation. Next, 6
The temperature was raised to 350° C. over 10 minutes from 0 minutes, and sulfuric acid was evaporated for up to 150 minutes. TA was completely decomposed.

The amount of 63% nitric acid used was 25 ml.

(Comparative Example 4) Automatic wet decomposition equipment using microwave heating (MICR)
The oxidative decomposition operation of TA was carried out using ODIGEST 300).

TALg and 10 ml of 98% sulfuric acid were charged into a reaction vessel and set in an automatic wet decomposition apparatus. The program for the automatic wet decomposition apparatus was set as shown in FIG. That is, Step 1: Heated for 10 minutes at 20% microwave output, then turned off. Next, the oxidizing agent feeding pump was operated to feed 5 ml of 63% nitric acid into the reaction vessel.

Step 2: Microwave was heated at 30% pressure for 15 minutes, then turned off. Activate the oxidizing agent pump 6
5 ml of 3% nitric acid was delivered.

Step 3: Heat at 40% microwave power for 20 minutes, then turn off. Activate the oxidizing agent pump 6
5 ml of 3% nitric acid was delivered.

Step 4: Heat at 60% microwave power for 20 minutes, then turn off. Activate the oxidizing agent pump 6
5 ml of 3% nitric acid was delivered.

Step 5: Heated for 20 minutes at 80% microwave power, then turned off. Activate the oxidizing agent pump 6
5 ml of 3% nitric acid was delivered.

While increasing the microwave output intermittently, the oxidizing agent feeding pump was automatically operated each time, and 63% nitric acid was added intermittently each time. Oxidative decomposition was carried out using 25 ml of 63% nitric acid at a microwave power of 80%. After decomposition, the resulting liquid was clear and pale yellow, and the TA was either almost decomposed or not completely decomposed. Furthermore, even at the highest microwave output, sulfuric acid could not be removed by evaporation.

<Effects of the Invention> According to the apparatus and method of the present invention, anyone can perform a wet oxidation decomposition process simply, efficiently, quickly, and with good reproducibility, and the minimum amount of liquid oxidation is required. Since oxidative decomposition can be carried out using reagents, contamination from reagents can be minimized. That is, the sample is decomposed while the liquid oxidant is continuously or intermittently fed dropwise into the heated sample, and the amount of liquid oxidant used can be kept to the minimum necessary.

In addition, when quantifying metal elements, it is possible to remove interference such as sulfuric acid, and to minimize contamination of the sample with trace metals contained in the liquid oxidizer. When quantifying metals, the lower limit of quantification can be lowered, and the precision of quantification improves, which improves the reliability of the analytical values.

Furthermore, there is an optimum temperature for adding the liquid oxidant depending on the type of organic sample to be oxidized and decomposed, but by adding the liquid oxidant at a constant flow rate at that optimum temperature, the amount of liquid oxidant used can be kept to the minimum necessary. I can do it.

In addition, by quantifying the various conditions of wet oxidative decomposition,
Anyone can perform wet oxidative decomposition automatically under the same conditions, eliminating human error and dispersion in quantitative values. Furthermore, by quantifying various conditions, all wet decomposition operations can be automated, resulting in lower costs.

In this way, by automating the wet oxidation decomposition operation, it is possible to perform the decomposition operation quickly and with good reproducibility.

Furthermore, in the method and apparatus of the present invention, the liquid oxidizing agent is not directly pumped as in the conventional method, but is pumped using gas pressure, so there is no contamination from the materials used in the pump.

Further, although some of the waste liquids and gases produced by oxidative decomposition are toxic, they can all be recovered, so they do not pollute the air or water quality, making them industrially useful.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating a preferred embodiment of the present invention.
3 is a diagram illustrating the steps of oxidative decomposition treatment performed in Example 1. FIG. FIG. 3 is a diagram illustrating the steps of oxidative decomposition treatment performed in Comparative Example 3. FIG. 4 is a diagram illustrating the steps of oxidative decomposition treatment performed in Comparative Example 4. Explanation of symbols 1... Reaction container, 2... Heating means, 3... Liquid oxidizing agent supply means, 4... Gas pressure feeding means, 5... Program temperature control means, 6... Sample, 7...Liquid oxidant inlet, 8...Gas outlet, 9...Liquid oxidant supply path, 10...Control signal for temperature adjustment from program temperature control means 511...Liquid oxidation agent, 12...pressure feeding route, 4...gas exhaust route d, 15...gas cooler, 16...cooling water, 17...liquid collection means, 19.21...gas Collection means, 22... Purge gas flow rate adjustment means, 3... TIII valve, 4... Purge gas, 5... Filter 6... Distribution path, 1... Liquid oxidizer storage tank FIG, 2 FIG , 3 (τs

Claims (2)

[Claims] (1) A method for wet oxidative decomposition of a sample, which involves a reaction vessel for oxidative decomposition of the sample, a heating means for the sample, and a liquid oxidizing agent that is continuously or intermittently pumped with pressurized gas into the reaction vessel. A wet oxidation decomposition apparatus having an oxidizing agent supply means, a purge gas flow rate adjustment means for adjusting the flow rate of the purge gas supplied in the middle of the liquid oxidant supply path connecting the reaction vessel and the liquid oxidant supply means, and a program temperature adjustment means. The programmed temperature control means includes, depending on the sample to be oxidized and decomposed, the oxidative decomposition temperature, temperature increase rate, operating conditions of the liquid oxidant supply means for supplying the liquid oxidant to the reaction vessel, and the purge gas flow rate. Operation of adjustment means
Data on the stop conditions is input, and based on the data, control signals related to the holding temperature and temperature increase rate are sent from the program temperature control means to the heating means, and control signals related to the liquid oxidant are sent to the liquid oxidizer supply means. A control signal for adjusting the flow rate of the purge gas is sent to the purge gas flow rate adjusting means to control the oxidative decomposition reaction of the sample. (2) An apparatus for wet oxidative decomposition of a sample,
A reaction vessel for oxidative decomposition of the sample, a heating means for the sample,
A liquid oxidant supply means that continuously or intermittently pumps a liquid oxidant into a reaction vessel using pressurized gas, and a flow rate of purge gas supplied in the middle of a liquid oxidant supply route connecting the reaction vessel and the liquid oxidizer supply means. a purge gas flow rate adjustment means for adjusting the purge gas flow rate, and a program temperature adjustment means for controlling the oxidation decomposition temperature, temperature increase rate, and supplying a liquid oxidant to the reaction vessel according to the sample to be oxidized and decomposed. Data on the operating conditions of the liquid oxidizer supply means and the operation/stop conditions of the purge gas flow rate adjustment means are inputted, and based on the data, the program temperature adjustment means controls the heating means regarding the holding temperature and temperature increase rate. A signal is sent, a control signal related to the liquid oxidant is sent to the liquid oxidant supply means, a control signal for adjusting the flow rate of the purge gas is sent to the purge gas flow rate adjustment means, and the oxidative decomposition reaction of the sample is controlled. A wet oxidative decomposition device that performs this process.