JPS5928645A - Apparatus for thermal analysis - Google Patents

Abstract

PURPOSE:To analyze continuously many samples at high speed and with sensitivity by bringing a place generating reaction heat to a solid phase to prevent diffusion of the reaction heat and keeping the reaction level constant to improve the sensitiveness of temperature fluctuation and the reproducibility. CONSTITUTION:A carrier liquid is sucked up continuously from a carrier liquid tank 1 by a liquid feeding pump 2 and is moved in a carrier tube 3 at a fixed speed. Then, the liquid is equilibrated thermally in a preheating coil part 10 of a thermostat 4 and is flowed into a column 5 and then, is discharged from an exit. At this time, a temperature is detected continuously by a heat-sensitive element 6 provided in the neighborhood of the exit. On one hand, a sample is sucked continuously by a suction pump 7. Further, an injector is switched at the time of measurement to send a fixed quantity of sample to the column 5 by the carrier liquid. The sample reacts with a solid phase in the column 5 and the temperature fluctuates by generating or absorbing heat. This temperature fluctuation is detected by the element 6 to perform concentration conversion processing by an electric circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an enthalpymetric analysis device that performs analysis by measuring calorific value.

The method of quantifying a specific component from the heat of reaction by appropriately selecting a reaction solution for a specific component in a sample is superior in measurement speed and accuracy, and is said to be a direct measurement that does not require indicators. In this respect, the influence of obstructions is also a slightly better means of analysis.

Conventionally, a calorimeter has been used as a device for detecting thermal changes such as reaction heat, and it is not impossible to use this calorimeter as a detector in the above analysis means. For example, it is possible to measure the heat of reaction by continuously mixing the sample solution and reaction solution and introducing them into a flow-type microcalorimeter, but in this case, the reaction solution and sample reach thermal equilibrium within the device. Problems include the fact that the reproducibility of temperature detection is poor because heat is then diffused through the reaction, and as a result, a large amount of sample and reaction solution is required.

Additionally, a temperature titration device is well known as an analytical device that measures the amount of heat generated by a reaction.
This device uses the change in calorific value due to the reaction between the titrant and the sample that is continuously dropped to detect the end point of titration, and the first measurement is the volume of the titrant consumed.

It is also possible to use this device to directly and instantaneously inject an excess titrant into a sample of a certain standard, and then use the heat of reaction to determine the limit using a calibration curve prepared in advance, but this would result in patch measurement. However, it is not possible to process many samples in a short period of time.

The present inventors considered the characteristics of such conventional thermal analysis devices, and as a result of various studies that found a way to increase the measurement cycle speed and efficiently detect reaction heat, they found that the reaction that generates reaction heat can be fixed. It has been discovered that thermal changes can be detected with high sensitivity and good reproducibility by conducting the process in a column filled with a phase.Therefore, it is also possible to detect thermal changes by adding a small amount of a sample to a carrier liquid. We have discovered that it is possible to reduce the amount of sample and increase the measurement cycle speed, and based on this we have completed the present invention.

That is, the present invention comprises a column filled with a solid phase that reacts with a sample, a carrier tube connected to the column to send a carrier liquid, a pump to send the carrier liquid to the column, and A sample introduction section provided in the -1- flow of the column, a heat-sensitive element provided within the column or near the outlet of the column, and an electric circuit that converts the signal of the heat-sensitive element into a concentration. The present invention relates to an analytical device that utilizes the heat of reaction.

It is a solid phase that reacts with the sample and generates reaction heat through a solid-liquid reaction with the sample.Acids such as ion exchange resins, alkalis, etc. What is necessary is just to select appropriately the one which generates the reaction heat of . The ion exchange resin is not limited to only strongly acidic and strongly basic ones, but weakly acidic or weakly basic ones are also appropriately selected depending on the test.

It goes without saying that the reaction heat used in the present invention should preferably generate a large amount of heat, and in that respect, neutralization heat is most suitable. However, all other reaction heats such as adsorption/desorption heat, metal coordination heat, and catalytic heat can be used.

It goes without saying that the heat of reaction is not limited to one type, and a case may be selected in which two or more types of heat of reaction are generated at the same time. For example, if a chelate resin is selected for the measurement of caustic sorb, heat of neutralization and heat of metal coordination will be generated.

It is sufficient to have a sufficient amount of the solid phase to completely react with the sample, but it is inconvenient to regenerate or replace the solid phase every time, so it is necessary to react with the sample dozens to tens of thousands of times. It is best to fill the column with as much as possible.

The carrier liquid is used to transport the sample into the column and discharge it further, and is appropriately selected from various liquids such as water, various buffer solutions, and organic solvents, depending on the purpose. A reagent for reaction with the assay may be mixed into the carrier liquid. For example, when the sample is caustic soda, hydrochloric acid is used as the carrier liquid. In that case, it goes without saying that the concentration is appropriately adjusted so that the amount of heat generated is appropriate.

The apparatus of the present invention is constructed to successfully carry out such a reaction. FIG. 1 shows an outline of an apparatus that is an embodiment of the present invention.

As shown in the figure, the carrier liquid is fed from the carrier liquid tank 1 to 4? The carrier is continuously sucked up by the pump 02 and moves at a constant speed within the carrier cheep 3. Then, thermal equilibrium is reached within the preheating coil 10 of the constant temperature bath 4, and the heat flows into the column 5 and is discharged from the outlet. At this time, the temperature is continuously detected by a heat-sensitive element 6 provided near the exit. On the other hand, the sample is continuously suctioned by the suction pump 7. Then, during measurement, the injector 8 is switched to inject a fixed amount of the sample into the column 5 as a carrier liquid. The sample reacts with the solid phase in the column 5 and generates or absorbs heat, causing a temperature change. The heat-sensitive element 6 detects this temperature change, and the electric circuit 9 performs a zero concentration conversion process.

In an embodiment, the liquid delivery team is a carrier team.
Although only two pipes are provided, namely the pipe 3 and the sample cheep, it goes without saying that further cheeps such as reaction aids, solid phase regeneration reagents, cleaning agents, etc. may be provided as necessary. For the sample introduction section 8, the injector shown in the figure, which is often used in liquid chromatography, etc., may be used.
In short, it is sufficient to be able to inject a certain amount of sample into the upstream side of the column, and it is possible to appropriately select and employ a variety of known mechanisms. The heat-sensitive element 6 is preferably provided at a location in the system where the temperature change due to the heat of reaction peaks, and is preferably provided at or near the outlet end of the column, or in the column on the outlet side.

As the heat-sensitive element 6, a thermistor, a platinum resistance temperature sensor, or the like may be appropriately selected and used.

The in-phase is regenerated or replaced when the reaction capacity decreases. In the case of regeneration, for example, a new regenerant line may be installed in the apparatus shown in Figure 1 and the changeover can be made, but if a regenerant is mixed into the carrier liquid, the solid phase can be regenerated immediately after sample analysis. Continuous high-speed analysis is possible. When separately passing the regenerant, two columns may be provided in parallel and used alternately.

Next, a case will be described in which the apparatus of the present invention is applied to product control in a caustic soda manufacturing process. In the caustic soda manufacturing industry, a caustic soda concentration solution of about 20 to 50 parts is produced in an electrolytic cell.

This concentrated solution was continuously analyzed without dilution using the apparatus outlined in FIG. For the same phase, strongly acidic cation exchange resin WK-20H type (Mitsubishi Kasei Corporation) or chelate resin UR-40H type (Unitika Co., Ltd.) was used, and the diameter was 2.
A cylindrical column with a length of 39 mm was packed. Water or o,s NHct was used as the carrier liquid, and 1.2 m
The liquid was passed through at a constant flow rate of 1/min. The amount of sample was 20μ at a time, and the injection was carried out at 30 second intervals and 60 second intervals.

The constant temperature bath was set at 342°C.

Thermistor 5B-10K (Zen Kogyo Co., Ltd.) is used as the heat-sensitive element.
(manufactured by) was used. When the caustic soda concentration was continuously measured under these conditions, it was found that in addition to neutralization heat, dissolution heat was also generated, and metal coordination heat may also be generated, but in any case, the results are shown in Figure 2. A good linear relationship was obtained between temperature change and caustic soda concentration. The results shown in this figure were obtained using UR-40 and pure water as the carrier liquid. Continuously measure each of the solid phases,
The results of measuring the coefficient of variation are shown in the table below.

Incidentally, a chart of the measurement results obtained using UR-40 among the two items is shown in FIG.

The present invention prevents the diffusion of the reaction heat and keeps the reaction site constant by bringing the site where the reaction heat is generated into the solid phase. This increases the sensitivity of temperature changes and improves reproducibility, making it possible to perform continuous analysis of many samples at high speed and with high sensitivity, especially for process control analysis where many samples of the same type are analyzed. It is suitable as

[Brief explanation of the drawing]

FIG. 1 shows an outline of an apparatus that is an embodiment of the present invention, and FIG. 2 shows the results of determining the relationship between the caustic soda concentration and the amount of temperature change using the apparatus of the present invention. Figure 3 is a chart showing each peak of the measurement results. 2...Liquid pump, 3...Carrier cheese, 5.
...Column, 6...Thermosensitive element, 8...Sample introduction part,
9... Electric circuit, 10... Preheating coil. Patent applicant: Denki Kagaku Keiki Co., Ltd. Representative: Patent attorney 1) Masahiro Naka

Claims (1)

[Claims] A column filled with a solid phase that reacts with a sample, a carrier cheep connected to the column to send a carrier liquid, and a 4? and
A sample introduction section provided upstream of the column, a heat-sensitive element provided within the column or near the outlet of the column, and an electric circuit that converts the signal of the heat-sensitive element into a concentration. Analyzer that uses reaction heat.