JPH05281121A - Method of verifying correctness of quantification of moisture of solid - Google Patents

Abstract

PURPOSE:To verify whether a minute amount of moisture is surely measured in a moisture quantifying method, by heating a substance including water or crystal water with a solid, and confirming the collecting amount of water or crystal water. CONSTITUTION:A solvent such as methanol, chloroform, pyridine or the like is introduced into a titration cell 5 beforehand. The moisture in the cell 5 is turned to 0 through titration. A substance including crystal water, for example, barium hydrochloride, etc., is introduced along with a solid into a sample port 3 within a heater/evaporator 1 and inserted into a heating furnace 2. The substance is heated to 120-200 deg.C while being purged by nitrogen gas. Accordingly, the moisture in the crystal water and the solid is evaporated and, extracted into the solvent in the cell 5 via a pipe 4. The extracted moisture is titrated. The amount of moisture in the solid is calculated from the obtained value of the titration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for verifying the accuracy in the determination of the water content of solids, and more particularly to a method for verifying that the water content of several tens of ppm in sulfur can be accurately determined. ..

[0002]

2. Description of the Related Art Conventionally, as a method for measuring the water content of a solid, there is a gravimetric method. This method is a method in which a solid sample is heated in a dryer and then the weight loss is quantified as water content. In the Karl Fischer coulometric titration method, a solid sample such as sulfur is put into a solvent for extracting water, and the extracted water is reacted with iodine, and iodide is electrolytically oxidized to generate iodine to perform coulometric titration.

[0003]

However, according to such a conventional method for determining the moisture content of a solid, when the solid is sulfur, the heating temperature is 60 ° C. according to the weight loss method.
The water content in sulfur may not be completely removed. Further, when the temperature is further increased, sulfur itself is volatilized as SO ₂ , so that there is a problem that accurate quantification is difficult.

According to the Karl Fischer coulometric titration method described above, when the sulfur is in the form of lumps, it is difficult to extract the water inside the lumps. Further, when the sulfur is powder, there is a problem that the affinity with the solvent is poor and the solid floats on the upper part of the solvent, which makes the measurement operation difficult. Furthermore, it is not possible to quantify a trace amount of water of about several tens of ppm by any of the above methods.

An object of the present invention is to provide a method for verifying whether or not such a small amount of water could be accurately measured.

[0006]

The method for verifying the accuracy in determining the moisture content of a solid according to the present invention for solving the above-mentioned problems is a method of heating a solid in an inert gas stream to remove moisture as a molten state. In the method for quantifying water content, the proof that the quantitative value by this method is correct is characterized in that a substance having water or water of crystallization is heated together with a solid and confirmed by the amount of water or water of crystallization recovered.

It is characterized in that the heating temperature of the substance having water or water of crystallization and the solid is in the range of 120 to 200 ° C.
The substance having crystallization water is characterized in that the temperature at which the crystallization water can be removed by heating is in the range of 80 to 250 ° C. The substances with water of crystallization are characterized by barium chloride, sodium tartrate and trisodium citrate dihydrate.

It is characterized in that the solid is sulfur. At least one of argon, nitrogen and helium is used as the inert gas.

[0009]

By heating the substance having crystal water and the solid in an inert gas stream to a temperature of 120 to 200 ° C. and holding for a certain period of time, the water in the crystal water and the solid can be completely extracted into the solvent. Therefore, it is possible to judge whether or not the water content in the solid can be accurately quantified.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First, a solid moisture quantification device is shown in FIG. Figure 1
Shows the water extraction device 1. In FIG. 1, 1 indicates a heating vaporizer. A substance having water of crystallization and a solid are introduced into the sample boat 3 and inserted into the heating furnace 2. The inside of the heating furnace 2 is heated to a temperature of 120 to 200 ° C. to vaporize the water of crystallization and the water in the solid, and the water in the titration cell 5 is extracted via the pipe 4.

Details of the titration cell 5 are shown in FIGS. Into the titration cell 5, a commercially available solvent such as methanol, chloroform, pyridine or the like is previously introduced from the sample charging plug 6. Then, water is introduced into the solvent in the container 8 through the inlet pipe 7 connected to the pipe 4 shown in FIG. Next, the quantitative operation is as follows. The water content in the titration cell 5 is previously titrated to zero. A substance and a solid having crystallization water are put into a sample boat 3 in the heating vaporizer 1 and heated to a temperature of 140 ° C. while purging with nitrogen to make the solid in a molten state and hold for about 10 minutes to extract water into a solvent. .. The extracted water content is titrated. The amount of water in the solid is calculated from the obtained titration value.

Experimental Example 1 Experimental Example 1 is the result of examining the amount of crystal water recovered in a substance having crystal water. As the substance having water of crystallization, it is desirable to use a substance whose temperature at which the water of crystallization can be removed by heating is 80 to 250 ° C. For example, barium chloride, sodium tartrate, trisodium citrate dihydrate and the like.

A material having water of crystallization is selected at a temperature of 120 to
The following compounds, which can recover 100% of water of crystallization at 200 ° C., are suitable. Barium chloride (BaCl ₂ · 2H ₂ O),
Sodium tartrate (Na ₂ C ₄ H ₄ O ₆・ 2H ₂
O), trisodium citrate dihydrate (Na ₃ C ₆ H
₅ O ₇ · 2H ₂ O). Hereinafter, the experimental conditions using barium chloride were carried out under the same conditions as the method for determining the water content in sulfur. The results of recovery experiments are shown in Table 1.

[0014]

[Table 1] Experimental Example 2 Experimental Example 2 is an example of verifying that the solid water quantification method is correct by recovering water of crystallization in the coexistence of sulfur and barium chloride. Table 2 shows the experimental results of the recovered amount.

[0015]

[Table 2] From the results in Table 2, it was estimated that the water content in sulfur was several ppm or less. Experimental Example 3 Experimental Example 3 is an example in which water in the coexistence of sulfur and water is recovered to verify that the solid water quantification method is correct. Table 3 shows the experimental results of the recovery amount.

[0016]

[Table 3] Next, the coulometric titration method used in the examples of the present invention will be described. 3 and 4 show an example of the coulometric titration device and the coulometric titration cell used in the examples of the present invention. The coulometric titration cell is composed of two chambers, an anolyte chamber 11 and a catholyte chamber 12, and the chambers 11 and 12 are separated by a diaphragm 13 such as ceramics or ion exchange resin. The diaphragm 13 is made of a material that does not mix the anolyte and the catholyte during electrolysis and has a low electric resistance. The anolyte compartment 11 and the catholyte compartment 12 each have an electrolytic electrode 15 and an indicator electrode for determining the end point of titration. A drying tube 18 filled with silica gel or the like is provided in the atmosphere opening portion.

Each part shown in FIG. 4 has the following functions. Polarization current detection unit 20: A constant voltage or constant current is applied to the indicator electrode from a DC or AC power source, and a minute current or minute voltage change in the indicator electrode tube is amplified to detect the end point. Current control unit 21: Controls electrolysis by receiving a signal from the detection amplification unit and intermittently or gradually decreasing the electrolysis current near the end point.

Electrolytic current power source 22: constant current (107.1 m)
A or multiple thereof) or variable current (0 to 500 mA)
Power. End point detection display unit 23: Displays the end of measurement when the polarization voltage or current reaches the set end point value in response to the signal from the detection amplification unit. Current accumulator 24: Accumulates the current required for titration and displays the amount of electricity or the amount of water (μg H ₂ O).

[0019]

As described above, according to the method for verifying the accuracy in determining the moisture content of a solid according to the present invention, the accuracy of the moisture content in the solid detected in the molten state of the solid can be easily and accurately verified. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a heating vaporizer of the present invention.

FIG. 2 is a schematic perspective view showing a titration cell.

FIG. 3 is a schematic configuration diagram showing a titration cell.

FIG. 4 is a schematic configuration diagram showing a titration device.

Claims (6)

[Claims] 1. A method for quantifying water content of a solid, which comprises heating a solid in an inert gas stream to remove water as a molten state, and demonstrating that the quantitative value obtained by this method is correct. A method for verifying the accuracy in determining the moisture content of a solid, which comprises heating and confirming the recovered amount of water or crystal water. 2. The method for verifying the accuracy in determining the water content of a solid according to claim 1, wherein the heating temperature of the solid and water or the substance having water of crystallization and the solid is in the range of 120 to 200 ° C. 3. The method for verifying the accuracy in quantifying the water content of a solid according to claim 1, wherein the substance having water of crystallization has a temperature at which the water of crystallization can be removed by heating in the range of 80 to 250 ° C. 4. The method for verifying the accuracy in determining the water content of a solid according to claim 1, wherein the substance having water of crystallization is barium chloride, sodium tartrate and trisodium citrate dihydrate. 5. The method for verifying the accuracy of moisture determination of a solid according to claim 1, wherein the solid is sulfur. 6. The method for verifying the accuracy in determining the water content of a solid according to claim 1, wherein at least one of argon, nitrogen and helium is used as the inert gas.