WO2009125493A1

WO2009125493A1 - Total organic carbon analyzer

Info

Publication number: WO2009125493A1
Application number: PCT/JP2008/057192
Authority: WO
Inventors: 将一明地; 浩久阿部; 陽一藤山
Original assignee: 株式会社島津製作所
Priority date: 2008-04-11
Filing date: 2008-04-11
Publication date: 2009-10-15

Abstract

[PROBLEMS] To use in a carbon dioxide separation part a gas-permeable membrane with which high-speed determination can be maintained and to diminish the influence of interfering ingredients. [MEANS FOR SOLVING PROBLEMS] An analyzer is provided which comprises: an organic-substance oxidation part where organic substances contained in a sample water supplied are oxidized into carbon dioxide; a carbon dioxide separation part where the carbon dioxide contained in the sample water which has passed through the organic-substance oxidation part is caused to permeate and move to a test water; and a conductivity measurement part where the conductivity of the test water from the carbon dioxide separation part is measured. The carbon dioxide separation part includes: a sample water channel where the sample water which has passed through the organic-substance oxidation part is caused to flow; an intermediate water channel where an intermediate water is caused to flow, the intermediate water having a pH value which is higher than that of the sample water flowing through the sample water channel and is in a neutral region; and a test water channel where the test water comprising deionized water is caused to flow. The sample water channel is in contact with the intermediate water channel through a gas-permeable membrane, and the intermediate water channel is in contact with the test water channel through a gas-permeable membrane.

Description

Total organic carbon measuring device

The present invention relates to a total organic carbon measuring device (also referred to as a TOC meter) that measures the total organic carbon content (TOC) in sample water, and is contained in, for example, pure water or ultrapure water with less impurities. The present invention relates to a total organic carbon measuring apparatus that separates an organic substance by a carbon dioxide separator and evaluates TOC by conductivity.

For the purpose of managing sample water with few impurities, such as pharmaceutical water, semiconductor manufacturing process water, cooling water, boiler water, and tap water, TOC measurement of organic substances contained in such water is performed.

The TOC measurement method includes a step of converting an organic substance in sample water into carbon dioxide in an oxidation reactor, a step of transferring carbon dioxide to measurement water through a gas permeable membrane, and measurement water in which carbon dioxide has moved. There is a method of measuring the TOC by the step of detecting the carbon dioxide concentration by sending it to a conductivity meter and measuring the conductivity (see Patent Documents 1 and 2).

For the measurement of carbon dioxide conductivity, at least two electrodes are placed at positions before and after oxidation of the sample water, and the TOC of the organic compound is determined by detecting the difference in conductivity before and after oxidation. There is a method of measuring (see Patent Document 3). One example is A-1000 manufactured by Anatel.

When measuring water with few impurities, such as semiconductors and pharmaceutical water, the organic substance is decomposed by ultraviolet light into carbon dioxide, and the method of measuring the conductivity via the carbon dioxide separator is a relatively small device It is known as a method that can measure with high accuracy.
Japanese Patent No. 2510368 JP 2006-90732 A JP 2001-281189 A

When organic substances are decomposed by ultraviolet light, a gas component other than carbon dioxide is generated from a compound containing elements other than carbon, such as nitrogen compounds contained in the compound, which moves with carbon dioxide and affects conductivity measurement. May interfere. As a method for avoiding such interference, a method using a carbon dioxide selective membrane that selectively transmits carbon dioxide as a gas permeable membrane has been proposed. However, since the carbon dioxide selective membrane is a non-porous membrane (gas molecules pass through gaps (about 3 to 10 mm) caused by thermal vibration of polymer chains), the permeation rate of gas components is slow and the measurement time is long. There are such disadvantages.

An object of the present invention is to provide a TOC measuring device that can maintain the high-speed measurement as the gas permeable membrane of the carbon dioxide separator and can suppress the influence of interference components.

In the present invention, as the gas permeable membrane of the carbon dioxide separation part, a membrane having no selectivity for carbon dioxide is used, such as a porous membrane usually used for maintaining high-speed measurement. On the other hand, intermediate water is interposed between the sample water and the measurement water with a gas permeable membrane therebetween. By adjusting the pH of the intermediate water to suppress gasification of the interfering component, the permeation of the interfering component from the intermediate water to the measuring water is suppressed. This achieves both reduction in the influence of disturbing components and high-speed measurement.

That is, the total organic carbon measurement device of the present invention oxidizes an organic substance in the supplied sample water to convert it into carbon dioxide, and allows carbon dioxide in the sample water that has passed through the organic substance oxidation part to permeate the measurement water. A carbon dioxide separation unit and a conductivity measurement unit that measures the conductivity of measurement water from the carbon dioxide separation unit are provided. And, the carbon dioxide separation unit is a sample water channel through which the sample water that has passed through the organic matter oxidation unit flows, an intermediate water channel through which intermediate water in a neutral region having a higher pH value than the sample water that flows through the sample water channel, And a measurement water channel through which measurement water made of deionized water flows, the intermediate water channel is in contact with the sample water channel via the first gas permeable membrane, the sample water side gas permeable portion, the measurement water channel, and the second gas permeable It has a structure provided with a measurement water-side gas permeation section that is in contact via a membrane.

In general, in the method of measuring the TOC by measuring the conductivity of the measurement water with a carbon dioxide separator, the sample water is used for the purpose of removing dissolved carbon dioxide components, promoting the movement of gas components to the sample water, and stabilizing the measurement. The sample water is strongly acidic due to the acid addition. When sample water containing nitrogen compounds such as urea is oxidized and decomposed with ultraviolet light under such strongly acidic conditions, nitric acid and nitrous acid are generated from the nitrogen compounds.

The abundance ratio of nitrous acid and nitrite ions varies depending on pH as shown in FIG. That is, it exists as nitrous acid which is a gas component under acidic conditions, and exists as nitrite ions from neutral to alkaline.

In the conventional TOC measuring device in which the sample water and the measurement water are in contact with each other through the gas permeable membrane in the carbon dioxide separator, the acidic sample water and the neutral measurement water are in contact with each other through the gas permeable membrane. The produced nitrous acid moves to the measurement water through the gas permeable membrane and becomes nitrite ions. As a result, nitrous acid has a positive disturbing effect in the direction of increasing conductivity in conductivity measurement.

On the other hand, in the present invention, there is an intermediate water channel through which intermediate region intermediate water having a higher pH value than the sample water flowing through the sample water channel flows between the sample water channel and the measurement water channel. Nitrous acid generated in water permeates the gas permeable membrane and moves to the intermediate water flow path, but maintaining the pH of the intermediate water near neutral reduces the abundance ratio of nitrous acid as a gas component. Become an ion. Since nitrite ions do not permeate the gas permeable membrane, the movement of nitrous acid into the measurement water can be suppressed.

When, for example, deionized water is used as the intermediate water and the measurement water, both are kept at a pH of 5 to 7 by dissolved carbonic acid. Under this condition, most of the carbonic acid component is a gas component, whereas most of nitrous acid exists as an ionic component. Since the moving speed of the gas from the intermediate water to the measuring water is determined by the concentration difference between them, the moving speed of nitrous acid, which is mostly present as ions, is lower than that of carbonic acid. By utilizing this speed difference and appropriately designing the film thickness of the gas permeable membrane between the intermediate water and the measured water and the wetted area with the membrane, the influence of nitrous acid on carbon dioxide can be reduced.

Thus, by providing the intermediate water flow path according to the present invention, it is possible to achieve both reduction of the influence of the interfering substance while maintaining the gas permeation rate of carbon dioxide at a high speed. As an interfering substance, nitrous acid is taken as an example, but if it is a component that exists in the gas state on the acidic side and ionizes from neutral to alkaline, the interfering influence can be suppressed.

However, although most of nitrous acid is ionized in the intermediate water, a part of it is transferred to the measuring water without being ionized, which affects the measurement. As a solution to this problem, in the present invention, (1) the first gas permeable membrane in which the contact time with the first gas permeable membrane per fixed volume of intermediate water in the sample water side gas permeable portion per fixed volume of sample water The contact time with the second gas permeable membrane per fixed volume of the intermediate water in the measurement water side gas permeation section, or the second gas permeable membrane per fixed volume of the measured water It was made to improve by making it shorter than the contact time.

The moving speed of the gas in the liquid across the gas permeable membrane depends on the gas concentration difference between the two liquids. When the gas concentrations of the two liquids become the same, the equilibrium is reached and the movement of the gas ends. In the sample water side gas permeation section, nitrous acid moves from the sample water to the intermediate water until the concentration of nitrous acid present as gas in the nitrous acid sample water and the intermediate water is the same, but the nitrous acid is ionized. Sample water having a pH of ₂ or less that can hardly be present as gas and intermediate water near pH ₇ where most of nitrous acid is ionized are present across the first gas permeable membrane. The concentration of nitrous acid hardly rises over time. Therefore, as the contact time with the first gas permeable membrane with a certain volume of intermediate water becomes longer than the contact time with the first gas permeable membrane with the sample water, an excessive amount of nitrous acid moves from the sample water to the intermediate water. It will be.

On the other hand, since most of carbon dioxide can exist as gas in the sample water and intermediate water, the difference in carbon dioxide concentration between the sample water and the intermediate water decreases with time. That is, the longer the contact time with the first gas permeable membrane of a certain volume of intermediate water, the higher the ratio of nitrous acid in the intermediate water as compared with carbon dioxide. If it becomes so, the ratio with respect to the carbon dioxide of the nitrous acid which moves from intermediate water to measurement water will increase, and the influence on measurement will become large. Therefore, by making the contact time with the first gas permeable membrane per fixed volume of intermediate water shorter than the contact time with the first gas permeable membrane per fixed volume of sample water, the sub-flow from the sample water to the intermediate water is reduced. It is possible to reduce the amount of nitrous acid transferred to the measurement water by suppressing excessive movement of nitric acid. This is the effect (1) of the present invention.

In the measurement water side gas permeation section, nitrous acid is mostly present as ions in the intermediate water, and the concentration of nitrous acid present as the intermediate water gas is low. Because the difference in nitrous acid concentration is small, the rate of nitrous acid transfer from intermediate water to measurement water is slow. On the other hand, since carbon dioxide is mostly present as gas in the intermediate water, the difference in carbon dioxide concentration between the intermediate water and the measured water is larger than that of nitrous acid, and more carbon dioxide is consumed in a shorter time than nitrous acid. Can move to the measuring water. From this, if the contact time with the gas permeable membrane per fixed volume of intermediate water is shorter than the contact time with the second gas permeable membrane per fixed volume of measured water, the moving speed of carbon dioxide to the measured water side Therefore, more carbon dioxide can be transferred to the measurement water for a fixed volume of measurement water than when the contact time between the intermediate water and the second gas permeable membrane of the measurement water is the same. On the other hand, since the movement speed of nitrous acid to the measurement water side is slow, only a small amount of nitrous acid can move to the measurement water in a short time, and the contact time with the second gas permeable membrane of intermediate water Therefore, most of the nitrous acid in the intermediate water passes through the measurement water gas permeation section without being transferred from the intermediate water to the measurement water. Therefore, by making the contact time with the second gas permeable membrane per fixed volume of the intermediate water shorter than the contact time with the second gas permeable membrane per fixed volume of the measured water, a constant volume compared to the case where it does not do so. The amount of carbon dioxide transfer from the intermediate water to the measurement water per shot can be increased, and at the same time, the amount of nitrous acid transferred from the intermediate water to the measurement water per fixed volume can be reduced. The proportion of carbon dioxide produced increases and the proportion of nitrous acid decreases, and the influence of nitrous acid on the measurement can be reduced. This is the effect (2) of the present invention.

The above (1) and (2) can be realized by making the flow rate of the intermediate water larger than the flow rate of the sample water or the measurement water. That is, (1) can be realized if the flow rate of the intermediate water is increased, and (2) can be realized if the flow rate of the intermediate water is larger than the flow rate of the measurement water. In addition, (1) and (2) can be implement | achieved simultaneously by making the flow volume of intermediate water larger than the flow volume of sample water and measurement water, and a bigger effect is acquired.

Further, the above (1), (1), (1), and (2) are also provided by covering only the intermediate water channel side of the gas permeable membrane of the sample water side gas permeable part or the measurement water side gas permeable part with a shielding film having a plurality of openings along the intermediate water channel. 2) can be realized. That is, if the shielding film is provided only on the intermediate water flow path side of the gas permeable membrane of the sample water side gas permeable part, (1) can be realized, and the shielding is provided only on the intermediate water flow path side of the gas permeable film of the measurement water side gas permeable part. If a film is provided, (2) can be realized. Then, by providing the shielding film only on the intermediate water flow path side of the gas permeable membrane of the sample water side gas permeable part and the measurement water side gas permeable part, (1) and (2) can be realized at the same time, and a greater effect can be obtained. .

In order to shorten the contact time of the intermediate water with the first or second gas permeable membrane, the distance between the sample water side gas permeable portion or the measurement water side gas permeable portion where the intermediate water and the gas permeable membrane are in contact with each other should be shortened. However, the movement of carbon dioxide in water is relatively slow due to diffusion (a few seconds is necessary). In order to move the carbon dioxide existing at the bottom of the flow path, the sample water side gas permeation section or the measurement water is used. A certain distance between the side gas permeable portions is necessary. If the intermediate water flow path side of the first or second gas permeable membrane is covered with a shielding film having a plurality of openings along the intermediate water flow path, the distance between the sample water side gas permeable portion or the measurement water side gas permeable portion. The contact time between the intermediate water and the first or second gas permeable membrane can be shortened without shortening.

One form of the carbon dioxide separation part is one in which the sample water channel, the first gas permeable membrane, the intermediate water channel, the second gas permeable membrane, and the measurement water channel are laminated and integrated.

In this way, if the sample water channel, the first gas permeable membrane, the intermediate water channel, the second gas permeable membrane, and the measurement water channel are laminated and integrated, diffusion of carbon dioxide in the intermediate water As a result, it is possible to measure with a small number of samples, and as a result, it is possible to realize a short-time measurement. The stacking direction of the sample water flow channel, the first gas permeable membrane, the intermediate water flow channel, the second gas permeable membrane, and the measurement water flow channel may be the horizontal direction in addition to the vertical direction.

In that case, the sample water side gas permeation part and the measurement water side gas permeation part of the intermediate water flow path are separated by a partition wall, and the intermediate water is supplied so as to flow to the measurement water side gas permeation part via the sample water side gas permeation part. It is preferred that The sample water side gas permeation part and the measurement water side gas permeation part may be separated vertically, or may be separated left and right.

For example, when nitrous acid moves from sample water to intermediate water, it takes some time for nitrous acid to change into nitrite ions. If nitrous acid comes into contact with the measurement water through the gas permeable membrane before the nitrous acid is changed to nitrite ions, nitrous acid may move to the measurement water. Therefore, when the sample water side gas permeation part and the measurement water side gas permeation part of the intermediate water flow path are divided to make the sample water side gas permeation part the upstream side, the intermediate water in contact with the sample water becomes the measurement water. It takes time to move before contact, and the nitrous acid can be changed into nitrite ions depending on the time, and the possibility that nitrous acid before ionization moves to the measurement water can be eliminated.

Further, the carbon dioxide separation unit may be laminated and integrated below the organic oxidation unit, and the conductivity measurement unit may be laminated and integrated below the carbon dioxide separation unit. You may do it. As a result, the entire TOC device can be reduced in size. The conductivity measuring unit may be stacked on the left and right of the carbon dioxide separation unit.

The pH setting is important for intermediate water. As the intermediate water, in addition to pure water and deionized water, a buffer solution whose pH is set in a neutral region can also be used.

In the TOC meter of the present invention, an intermediate water channel is provided in the carbon dioxide separator, and the intermediate region intermediate water having a higher pH value than the sample water flowing through the sample water channel of the carbon dioxide separator is circulated in the intermediate water channel. The intermediate water channel includes a sample water channel and a sample water side gas permeation unit that is in contact with the first gas permeable membrane, a measurement water channel and a measurement water side gas permeation unit that is in contact with the second water permeable membrane. In this way, the interfering component is captured by the intermediate water and is prevented from penetrating to the measurement water side, so that it is possible to realize continuous measurement at high speed while suppressing the influence of the interfering component. .

It is sectional drawing which shows typically one form of the carbon dioxide separation part in the TOC meter of this invention. It is sectional drawing which shows typically the other form of the carbon dioxide separation part in the TOC meter of this invention. It is sectional drawing which shows typically the other form of a carbon dioxide separation part. It is sectional drawing which shows typically the other form of a carbon dioxide separation part. It is a graph which shows the molecular component ratio with respect to pH of nitrous acid and a carbon dioxide. It is the schematic which shows the 1st form of a TOC meter. It is the schematic which shows the 2nd form of a TOC meter. It is the schematic which shows the 3rd form of a TOC meter. It is sectional drawing which shows one Example of the integrated TOC meter. It is sectional drawing which shows the other Example of the integrated TOC meter. It is a graph which shows the influence of the obstruction component with respect to the flow volume of intermediate water. It is another graph which shows the influence of the obstruction component with respect to the flow volume of intermediate water.

Explanation of symbols

2 Sample water flow path 4 Intermediate water flow path 4a Sample water side gas permeation section 4b Measurement water side gas permeation section 4c Connection section 4d Connection flow path 6 Measurement

water flow paths

8, 10

Gas permeation membranes

14, 16 Shielding membrane 18

Partition walls

20, 40 Carbon dioxide separation unit 24 Organic matter oxidation unit 26 UV lamp 30 Ion exchange resin 34

Conductivity meter

42, 44 Syringe 46 Syringe pump

FIG. 1A, FIG. 1B, and FIG. 2 are sectional views schematically showing some examples of the carbon dioxide separator in the embodiment. In the following description, there are places where dimensions are specifically shown, but these numerical values are merely examples, and do not limit the scope of the present invention.
In the carbon dioxide separation unit in FIG. 1A, the sample water channel 2, the intermediate water channel 4, and the measurement water channel 6 are stacked vertically and integrated with the intermediate water channel 4 interposed therebetween. The sample water that has passed through the organic matter oxidizing section (not shown here) that oxidizes the organic matter in the supplied sample water and converts it into carbon dioxide flows into the sample water flow path 2. A neutral region intermediate water having a pH value higher than that of the sample water flows through the intermediate water channel 4. Measurement water made of deionized water flows through the measurement water flow path 6. The sample water channel 2 and the intermediate water channel 4 are in contact via a gas permeable membrane 8, and the intermediate water channel 4 and the measurement water channel 6 are also in contact via a gas permeable membrane 10. That is, the intermediate water flow path 4 includes a sample water side gas permeable portion in contact with the sample water flow path 2 via the gas permeable film 8 (first gas permeable film) on the upper side, and the gas permeable film 10 (second second) on the lower side. The measurement water side gas permeation section is provided in contact with the measurement water flow path 6 through the gas permeation membrane.

As described above, (1) if the contact time with the gas permeable membrane per fixed volume of intermediate water is shorter than that of the sample water, an excessive amount of nitrous acid is prevented from moving from the sample water to the intermediate water. (2) If the contact time with the gas permeable membrane per fixed volume of intermediate water is shorter than the measurement water, a large amount of carbon dioxide can be measured while suppressing the movement of nitrous acid from the intermediate water to the measurement water. Can be taken into water. In this embodiment, in order to achieve the above (1) and (2), the flow rate of the intermediate water is larger than that of the sample water or the measurement water, so that the gas

permeable membranes

8 and 10 per fixed volume of the intermediate water The contact time is shorter than that of sample water or measurement water.

Moreover, in the example of FIG. 1B, in order to suppress the movement of interfering components such as nitrous acid from the sample water to the intermediate water and from the intermediate water to the measuring water, the gas

permeable membranes

8 and 10 on the side of the intermediate water flow path 4 are used. Further, shielding

films

14 and 16 for adjusting the exposed areas of the gas

permeable films

8 and 10 on the intermediate water flow path 4 side are provided. When the flow rates of the sample water, the intermediate water, and the measurement water are the same by providing the shielding

films

14 and 16 that adjust the exposed areas of the gas

permeable membranes

8 and 10 toward the intermediate water flow path 4 according to the areas of the

openings

14a and 16a. However, the contact time with the gas permeable membrane per fixed volume of intermediate water is set to be shorter than that of the sample water or the measurement water.

In this way, by controlling the movement of nitrous acid from the sample water to the intermediate water, or suppressing the movement of nitrous acid from the intermediate water to the measuring water and increasing the amount of carbon dioxide transferred, Since the ratio of carbon dioxide to nitrous acid can be increased, the influence of interfering components in the measurement can be reduced. The same applies to the examples of FIGS. 2 and 3 below. The shielding

films

14 and 16 shown in the example of FIG. 1B are not particularly limited. For example, an adhesive fluororesin having a thickness of about 100 μm (for example, NEOFRON EFEP (Daikin Industries, Ltd. (Registered trademark)) film and PDMS (polydimethylsiloxane) (for example, Dow Corning Sylgard 184 (registered trademark)) film can be used.

The carbon dioxide separation unit shown in FIG. 2 includes a sample water side gas permeation unit 4a in contact with the sample water channel 2 via the gas permeable membrane 8 by the partition wall 18 and the measurement water channel via the gas permeable membrane 10. The sample water side gas permeation part 4b is divided into contact with the measurement water side gas permeation part 4b, and the sample water side gas permeation part 4a and the measurement water side gas permeation part 4b are connected by a connecting part 4c provided at the end. The intermediate water is supplied so as to flow from the sample water side gas permeation unit 4a to the measurement water side gas permeation unit 4b via the connection unit 4c. The other structure is the same as that of the carbon dioxide separation part of FIG.

The carbon dioxide separation unit shown in FIG. 3 includes a sample water side gas permeation unit 4 a that contacts the sample water channel 2 via the gas permeable membrane 8, and a measurement water side gas permeation unit 4 b that contacts the sample water channel 6 and the gas permeable membrane 10. And the sample water side intermediate water part 4a and the measurement water side intermediate water part 4b are connected by a connecting channel 4d, and the intermediate water is supplied from the sample water side gas permeation part 4a to the measurement water side. It is supplied so as to flow to the gas permeable part 4b.

The measured water from any of the carbon dioxide separators in FIGS. 1 to 3 is led to a conductivity measuring unit (not shown) in order to measure its conductivity.
2 and 3, similarly to the example of FIG. 1B, the shielding

membranes

14 and 16 are provided on the intermediate water flow path 4 side of the gas

permeable membranes

8 and 10 so that the gas permeation per fixed volume of the intermediate water is achieved. It is also possible to adjust the relationship between the contact time with the membrane and the contact time with the gas permeable membrane per fixed volume of sample water or measurement water.

FIG. 5 is a schematic diagram of the first form of the TOC meter. In order to supply the sample water to the carbon dioxide separation unit 20 shown in FIG. 1 or FIG. 2, the sample water is supplied to the sample water flow path by the pump 22 via the organic matter oxidation unit 24. The organic oxidation unit 24 includes an ultraviolet irradiation unit that irradiates the sample water with ultraviolet rays from the ultraviolet lamp 26, and the organic matter is oxidized to carbon dioxide by the ultraviolet irradiation while the sample water flows through the ultraviolet irradiation unit. The organic matter oxidation unit 24 may be integrated with the carbon dioxide separation unit 20, or may be configured separately and connected by a flow path. The sample water that has passed through the sample water flow path 2 of the carbon dioxide separator 20 is discharged.

The ion exchange water is supplied to the measurement water channel 6 of the carbon dioxide separator 20 as deionized water. As for the ion exchange water, pure water stored in the liquid reservoir 28 is sucked by the pump 32 and supplied to the measurement water flow path 6 of the carbon dioxide separation unit 20 through the ion exchange resin 30. The conductivity of the measurement water that has passed through the measurement water channel 6 is measured by the conductivity meter 34. The conductivity is the conductivity by carbon dioxide that has moved from the intermediate water to the measurement water in the carbon dioxide separator 20. The measured water that has passed through the conductivity meter 34 is returned to the liquid reservoir 28 and reused. The conductivity meter 34 may also be provided integrally with the carbon dioxide separator 20, or may be configured separately and connected by a flow path.

In the intermediate water channel 4, pure water or deionized water is supplied as intermediate water at a larger flow rate than the sample water and the measurement water. The deionized water that has passed through the ion exchange resin 30 may be supplied separately to the intermediate water flow channel 4 side and the measurement water flow channel 6 side so that the flow rate on the intermediate water flow channel 4 side is larger. The intermediate water comes into contact with the sample water through the gas permeable membrane on the sample water flow path side, and also comes into contact with the measurement water through the gas permeable film on the measurement water flow path side. The intermediate water that has passed through the intermediate water flow path 4 is discharged.

FIG. 6 schematically shows a configuration of one form of the TOC meter using the carbon dioxide separator shown in FIG. The carbon dioxide separation unit 40 is separated into a gas exchange unit 40a on the sample water side and a gas exchange unit 40b on the measurement water side. The intermediate water flow path 4 is separated into a sample water side gas permeation part 4a and a measurement water side gas permeation part 4b, and a connection between them is connected. The other configuration is the same as the TOC meter shown in FIG.

FIG. 7 shows an example of a form in which a common syringe pump is used to maintain a constant flow rate ratio between the intermediate water flow rate and the measured water flow rate. As shown in FIG. 5, the carbon dioxide separator 20 is shown in the embodiment of FIG. 1A, FIG. 1B or FIG. 2, but is separated into the sample water side and the measurement water side as shown in FIG. It may be what was done. What was supplied with the pump 32 via the same ion exchange resin 30 as intermediate water and measurement water is used. Measurement water flows from the measurement water flow path 6 through the conductivity meter 34. The intermediate water is passed through the intermediate water flow path 4.

Valves

48 and 50 are respectively provided in the flow paths in which the intermediate water and the measurement water are returned to the liquid reservoir 28, and two

syringes

42 and 44 of one syringe pump 46 are respectively provided to adjust the respective flow rates. It is connected to the flow path. When flowing the intermediate water and measurement water, the

syringes

42 and 44 are simultaneously sucked with the

valves

48 and 50 closed, and the intermediate water and measurement water are flowed at a flow rate determined by the inner diameter of each

syringe

42 and 44. . After the measurement is completed, the

valves

48 and 50 are opened, and the

syringe

42 and 44 are switched in the discharge direction, whereby the intermediate water and the measurement water sucked into the

syringes

42 and 44 are returned to the liquid reservoir 28.

As described above, when two

syringes

42 and 44 are attached to one syringe pump 46 and the intermediate water discharged from the intermediate water flow path 4 and the measurement water discharged from the measurement water flow path 6 are sucked simultaneously, By selecting the diameters of the

syringes

42 and 44, the flow rate ratio between the intermediate water and the measured water can be maintained at a predetermined constant value. By maintaining the flow rate ratio between the intermediate water and the measurement water constant, the distribution ratio of the gas component from the intermediate water to the measurement water is maintained constant, and the reproducibility of the measurement is enhanced.

Next, an embodiment in which the organic matter oxidation unit 24, the carbon dioxide separation unit 20, and the conductivity meter 34 are integrated will be described with reference to FIG. When the front and back surfaces of each substrate are distinguished from each other, the upper surface is referred to as “front surface” and the lower surface is referred to as “back surface” in the state of FIG.

The organic matter oxidation unit 24 is composed of a substrate 60 on the side on which ultraviolet rays are incident and a substrate 62 bonded thereto. As one substrate 60, a quartz substrate that transmits ultraviolet light is used in order to decompose organic substances with ultraviolet light. Of the substrate 60, the portion where the ultraviolet rays are incident becomes an ultraviolet incident portion. The substrate 60 is provided with a through hole 64 serving as a sample water introduction port and a through hole 66 serving as a sample water discharge port. A quartz substrate is also used as the other substrate 62. An oxidation portion flow path 68 having one end at the position of the sample water inlet 64 is formed on the surface of the substrate 62. A sample water channel 2 having one end at a position corresponding to the sample water discharge port 66 is formed on the back surface of the substrate 62. The substrate 62 is provided with a through hole 70 that connects the other end of the oxidation unit flow path 68 and the other end of the sample water flow path 2, and a through hole 72 that connects one end of the sample water flow path 2 and the sample water discharge port 66. It has been. A light shielding metal film 33 that defines an ultraviolet irradiation region is formed on the back surface of the substrate 62, that is, the surface opposite to the bonding surface with the substrate 60. The light shielding metal film 33 is, for example, a Pt / Ti film having a thickness of 0.05 μm or more (a titanium film formed as an adhesion layer and a platinum film formed thereon).

The oxidation portion flow path 68 and the sample water flow path 2 are not particularly limited in size, but have a width of about 1 mm, a depth of 0.2 mm, and a length of about 200 mm, for example, wet etching or dry etching. The through holes 64, 66, and 70 can be formed by sandblasting or the like. Bonding between the

substrates

60 and 62 can be realized by hydrofluoric acid bonding.

The conductivity meter 34 is formed by bonding the back surface of the quartz substrate 80 to the electrode pattern 76 made of a Pt / Ti film formed on the quartz substrate 74 via a film 78 having a flow path portion cut off. .

Examples of the film 78 include an adhesive fluororesin (for example, 100 μm-thick NEOFLON EFEP (registered trademark of Daikin Industries)) film and PDMS (polydimethylsiloxane) (for example, 100 μm-thick Dow Corning Sylgard). 184® film is used. On the electrode pattern 76, a flow path through which measurement water flows is formed by a film 78.

The electrode pattern 76 can be formed by sputtering a Pt / Ti film and patterning it by photolithography and etching used in the fields of semiconductor manufacturing processes and microfabrication technology. Is not particularly limited. Further, the film for forming the flow path on the electrode pattern 76 is not limited to the neoflon film or the PDMS film, but can be realized by an adhesive organic film or a thin film coated with an adhesive, and is limited to these methods. Is not to be done.

A measuring water channel 6 is formed on the surface of the quartz substrate 80, and the measuring water branch channel 82 connected to one end of the measuring water channel 6 and the other end of the measuring water channel 6 are connected to the electrodes of the conductivity meter 34 on the quartz substrate 80. A through hole 84 connected to the flow path of the pattern 76 is formed. Further, the quartz substrate 80 is also provided with a through hole 86 serving as an intermediate water branch channel for guiding intermediate water and a through hole 88 serving as an intermediate water discharge port for discharging the intermediate water. The thickness of the quartz substrate 80 is not particularly limited, but, for example, that having a thickness of 1 mm is used.

The quartz substrate 74 is also provided with a through hole 90 serving as an ion exchange water introduction port for supplying ion exchange water as deionized water and a through hole 92 serving as an ion exchange water discharge port for discharging excess ion exchange water. Yes. The ion exchange water introduction port 90 is connected to the measurement water branch channel 82, the intermediate water branch channel 86, and the ion exchange water discharge port 92 by a channel formed by the PDMS film 78 sandwiched between the

substrates

74 and 80. .

The quartz substrate 74 is connected to a through hole 94 serving as a measurement water discharge port for discharging measured water after detection from the flow path of the electrode pattern 76 of the conductivity meter 34, and an intermediate water discharge through hole 88 of the quartz substrate 80. In addition, a through hole 96 serving as an intermediate water discharge port for discharging intermediate water is also opened.

The two gas permeable membranes 2 constituting the carbon dioxide separation unit between the back surface of the substrate 62 constituting the organic oxidation unit 24 and the surface of the substrate 80 constituting the unit of the conductivity meter 34. 6 are joined. A PDMS film 98 is sandwiched between the gas

permeable membranes

2 and 6, a gap is formed by the thickness of the PDMS film 98, and the intermediate water flow path 4 is formed by the pattern of the PDMS film 98. The intermediate water channel 4 is formed in such a shape that one end is connected to the intermediate water branching channel 86 for introducing intermediate water of the quartz substrate 80 and the other end is connected to the through hole 88 for discharging the intermediate water.

The sample water channel 2 is formed between the gas permeable membrane 2 and the substrate 62, and the gas

permeable membranes

2, 6 and the substrate 62 are formed so that the measurement water channel 6 is formed between the gas permeable membrane 6 and the substrate 80. , 80 are sealed with a film such as a PDMS film.

The gas

permeable membranes

8 and 10 are not particularly limited, and those having no selectivity for carbon dioxide are used. As such gas

permeable membranes

8 and 10, for example, a porous fluororesin membrane (for example, a pore fluorocarbon having a thickness of 30 μm; manufactured by Sumitomo Electric Fine Polymer Co., Ltd.) can be used.

In this embodiment, the sample water is introduced from the sample water introduction port 64 of the substrate 60, and is discharged from the oxidation unit channel 68 through the sample water channel 2 and from the sample water discharge port 66. In the meantime, the sample water is oxidized by being irradiated with ultraviolet light at the oxidation unit 24 and comes into contact with the intermediate water through the gas permeable membrane 8 of the carbon dioxide separation unit 20, and gas components such as carbon dioxide are distributed to the intermediate water. .

イオン Ion exchange water is generated outside the apparatus and introduced from the ion water exchange water inlet 90. Most of the introduced ion exchange water is discharged as it is from the ion exchange water discharge port 92, but only a necessary flow rate is supplied from the measurement water branch channel 82 to the measurement water channel 6, and from the intermediate water branch channel 86. It is supplied to the intermediate water channel 4.

Since the intermediate water flow path 4 is in contact with both the gas permeable membrane 2 in contact with the sample water and the gas permeable membrane 6 in contact with the measurement water, the gas component entering from the sample water reaches equilibrium with ions in the intermediate water. A gas component is distributed to the measurement water and discharged to the outside through the intermediate

water discharge ports

88 and 96. The measurement water is discharged from the measurement water discharge port 94 through the conductivity meter 34 after receiving the gas component in the measurement water channel 6.

FIG. 9 shows another embodiment in which the organic matter oxidation unit 24, the carbon dioxide separation unit 20, and the conductivity meter 34 are integrated. The difference between this embodiment and the embodiment of FIG. 8 is that the sample water side gas permeation section 4a and the measurement water side gas permeation section 4b of the intermediate water flow path 4 are separated by a partition, and the intermediate water passes through the sample water side gas permeation. That is, after passing through the portion 4a, the measurement water side gas permeation portion 4b flows.

PDMS films

98a, 98b, and 98c are sandwiched between the gas

permeable membranes

2 and 6, and the PDMS film 98c therebetween serves as a partition to pass through the intermediate water channel 4 through the sample water side gas permeable portion 4a and the measured water side gas permeable. It is separated from the portion 4b. Instead of the intermediate

water discharge ports

88 and 96 in FIG. 8, a discharge port 4e is provided at the downstream end of the measurement water side gas permeable portion 4b. Although not shown in FIGS. 8 and 9, in these embodiments as well, the gas

permeable membrane

8 or 10 contacts the gas

permeable membrane

8 or 10 per fixed volume of intermediate water on the intermediate water flow path 4 side of the gas

permeable membrane

8 or 10. A shielding film that shortens the time may be provided.

FIG. 10 shows the experimental results of evaluating changes in the influence of nitrous acid when sample water and measurement water are flowed at 100 μL / min and the flow rate of intermediate water is changed. As for the result of the broken line and the solid line, the sample water is a sodium carbonate aqueous solution, but the sample water of the broken line is a mixed solution containing sodium nitrite as a disturbing component. All sample waters had the same total concentration of dissolved components.

Further, FIG. 11 is a bar graph showing the relationship between the flow rate of the intermediate water, sample water, and measurement water and the TOC equivalent value when the measurement result of the inorganic carbon standard solution is 100%. In this experiment, using the chip in FIG. 9, a calibration curve was created using an inorganic carbon standard solution (mixed solution of sodium hydrogen carbonate and sodium carbonate), and the measurement result of the inorganic carbon standard solution was 100%. Of 1 mg C / L inorganic carbon standard solution and 0.18 mg N / L sodium nitrite mixed to measure urea.

According to the results of FIGS. 10 and 11, the flow rate of the intermediate water is smaller than that of the sample water and the measurement water, and the contact time with the gas

permeable membranes

8 and 10 per fixed volume of the intermediate water is shorter than that of the sample water and the measurement water. If it is long, excess nitrous acid moves from the sample water to the intermediate water, and the time that the nitrous acid stays in the intermediate water flow path becomes longer, so some of the nitrous acid is distributed to the measurement water, and interference effects appear. However, as is clear from FIG. 11, the measured value of the sample approaches 100% as the flow rate of the intermediate water becomes larger than that of the sample water and the measured water. The amount of nitrous acid transferred to the measurement water is suppressed by making the contact time with the gas

permeable membranes

8 and 10 per fixed volume of the intermediate water shorter than the sample water and the measurement water. I understand.

In addition, the inventors of the present application prepared a calibration curve using urea having a known TOC value as a sample, potassium hydrogen phthalate as a standard substance, and flowing sample water and measurement water at 100 μL / min. Measurement was performed by changing the flow rate of the intermediate water. As a result, the TOC measurement value when the flow rate of the intermediate water was 100 μL / min (time spent in the carbon dioxide separation unit 20: about 6 seconds) was 118% of the true value, but 200 μL / min (in the separation unit). The TOC measurement value at the time of stay: about 3 seconds) was 105% of the true value. Therefore, even in a sample such as urea that is actually measured, the flow rate of the intermediate water is made larger than that of the sample water or the measurement water, and the contact time with the gas

permeable membranes

8 and 10 per fixed volume of the intermediate water is determined as the sample water. It was also found that the movement of nitrous acid to the measurement water can be suppressed by making it shorter than the measurement water.

Each embodiment described above is an example, and does not limit a substrate material or a sealing material that can obtain an equivalent function, and it is not indispensable to form an integrated chip. The device configuration is not limited to the vertical stacking as in the embodiments of FIGS. 8 and 9, and the same function can be obtained by expanding in the plane direction.

Claims

An organic oxidation part that oxidizes organic substances in the supplied sample water and converts them into carbon dioxide;
A sample water channel through which the sample water that has passed through the organic oxidation part flows, an intermediate water channel through which intermediate water in a neutral region having a pH value higher than that of the sample water, and a measurement water flow through which measurement water including deionized water flows A carbon dioxide separator having a channel;
A conductivity measuring unit for measuring the conductivity of the measurement water from the carbon dioxide separation unit,
The intermediate water channel includes a sample water side gas permeation unit that contacts the sample water channel via a first gas permeable membrane, and a measurement water side gas permeation unit that contacts the measurement water channel and a second gas permeable membrane,
In at least one of the sample water side gas permeable portion and the measurement water side gas permeable portion, the contact time with the first or second gas permeable membrane per fixed volume of intermediate water is constant. The total organic carbon measuring device that is shorter than the contact time with the first or second gas permeable membrane per volume.
2. The total organic carbon measurement according to claim 1, wherein the contact time between the intermediate water and the gas permeable membrane is shortened because the flow rate of the intermediate water is greater than the flow rate of the sample water or measurement water. apparatus.
The contact time between the intermediate water and the gas permeable membrane is such that the surface of the first or second gas permeable membrane is covered with a shielding film having a plurality of openings along the intermediate water flow channel only on the intermediate water flow channel side. The total organic carbon measuring device according to claim 1, which is shortened by
4. The carbon dioxide separation unit according to claim 1, wherein the sample water flow path, the first gas permeable film, the intermediate water flow path, the second gas permeable film, and the measurement water flow path are laminated and integrated. The total organic carbon measuring device according to Item.
The sample water side gas permeation part and the measurement water side gas permeation part of the intermediate water channel are separated by a partition, and the intermediate water is supplied so as to flow to the measurement water side gas permeation part via the sample water side gas permeation part. The total organic carbon measuring device according to claim 4.
The total organic carbon measuring device according to claim 4 or 5, wherein the organic matter oxidizing part and the carbon dioxide separating part are laminated and integrated.
The total organic carbon measurement device according to any one of claims 4 to 6, wherein the carbon dioxide separation unit and the conductivity measurement unit are laminated and integrated.
The said organic matter oxidation part is equipped with the flow path through which sample water flows, and the ultraviolet-ray incident part for irradiating a sample water which flows through the flow path with an ultraviolet-ray in any one of Claim 1 to 7 Organic carbon measuring device.
The total organic carbon measurement apparatus according to any one of claims 1 to 8, wherein a buffer solution having a pH set in a neutral region is used as intermediate water.