JP4813416B2 - Sensor having wetted part and measuring method using the same - Google Patents

Description

  The present invention relates to a sensor having a wetted part and a measurement method using the same, and relates to, for example, a sensor for detecting characteristics such as pH and inorganic ion concentration of a sample solution extracted from soil and a measurement method using the same.

  Environmental water, biological water, industrial water, factory effluent, etc., may have drastic changes in the properties of the solution due to various coexisting components, and it is obliged to monitor continuously or regularly, or it is voluntarily managed. Often. It is also obliged to manage soil that has a deep relationship with environmental water. For such monitoring and management, various components in the solution such as the pH of the solution and the concentration of inorganic ions are listed as measurement items, and an ion sensor is useful as a simple detection means.

  Specifically, regarding a soil analysis method and apparatus for analyzing soil components, for example, as shown in FIG. 10, a plurality of components in soil 101 are combined with other ions as base compounds to extract and remove. Extraction step (a), (b) for adding a soil 101 to an aqueous solution 102 of salt and shaking to extract a plurality of components in the soil 101, and the extract 109a A substance (sulfuric acid) 111 that generates ions is added, and a plurality of components in the soil are measured from the precipitation / removal steps (e) and (f) for precipitating and removing the salt, and the extract 109b after the precipitate is removed. There has been proposed a soil analysis method and apparatus characterized by having an analysis step (g) (see, for example, Patent Document 1). Here, 103 is a reciprocating shaker, 104 is a supernatant, 105 is a supernatant removal device, 106 is a first filtration device, 107a and 107b are funnels, 108a and 108b are containers for receiving filtrate, 110 is a precipitation device , 112 is a second filtration device, and 113 is an analytical instrument.

  In recent years, as an ion sensor, in the ion electrode method, measurement is performed by immersing the sensor in a sample solution, or the sample solution is dropped on a flat sensor part, and both the liquid junction part and the response film are covered with a liquid. Measure in state. Therefore, the former and the latter require a sample solution of at least several ml or more and 0.3 ml or more.

Japanese Patent Laid-Open No. 11-37996

  However, the above-described sensor or the measurement method using such a sensor has some problems.

  (1) Since the solution obtained by extraction is a suspension, filtration with a filter is indispensable. However, in the filtration process, sample solution loss or change in concentration of measured components due to absorption or adhesion in the filter medium. May occur. In particular, when the sample solution that can be obtained is very small, such loss or the like becomes a large measurement error. In addition, a sufficient amount of sample solution may not be obtained due to filter clogging.

  (2) On the other hand, when measuring a sample solution containing suspended solids (hereinafter referred to as “suspension”), measurement errors may occur due to the suspended solids. It is essential to reduce this loss.

  (3) In the environmental measurement, since it may be assumed that a sample solution cannot be obtained sufficiently, measurement in a smaller amount may be required. In the conventional method, not only when the sample solution itself is a small amount, but also loss due to filtration, loss during collection and transfer of the sample solution cannot be ignored. In particular, the effect is large when there are many sample processing steps.

  (4) When measuring the concentration of inorganic ions in the soil using an ion electrode, suspended particles can be removed by filtration or centrifugation, but the process often requires a long time and the operation itself is complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sensor having a liquid contact portion that makes it possible to reduce the amount of a sample solution and improve the collection performance, and a measurement method using the sensor.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by a sensor having a liquid contact portion and a measurement method using the same, and have completed the present invention.

  The present invention is a sensor having a wetted part, a device having a sensing part that comes into contact with a sample solution, a cell responsible for introducing the sample solution into the sensing part, and the sensing attached to one end of the cell. And the sensing part and the cell are joined through the filter medium to form a sealed state.

  As mentioned above, for samples that require continuous or periodic monitoring, such as environmental water and soil, the sample solution prepared at the time of measurement is a suspension or a suspension of particles or powder. In many cases, the presence of such particles, powders, or suspended substances can cause measurement errors for sensors having wetted parts. Previously, these substances were filtered and then introduced into the sensor wetted part. However, if only a small amount of sample solution could be prepared due to loss of the sample solution during the sample processing process, measurement could be difficult. .

  In view of this, the present invention provides a filter medium in a cell that is joined to a sensing unit of a sensor and into which a sample solution is introduced, and the sensing unit and the cell form a sealed state, so that the pre-filtration as in the example of FIG. Even if the extract solution is a small amount, it can be directly introduced into the cell as a sample solution, and even with a small amount, the filtered sample solution can be brought into contact with the sensing unit. In addition, by covering the entire sensing part with the filter medium, the surface tension of the solution acts between the filter medium and the sensing part, and the sample solution can diffuse into the entire sensing part and form an even thin layer. It has become possible to handle a sample solution as a sufficiently measurable sensor. In particular, by appropriately selecting the flatness of the sensing unit and the gap between the filter medium and the sensing unit, the sample solution can form a uniform thin layer on the entire sensing unit. Furthermore, the filter medium covering the entire sensing unit also has a function of protecting the sensing unit. Therefore, it is possible to provide a sensor having a wetted part that can cope with a small amount of sample solution and has high collection performance by such a function.

  The present invention is a sensor having the above-mentioned liquid contact part, and has a shape in which an opening diameter of one end joined to the sensing part in the cell is narrowed to be smaller than an opening diameter of a sample solution introduction part, The filter medium is sandwiched between the one end and the device to form a sealed state.

  In a sensor using a normal liquid as a subject, it is preferable that the size of the liquid contact portion is small except for the case where two-dimensional information of the liquid is required because of the influence of disturbance and the quantitative limitation of the subject. On the other hand, when the sample solution is introduced into the cell, it is preferable that the opening diameter is large in order to prevent scattering of the solution and workability. In consideration of these, the present invention has a shape in which the opening diameter of one end portion of the cell is narrowed to be smaller than the opening diameter of the sample solution introduction portion, and the cell, the filter medium, and the sensing portion are integrally sealed by the one end portion. It has become possible to form a wetted part with the property. Therefore, even if the amount of the sample solution is small, the solution does not remain on the cell wall surface, and it is possible to provide a sensor having a liquid contact portion that can handle a small amount of the sample solution and has a high collection property. It was.

  The present invention is a sensor having the liquid contact part, wherein a sensor main body that accommodates the device and a holder part having the cell are rotatably joined with the joint part as a fulcrum, and the one end of the cell. Further, the filter medium is attached in a removable state.

  The filter medium used for removing particles, powder, suspended substances, etc. contained in the sample solution is preferably replaced for each measurement, but the ease of replacement is important. Further, according to the present invention, the holder portion having the cell can be rotated with the sensor body, and the above sealing performance can be ensured with high operability by the mounting structure in which the filter medium can be removed. Further, even when a substance collected from the filter medium contains a useful substance, it can be easily recovered.

  The present invention is a sensor having the liquid contact part, wherein an ion electrode including a liquid junction part is formed on the sensing part, and the ion concentration in the sample solution is measured.

  In general, the ion electrode method in solution measurement sometimes has a liquid junction in the solution in order to set a reference value, correct measurement error factors such as temperature, and the like. Conventionally, the sensing part and the liquid junction part are often separated from each other, and proper correction or the like is often difficult due to a difference in sensor installation conditions. In the present invention, by integrating these and forming an ion electrode including a liquid junction part in the sensing part, it is possible to improve the compensation accuracy by making the liquid contact conditions common and to make the apparatus compact. It becomes.

  The present invention is a sensor having the liquid contact part, wherein the filter medium is formed of a material that does not have an absorptivity or does not have an affinity for the sample solution.

  For the measurement of a small amount of sample solution, it is important how to achieve a uniform solution distribution in the sensing part, and it is important to prevent loss of the sample solution in the filter medium. In the present invention, the loss of the sample solution in the filter medium can be prevented by limiting the filter medium to a material that does not have an absorptivity with respect to the sample solution or is formed from a material having no affinity. In particular, when a material having no affinity is used, it is possible to reduce the residual sample solution in the pores of the filter medium, so that an even thin layer is formed between the filter medium and the sensing unit. It becomes possible. Therefore, it is possible to provide a sensor having a liquid contact portion that enables a further reduction in the amount of sample solution and improvement in collection performance. Specifically, as described later, when the base of the sample solution is water, such as environmental water, a non-water-absorbing / hydrophilic material such as PET (polyethylene terephthalate) is preferable.

The present invention is a measurement method using a sensor having any one of the above-mentioned wetted parts,
(1) A step of setting a filter medium in the cell of the sensor and fixing the cell and the sensing unit in a joined state;
(2) A process of preparing an extract when extraction is required for measurement such as soil and waste liquid, and preparing a stock solution when extraction such as environmental water is not required,
(3) liquid-solid separation of the extract or stock solution and collecting as a sample solution;
(4) Injecting the sample solution into the cell;
(5) measuring the physical or chemical characteristics of the sample solution in contact with the sensing unit or the concentration of a specific component in the sensing unit;
It is characterized by comprising.

  In the method for measuring the sample solution using the sensor, there is a request for a type in which the sample solution is supplied to the sensing unit and a type in which the sensing unit is immersed in the sample solution. In the conventional sensor, the former request is that the sample solution is supplied to the cell responsible for introducing the sample solution into the sensing unit as described above, so that particles, powder, suspended matter, etc. are contained in the sample solution. However, in the latter immersion type, in addition to the sealing property, it is sufficient to preliminarily perform the filtration process in the middle to ensure the sealing property of the sensing unit and the cell. It is necessary to immerse in the filtered sample solution. The sensor according to the present invention can meet both of these requirements. In the former case, the intermediate filtration treatment operation of the sample solution can be omitted, and in the latter case, the sample solution can be omitted. No prior filtration is required, and measurement is possible simply by immersing in the supernatant. The measurement method according to the present invention is a clarification of the former measurement method, and the measurement method using the sensor having any one of the liquid contact parts described above can reduce the amount of the sample solution and improve the collection property. It has become possible.

The present invention is a measurement method using a sensor having any one of the above-mentioned wetted parts,
(1) A step of preparing an extract when the sample solution requires extraction for measurement such as soil and waste liquid, and preparing a stock solution when extraction such as environmental water is required,
(2) liquid-solid separation of the extract or stock solution to produce a sample solution;
(3) a step of impregnating a sampling sheet functioning as a filter medium with the sample solution;
(4) setting the sampling sheet in the cell of the sensor, and fixing the cell and the sensing unit in a joined state;
(5) a step of measuring the physical or chemical characteristics of the sample solution in contact with the liquid or the concentration of a specific component;
It is characterized by comprising.

  As described above, the sensor according to the present invention can respond to both the type of supplying the sample solution to the sensing unit and the type of immersing the sensing unit in the sample solution. Filtration treatment operation in the middle of the solution can be omitted, and in the latter case, prior filtration of the sample solution is unnecessary, and measurement is possible only by immersing in the supernatant. The measurement method according to the present invention is a measurement method in which the former sample solution is transferred using a sampling sheet without using a container such as a spoid. In this case, a sampling sheet that functions as a filter medium is immersed in the supernatant of the undiluted solution, impregnated with the sample solution itself, set in a cell, and measured directly to measure the minimum amount of sample solution sufficient to cover the entire sensing area. Therefore, it is possible to reduce the amount of the sample solution and improve the collection property.

The present invention is a measurement method using a sensor having any one of the above-mentioned wetted parts,
(1) A step of setting a filter medium in the cell of the sensor and fixing the cell and the sensing unit in a joined state;
(2) A process of preparing an extract when extraction is required for measurement such as soil and waste liquid, and preparing a stock solution when extraction such as environmental water is not required,
(3) liquid-solid separation of the extract or stock solution to produce a sample solution;
(4) a step of immersing the sensor in the sample solution;
(5) measuring the physical or chemical characteristics of the sample solution in contact with the sensing unit or the concentration of a specific component in the sensing unit;
It is characterized by comprising.

  As described above, the sensor according to the present invention can respond to both the type of supplying the sample solution to the sensing unit and the type of immersing the sensing unit in the sample solution. Filtration treatment operation in the middle of the solution can be omitted, and in the latter case, prior filtration of the sample solution is unnecessary, and measurement is possible only by immersing in the supernatant. The measurement method according to the present invention clarifies the measurement method in the latter, and directly measures by using one of the sensors described above and immersing the extract or environmental water in the supernatant of the stock solution. After measurement, the sample solution introduced into the cell is returned to the original extract and stock solution by removing the sensor from the immersion liquid, so that the sample solution can be substantially reduced in volume and collected. It became possible to improve.

  As described above, according to the sensor of the present invention and the measurement method using the same, when measuring the physical or chemical characteristics of the sample solution or the concentration of a specific component, the sample solution is reduced in volume and the collection property is improved. Can be achieved. In particular, even when particles, powders, suspended substances, etc. are present in the sample solution, such sample solution can be directly measured, so that it is possible to perform measurement with excellent operability. Become.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Basic configuration of sensor having liquid contact portion according to the present invention>
FIG. 1A illustrates a basic configuration of a sensor (hereinafter referred to as “the present sensor”) having a liquid contact portion according to the present invention. This sensor includes a device 2 having a sensing unit 1 that comes into contact with a sample solution, a cell 3 that is responsible for introducing the sample solution into the sensing unit 1, and a filter medium that is attached to one end 3a of the cell 3 and covers the entire sensing unit 1 4, and the sensing unit 1 and the cell 3 are joined via the filter medium 4 to form a sealed state.

The device 2 is made of, for example, a semiconductor substrate made of p-type Si (silicon) and has a thickness of about 500 μm. The sensing unit 1 is provided at the center of one surface of the device 2 and forms, for example, a film having good passivation properties such as a silicon nitride (Si ₃ N ₄ ) film or tantalum pentoxide (Ta ₂ O ₅ ). As a result, the pH and ion concentration sensitive film of the sample solution and the response film corresponding to the physical or chemical phenomenon in the sample solution are formed. The MOS type field effect transistor (MOS type FET), the ion sensitive field effect A type transistor (ISFET) or a so-called chemical CCD (charge coupled device).

  Moreover, in this sensor, it is also preferable to provide the liquid junction part 1a in addition to the sensing part 1 on the device 2, as illustrated in FIG. By forming an ion electrode that integrates them, it is possible to measure changes in potential, etc. under uniform liquid contact conditions. This increases the accuracy of compensation for disturbances such as changes in ambient temperature, and reduces the size of the device. It becomes possible to plan. Moreover, it is preferable that the sensing unit 1 and the liquid junction 1a have higher flatness. By ensuring a uniform distribution state of the sample solution existing between the two in contact with the filter medium 4, it is possible to increase measurement accuracy and obtain a measurement value with good reproducibility.

  The cell 3 is required to have a function of appropriately introducing the sample solution into the sensing unit 1 through the filter medium 4 and a function of joining the sensing unit 1 and the cell 3 through the filter medium 4 to form a sealed state. The material and shape are selected according to the composition and the amount of liquid that can be used for measurement. The cell 3 is made of a material that can be used in terms of corrosion resistance, reactivity, etc., when the sample solution is prepared from general soil or environmental water, or from industrial wastewater containing various treatment liquids. Although different, in this sensor, a material having high liquid repellency is preferable, and considering the versatility of the sensor and the processability of the material, it is preferable to use plastics such as polyethylene, polypropylene, or PET. Stainless steel (SUS) or ceramics can also be used.

  The shape or structure of the cell 3 is not particularly limited as long as the above two functions are ensured, and can be any structure depending on the sensor measurement method, measurement items, specifications, and the like. is there. In this sensor, as illustrated in FIG. 1, it is preferable that the opening diameter Da of the one end portion 3a is narrowed down to be smaller than the opening diameter Db of the sample solution introducing portion 3b. This is because, in order to measure a small amount of the sample solution, the minimized sensing unit 1 that can ensure the measurement accuracy is preferable, but on the other hand, it is preferable that the opening diameter is large in order to prevent scattering of the solution when the sample solution is charged and workability. . Here, the side wall 3c of the cell 3 does not necessarily need to be straight (cone shape as a whole of the cell 3), but it is preferable to have an inclination and a middle bulge (or dent) in which no falling droplets remain. In the inventor's verification, it was found that the inclination angle θ is preferably in the range of about 0 to 60 ° with respect to the central axis M of the cell 3, and more preferably about 10 to 45 °. If it exceeds 60 °, it is necessary to increase the opening diameter Db of the sample solution introduction part 3b, and the residual liquid droplets on the cell wall surface 3c cannot be ignored.

  Further, in FIG. 1, in order to secure a sealed state, the filter medium 4 is fixed to the one end 3 a of the cell 3 by the O-ring 5, and the filter medium 4 is sandwiched with the device 2 by the one end 3 a to form a sealed state. . It is preferable to replace each measurement, and the structure that can be easily replaced by the mounting structure from which the filter medium can be removed can ensure the above-mentioned sealing performance as well as high operability.

  The filter medium 4 can be arbitrarily selected according to the properties of the sample solution, such as filtration performance and material. However, in this sensor, the material of the filter medium and the method of use can be selected according to the measurement method, including the case where it is used for collecting the sample solution. It is preferable to select. Here, as the filter medium 4 used in the present sensor, a membrane filter having a thickness of about 0.1 to 1 mm and a pore size of about 0.1 to 1 μm is preferable. In addition to being chemically stable and not affecting the sample solution or measurement, it is preferable to use a fiber filter, a mesh filter, a non-woven fabric, or the like that has flexibility that allows easy attachment to and removal from the cell. For example, glass fiber may cause alkali elution into the sample solution and may not be suitable for use as the present sensor. Moreover, the case where it has and does not have about the absorptivity or affinity with respect to a sample solution is demonstrated.

(1) Case of Absorbability or Affinity In this sensor, as illustrated in FIG. 1, the filter medium 4 has a structure that can be removed from the cell 3 at any time. At this time, when the filter medium 4 has an absorptivity or affinity, the sample solution can be transferred using a sampling sheet that functions as a filter medium without depending on a container such as a spoid. That is, the filter medium 4 is immersed in the sample solution, impregnated with the sample solution itself, and set in the cell 3 in this state, so that the sample solution impregnated on the entire surface of the sensing unit 1 can be in contact with the liquid. In particular, when a compressive force is applied to the filter medium 4 when the sensing unit 1 and the cell 3 are joined, more uniform liquid contact can be achieved on the entire surface of the sensing unit 1. At this time, since the amount of the sample solution necessary for the measurement is sufficient as the minimum amount sufficient to cover the entire surface of the sensing unit 1, it is possible to reduce the amount of the sample solution and improve the collection property. is there.

  At this time, there is a case where a material having an absorptivity or affinity for the material itself is used as the filter medium 4 as having absorptivity or affinity. In this case, a thin membrane filter is preferable because the sample solution is lost in an amount absorbed by the filter medium. Specific examples of the material include cellulose-based and acrylate-based fibers. On the other hand, the material itself does not have absorbability or affinity, but there are cases where the sample solution can be absorbed by capillary action in the voids of the filter medium 4. Although the range varies depending on the material, for example, a cellulose or acrylate membrane filter having a pore size of 0.2 to 10 μm or less can be used.

(2) Absorptivity or affinity A filter medium formed from a material that does not have an absorptivity or affinity for the sample solution, or an absorptivity or affinity while having a filtration function independent of the material. By using a filter medium that does not have a filter medium, it is possible to prevent loss of the sample solution in the filter medium. If a material that does not have affinity is used, the residual sample solution in the pores of the filter medium can be reduced, so that an even thin layer can be formed between the filter medium and the sensing part. Is possible. Therefore, it is possible to provide a sensor having a liquid contact portion that enables a further reduction in the amount of sample solution and improvement in collection performance. Specifically, non-water-absorbing / hydrophilic materials such as cellulose-based, silica-based, polyester-based, and fluorine-based fiber filters and nonwoven fabrics are preferable.

  In this sensor, as illustrated in FIG. 2, a sensor main body 6 that accommodates the device 2 and a holder portion 7 having a cell 3 are joined to each other so that the joint portion 6a can be rotated as a fulcrum. It is preferable that the filter medium 4 is attached to the part 3a in a removable state.

  As the mounting structure to which the filter medium 4 can be specifically removed, various structures are possible. For example, by fitting the filter medium 4 and the cell 3 with an O-ring 5 as shown in the state A of FIG. The structure which can be removed from the cell 3 by fixing and removing the filter medium 4 together with the O-ring 5 can be mentioned. Although various structures are possible for the structure in which the holder part 7 is joined to the sensor body 6, for example, as shown in FIG. 2, the holder part 7 remains in a state where the filter medium 4 and the cell 3 are joined in the state A. 7 and the sensor body 6 as a fulcrum, the sample solution is composed of the cell 3, the filter medium 4 and the sensing unit 1 as well as being able to be fixed at the joint surface 6b by rotating to the state B. It is possible to create a space for introducing a sealant and to ensure sealing performance by the O-ring 5. In addition, both of them may be fixed by fitting the outer peripheral surface 3d of the cell 3 and the inner peripheral surface 6d of the sensor body 6 without using a special fixing member, not only when fixing at the joint surface 6b. Is possible.

<Measurement method of sample solution using this sensor>
Next, a method for measuring a sample solution using the present sensor (hereinafter referred to as “the present measurement method”) will be described. In this measurement method, (A) a sample solution is dropped into a cell using a container such as a spoid as a solution transfer means, and the sample solution is supplied to a sensing unit using a diffusion function of a filter medium, (B There is a type in which a filter medium (sampling sheet) impregnated with a sample solution is set in the cell and the sample solution is supplied, and (C) a type in which the entire cell including the sensing unit is immersed in the sample solution.

(A) Method Using Diffusion Function of Filter Medium This measurement method is operated by the following process, and the sample solution is supplied to the sensing unit using the diffusion function of the filter medium in this sensor and the sample solution is measured. it can. In other words, by taking advantage of the filtration function and the sample solution reduction function of this sensor, the sample solution filtration process in the previous method can be omitted, and the sample solution can be reduced in volume and improved in sampling performance. Can do.

Specifically, as illustrated in FIG. 3, the operation is performed according to the following procedure.
(A-1) Step of setting the sensor As shown in FIG. 3A-1, the filter medium 4 is set in the cell 3 of this sensor, and the cell 4 and the sensing unit 1 are fixed in a joined state. Thereby, it is possible to prepare for the measurement of the sample solution by this sensor.
(A-2) Step of preparing extract or preparing undiluted solution When sample solution requires extraction for measurement such as soil and waste liquid, extract solution is prepared, and when extraction such as environmental water is required Prepare the stock solution. Specifically, for example, when soil is targeted, as shown in FIG. 3 (A-2), the soil 8 and water 9 are introduced into the container 10 and the extract 11 is stirred while stirring manually or automatically. Make it.
(A-3) Step of Collecting Sample Solution As shown in FIG. 3 (A-3), the prepared extract 11 (or stock solution) is subjected to liquid-solid separation, and the supernatant 10a is collected as a sample solution. By collecting the sample solution with the syringe 12, it is possible to efficiently collect even a small amount of the sample solution.
(A-4) Step of Injecting Sample Solution into Cell The sample solution collected in the syringe 12 is injected into the cell 3 from the sample solution introduction part 3b as shown in FIG. 3 (A-4).
(A-5) Step of measuring sample solution As shown in FIG. 3 (A-5), the introduced sample solution includes the sample solution 10b, the suspended substance 10c, and the like that are cleaned through the filter medium 4. The physical or chemical characteristics of the sample solution 10b or the concentration of a specific component is measured by the sensing unit 1 and the liquid junction unit 1a that are separated into the sample solution 10d and are in contact with the sample solution 10b.

(B) Method using the impregnation function of the filter medium with respect to the sample solution This measurement method is operated by the following process, and the sample solution is supplied to the sensing unit using the impregnation function of the filter medium with respect to the sample solution in this sensor. The solution can be measured. That is, by immersing a sampling sheet functioning as a filter medium in the sample solution and impregnating the sampling sheet with the sample solution, the sample solution can be supplied to the sensing unit and the sample solution can be measured. Since the entire sensing portion can be covered and measured with the minimum amount of sample solution impregnated in the sampling sheet, the sample solution can be reduced in volume and the collection property can be improved. In addition, the sampling sheet is not only capable of measuring with a small amount of sample solution, but also has an advantage in that even a small amount of sample solution that is widely distributed and difficult to collect can be collected and measured in the manner of wiping it off. Specifically, collection of a liquid sample adhering to a desk, collection of liquid exuding from a cut portion of a crop body, and the like are assumed.

Specifically, as illustrated in FIG. 4, the operation is performed according to the following procedure. In addition, description is abbreviate | omitted when it is the same as the operation procedure illustrated in the said FIG.
(B-1) Preparation of Extract or Preparation of Stock Solution As shown in FIG. 4 (B-1), preparation of the extract or preparation of the stock solution is performed by the same method as the operation of (A-2) above. Do.
(B-2) Step of Preparing Sample Solution As shown in FIG. 4 (B-2), the extract 11 (or stock solution) is subjected to liquid-solid separation, and the supernatant 10a is prepared as a sample solution.
(B-3) Step of Impregnating Sampling Sheet with Sample Solution As shown in FIG. 4 (B-3), the sampling sheet 4a (filter medium) is immersed in the supernatant 10a (sample solution) and impregnated therewith. At this time, it is possible to bring a clean sample solution into contact with the sensing unit 1 by impregnating only one surface of the sampling sheet 4a with the supernatant 10a while bringing the other surface into contact with the sensing unit 1.
(B-4) Step of fixing the sampling sheet to the cell and setting the sensor By the same method as in the state A of FIG. 2, the sampling sheet 4a is set in the cell 3, and as shown in FIG. The cell 3 and the sensing unit 1 are fixed in a joined state. At this time, the sample solution impregnated in the sampling sheet 4 a fixed to the cell 3 comes into contact with the sensing unit 1.
(B-5) Step of measuring sample solution The contacted sample solution is clean, and as shown in FIG. 4 (B-5), the sensing solution 1 and the liquid junction portion 1a are used to physically or Measure chemical properties, or concentrations of specific components.

(C) Method of immersing the entire cell in the sample solution This measurement method is operated by the following process. Using the immersion function of this sensor, the sample solution is applied to the sensing unit via the cell immersed in the sample solution. The sample solution can be measured. In other words, by directly measuring the sample solution using the filtration function of this sensor, it is possible to omit the sample solution filtration operation in the previous method, and after the measurement, the sensor is taken out from the immersion liquid. As a result, the sample solution introduced into the cell is refluxed to the original extract and the stock solution, so that the sample solution can be substantially reduced in volume and collected.

Specifically, as illustrated in FIG. 5, the operation is performed according to the following procedure. In addition, description is abbreviate | omitted when it is the same as the operation procedure illustrated to the said FIG.3 and FIG.4.
(C-1) Step of setting the sensor As shown in FIG. 5 (C-1), the cell 3, the filter medium 4 and the sensing unit 1 are fixed in a joined state.
(C-2) Preparation of extract or preparation of stock solution As shown in FIG. 5 (C-2), preparation of extract 11 or preparation of stock solution by the same method as the operation of (A-2) above. I do.
(C-3) Step of Preparing Sample Solution As shown in FIG. 5 (C-3), a sample solution is prepared by the same method as in the operation (B-2).
(C-4) Step of immersing the sensor in the sample solution As shown in FIG. 5 (C-4), the entire cell 3 of the sensor 20 is immersed in the supernatant 10a (sample solution). At this time, a clean sample solution can be brought into contact with the sensing unit 1 via the cell 3 (and the filter medium 4). In addition, when the sensor 20 is immersed, it is preferable to operate gently so that bubbles do not occur in the filter medium 4 and the sensing unit 1, but in this sensor, the generated bubbles pass through the inclined surface of the cell 3 and the sample. Since it is released into the solution 10a, its influence is small.
(C-5) Step of measuring sample solution As shown in FIG. 5 (C-5), the sample solution 10b cleaned through the filter medium 4 is introduced into the sensing unit 1 as the sample solution introduced, The sensing unit 1 and the liquid junction unit 1a measure the physical or chemical characteristics of the sample solution 10b or the concentration of a specific component.

  The measurement method was compared with the previous method. Specifically, as a conventional measurement method, a method (hereinafter referred to as “solution dropping method”) in which a filtered sample solution is dropped onto a sensing portion and measured, and the above (A) diffusion function of the filter medium is used as the present measurement method. The two methods were compared using a method using the method (hereinafter referred to as “sampling sheet method”). In the experiment, (1) the characteristics of the filter medium (sampling sheet) were confirmed, and then (2) the sample was used as soil, and after the predetermined treatment by each measurement method, the nitrate ion concentration in each sample solution was measured. .

(1) Confirmation of characteristics of filter medium (sampling sheet) (1-1) Experimental method As shown in FIGS. 6 (A) and (B), the characteristics of the sampling sheet are confirmed using the solution dropping method and the sampling sheet method. went.
In the solution dropping method, as shown in FIG. 6A, the syringe 12 was used to drop the sample solution directly onto the sensor device, and the sensing unit 1 and the liquid junction 1a were covered with the sample solution.
In the sampling sheet method, as shown in FIG. 6B, a 0.1 mm-thick water-absorbing sheet (nonwoven fabric made of cellulose) is used as the sampling sheet 4a, and the sampling sheet 4a impregnated with the sample solution is used as a sensing unit. 1 and the liquid junction 1a were grounded so as to cover.

(1-2) Experimental conditions An ion electrode (manufactured by Horiba, model TWIN: B-34 equivalent) was used as the sensing unit 1, and in both measurement methods, the potential of 20 ppm, 200 ppm and 2000 ppm potassium nitrate aqueous solution was measured. The amount of sample solution required for the measurement was measured.

(1-3) Experimental result In FIG. 7, the result of having measured the nitrate ion concentration by both methods is shown. It was confirmed that both results were almost the same.
Regarding the amount of sample solution required for measurement, in the solution dropping method, the surface tension between the sample solution and the surface of the sensing unit increases the thickness of the solution, which requires at least 0.3 ml of sample solution. there were.
On the other hand, in the sampling sheet method, although depending on the volume of the sampling sheet, the sampling sheet that has absorbed the sample by capillary action can cover the entire sensing portion and the liquid junction portion. As a result, the sample thickness was reduced and the volume could be reduced. As a result of actual measurement, a sample solution amount of 0.1 ml was sufficient.

(2) Comparison of measurement methods (2-1) Experimental method As shown in FIG. 8, using the solution dropping method and sampling sheet method, comparison of measured values of nitrate ion concentration by each measurement method when the sample was soil. Evaluation was performed. The nitrate ion concentration in the soil was confirmed by an ion chromatograph (manufactured by Shimadzu Corporation, model PIA-1000).
In the solution dropping method, (i) the soil 8 is extracted with water 9, (ii) the solid is separated by decantation, and the supernatant 10a is collected. (Iii) The sample solution filtered by the filter unit 13 is used as the sensing unit. 1 and the sample treatment of dropping on the liquid junction 1a was performed.
On the other hand, in the sampling sheet method, a glass fiber filter paper having a thickness of 0.5 mm is used as the sampling sheet 4a, and the step (iii) is performed by replacing the sampling sheet 4a placed on a flat ion electrode with a cell 3 (funnel-shaped support). Body) and adding a suspended soil extract from the top.
In addition, the sample solution in a suspended state without these treatments was measured without using a filter medium.

(2-2) Experimental conditions Using the same ion electrode as the above (1-1) as the sensing unit 1, in both measurement methods, the potential of various concentrations of potassium nitrate aqueous solution as shown in FIG. The amount of sample solution required was measured.

(2-3) Experimental results As shown in FIG. 9, the nitrate ion concentration in the soil extract was measured while the solution dropping method, the sampling sheet method and the suspension were used, and the results obtained by the ion chromatograph. Compared with.
The results measured by the solution dropping method and the sampling sheet method are in good agreement with the results measured by the ion chromatograph. Therefore, it was confirmed that the same result as that obtained by the solution dropping method can be obtained in the sampling sheet method.
However, in many cases, the results of measuring the suspension did not match the results measured by ion chromatography.
In addition, in the solution dropping method, it is necessary to obtain a sample that does not contain suspended substances that have been completely passed through a filter paper, and a sample solution in units of at least several ml is required for the amount of sample solution required for measurement. Further, in the filtering operation, the filter paper is often clogged and complicated.
On the other hand, in the sampling sheet method, it is not necessary for the sample to be completely filtered, and it is sufficient that the bottom surface of the sheet is wetted by the sample that does not contain suspended solids. Therefore, it was found that the sample preparation process can be simplified and the amount of measurement sample can be reduced.

  The above describes the case where the crop body and soil are targeted as the specific sample, but this method or this apparatus can also be applied to biological fluids, natural water, process products, groundwater or industrial / agricultural wastewater, If this sensor can be applied as a measuring means in a sample solution, a wider range can be applied in the field.

  In addition, the present invention is not limited to the case where a sample solution is introduced into a cell, it is also possible to use a cell as a reaction vessel, introduce a plurality of solutions into the cell, and track the reaction process or changes in the sample solution after the reaction. is there. It can be used for the neutralization reaction and verification of the production process of specific substances.

  As described above, the present invention can be suitably used for a sensor for measuring the ion concentration of a sample such as a solution, and can be applied not only to environmental measurement but also to a wide field such as food inspection and medical inspection.

  The measurement target (sample) may be any of gas, liquid, solid, and powder. Chemical sensing that reacts selectively with a specific sensitive layer in the sensing part and the charge fluctuation due to the interface phenomenon caused by physical contact It can be applied to any phenomenon.

Explanatory drawing which shows the basic structure of the sensor which has a liquid-contact part which concerns on this invention. Explanatory drawing which illustrates the structure of the holder part in the sensor which concerns on this invention. Explanatory drawing which illustrates the 1 measuring method which concerns on this invention. Explanatory drawing which illustrates 1 of the other measuring method which concerns on this invention. Explanatory drawing which illustrates 2 of other measuring methods concerning the present invention. Explanatory drawing which illustrates the experimental method of confirmation of the characteristic of the filter medium which concerns on this invention. Explanatory drawing which illustrates the experimental result of confirmation of the characteristic of the filter medium which concerns on this invention. Explanatory drawing which illustrates the experimental method for the comparative evaluation of the measuring method which concerns on this invention. Explanatory drawing which illustrates the experimental result for the comparative evaluation of the measuring method which concerns on this invention. Explanatory drawing which shows the soil analysis method which analyzes the soil component which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensing part 1a Liquid junction part 2 Device 3 Cell 3a One end part 3b Sample solution introduction part 3c Side wall 3d Outer peripheral surface 4 Filter medium 4a Joint part 5 O-ring 6 Sensor main body 6a Joint part 6b Joint surface 6d Inner peripheral surface 7 Holder part 8 Soil 9 Water 10 Container 10a Supernatant 10b Sample solution 10c Suspended substance 11 Extraction liquid 12 Syringe 20 Sensor Da, Db Opening diameter

Claims (7)

A device having a sensing unit in contact with the sample solution, a cell responsible for introducing the sample solution into the sensing unit, and a filter medium attached to one end of the cell and covering the entire sensing unit;
The sensing part and the cell are joined through the filter medium to form a sealed state ,
The cell is formed in a sealed state by sandwiching the filter medium detachably by the one end portion,
A sensor having a wetted part, wherein the filter medium is made of a material that does not absorb or has no affinity for the sample solution . Opening diameter of one end portion to be bonded to the sensing portion in the cell, the liquid contact portion of claim 1, wherein the benzalkonium which have a small grain incorporated shape than the opening diameter of the sample solution introduction part Having sensor. Sensor having a holder portion having a sensor body and the cells for accommodating the device, wetted according to claim 1, wherein the benzalkonium be joined pivotally to the joint portion as a fulcrum.   The sensor having a wetted part according to any one of claims 1 to 3, wherein an ion electrode including a liquid junction part is formed in the sensing part, and an ion concentration in the sample solution is measured. It is a measuring method using the sensor which has a liquid-contacting part in any one of Claims 1-4 ,
(1) A step of setting a filter medium in the cell of the sensor and fixing the cell and the sensing unit in a joined state;
(2) A process of preparing an extract when extraction is required for measurement such as soil and waste liquid, and preparing a stock solution when extraction such as environmental water is not required,
(3) liquid-solid separation of the extract or stock solution and collecting as a sample solution;
(4) Injecting the sample solution into the cell;
(5) measuring the physical or chemical characteristics of the sample solution in contact with the sensing unit or the concentration of a specific component in the sensing unit;
A measuring method using a sensor having a wetted part, characterized by comprising: It is a measuring method using the sensor which has a liquid-contacting part in any one of Claims 1-4 ,
(1) A step of preparing an extract when the sample solution requires extraction for measurement such as soil and waste liquid, and preparing a stock solution when extraction such as environmental water is required,
(2) liquid-solid separation of the extract or stock solution to produce a sample solution;
(3) a step of impregnating a sampling sheet functioning as a filter medium with the sample solution;
(4) setting the sampling sheet in the cell of the sensor, and fixing the cell and the sensing unit in a joined state;
(5) a step of measuring the physical or chemical characteristics of the sample solution in contact with the liquid or the concentration of a specific component;
A measuring method using a sensor having a wetted part, characterized by comprising: It is a measuring method using the sensor which has a liquid-contacting part in any one of Claims 1-4 ,
(1) A step of setting a filter medium in the cell of the sensor and fixing the cell and the sensing unit in a joined state;
(2) A process of preparing an extract when extraction is required for measurement such as soil and waste liquid, and preparing a stock solution when extraction such as environmental water is not required,
(3) liquid-solid separation of the extract or stock solution to produce a sample solution;
(4) a step of immersing the sensor in the sample solution;
(5) measuring the physical or chemical characteristics of the sample solution in contact with the sensing unit or the concentration of a specific component in the sensing unit;
A measuring method using a sensor having a wetted part, characterized by comprising:

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