JPH0136116Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an enthalpymetric analysis device that performs analysis by measuring the amount of heat generated during a reaction.

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 a direct measurement method that does not require an indicator. In this sense, it is an excellent analytical method that is less affected by interference.

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. The reaction starts after the two liquids are combined, so the measurement takes time.The reaction starts immediately when the two liquids are combined, and the heat diffuses as the liquid flows, resulting in poor reproducibility of temperature detection. Problems include the need for a large amount of reaction solution.

In addition, a temperature titration device is well known as an analytical device that measures the amount of heat generated by a reaction. Changes are used to detect the end point of titration, and the object of measurement is the volume of titrant consumed. Using this device, it is possible to directly and instantaneously inject excess titrant into a fixed amount of sample and quantify it using a calibration curve created in advance from the reaction heat, but it is necessary to measure in batches. However, it is not possible to process many samples in a short period of time.

The inventors of the present invention considered the characteristics of conventional thermal analysis devices and conducted various studies aimed at speeding up the measurement cycle and efficiently detecting the heat of reaction. By selecting the reaction reagent to be generated and causing the reaction between this reaction reagent and the sample to occur in or immediately before a column packed with a packing that does not react with the sample and has a small heat capacity or thermal conductivity. Therefore, thermal changes can be detected with high sensitivity and good reproducibility.Therefore, it is also possible to detect thermal changes by adding a small amount of sample to the carrier liquid, making it possible to reduce the amount of sample and speed up the measurement cycle. We discovered that it is possible to realize this, and based on this we completed the present invention.

In other words, the present invention consists of a column filled with a packing that does not react with the sample and has a small heat capacity or a low thermal conductivity, a sample liquid tube connected to the column to send the sample liquid, and the column or A reaction liquid tube connected to the sample liquid tube, a pump that sends the sample liquid and reaction liquid to the column, a heat-sensitive element installed within the column or near the outlet of the column, and a signal from the heat-sensitive element that converts the signal of the heat-sensitive element into a concentration The present invention relates to an analytical device that utilizes reaction heat, and is characterized by being equipped with an electric circuit that converts heat of reaction into

A packing that does not react with the sample and has a small heat capacity or low thermal conductivity is a packing that does not inhibit the reaction between the sample and the reaction reagent described below, and that narrows the reaction field and allows the reaction to occur. It has been clarified that this technology enables the sensitive detection of temperature changes due to This is because if the heat capacity is small, the reaction heat will be accumulated in the reaction liquid, and even if the thermal conductivity is small, the reaction heat will be accumulated in the width of the reaction liquid. Examples of such fillers include Teflon beads, polyethylene beads, and the like.

The reaction reagent contained in the reaction solution reacts with the sample to generate an appropriate amount of reaction heat. The type of reaction heat is not limited, but one that generates a large amount of heat is preferable, and in that respect, neutralization heat is most suitable. However, all other reaction heats such as adsorption/desorption heat, metal coordination heat, catalytic heat, and dilution heat can be used. Moreover, this reaction heat may be not only a positive reaction heat but also a negative reaction heat. It goes without saying that the reaction reagent is determined depending on the sample, taking into account the amount of heat generated and the reactivity with impurities.

The sample liquid may be sent to the column continuously, but usually it is sent intermittently. This sample solution may be sent to the column as it is, or it may be sent using a carrier liquid. The carrier liquid is appropriately selected from among water, various buffer solutions, organic solvents, etc., depending on the sample and reaction reagent.

The apparatus of the present invention is constructed to allow such a reaction to occur successfully. FIG. 1 shows an outline of an apparatus which is an embodiment of the present invention.

As shown in the figure, the reaction liquid is continuously sucked up from the reaction liquid tank 1 by the liquid sending pump 2 and moves at a constant speed within the reaction liquid tube 3. Then, thermal equilibrium is reached within the preheating coil 11 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 the heat-sensitive element 6 provided near the outlet. On the other hand, the sample is continuously sucked by the suction pump 7 and is flowing inside the sample liquid tube 8 . Then, during measurement, the injector 9 is switched, and a certain amount of the sample is fed into the column 5 while being sandwiched between the reaction liquid. The sample reacts with the reaction reagent in the column and generates or absorbs heat, causing a temperature change. The thermosensitive element 6 detects this temperature change, and the electric circuit 10 performs a concentration conversion process.

In the embodiment, there are only two liquid feed tubes, the reaction liquid tube 3 and the sample liquid tube 8, but if necessary, additional tubes for carrier liquid, reaction aid, cleaning agent for the packed layer, etc. may be provided. Needless to say, it is okay. The injector for injecting a fixed amount of the sample liquid into the column or reaction liquid tube may be appropriately selected from among various known injectors. For example, the injector 9, which is often used in liquid chromatography, may be used. When connecting the sample liquid tube 8 to the reaction liquid tube 3, it is preferable to connect it near the inlet of the column 5 in order to generate as much reaction heat within the column 5 as possible. 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.

Next, a case will be described in which the device of the present invention is applied to product control in a caustic soda manufacturing process. In the caustic soda manufacturing industry, 20 to 50% of
A concentrated solution of caustic soda is produced. This concentrated solution was continuously analyzed without dilution using the apparatus outlined in FIG. Fluoropak 80 (trade name, manufactured by Gascro Industries Co., Ltd.), which is a Teflon bead, was used as a packing material, and was packed into a cylindrical column with a diameter of 2 mm and a length of 39 mm. Using 0.5NHCl as the reaction solution,
The liquid was passed through at a constant flow rate of 1.2 ml/min. The sample amount was 20μ per injection, and the injections were made at 30 or 60 second intervals. The constant temperature bath was set at 34.2°C. A thermistor SB-10K (manufactured by Takara Kogyo Co., Ltd.) was used as the heat-sensitive element.

The caustic soda concentration was continuously measured under these conditions and the coefficient of variation was found to be 0.8%.
On the other hand, the coefficient of variation when measuring without filling the column with anything was 3.3%. Next, when the concentration of caustic soda was changed and the relationship with temperature change was determined, a good linear relationship was obtained as shown in FIG.

This invention prevents the diffusion of reaction heat by bringing it into the solid phase, which increases the sensitivity of temperature changes and improves reproducibility, resulting in high speed and high sensitivity. It enables continuous analysis of a large number of samples, and is particularly suitable for process control analysis in which a large number of samples of the same type are analyzed.

[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 concentration of caustic soda and the amount of temperature change using the apparatus of the present invention. 1... Reaction liquid tank, 2... Liquid sending pump, 3... Reaction liquid tube, 4... Constant temperature bath, 5... Column, 6... Heat sensitive element, 7... Suction pump, 8... Sample liquid tube, 9
...Injector, 10...Electric circuit, 11...Preheating coil.

Claims (1)

[Scope of utility model registration request] A column packed with a packing that does not react with the sample and has a small heat capacity or low thermal conductivity, a sample liquid tube connected to the column to send the sample liquid, and a column connected to the column or the sample liquid tube. a reaction liquid tube, a pump for feeding the sample liquid and the reaction liquid to the column, and a heat-sensitive element provided within the column or near the outlet of the column;
An analysis device that utilizes reaction heat, characterized by comprising an electric circuit that converts a signal from the heat-sensitive element into a concentration.