JP2023058213A - Concentration measurement method and device of underwater trace gas composition - Google Patents

Abstract

To provide a concentration measurement method and device of an underwater trace gas composition suitable for highly accurately measuring a trace gas composition existing in the water like ultra pure water.SOLUTION: A concentration measurement device of an underwater trace gas composition comprises: introduction means which introduces a prescribed amount of measurement object water into a flow passage of measurement means; gas-water separation means which separates the measurement object water introduced into the flow passage of the measurement means to the trace gas composition and water with a precolumn; concentration means which cools the trace gas composition separated from the water to concentrate it and warms the concentrated trace gas composition to feed it to a main column portion; oxygen removal means which removes oxygen from the fed trace gas composition; gas composition separation means which separates the trace gas composition from which oxygen has been removed to one or plural types of gas compositions excluding the oxygen composition with the main column portion; and detection means which detects the one or plural types of separated gas compositions.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method and apparatus for measuring the concentration of trace gas components in water. Regarding.

In general, ultrapure water is used for cleaning semiconductor wafers and liquid crystals, water for steam generators in power generation turbines required for stable operation of power plants, and water for injections in the pharmaceutical industry where safety is required in all situations. It is necessary to remove even a very small amount of impurities depending on the intended use. Impurities are all target substances other than H ₂ O, such as gases, fine particles, metal ions, inorganic substances, and organic substances.

A gas chromatograph method is used as a technique for measuring minute amounts of impurities, particularly gas components, which are present by being mixed or dissolved in such water.

Various proposals have been made as measurement methods using gas chromatography (see, for example, Patent Document 1).

Retable 2014-109410

However, there are problems with measuring trace gas components in water using the conventional gas chromatographic method.

In recent years, the concentration of gas in water, for example, in ultrapure water in which the management of dissolved gas is required, sometimes reaches an extremely low level of several tens to several ppb. It was impossible to measure this concentration directly with the existing gas chromatograph due to sensitivity.

Furthermore, for example, when measuring a small amount (a few μL or less) of sample water that is present due to contamination of trace gas components in water by injecting a small amount (a few μL or less) directly into the analysis column with a microsyringe, water gradually remains in the analysis column. When the water content accumulates to the extent that it affects the separation, the column temperature is raised to perform aging to regenerate the activity of the column, thereby enabling re-analysis. However, in this method, since the amount injected into the analysis column is very small, there is a problem that the mixed gas component cannot be measured when the concentration thereof is very small. Specifically, the measurable range has a lower measurement limit of about several ppm, and it has been impossible to measure trace gas components in water below ppm.

Concentration measurements by headspace or purge trap methods have also been implemented.

For example, when concentrating and measuring trace amounts of VOCs (volatile organic compounds) in water using a purge trap, in the process of loading the sample water into the sample vial bottle, the gas phase is filled with a large amount of air. be done. This air-containing gas phase portion or liquid phase portion is purged by bubbling with an inert gas to expel and trap VOC components, and is subjected to GC-MS (gas chromatograph-mass spectrometer) or GC-FID (flame ionization detector). It is measured by a gas chromatograph with The GC-MS or GC-FID used for this measurement cannot detect air components due to the characteristics of the detector.

In addition, when measuring argon among gas components in particular, argon and oxygen cannot be separated under general analysis conditions if oxygen in the air is mixed. is important.

Furthermore, in the method proposed in Patent Document 1, in which the dissolved gas is sampled with a gas-tight syringe through a septum by the vacuum air sampling bottle method and introduced into the gas chromatograph, contamination of air components cannot be avoided. Measurement of trace amounts of argon is not possible.

Therefore, in the measurement method in which contamination of ambient gas (air component) cannot be avoided by such pretreatment, there is a problem that it cannot be applied to the measurement of a trace amount of argon in water, in which argon is the contamination gas component of water.

Thus, when the object to be measured is a trace gas component in water, it is difficult to prevent contamination with ambient air, it is difficult to measure an accurate concentration amount, and bubbling purge There is an inconvenience that the operation is very complicated and requires a high level of skill of the operator, such as the need to calculate the recovery rate.

The present invention has been made in view of these points, and is intended to avoid human complexity, improve sensitivity by sample water collection method and concentration operation, and take measures to prevent deterioration of column separation performance due to a large amount of sample water. An object of the present invention is to provide a concentration measurement method and apparatus for trace gas components in water suitable for highly accurate measurement of trace gas components present in water such as ultrapure water.

In order to solve the above-mentioned problems, a first aspect of the present invention provides a method for measuring concentration of trace gas components in water, which comprises: A method for measuring concentration of a trace gas component, comprising: an introduction step of introducing a predetermined amount of water under measurement in which the trace gas component is present into the measuring means; and the water under measurement introduced into the measuring means. is separated into the trace gas component and water by a pre-column, a concentration step of cooling and concentrating the trace gas component separated from the water, and heating the concentrated trace gas component an oxygen removing step of removing oxygen from the delivered trace gas component; and removing the oxygen component from the trace gas component from which oxygen has been removed by the main column portion, or A gas component separation step of separating a plurality of types of gas components and a detection step of detecting one or more of the separated gas components are performed in order to determine the concentration of the trace gas components present in water. It is characterized by measuring.

Since the present invention is configured in this way, it is possible to avoid human complexity, to provide a method for collecting the water to be measured, which is the sample water, to improve sensitivity by concentration operation, and to prevent deterioration of column separation performance due to a large amount of sample water. This makes it possible to measure trace gas components present in water such as ultrapure water with high accuracy.

Further, the second aspect of the present invention is a method for measuring concentrations of trace gas components in water according to the first aspect, wherein in the introducing step, a predetermined amount of the water to be measured filled in a metal sample cylinder or a flexible container is is introduced into the measuring means in a state separated from the outside air, and a step of discharging the moisture separated in the air-water separation step from the measuring means by causing a purge gas to flow back in the pre-column portion characterized by comprising

Since the present invention is configured in this manner, the introduction of the water to be measured into the measuring apparatus can be carried out in isolation from the outside, and the moisture remaining in the pre-column can be reliably discharged out of the measuring apparatus. It is possible to measure trace gas components present in water such as ultrapure water with high accuracy.

Further, in the method for measuring concentration of trace gas components in water according to the third aspect of the present invention, in the first or second aspect, the trace gas components measured in the detection step are argon, methane, carbon monoxide, It is characterized by being one or more of carbon dioxide, krypton and xenon.

Since the present invention is configured as described above, it is possible to reliably measure a specific type of gas component such as argon with high accuracy.

A concentration measuring device for trace gas components in water according to the first aspect of the present invention is a concentration measuring device for trace gas components in water that measures the concentration of trace gas components present in water by a measuring means using a gas chromatograph. introducing means for introducing a predetermined amount of the water to be measured into the flow path of the measuring means; air-water separation means for separating, concentrating means for cooling and concentrating the trace gas component separated from water, heating the concentrated trace gas component and sending it to the main column portion, and sending the sent oxygen removal means for removing oxygen from trace gas components; gas component separation means for separating the oxygen-removed trace gas components into one or more types of gas components excluding the oxygen component by the main column portion; and detection means for detecting one or more of the separated gas components.

Since the present invention is configured as described above, by executing the method of the first aspect of the present invention using the apparatus of the first aspect of the present invention, human complexity can be avoided and water to be measured, which is sample water, can be obtained. It is possible to measure trace gas components present in water such as ultrapure water with high accuracy by using a sampling method, increasing sensitivity by concentration operation, and taking measures to prevent deterioration of column separation performance due to a large amount of sample water.

The second aspect of the present invention is an apparatus for measuring concentration of trace gas components in water according to the first aspect, wherein the introducing means is a metal sample cylinder or a flexible container capable of being filled with a predetermined amount of the water to be measured. The water-to-be-measured water is introduced into the flow path in a state of being connected to the flow path and separated from the outside air, and the air-water separation means separates the separated water from the pre-column. It is characterized in that it is formed so that the purge gas is reversely flowed at a portion thereof and discharged out of the measuring means.

Since the present invention is constructed in this manner, the introduction of the water to be measured into the measuring apparatus can be isolated from the outside by executing the method of the second aspect of the present invention with the apparatus of the second aspect of the present invention. In addition, water remaining in the pre-column can be reliably discharged outside the measuring device, and trace gas components present in water such as ultrapure water can be measured with high accuracy.

The third aspect of the present invention is an apparatus for measuring concentration of trace gas components in water according to the first or second aspect, wherein the flow path includes an operating gas supplied into the flow path from the outside of the measuring means. It is characterized in that the water to be measured, the separated trace gas component, moisture, and the concentrated trace gas component can be conveyed by the gas and a switching valve installed in the middle of the flow path. do.

Since the present invention is configured as described above, the connection state of the flow path can be switched according to the purpose by the switching valve, and the trace gas component can be measured with good working efficiency.

The fourth aspect of the present invention is an apparatus for measuring concentration of trace gas components in water according to any one of the first to third aspects, wherein the trace gas components measured by the detecting means are argon, methane, and It is characterized by being one or more of carbon oxide, carbon dioxide, krypton, and xenon.

Since the present invention is constructed as described above, by executing the method of the third aspect of the present invention with the apparatus of the fourth aspect of the present invention, it is possible to reliably measure a specific type of trace gas component with high accuracy. can be done.

In this way, the present invention avoids human complexity, improves the sensitivity by a sample water collection method, concentration operation, and measures to prevent column deterioration due to a large amount of sample water. It is possible to provide a method and apparatus for measuring concentration of trace gas components in water suitable for highly accurate measurement of trace gas components in water.

1 is a block diagram showing the overall configuration of an embodiment of the present invention; FIG. Block diagram showing the overall configuration of another embodiment of the present invention FIG. 2 is a characteristic diagram showing chromatographic data of a standard gas measured by the present invention; FIG. 2 is a characteristic diagram showing chromatographic data of gases present in water 1 to be measured measured by the present invention; FIG. 2 is a characteristic diagram showing chromatographic data of gases present in the water to be measured 2 measured by the present invention;

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 and 2. FIG.

FIG. 1 shows the overall configuration of an embodiment of an apparatus for measuring the concentration of trace gas components in water according to the present invention.

In the apparatus 1 for measuring the concentration of trace gas components in water according to the present embodiment, the water to be measured is introduced from the introduction unit 2 as the introduction means shown in the left part of FIG. The tograph 4 is configured to measure the concentration of trace gas components in the water to be measured. From the introduction unit 2 to the gas chromatograph 4, each constituent part is connected in order with a flow path F for flowing water to be measured, gas components, etc., and the flow state is controlled by switching valves V1 to V4 provided in the middle. there is

Each component will be described below in order from the upstream side to the downstream side.

The introduction unit 2 is formed so that a metal sample cylinder 5 for storing water to be measured that is present due to the mixture of trace gas components can be detachably attached to the flow path F1. Stop valves ST1 to ST4 are provided on the downstream side for controlling the flow of the water to be measured when it is introduced.

A flow path F1 of the introduction unit 2 is connected to a flow path F2 of the measuring device 3, and a measuring pipe 6 for measuring the amount of the introduced water to be measured is connected to the flow path F2 via a switching valve V1. ing.
On the downstream side of the switching valve V1, a pre-column 7 is provided via a flow path F3 and a switching valve V2, and a steam separation unit 8 is connected as a separation means for separating the water to be measured into moisture and trace gas components. It is Connected to the switching valve V2 are a flow path FPG1 for supplying a purge gas PG1 as an operating gas for reversely discharging moisture remaining in the pre-column 7, and a discharge flow path P1 for discharging moisture. . Further, the switching valve V1 is connected to a discharge flow path P2 for discharging excess water to be measured in the metering pipe 6 when measuring the water to be measured.
On the downstream side of the steam separation unit 8, the trace gas components separated from water via the switching valve V2, the flow path F4 and the switching valve V3 are cooled and concentrated, and the concentrated trace gas components are heated. A trap tube 9 is connected as a concentrating means for sending out to the main column portion 4a. A heater 10 for heating is wound around the outside of the trap tube 9 . A durbin 11 in which liquid nitrogen is stored is arranged so as to be vertically movable with respect to the trap tube 9 .

A gas chromatograph 4 is connected to the downstream side of the trap tube 9 via a switching valve V3, a flow path F5, a switching valve V4 and a flow path F6. The switching valve V4 is connected to a channel FCG for supplying a carrier gas CG as a working gas for sending the concentrated trace gas components in the trap tube 9 to the gas chromatograph 4. FIG.

An oxygen trap 12 is connected to the flow path F6 as oxygen removing means for removing oxygen from trace gas components.

A main column section 4a is connected to the downstream side of the oxygen trap 12 as gas component separation means for separating a plurality of types of gas components excluding the oxygen component from the oxygen-removed trace gas component. A detector 13 is connected to the downstream side of the main column portion 4a as detection means for detecting the separated plural kinds of gas components.

A chromatographic signal is transmitted from the detector 13 to a PC (personal computer) 15 (hereinafter referred to as "PC 15") of the data processing device 14. FIG. The concentrations of the gas components obtained by arithmetic processing by the PC 15 are displayed on a display device (not shown) or printed. Furthermore, a sequence control signal is sent from the PC 15 to the control unit 16, and the vertical movement control of the switching valves V1 to V4, the trap tube 9, the heater 10 and the durbin 11 is performed.

Next, a concentration measurement method for trace gas components in water according to this embodiment will be described.

In the present embodiment, argon is used as the gas present by being mixed with water.

<Introduction process>
In the introduction step, a predetermined amount of the water to be measured that is present due to the presence of trace gas components is introduced into the measuring device 3 as measuring means.

Specifically, first, water to be measured is enclosed in a metal sample cylinder 5 having an inner volume of about 1 L so as not to contain air components, and then connected to the flow path F1 of the introduction unit 2 .

After that, the sample cylinder 5 is placed vertically, and the purge gas PG2 (high-purity helium gas (He)) is connected to the upper stop valve ST1. While keeping the stop valve ST3 closed, the two stop valves ST1 and ST2 are alternately opened and closed several times or more to replace the air component in the flow path F1 with helium. After that, both stop valves ST1 and ST2 are finely adjusted to constantly flow helium at about 100-500 ml/min.

After that, the other stop valves ST3 and ST4 are carefully opened, and the water to be measured is adjusted to flow through the flow passages F1 and F2 in the lower stage to the metering tube 6. FIG. Helium compensates for the decrease in the amount of water to be measured in the metal sample cylinder 5, so that the inside of the metal sample cylinder 5 does not become negative pressure. Alternatively, it is also possible to pressurize the helium slightly to push out the water to be measured and introduce it into the measuring tube 6 .

Next, the switching valve V1 is operated to expel the water to be measured in the metering tube 6 with a purge gas PG1 (high-purity helium (He)) and introduce it into the pre-column 7 .

Here, the measuring tube 6 has an internal volume of about 200 μL, which is a relatively large volume for the amount of liquid introduced into the gas chromatograph. By connecting directly to the measuring tube 6 and passing water, it is possible to measure the amount of water to be measured as a sample amount about 100 times the normal measurement level while preventing contamination of air components at the time of sampling, so highly sensitive measurement is possible. Become.

<Steam separation process>
In the air-water separation step, the water to be measured introduced into the air-water separation unit 8 is separated into trace gas components and water by the pre-column 7 .

Specifically, gas components containing argon are separated from moisture in the precolumn 7 , and the argon is introduced into the trap tube 9 cooled by liquid nitrogen in the durbin 11 . On the other hand, in a state where water remains in the pre-column 7, the switching valve V2 is operated to reverse the flow direction of the purge gas PG1 in the pre-column 7, and the water flows through the switching valve V2 and the discharge flow path P1. It is discharged outside the pre-column 7 system.

Here, the water is discharged out of the system of the pre-column 7, and the deterioration of the separation performance of the pre-column 7 due to a large amount of water remaining in the pre-column 7 can be prevented, and the analysis time can be shortened.

<Concentration process>
In the concentration step, liquid nitrogen is used to cool and concentrate the trace gas components separated from the water.

Specifically, by raising the durbin 11 and immersing the trap tube 9 in liquid nitrogen, the trace gas components in the trap tube 9 are condensed and collected in a concentrated manner.

Here, since a large amount of the trace gas component separated from the water in the pre-column 7 is injected, the peak tends to broaden in the main column 4a. Therefore, by introducing the trace gas component into the trap tube 9 once cooled with liquid nitrogen and concentrating and collecting it, the band width of the measured component is narrowed, and when it is introduced into the main column 4a, it is detected with a sharp peak shape. It will be done.

The trap tube 9 is formed by forming a sulfinate tube whose inner surface is deactivated into a U-shape, wrapped with a heater 10, and filled with an adsorptive filler. Before starting the measurement, the small durbin 11 filled with liquid nitrogen is raised to immerse and cool the trap tube 9 in the liquid nitrogen. Then, the heater 10 is energized to heat it, and the trace gas components collected are expelled by the carrier gas CG and delivered to the main column 4a.

<Delivery process>
In the delivery step, the trace gas component concentrated in the trap tube 9 is heated and delivered to the main column portion 4a.

Specifically, at the timing when the concentration collection by the trap tube 9 is completed, the connection state of the switching valves V3 and V4 is operated to transfer the gas chromatograph carrier gas (He) CG to the flow path FCG, the switching valve 4, and the flow path F5a. , to the trap tube 9 through the switching valve V3, and then through the trap tube 9 and the switching valve 3 to the flow paths F5 and F6 directed to the gas chromatograph 4.

Next, the durbin 11 charged with liquid nitrogen is lowered to pull up the trap tube 9 from the liquid nitrogen, and then the heater 10 is energized to heat the trap tube 9 .

As a result, argon, which is a trace gas component that has been cooled and trapped by liquid nitrogen, is expelled as the trap tube 9 is heated, and is directed to the gas chromatograph 4 through the switching valve V3, the flow path F5, the switching valves V4 and F6 in order. is sent out.

<Oxygen removal step>
In the oxygen removal step, oxygen is removed from the trace gas components delivered from the trap tube 9 .

Specifically, oxygen is adsorbed and trapped from trace gas components introduced into the oxygen trap 12 by the carrier gas CG through the flow path F6 and removed.

Here, regarding the separation of oxygen and argon by the oxygen trap 12, oxygen is adsorbed and removed by passing trace gas components through the oxygen trap 12, and only argon is detected. The oxygen trap 12 is generally commercially available, and its effectiveness deteriorates when it adsorbs a large amount of oxygen. Since the oxygen in the components is in trace amounts of ppm level, aging regeneration of the oxygen trap 12 is rarely necessary.

<Gas Component Separation Process>
In the gas component separation step, the trace gas component from which oxygen has been removed is separated into a plurality of types of gas components excluding the oxygen component by the main column portion.

Specifically, the trace gas components from which oxygen has been removed are separated into argon, nitrogen, and other gas components in the main column portion 4a.

Here, under general conditions, the gas components introduced into the main column portion 4a are separated into argon+oxygen and nitrogen, and argon and oxygen are not separated and detected as one peak. In contrast, in the present invention, by providing the oxygen trap 12 in the preceding stage of the main column portion 4a, oxygen is adsorbed and collected by the oxygen trap 12, and as a result, argon is detected as a single peak. Become.

<Detection process>
In the detection step, a plurality of types of gas components from which oxygen has been removed in the previous stage are detected.

Specifically, a plurality of types of gas components are detected by a detector 13 such as a thermal conductivity detector. The gas subjected to this detection is then discharged outside the concentration measuring device 1 .

The detection result is output by the PC 15 of the data processing device 14 as indicated by a thick line arrow and displayed on a display (not shown) or printed.

The above measuring method is executed by automatic control by the PC 15 and the control unit 16 . Alternatively, it may be executed manually.

As described above, according to the measurement method of the present embodiment, human complexity is avoided, the method for collecting the water to be measured which becomes the sample water, the sensitivity is improved by the concentration operation, and countermeasures are taken to prevent deterioration of the column due to a large amount of sample water. Therefore, it is possible to measure, with high accuracy, trace gas components that are present in water such as ultrapure water.

Next, the embodiment shown in FIG. 2 will be described.

FIG. 2 shows the overall configuration of another embodiment of the apparatus for measuring concentration of trace gas components in water according to the present invention.

In this embodiment, the introduction unit 2 as introduction means for introducing the water to be measured into the measuring device 3 is changed from the embodiment shown in FIG. Since there is no change in other configurations, the same reference numerals are given.

In this embodiment, a flexible container 25 (for example, a medical infusion bag or the like) is used in place of the metallic sample cylinder 5 of the previous embodiment. Only the water to be measured is collected in this flexible container 25 so as not to contain air components. Furthermore, the flexible container 25 is connected to the flow path F1 communicating with the flow path F2 of the measuring device 3, and is housed in the pressure case 26 and installed. Stop valves ST1 and ST2 are attached to the upstream and downstream flow paths F1 of the flexible container 25, respectively.

Next, the measuring method according to this embodiment will be described.

<Introduction process>
In the introduction step, a predetermined amount of the water to be measured that is present due to the presence of trace gas components is introduced into the measuring device 3 as measuring means.

Specifically, first, the water to be measured is enclosed in a flexible container 25 having an inner volume of about 1 L so as not to contain air components, and then connected to the flow path F1 of the introduction unit 2 .

After that, the stop valves ST1 and ST2 are carefully opened, and the flexible container 25 is slightly pressurized from the outside with a purge gas PG2 (the type of purge gas is not limited, but He is recommended to prevent contamination). Then, the water to be measured is pushed out to the downstream side of the flow path F1 and then introduced into the metering tube 6 through the flow path F2.

In addition to the above, the flexible container 25 may be installed at a position above the measuring device 3, and the water to be measured may be adjusted to flow through the flow paths F1 and F2 on the downstream side to the measuring tube 6 by its own weight. .

From <Water Separation Process> to <Detection Process>
Since the steps from <air-water separation step> to <detection step> in the above-described embodiment are performed in exactly the same manner, the description is omitted.

Furthermore, according to the present embodiment, the same effects as those of the above-described embodiment can be exhibited, so the description will be omitted.

<Example>
Next, an embodiment of concentration measurement by the apparatus 1 for concentration measurement of trace gas components in water according to the present invention shown in FIG. 1 or 2 will be described. Since both figures are carried out in the same way, in the following description, an example of concentration measurement by the apparatus 1 for measuring the concentration of trace gas components in water shown in FIG. 1 will be described.

<Measurement of standard gas>
Before the measurement of the water to be measured, the above <introduction step> to <detection step> were performed for the standard gas containing predetermined amounts of argon and helium.

Specifically, the standard gas Ar 1000 ppm/He was connected to the flow path F2, loaded into the measuring tube 6 of the switching valve V1, and then all the steps from <introduction step> to <detection step> were sequentially performed to perform the measurement. . Incidentally, the standard gas Ar 1000 ppm/He is loaded with 0.3324 μg in a measuring tube of 200 μL at 20° C. and 1 atm.

The chromatographic data, which are the measurement results obtained by the detector 13, are processed by the PC (personal computer) 15 of the data processing device 14 and displayed on a display device (not shown) as the standard gas chromatographic data shown in FIG. or printed out. As shown in FIG. 3, 0.3324 μg of argon was measured at a height of 2518 μV at a retention time of 6.062 minutes. Although the peak position of oxygen appears superimposed on the peak position of argon, the reliability of the measurement result of argon shown in FIG. 3 is extremely high because oxygen is not contained in the standard gas. Further, even if the standard gas contains oxygen, in this example, the oxygen is reliably removed in the <oxygen removal step>, so the oxygen peak is not measured, and the argon gas is The reliability of the measurement results of is maintained at a high level. The result of this argon measurement was used as a reference for subsequent measurement of argon in the water to be measured.

<Measurement of water to be measured 1>
As the water 1 to be measured, ultrapure water in which a small amount of argon is present and which has not been degassed was prepared, and the above-mentioned <introduction step> to <detection step> were performed.

Specifically, the water 1 to be measured was prepared and supplied to the metal sample cylinder 5, and then all the steps from <introduction step> to <detection step> were sequentially performed to carry out the measurement.

The chromatographic data, which is the measurement result obtained by the detector 13, is processed by the PC (personal computer) 15 of the data processing device 14, and is displayed on the display device as chromatographic data of trace gases present in the water 1 to be measured shown in FIG. (not shown) or printed out. As shown in FIG. 4, argon was detected as a peak with a height of 360 μV at a retention time of 5.897 minutes, and the concentration was measured as 0.0407 μg (203.5000 ppb when converted to concentration in water). The argon peak retention time of 5.897 minutes for the measured water 1 coincides with the argon peak retention time of 6.062 minutes for the standard gas, and the reliability of the argon measurement results shown in FIG. 4 is high. there were. Moreover, the content of argon was reliably measured in spite of the minute order of ppb. In addition, the oxygen present in the sample water 1 is reliably removed in the <oxygen removing step> in this embodiment, so that the peak of oxygen is not measured, and the peak of argon is not measured. Reliability of results remains high. In FIG. 4, the peak to the right of the arcon indicates nitrogen gas.

<Measurement of water to be measured 2>
Ultrapure water containing a small amount of argon after degassing was prepared as the water 2 to be measured, and the above <introduction step> to <detection step> were performed.

Specifically, the water 2 to be measured was prepared and supplied to the metal sample cylinder 5, and then all the steps from <introduction step> to <detection step> were sequentially performed to carry out the measurement.

The chromatographic data, which are the measurement results obtained by the detector 13, are processed by the PC (personal computer) 15 of the data processing device 14, and are displayed on the display device as chromatographic data of trace gases present in the water 2 to be measured shown in FIG. (not shown) or printed out. As shown in FIG. 5, a peak of 44 μV in height was detected for argon at a retention time of 5.925 minutes, and the concentration was measured as 0.0047 μg (23.5000 ppb when converted to concentration in water). The argon peak retention time of 5.925 minutes for the measured water 2 coincides with the argon peak retention time of 6.062 minutes for the standard gas, and the reliability of the argon measurement results shown in FIG. 5 is high. there were. Moreover, the content of argon was reliably measured in spite of the minute order of ppb. In addition, the oxygen present in the sample water 2 is reliably removed in the <oxygen removal step> in this embodiment, so the oxygen peak is not measured, and the argon measurement Reliability of results remains high. In FIG. 5, the peak to the right of the arcon indicates nitrogen gas.

As shown in the measurement results of the examples in FIGS. 4 and 5, according to the apparatus 1 for measuring the concentration of trace gas components in water of the present invention, trace gases contained in the sample waters 1 and 2 (on the order of ppb) Content) of argon can be reliably measured with high precision without being affected by oxygen, and the reliability is also very high.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible. For example, the introduction means may be configured to supply the water to be measured to the flow path F2 of the measuring device 3 through the flow path F1 online without using the metallic sampling cylinder 5 or the flexible container 25. .

1 Concentration measurement device for trace gas components in water 2 Introduction unit 3 Measurement device 4 Gas chromatograph 4a Main column 5 Metal sample cylinder 6 Measuring tube 7 Pre-column 8 Air-water separation unit 9 Trap tube 10 Heater 11 Duavin 12 Oxygen trap 13 Detector 14 Data processing device 15 PC (personal computer)
25 Flexible container V1-V4 Switching valve F1-F6 Flow path ST1-ST4 Stop valve

Claims (7)

A concentration measurement method for trace gas components in water for measuring the concentration of trace gas components present in water by a measuring means using a gas chromatograph, comprising:
an introducing step of introducing a predetermined amount of the water to be measured in which the trace gas component is present into the measuring means;
a gas-water separation step of separating the water to be measured introduced into the measuring means into the trace gas component and water by a pre-column;
a concentration step of cooling and concentrating the trace gas component separated from water;
a delivery step of heating the concentrated trace gas component and delivering it to the main column portion;
an oxygen removing step of removing oxygen from the delivered trace gas component;
a gas component separation step of separating the oxygen-removed trace gas component into one or more gas components excluding the oxygen component by the main column portion;
A concentration measurement of a trace gas component in water characterized by measuring the concentration of the trace gas component present in water by successively proceeding with a detection step of detecting one or more of the separated gas components. Method. In the introducing step, a predetermined amount of the water to be measured is introduced into the measuring means in a state separated from the outside air,
2. The method for measuring the concentration of trace gas components in water according to claim 1, wherein the water separated in the gas-water separation step is discharged out of the measuring means by allowing a purge gas to flow backward in the pre-column portion. 3. The method according to claim 1, wherein the trace gas component measured in the detection step is one or more of argon, methane, carbon monoxide, carbon dioxide, krypton, and xenon. Method for concentration measurement of trace gas components in water. An apparatus for measuring the concentration of trace gas components in water, which measures the concentration of trace gas components present in water by a measuring means using a gas chromatograph,
introduction means for introducing a predetermined amount of water to be measured into the flow path of the measurement means;
air-water separation means for separating the water to be measured introduced into the flow path of the measurement means into the trace gas component and water by a pre-column;
concentrating means for cooling and concentrating the trace gas component separated from water, heating the concentrated trace gas component, and delivering the concentrated trace gas component to the main column portion;
oxygen removing means for removing oxygen from the sent trace gas component;
gas component separation means for separating the trace gas components from which oxygen has been removed into one or more types of gas components excluding the oxygen component by the main column portion;
and detection means for detecting one or more of the separated gas components. The introducing means is a metal sample cylinder or a flexible container capable of being filled with a predetermined amount of the water to be measured, and is connected to the flow channel and is separated from the outside air. is designed to introduce into
5. The concentration of trace gas components in water according to claim 4, wherein the gas-water separation means is formed so that the separated water is caused to flow back with a purge gas in the pre-column portion and is discharged outside the measurement means. measuring device. The flow path is provided with the water to be measured and the separated trace gas component by a working gas supplied into the flow path from the outside of the measuring means and a switching valve installed in the flow path. 6. The apparatus for measuring the concentration of trace gas components in water according to claim 4 or 5, wherein the apparatus is formed so as to be capable of transporting , moisture, and concentrated trace gas components. 7. The trace gas component measured by the detection means is one or more of argon, methane, carbon monoxide, carbon dioxide, krypton and xenon. 2. The apparatus for measuring the concentration of trace gas components in water according to item 1.

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