JPS5828662A - Method and apparatus for quantitative analysis of heavy water - Google Patents

Abstract

PURPOSE:To make a quantitative analysis of heavy water with a trace quantity of a sample accurately in a short time, by making the sample of the heavy water carried on reacting and carrying gas of high purity and passing it through a tube packed with an isotope exchange catalyst and then, passing the reaction gas through an adsorbent and detecting separated heavy water. CONSTITUTION:Gaseous H2 refined in ultra high purity through an H2 refining apparatus having a diaphragm made of Pd (alloy) is sent from a gaseous H2 supply source 1 to an analyzing apparatus in which air has been replaced by sending an inactive gas 9 preliminarily and a large part of gaseous H2 is sent to a sample gasifying room 5 through a flow meter 4 as the reaction and conveyance gas of a heavy water sample and also, the remainder is sent to a heavy hydrogen (D) detecting apparatus 8 for the reference purpose. The heavy water sample is weighed in a microsyringe and is poured from an injection opening 5' and then, is sent to the room 5 together with H2. Mixed gas is allowed to react completely in a tube 6 packed with carrier which carries a reaction catalyst of a water-hydrogen or steam-hydrogen isotope reaction such as Pt, Pd and is converted into HD. Then, other components are adsorbed and separated by an adsorbent in a separation column 7 and passed HD is determined in an detection apparatus 8. The heavy water sample similar to natural water is detected with the trace amount of the sample in a short time at most in about five minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for quantitatively analyzing heavy water at any concentration present in water, and an apparatus used therefor.

Japanese Patent No. 942709 (Japanese Patent Publication No. 53-16319) is known as a method for analyzing the deuterium concentration in hydrogen gas. However, this method should only be applied to hydrogen gas, and in order to apply this method to measuring the concentration of heavy water in water, it is necessary to add a method and apparatus for quantitatively generating HD from heavy water samples. There is a need to.

Conventionally, as a method for quantitatively generating hydrogen from water, a water reduction method (or decomposition method) in which water is vaporized and brought into contact with a heated metal such as zinc, tungsten, or uranium has been put into practice. However, this method not only requires time and skill, but the reducing ability of the metal decreases with repeated use, so if some unreacted water remains, the D
The basic drawback is that the concentration is different from that when all water is converted to hydrogen (Edited by the Chemical Society of Japan, Experimental Chemistry Course 1)
Basic Technology I (Part 1) pp. 468-472 1957 No. 5
Printed by Maruzen Co., Ltd.). Another method is called the equilibrium method, in which the deuterium exchange reaction HDO + H: The purpose is to perform i' H20+ HD and indirectly measure the heavy water concentration from the deuterium concentration in hydrogen gas at exchange equilibrium. This method is
Not only does it require a relatively large amount of sample (0.5 to 5 m/liter), but even if a highly active catalyst is used, it takes a long time (30
11) The residual effect is large, and (1) not all of the deuterium in water is transferred to hydrogen gas, so the sensitivity for deuterium determination is theoretically lower than that of the reduction method. It has the disadvantage of being inferior (Ibid., pp. 472-474,
Japan Society for Analytical Chemistry, Hokkaido Branch, 1979 Summer Research Presentation, B-12 Odate, Takaran, Sawara, July 1979). Therefore, it has been extremely difficult to connect these water reduction methods or equilibrium methods to the deuterium quantitative analyzer for continuous analysis.

In order to overcome the drawbacks of the conventional methods described above, the present inventors have developed a heavy water analysis method that can analyze a trace amount of heavy water at any concentration in a short time and with simple operations, and that can be repeatedly analyzed over a long period of time. As a result of extensive research to develop A method for quantitative analysis of heavy water characterized by passing through an adsorbent and then passing through a deuterium detection device, and 2. (a) High-purity hydrogen gas quantitative supply device (b) Sample vaporization chamber (c) Water-hydrogen or To complete and provide a quantitative analysis device for heavy water, consisting of: (d) a separation column filled with an adsorbent; and (e) a deuterium detection device connected in that order. It's arrived.

According to the method of the present invention, it is possible to analyze heavy water of any concentration, including natural water, in a short time of 5 minutes at most, and unlike conventional methods, it can be performed using a micro syringe.
Only a fixed amount of 0.1 to 10 μl, preferably 0.5 to 5 μl, of a trace amount of sample water is injected, and this operation can be repeated for a long time.

The method is similar to the equilibrium method in that it uses a catalyst, but the equilibrium method uses a closed reaction system separate from the analysis system, whereas the method of the present invention uses a flow-through reaction system. Basically different in this respect.

That is, when using the equilibrium method, it is impossible to obtain DttHD completely in water due to isotopic equilibrium between water and hydrogen, but when using the method of the present invention, hydrogen gas can be used both as a reaction gas and as a carrier gas. Therefore, the HD produced by the reaction
Since D is quickly removed from the reaction system, the reaction proceeds completely, and substantially all of the D in the sample can be converted to HDK. In addition, since the reactor and deuterium analyzer are directly connected, rapid analysis can be performed, and if high-purity hydrogen gas is used, contamination with pure substances can be avoided as much as possible. In a deuterium detection device such as a thermal conductivity detector, it becomes possible to flow the current in the thermal conductivity detection cell to a value close to the maximum φ value, thereby obtaining the highest sensitivity, which is close to the natural level. It has become possible to quantify low concentration heavy water.

Catalysts that can be used in this reaction include known highly active water-hydrogen or water vapor-hydrogen isotope exchange reaction catalysts, such as
Examples include catalysts in which noble metals such as platinum and palladium are supported on hydrophobic carriers (low temperature active), nickel/chromia catalysts, iron-based catalysts (high temperature active), etc. The hydrogen gas for reaction and transport is ultra-high purity, passed through a palladium membrane, etc., in order to take into account the life of the catalyst, the life of the separation column packed with adsorbent, the life of the deuterium detection equipment, and the improvement of detection sensitivity and accuracy. Preferably, hydrogen gas is used. The sample in the hydrogen gas for transportation is adsorbed on the catalyst layer and reacts with excess hydrogen gas to become HD and removed, and unreacted HDO continues to react in the catalyst layer and is completely converted to HD. It is estimated that

In the present invention, these catalysts are referred to as water-hydrogen or water vapor-hydrogen isotope exchange catalysts, and this packed bed is
It is called a generator tube.

The gas after this reaction is mainly a mixed gas of water and hydrogen, and also contains trace amounts of oxygen, nitrogen, carbon dioxide, and other gases contained in the sample. When passed through a layer of activated carbon, zeolite, mordenite, alumina, etc., preferably synthetic zeolite, 5A, 13X, etc., hydrogen and HD substantially pass through, while oxygen, nitrogen, etc. flow out later than this, and water, dioxide, etc. Carbon and the like are separated by being adsorbed. The adsorbent is heated to 200 to 300'C and continuously passed with high-purity hydrogen, so that it can be used for analysis continuously without having to be replaced.

Although deuterium detection devices include ultrasonic velocity detectors and thermal conductivity detectors, thermal conductivity detectors are preferred because they are easily available and easy to operate.

As can be seen from the above explanation, by modifying the gas chromatograph apparatus, it can be converted into the apparatus of the present invention.

Next, embodiments of the present invention will be described in more detail with reference to the drawings.

The drawings are 1. A schematic explanatory diagram of an apparatus of the present invention suitable for carrying out the method of the present invention, and is a hydrogen gas supply for both transportation (or development) and reaction. For example, hydrogen supplied from a hydrogen cylinder passes through a pressure reducing valve 2 and enters a hydrogen purification device 3. There is a diaphragm made of palladium or palladium alloy in this hydrogen purification device 3, and hydrogen gas is purified into ultra-high purity gas by passing through this diaphragm. The purified hydrogen gas passes through a flow rate regulator 4, most of which is sent to a heavy water sample vaporization chamber 5, and the remaining hydrogen gas is sent to a heavy hydrogen sample vaporization chamber 5. The deuterium flow rate regulator 4 constitutes a high-purity hydrogen gas quantitative supply device.

A certain amount of the heavy water sample is weighed into a microsyringe, passed through the heavy sample inlet 5', and injected into the middle horizontal sample vaporization chamber 5, where it immediately becomes water vapor, which is then transported by hydrogen gas and introduced into the HD generation tube 6. Ru.

) ID generating tube 61Ii This is a column filled with a known highly active water-hydrogen or water vapor-hydrogen amount exchange catalyst, and is maintained at an appropriate temperature for the catalyst used, and the heavy water in the introduced water vapor is used for transportation. It reacts with hydrogen gas H2 and is sent to the separation column 7 as deuterated hydrogen HD. This column is filled with an adsorbent, and the HDt/i after the 0 to b reaction almost passes through the column and is sent to the measurement inlet of the thermal conductivity detector 8, whereas water vapor, etc. It is adsorbed by the separation column and does not flow out, and the trace amounts of oxygen and nitrogen present in the water sample flow out of the column later than the tfHD.

As a result, it first flows out of the column and is detected as D&'iHD in the heavy water sample.

Preferably, the air filling the tube is sufficiently replaced with an inert gas, such as helium, preferably nitrogen.

In other words, the low-temperature active catalyst used for HD generation is highly active for oxyhydrogen reactions and promotes the reaction even at room temperature, so when hydrogen gas is introduced into an air-filled HD generation tube, oxyhydrogen reactions occur. This occurs rapidly, producing water and at the same time locally generating a large amount of heat, inducing combustion and sintering of the catalyst, and even if reactivation is possible, the result is damage to the catalyst activity. A similar phenomenon occurs when hydrogen is used for transportation after analysis is completed. The inert gas supply source 9 and its conduit shown in the drawings are used for this purpose.

The rapid vaporization of the sample increases the pressure, which is transmitted to the heat conduction dust detection cell and detected as a ghost peak, but the characteristics of the gas chromatograph, including the above factors, are affected by By adjusting , it is possible to obtain analytical conditions that do not cause ghost beaks even when analyzing heavy water that is similar to natural water.

In the exchange reaction between a highly concentrated heavy water sample containing deuterium of 1O molar coefficient or more and hydrogen gas, deuterated hydrogen HD is not generated. HD
and D2 have different thermal conductivities, but the compositions of HD, D2, and H2 in the water vapor-hydrogen amount reaction equilibrium are uniquely determined by the heavy water concentration in the heavy water sample under certain reaction conditions, so HD + D2- This is because the peak height or area of the gas chromatogram of this mixed gas produced in step 9 due to the difference between the average heating conductivity of the two mixed gases and that of H2 has a 1:1 correspondence with the heavy water concentration. (See the above-mentioned literature by Odate, Takanan, and Sahara). Furthermore, if necessary, if a highly concentrated heavy water sample is diluted to 10 to 1 molar with normal water and analyzed by this analytical method, the original heavy water concentration can be calculated taking into account the dilution rate.

Example 1 In the drawings, a commercially available hydrogen cylinder with a purity of 999° C. is used as a hydrogen gas supply source 1 for reaction and transportation, and a permeation device with a palladium alloy membrane heated to 400° C. is used as a hydrogen purification device 3, and a permeation device with a palladium alloy membrane heated to 400° C. is used as an HD generation tube 6 in advance. Filled with styrene-divinylbenzene copolymer beads with a particle size of 60 to 80 mesh carrying two platinum particles, inner diameter 3M and length 30ffl.
A stainless steel tube with an inner diameter of 31 mm was filled with Molecular Sheep 5A having a particle size of 60 to 80 mesh, which had been activated in advance as an adsorbent, in the separation column 7! I11. After a two-day period, a thermal conductivity detector was used, and a current of 140 mA was applied using a 110 Ω platinum resistance wire as a filament to maintain the detection cell at 110°C. Reaction and delivery results 256
A sharp HD peak with a height of 9111111 and an elution time of 0.7 minutes was detected by a recorder with mV sensitivity.

Example 2 Under the same conditions as Example 1, deuterium concentration 10%, 25%, 5%
Heavy water samples of 0q6.75q6.99.8ch were injected five times at 2 μE each. The average value of each peak height is 19.
Qllllll, 48.5tllll+, 97.611
111.147■, 195■, extremely linear force (
Good things have power (I understand.

Example 3 Heavy water desert 7j (t49.96pp
m, 159.97ppm, 170. O7ppm, 179
．． The results shown in Table 1 were obtained when heavy water samples of 27 ppm (all FCEs concentrations) were measured 10 times for each concentration. From now on, it will be possible to analyze heavy water at the level of natural water with a measurement accuracy of about 5 inches or less.

Table 1 Example Same as Example 1 except for the conditions of 4° or less. The temperature of the sample vaporization chamber 5 is 180°C, and the HD generation tube 6 is made of iron oxide (
Iron ore consisting mainly of 90% Ja and mixed oxides of aluminum, titanium, calcium, ion, potash, copper, etc. is crushed into 60 to 100 mesh pieces, and then crushed into a quartz tube ( The reaction temperature was raised to 920°C, and the temperature of the separation column 7 was maintained at 25°C. A 100 Ω tank sterenium resistance wire was used as the filament of the thermal conductivity detector 8, and a current of 200 mA was passed through it to maintain the detection cell temperature at 110°C.

injected into. As a result, a sharp HD peak with a height of 150 m was detected at a position with an elution time of 0.5 minutes on a recorder having a sensitivity of 512 mV.

Example 5 Under the same conditions as Example 4, heavy water concentrations were 0.5%, 1%, 2%,
1 μl of each of the 10 heavy water samples was injected five times.

The area count number of each average peak height is 11.7
It was 92.22, 836.44, 960.222.365. The heavy water concentration and peak area show good linearity.

Example 6 Example of ability f. -9 cases T7 Kaaeyoyo. . circle.

1 μl of each sample, which was adjusted to 99,249,498 ppm (Fcess concentration) by adding water, was repeatedly injected five times.

Their respective average peak heights are 7o, 4.121.6.
It was 201.2,322.4/jV.

Example 7 As the HD generating tube 6, an inner diameter 3fil filled with styrene-divinylbenzene copolymer beads with a particle size of 60 to 8o mesh carrying 14 pieces of Ni-Cr (weight ratio 4:1) was used.
+ Using a stainless steel tube with a length of 100M, the reaction temperature was set to 15
0.5 liter of a heavy water sample with a deuterium concentration of 1 liter was maintained at 0° C. and the other conditions were the same as in Example 1.
0 μ42. OIl! , 5 μ/, 10 Ill was injected 5 times each, and the average values of the respective peak areas were 1.17X10, '2.116X10', and 3.3
52X10. 5.108XlO, 9,406X10
(All units are counts).

[Brief explanation of the drawing]

The drawings show the present invention 3... suitable for carrying out the method of the present invention.
Hydrogen purification device, 5... Sample vaporization chamber, 5'... Sample inlet, 6... HD generation tube, 7... Separation column, Death... Deuterium detection device, 9... Inert Gas supply source. Agent: Sei Kikuchi, Patent Attorney - Continued from page 1 0 Inventor: Hiroshi Noguchi, Kou Kogyo Co., Ltd., 4-2-11 Ginza, Chuo-ku, Tokyo Applicant: Kou Kogyo Co., Ltd., 4-2 Ginza, Chuo-ku, Tokyo No. 11 Representative Patent Attorney Sei Kikuchi

Claims (2)

[Claims] (1) A heavy water sample is supported on hydrogen gas for reaction and transportation, and is brought into contact with a water-hydrogen or water vapor-hydrogen isotope exchange catalyst to perform an exchange reaction, and then the reaction gas is passed through an adsorbent. A quantitative analysis method for heavy water, which is characterized by passing it through a deuterium detection device. (2) (a) High-purity hydrogen gas quantitative supply device (b) Sample vaporization chamber (c) Water-hydrogen or water vapor-hydrogen amount HD generation tube filled with isotope exchange catalyst) Separation column filled with adsorbent (e) A heavy water quantitative analysis device in which deuterium detection devices are connected in that order.