Sulfur compound detector, method for producing the sulfur compound detector, and method for detecting sulfur compounds

Abstract

To provide a sulfur compound detector and detection method, which enable highly sensitive and easy measurement of sulfur compounds contained in a gas.SOLUTION: A sulfur compound detector of the present invention comprises a detection agent and a detection agent carrier carrying the detection agent. The detection agent contains a disulfide compound having a disulfide in a molecule and salts of a weak acid and a strong base. The detection agent carrier comprises fiber.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sulfur compound sensor, a method for producing the sulfur compound sensor, and a method for detecting a sulfur compound. In particular, it relates to a sulfur compound sensor and a detection method for detecting a sulfur compound present in a gas.

Background Art

[0002] Periodontal disease is the most prevalent disease found in people from children to the elderly, is associated with eating habits, smoking, etc., and is also known as one of the lifestyle diseases. Furthermore, it has become clear that periodontal disease and its treatment affect systemic diseases such as diabetes, coronary artery disease, and aspiration pneumonia. Therefore, performing appropriate periodontal disease treatment contributes not only to improving the oral health of the nation but also to maintaining and promoting overall health.

[0003] Currently, examinations for periodontal disease are mainly carried out by measuring the depth of the pocket, bleeding, X-ray examination, photography, bacterial examination, etc. However, since such examinations are basically carried out at a dental clinic, there is a problem that it is difficult in terms of time and money to regularly visit a dental clinic for examinations.

[0004] Therefore, it has been proposed to analyze the concentration of sulfur compounds, which are known as causative substances of bad breath in people suffering from periodontal disease, in exhaled breath. Analysis of exhaled breath has the advantages of being non-invasive, not causing pain to the subject, and not requiring special techniques.

[0005] As conventional analysis techniques for sulfur compounds in exhaled breath, semiconductor sensors using zinc oxide, cerium oxide, etc. (see Patent Documents 1, 2, Non-Patent Document 1), biosensors (see Non-Patent Document 2), crystal oscillator sensors (see Non-Patent Document 3), etc. have been proposed. Also, a method of detecting by contacting saliva with a detection paper containing lead acetate (see Patent Document 3) has been proposed.

[0006] For example, Non-Patent Document 1 discloses the existence of a commercially available breath odor meter called Breastron® II, which uses a semiconductor sensor made by coating and sintering cerium oxide on a comb-shaped electrode of a Pt thin film and can detect tens of ppb of hydrogen sulfide and methyl mercaptan in 30 seconds. Since this semiconductor sensor is also sensitive to organic compounds such as alcohol, interference from these gases is eliminated by passing the analytical gas through a mouthpiece with an acid-treated silica gel filter.

[0007] Non-patent document 2 discloses the detection of methyl mercaptan in an aqueous solution using a sensor that utilizes two enzymes: alcohol oxidase and horseradish peroxidase. The enzymes are immobilized on an osmium wire, and the detection of concentrations as low as 0.2 μM is possible by electrochemically detecting the H2O2 produced by the enzymatic reaction.

[0008] Non-patent document 3 discloses that it is possible to detect micrograms of hydrogen sulfide using a quartz crystal oscillator having a gas permeable membrane and a silver electrode.

[0009] However, the above-mentioned analytical techniques for sulfur compounds in exhaled breath had the problem of not being able to selectively and easily measure sulfur compounds.

[0010] For example, in the semiconductor sensor described in Non-Patent Document 1, it was necessary to combine multiple sensors and analyze the output in order to achieve selectivity, and it was also necessary to remove interfering gases through a filter. Furthermore, it was necessary to provide a heater to keep the semiconductor surface at a high temperature during measurement, and it was necessary to keep it powered at all times in order to extract the signal in real time. Non-patent document 2, which combines a biosensor using an enzyme reaction, has several problems: it requires highly specialized handling, is unstable due to being a biosensor, and the device is large. Non-patent document 3 required precise control of the temperature of the quartz crystal oscillator. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 01-035368 [Patent Document 2] Japanese Patent Publication No. 2004-108861 [Patent Document 3] Japanese Patent Publication No. 2004-309283 [Non-patent literature]

[0012] [Non-Patent Document 1] Kengo Suzuki, Tsuyoshi Ueda, "Measurement of Halitosis Components Using Semiconductor Gas Sensors," Electrochemistry, 2018, 86, 134-137. [Non-Patent Document 2] ZH Li, et al., “Design and characterization of methyl mercaptan biosensor using alcohol oxidase”, Sensors & Actuators B, 2014, 192, 680-684 [Non-Patent Document 3] F. He, et al., “A Novel QCM-based Biosensor for Detection of Microorganisms Producing Hydrogen Sulfide”, Anal. Lett., 2008, 41, 2697-2709 [Overview of the project] [Problems that the invention aims to solve]

[0013] The present invention aims to provide a sulfur compound detector and a detection method that can measure sulfur compounds contained in a gas with high sensitivity, high selectivity, and ease of use. [Means for solving the problem]

[0014] As a result of intensive studies in view of the above circumstances, the present inventors have found a sulfur compound detector and a detection method capable of highly sensitively and simply measuring sulfur compounds contained in a gas.

[0015] That is, the sulfur compound detector of the present invention includes a detection agent and a detection agent carrier material carrying the detection agent, the detection agent includes a disulfide compound having a disulfide in the molecule and a salt of a weak acid and a strong base, and the detection agent carrier material is characterized by including fibers.

[0016] The disulfide compound preferably further has a pyridine ring.

[0017] An electron-withdrawing group is preferably further bonded to the pyridine ring of the disulfide compound.

[0018] The salt of the weak acid and the strong base is preferably one or more salts selected from sodium acetate, sodium citrate, disodium hydrogen phosphate, and sodium hydrogen carbonate.

[0019] The detection agent carrier material is preferably made of cellulose fibers and is in a sheet shape or a flat plate shape.

[0020] The sulfur compound of the sulfur compound detector is preferably a volatile sulfur compound.

[0021] The method for producing the sulfur compound detector of the present invention includes a step of immersing the detection agent carrier material in a detection agent solution and a step of drying the detection agent carrier material immersed in the detection agent solution, and the detection agent solution is characterized by including the detection agent and a solvent.

[0022] The solvent may be ethanol, methanol, or isopropyl alcohol.

[0023] The present invention provides a method for detecting sulfur compounds, comprising: an exposure step of exposing a sulfur compound detector to a gas; a measurement step of measuring the amount of light absorbed or reflected by the sulfur compound detector exposed to the gas in the exposure step; and a detection step of detecting whether or not the gas contains a sulfur compound, and / or the amount of sulfur compound in the gas, based on the amount of light absorbed or reflected measured in the measurement step.

[0024] The present invention also provides a method for detecting sulfur compounds, comprising: an exposure step of exposing a sulfur compound detector to a gas; an image acquisition step of acquiring an image of the sulfur compound detector exposed to the gas in the exposure step; and a detection step of detecting, from the image obtained in the image acquisition step, whether or not a sulfur compound is present in the gas and / or the sulfur compound content of the gas. [Effects of the Invention]

[0025] The sulfur compound detector of the present invention enables the detection of sulfur compounds such as mercaptans, which are representative odor components, without requiring complex processes. Specifically, it is possible to measure the content of sulfur compounds in a gas even when the gas to be measured is in its gaseous state without dissolving it in a solution. Furthermore, the detection agent support material of the sulfur compound detector of the present invention contains fibers and can support a large amount of detection agent, so it is possible to measure the content of trace amounts of sulfur compounds with high sensitivity. Moreover, since the detection agent containing a salt of a weak acid and a strong base is supported on the sulfur compound detector, the content of sulfur compounds can be measured without adjusting the pH using a buffer solution during measurement. [Brief explanation of the drawing]

[0026] [Figure 1] An example of a method for producing a sulfur compound detector and a method for measuring sulfur compounds according to the present invention is shown. [Figure 2] An example of an absorbance spectrum obtained by measuring the absorbance of a gas using the sulfur compound detector of the present invention is shown. [Figure 3]An example of an absorbance spectrum obtained by measuring the absorbance of a gas using a comparative example sulfur compound detector is shown. [Figure 4] Another example of an absorbance spectrum obtained by measuring the absorbance of a gas using a comparative example sulfur compound detector is shown. [Figure 5] The absorbance spectrum obtained by measuring the absorbance of a gas using the comparative example sulfur compound detector shows the change in spectral intensity at a wavelength of 387 nm over time. [Figure 6] This shows the relative sensitivity of a sulfur compound detector when the detection agent carrier is made of fiber (example) and porous material (comparative example), depending on the relative humidity. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described in detail below.

[0028] The sulfur compound detector of the present invention comprises a detection agent and a detection agent support material.

[0029] (Sulfur compounds detected by sulfur compound detectors) The sulfur compounds detected by the sulfur compound detector of the present invention contain an S atom in their molecular structure, but it is preferable that they react with the detection agent described later, and that the properties of the detection agent, such as absorbance, differ before and after the reaction. It is especially preferable that the sulfur compound contains an SH group (also called a mercapto group, thiol group, etc.) in its molecular structure. Examples of sulfur compounds containing an SH group include mercaptan (CH3-SH) and hydrogen sulfide (H2S), but are not limited to these. Furthermore, while there are no restrictions on the form of the sulfur compound to be detected, whether gas or liquid (including dissolved in solution), as long as it reacts with the detection agent, it is preferable that it be a volatile sulfur compound. When the sulfur compound to be detected is volatile, the sulfur compound content in a gaseous sample can be easily determined by simply pre-treating the gaseous sample, such as breath, with a sulfur compound detector.

[0030] (Detector) The detection agent contains a disulfide compound having a disulfide molecule, and a salt of a weak acid and a strong base.

[0031] The disulfide compound contained in the detection agent is capable of reacting with the sulfur compound detected by the sulfur compound detector, and it is sufficient that the disulfide compound before the reaction and the reaction product after the reaction have different colors in terms of light absorption, light reflection, visual inspection, or image processing. For example, if the sulfur compound to be detected is mercaptan, and the disulfide compound that serves as the reaction starting material in the detection agent is 2,2'-dithiobis(5-nitropyridine), the disulfide group of the reaction starting material will cleave upon reaction with mercaptan, resulting in a reaction product containing a thiol group. At this time, the wavelength at which the light absorption of the reaction starting material is maximum is 310 nm, and the wavelength at which the light absorption of the reaction product is maximum is 425 nm. Alternatively, visually, the reaction starting material appears pale yellow, and the reaction product appears yellow. In particular, when measuring by absorbance, it is preferable that the difference between the wavelength at which the light absorption of the reaction starting material is maximum and the wavelength at which the light absorption of the reaction product is maximum is 25 nm or more.

[0032] The disulfide compound contained in the detection agent preferably further has a pyridine ring, and more preferably has an electron-withdrawing group bonded to the pyridine ring. Here, the electron-withdrawing group is a group that can accept π electrons from an aromatic ring when substituted with an aromatic group, such as a nitro group, cyano group, carbonyl group, carboxyl group, or sulfone group. When the disulfide compound has a pyridine ring or a pyridine ring to which an electron-withdrawing group is bonded, the reaction with the sulfur compound to be detected proceeds more easily. Furthermore, when the disulfide group is bonded to the 2nd or 4th position of the pyridine ring, the disulfide bond becomes more easily cleaved, and the reaction with the sulfur compound to be detected proceeds more easily.

[0033] Examples of disulfide compounds included in detection agents include disulfide compounds that do not contain a pyridine ring, disulfide compounds that contain a pyridine ring, and disulfide compounds that have a pyridine ring to which an electron-withdrawing group is attached. Specifically, examples include 2,2'-dithiobis(5-nitropyridine), 2-nitro-p-tolyl disulfide, pyritinol, bis(3-nitrophenyl) disulfide, 4,4'-dichloro-2,2'-dinitrobiphenyl disulfide, 2,2'-dibenzothiazole disulfide, 5,5'-dithiobis(2-nitrobenzoic acid), 2,2'-dipyridyl disulfide, 4,4'-dipyridyl disulfide, bis(2-nitrophenyl) disulfide, 6,6'-dithionicotinic acid, 4-methyl-2-quinolyl disulfide, and bis(5-(2-methoxyethoxy)-2-pyrimidinyl) disulfide.

[0034] The appropriate concentration of the disulfide compound contained in the detection agent varies depending on the concentration of the detection agent solution, the immersion time in the detection agent solution, the surface area or volume of the detection agent support material, etc., as described later. However, it can be primarily adjusted by the concentration added to the detection agent solution. The concentration of the disulfide compound relative to the detection agent solution is preferably adjusted in the range of 0.1 mM to 10 mM, and more preferably in the range of 0.1 mM to 1 mM.

[0035] The salts of weak acid and strong base contained in the detection agent adjust the pH of the detection agent to a neutral to basic range. For example, the pH is adjusted to around 5-8. In addition, the salts of weak acid and strong base enhance moisture retention, allowing the sulfur compound detection material containing fibers such as paper to adhere to it, thus enabling sensitive measurement of sulfur compounds in the sample. Examples of salts of weak acids and strong bases include sodium acetate, sodium citrate, disodium hydrogen phosphate, and sodium bicarbonate. One of these salts may be used, or two or more may be used in combination.

[0036] The concentrations of the weak acid and strong base salts contained in the detection agent vary depending on the concentration of the detection agent solution, the immersion time in the detection agent solution, and the surface area or volume of the detection agent support material, as described later. However, they can primarily be adjusted by controlling the concentrations of the salts added to the detection agent solution and the concentration of the disulfide compound. The concentrations of the weak acid and strong base salts in the detection agent solution should preferably be adjusted within the range of 5 mM to 100 mM, and more preferably within the ranges of 10 mM to 70 mM and 35 mM to 55 mM. Furthermore, it is desirable to adjust the concentrations of the salts of the weak acid and strong base to the molar concentration of the disulfide compound within a range of 5 to 600 times, and more preferably within a range of 10 to 60 times.

[0037] (Detector-carrying material) The detection agent carrier is a component that carries the above-mentioned detection agent and contains fibers. The inclusion of fibers in the detection agent support material allows for the effective adsorption of a large amount of sulfur compounds contained in the sample, especially in gases, and promotes the reaction between the adsorbed sulfur compounds and the detection agent. From the viewpoint of adsorption properties for the detection agent and the sulfur compound to be detected, the fibers contained in the detection agent support material are preferably fibers having polar groups, and more preferably cellulose fibers.

[0038] Furthermore, the detection agent support material is preferably in the form of a sheet or plate, such as paper or filter paper. The size of the detection agent support material is not limited as long as it can be placed in the detection agent immersion container or gas exposure container described later. For example, a size of about 2 cm x 2 cm is exemplified. If it is in the form of a sheet, it can be folded for immersion and exposure, so a larger size of detection agent support material may be used as needed to increase the adsorption area of ​​sulfur compounds contained in the sample. It is also possible to use a porous material containing silicon, such as porous glass, as the detection agent support material, but compared to the case where the detection agent support material is made of fiber, the reaction products produced by exposure to gas are more easily decomposed.

[0039] (Sulfur compound detector) The sulfur compound detector includes a detector support material on which the above-mentioned detector agent is supported and fixed, and it is possible to measure the presence and / or content of sulfur compounds in a gaseous sample, such as breath, without dissolving it in a solvent. From this perspective, it is possible to perform measurements more simply than with conventional techniques, which were limited to measuring solutions.

[0040] A sulfur compound detector, in which a salt of a disulfide compound, a weak acid, and a strong base is immobilized on a detection agent support material contained in fibers, can sensitively measure sulfur compounds in a sample in a gaseous state. Specifically, it can detect sulfur compounds at sub-ppm to ppb levels in a sample gas. For example, even with a sample gas of about 100 ml to 500 ml of exhaled breath, it can measure the presence and / or content of sulfur compounds such as mercaptans at a concentration of about 0.1 ppm.

[0041] (Method for manufacturing sulfur compound detectors) The present invention provides a method for producing a sulfur compound detector, comprising the steps of immersing a detector-supported material in a detector solution and drying the detector-supported material that has been immersed in the detector solution.

[0042] The step of immersing the detection agent-supported material in the detection agent solution is the step of immersing the above-mentioned detection agent-supported material in the detection agent solution containing the above-mentioned detection agent and solvent. The solvent can be any solvent that can dissolve the disulfide compound and the detection agent containing a salt of a weak acid and a strong base, and that can be dried with a nitrogen gas stream. Examples include ethanol, methanol, and isopropyl alcohol. The concentration of the disulfide compound in the detection agent solution is preferably adjusted to a range of 0.1 mM to 10 mM, and more preferably to a range of 0.1 mM to 1 mM. Furthermore, the concentrations of the weak acid and strong base salts in the detection agent solution are preferably adjusted to a range of 5 mM to 100 mM, and more preferably to a range of 10 mM to 70 mM or 35 mM to 55 mM. Additionally, the concentrations of the weak acid and strong base salts relative to the molar concentration of the disulfide compound are preferably adjusted to a range of 5 to 600 times, and more preferably to a range of 10 to 60 times. The immersion time should preferably be set within the range of 5 seconds to 24 hours or 1 minute to 24 hours, and it is also possible to set it within the range of 10 minutes to 12 hours. For example, a 2cm x 2cm paper sheet can be placed in a 3cm (width) x 3cm (depth) x 10cm (height) container filled with 25ml of detection agent solution and immersed for 1 hour to obtain a detection agent-carrying material immersed in the detection agent solution.

[0043] The step of drying the detection agent support material immersed in the detection agent solution can be carried out using any known drying method, but drying with a nitrogen gas stream is preferred. Specifically, examples include placing a detection agent support material immersed in a detection agent solution into a drying container and drying it by circulating a nitrogen gas stream. Examples of drying times include 6 to 48 hours and 12 to 24 hours for a nitrogen gas flow rate of 1 L / min. Vacuuming may also be used. A sulfur compound detector can be obtained by drying the detection agent-supported material.

[0044] (Method 1 for detecting sulfur compounds) The present invention provides a method for detecting sulfur compounds, comprising: an exposure step of exposing a sulfur compound detector to a gas; a measurement step of measuring the amount of light absorbed or reflected by the sulfur compound detector exposed to the gas in the exposure step; and a detection step of detecting the presence or absence of sulfur compounds in the gas and / or the sulfur compound content of the gas from the amount of light absorbed or reflected measured in the measurement step.

[0045] The exposure step, which involves exposing a sulfur compound detector to a gas, is a process of placing the sulfur compound detector in a sample gas and exposing it for a certain period of time. Specifically, examples include sealing the sample gas in a gas exposure container or bag, placing the sulfur compound detector inside, and exposing it for a certain period of time. The gas exposure container or bag can be any size that can accommodate the sulfur compound detector. The amount of sample gas is set in the range of approximately 100 ml to 2000 ml, although this depends on the detection conditions and the sulfur compound content. In particular, if the sample gas is exhaled breath, detection of mercaptan at a concentration of about 0.1 ppm is possible even with an amount of about 100 ml to 500 ml. Examples of exposure times include 30 minutes to 36 hours, 1 hour to 36 hours, and 1 hour to 6 hours. The exposure temperature should be any temperature at which the reaction between the sulfur compound and the detection agent proceeds, and room temperature (25°C) is preferred.

[0046] The measurement step for measuring the amount of light absorbed or reflected by a sulfur compound detector exposed to gas in the exposure process is a step that measures the absorbance (amount of light absorbed) in the thickness direction of the sulfur compound detector after the exposure process, or the amount of light reflected from the surface of the sulfur compound detector after the exposure process (amount of light reflected).

[0047] The detection step, which detects the presence or absence of sulfur compounds in a gas and / or the sulfur compound content of a gas based on the amount of light absorbed or reflected in the measurement step, detects the presence or absence of sulfur compounds in a sample gas and / or the content of sulfur compounds by measuring the intensity of the wavelength at which the absorption of light by the reaction product is maximum. For example, if the disulfide compound contained in the detection agent is 2,2'-dithiobis(5-nitropyridine), the wavelength at which the absorption of light by the reaction product is maximum is 425 nm. Therefore, the absorbance at a wavelength of 425 nm should be measured and analyzed.

[0048] Furthermore, a step may be added to measure the amount of light absorbed or reflected by the sulfur compound detector before exposing it to the sample gas in the exposure process. By measuring a blank value before the exposure process, it becomes possible to analyze the absorbance and other parameters after the exposure process more accurately.

[0049] (Method 2 for detecting sulfur compounds) The sulfur compound detection method of the present invention also includes an exposure step of exposing a sulfur compound detector to a gas; an image acquisition step of acquiring an image of the sulfur compound detector exposed to the gas in the exposure step; and a detection step of detecting the presence or absence of a sulfur compound in the gas and / or the sulfur compound content of the gas from the image obtained in the image acquisition step.

[0050] The exposure step, in which the sulfur compound detector is exposed to gas, is the same as in sulfur compound detection method 1 described above. This step involves placing the sulfur compound detector in the sample gas and exposing it for a certain period of time. Specifically, examples include sealing the sample gas in a gas exposure container or bag, placing the sulfur compound detector inside, and exposing it for a certain period of time. The gas exposure container or bag can be any size that can accommodate the sulfur compound detector. The amount of sample gas is set in the range of approximately 100 ml to 2000 ml, although this depends on the detection conditions and the sulfur compound content. In particular, if the sample gas is exhaled breath, detection of mercaptan at a concentration of about 0.1 ppm is possible even with an amount of about 100 ml to 500 ml. Examples of exposure times include 30 minutes to 36 hours, 1 hour to 36 hours, and 1 hour to 6 hours. The exposure temperature should be any temperature at which the reaction between the sulfur compound and the detection agent proceeds, and room temperature (25°C) is preferred.

[0051] The image acquisition process, which involves obtaining an image of a sulfur compound detector exposed to gas during the exposure process, acquires a digital image of the surface of the sulfur compound detector after the exposure process in order to perform information engineering processing. While digital images contain a lot of information, it is possible to obtain RGB values ​​related to color, among other things.

[0052] The detection step, which detects the presence or absence of sulfur compounds in a gas and / or the sulfur compound content of a gas from the image obtained in the image acquisition step, involves information engineering processing of the acquired image, image conversion, and extraction of information such as feature quantities (including RGB values) related to sulfur compound content, in order to analyze the sulfur compound content in the sample gas.

[0053] Furthermore, a step may be added to acquire an image of the surface of the sulfur compound detector before exposing it to the sample gas in the exposure process. By performing blank image processing before the exposure process, it becomes possible to analyze the image after the exposure process more accurately.

[0054] (Other methods for detecting sulfur compounds) The sulfur compound detection method of the present invention also allows for the visual detection of the presence or absence of sulfur compounds in the sample gas before and after exposure to the sulfur compound detector. Since the maximum absorbance of the reaction products is in the visible light range, the yellow color can be visually confirmed. When the disulfide compound contained in the detection agent is 2,2'-dithiobis(5-nitropyridine) and the sulfur compound to be detected is mercaptan, the reaction starting material is pale yellow and the reaction product is yellow. Visual detection is an even simpler method than other methods.

[0055] Furthermore, by placing a sulfur compound detector between an ultraviolet light-emitting diode with a central wavelength of 425 nm and a photodetector, detecting the light transmitted through the sulfur compound detector with the photodetector, and processing the output signal from the photodetector to output the change in absorbance of the sulfur compound detector, it is possible to detect sulfur compounds.

[0056] Furthermore, sulfur compounds can also be detected by irradiating a sulfur compound detector with an ultraviolet light-emitting diode having a central wavelength of 425 nm, detecting the reflected light with a photodetector, and processing the output signal from the photodetector to output the change in the reflected light of the sulfur compound detector. [Examples]

[0057] Next, the present invention will be described in more detail with reference to embodiments. Reference numerals are used in the description, but this does not limit the scope of the present invention.

[0058] (Embodiment 1) Figure 1 illustrates the method for producing and using a sulfur compound detector. First, detection solution 101 was prepared by dissolving 0.008 g of 2,2'-dithiobis(5-nitropyridine) and 0.12 g of sodium acetate in ethanol to a total volume of 25 ml. As shown in Figure 1(a), 25 ml of the detection agent solution 101 was placed in the detection agent immersion container 102 (100 ml beaker). As shown in Figure 1(b), a detection agent support material 103 made of fibers (manufactured by ADVANTEC, qualitative filter paper No. 1, 2 cm x 2 cm) was immersed in the detection agent solution 101 for 1 hour while protected from light.

[0059] The detection agent support material 103a, which had been immersed in the detection agent solution 101, was removed, and as shown in Figure 1(c), the detection agent support material 103a immersed in the detection agent solution was placed in a drying container and dried for 24 hours in a light-shielded state by circulating a nitrogen gas stream. Through this drying process, the detection agent consisting of 2,2'-dithiobis(5-nitropyridine), a disulfide compound, and sodium acetate, a salt of a weak acid and a strong base, was immobilized on the detection agent support material 103a.

[0060] Next, as shown in Figure 1(d), the absorbance in the thickness direction of the detection agent support material 103b on which the detection agent is fixed was measured. Specifically, the intensity I of the transmitted light transmitted through incident light with light intensity I0 was measured, and the absorbance (=log) was calculated. 10 (I0 / I)) was calculated.

[0061] Subsequently, as shown in Figure 1(e), the detection agent carrier 103b was placed in a sample gas containing 0.8 ppm mercaptan (methyl mercaptan) in a gas exposure container 104 (capacity 1000 ml), and the sample was exposed at room temperature (25°C) for 6 hours.

[0062] After exposure, the absorbance in the thickness direction of the detection agent-supported material 103c was measured, as shown in Figure 1(f).

[0063] The absorbance analysis results obtained in Figures 1(d) and (f) are shown in Figure 2. In Figure 2, the absorbance spectrum of the sample gas before exposure is shown by a dotted line, and the absorbance spectrum after exposure (immediately after and 18 hours later) is shown by a solid line and a dashed line. The absorption maximum wavelength of the reaction starting material 2,2'-dithiobis(5-nitropyridine) is 310 nm, and the absorption maximum wavelength of the reaction product 2-thiol5-nitropyridine is 425 nm. A large difference was observed between the solid line and the dotted line in the range of 380 nm to 500 nm, centered around the wavelength of 425 nm. At a wavelength of 425 nm, the absorbance before exposure was 2.98 au, while the absorbance after exposure was 3.18 au, resulting in an absorbance difference of 0.2 after exposure. Furthermore, since the wavelength range of 380nm to 500nm is in the visible region, the difference before and after exposure could be observed visually. Before exposure, the color was light yellow, and after exposure, it was yellow.

[0064] Furthermore, by preparing standard sample gases with varying mercaptan concentrations and performing similar spectrophotometric analysis, and creating a calibration curve using the absorbance at 425 nm, we were able to quantify the mercaptan concentration of the sample gas being detected.

[0065] (Comparative example) Regarding the comparative example, the method of producing the sulfur compound detector and the method of use will be explained using Figure 1. First, detection solution 101 was prepared by dissolving 0.01 g of 2,2'-dithiobis(5-nitropyridine) in ethanol to a total volume of 25 ml. Sodium acetate was not added at this stage. As shown in Figure 1(a), 25 ml of the detection agent solution 101 was placed in the detection agent immersion container 102 (100 ml beaker). As shown in Figure 1(b), a detection agent support material 103 made of fibers (manufactured by ADVANTEC, qualitative filter paper No. 1, 2 cm x 2 cm) was immersed in the detection agent solution 101 for 1 hour while protected from light.

[0066] The detection agent support material 103a, which had been immersed in the detection agent solution 101, was removed, and as shown in Figure 1(c), the detection agent support material 103a immersed in the detection agent solution was placed in a drying container and dried for 24 hours by circulating a nitrogen gas stream in a light-shielded environment. Through this drying process, the disulfide compound 2,2'-dithiobis(5-nitropyridine) was immobilized on the detection agent support material 103a.

[0067] Next, as shown in Figure 1(d), the absorbance in the thickness direction of the detection agent support material 103b on which the detection agent is fixed was measured. Specifically, the intensity I of the transmitted light transmitted through incident light with light intensity I0 was measured, and the absorbance (=log) was calculated. 10 (I0 / I)) was calculated.

[0068] Subsequently, as shown in Figure 1(e), the detection agent support material 103b was placed in a sample gas containing 1 ppm mercaptan in a gas exposure container 104 (capacity 1000 ml), and the sample was exposed at room temperature (25°C) for 6 hours.

[0069] After exposure, the absorbance in the thickness direction of the detection agent-supported material 103c was measured, as shown in Figure 1(f).

[0070] Figure 3 shows the absorbance analysis results obtained in Figures 1(d) and (f). In Figure 3, the absorbance spectrum of the sample gas before exposure is shown by a dotted line, and the absorbance spectrum after exposure (immediately after and 1 hour later) is shown by a solid line and a dashed line. The absorption maximum wavelength of the reaction starting material 2,2'-dithiobis(5-nitropyridine) is 310 nm, and the absorption maximum wavelength of the reaction product 2-thiol5-nitropyridine is 425 nm. No difference was observed between the solid and dotted lines in the range of 380 nm to 500 nm, centered at 425 nm. At a wavelength of 425 nm, the absorbance before exposure was 2.77 au, while the absorbance after exposure was 2.78 au, and the absorbance difference due to exposure was almost 0.01. Furthermore, since the wavelength range of 380nm to 500nm is in the visible region, the difference before and after exposure could be observed visually. The color was faint yellow both before and after exposure. From these results, it was found that if the detection agent does not contain salts of weak salts or strong bases, and the pH is not adjusted to neutral to basic, the disulfide group cleavage reaction proceeds slowly, and sulfur compounds are hardly detectable.

[0071] (Embodiment 2) The change in absorbance of the sulfur compound detector was measured under different manufacturing conditions (preparation conditions). Detector solution 101 was prepared by dissolving 0.008 g of 2,2'-dithiobis(5-nitropyridine) and sodium acetate (0.015 M, 0.035 M, 0.055 M) in ethanol to a total volume of 25 ml. As shown in Figure 1(a), 25 ml of the detection agent solution 101 was placed in the detection agent immersion container 102 (100 ml beaker). As shown in Figure 1(b), a fibrous detection agent support material 103 (manufactured by ADVANTEC, qualitative filter paper No. 1, 2 cm x 2 cm) was immersed in the detection agent solution 101 for 10 seconds or 3600 seconds (1 hour) while protected from light.

[0072] The detection agent support material 103a, which had been immersed in the detection agent solution 101, was removed, and as shown in Figure 1(c), the detection agent support material 103a immersed in the detection agent solution was placed in a drying container and dried for 24 hours in a light-shielded state by circulating a nitrogen gas stream. Through this drying process, the detection agent consisting of 2,2'-dithiobis(5-nitropyridine), a disulfide compound, and sodium acetate, a salt of a weak acid and a strong base, was immobilized on the detection agent support material 103a.

[0073] Subsequently, as shown in Figure 1(e), a sample gas containing 0.8 ppm mercaptan was placed in a gas exposure container 104 (capacity 1000 ml), into which the detection agent was immobilized. The sample was then exposed to room temperature (25°C) for 3 or 6 hours.

[0074] After exposure, the absorbance in the thickness direction of the detection agent-supported material 103c was measured, as shown in Figure 1(f).

[0075] The absorbance analysis results obtained in Figure 1(f) are shown in Table 1. Table 1 shows the absorbance at a wavelength of 425 nm after exposure to the sample gas.

[0076] [Table 1]

[0077] Table 1 shows that, under the same conditions except for the immersion time in the detection agent solution, a shorter immersion time resulted in a decrease in absorbance. In other words, when the amount of sulfur compound to be detected is the same, the amount of reaction from the disulfide compound (the reaction starting material) to the reaction product decreases. Furthermore, it was found that when the immersion time was extremely short, such as 10 seconds, the formation of reaction products was unstable, and the absorbance may decrease even when the concentration of sodium acetate increased.

[0078] Furthermore, it was found that when the immersion time in the detection agent solution was sufficiently long (1 hour) and the exposure time in the sample gas containing mercaptan was 3 hours, the reaction rate from the disulfide compound, the reaction starting material, to the reaction product tended to saturate at sodium acetate concentrations between 0.035 M and 0.055 M. Furthermore, it was found that when the immersion time in the detection agent solution was sufficiently long (1 hour) and the exposure time in the sample gas containing mercaptan was 6 hours, the reaction rate from the disulfide compound, the reaction starting material, to the reaction product tended to saturate when the amount of sodium acetate was 0.035 M.

[0079] (Evaluation Test 1) As mentioned above, it is possible to use a porous material containing silicon, such as porous glass, as the detection agent support material. However, compared to the case where the detection agent support material is made of fiber, as in the present invention, the stability of the reaction products was evaluated. Similar to the comparative example, the method for producing the sulfur compound detector and its usage will be explained using Figure 1. First, detection solution 101 was prepared by dissolving 0.008 g of 2,2'-dithiobis(5-nitropyridine) and 0.12 g of sodium acetate in ethanol to a total volume of 25 ml. As shown in Figure 1(a), 25 ml of the detection agent solution 101 was placed in the detection agent immersion container 102 (100 ml beaker). As shown in Figure 1(b), a detection agent support material 103 (manufactured by Panasonic, GEN0), which consists of a porous silica xerogel substrate, was immersed in the detection agent solution 101 for 24 hours under light-shielding conditions.

[0080] The detection agent support material 103a, which had been immersed in the detection agent solution 101, was removed, and as shown in Figure 1(c), the detection agent support material 103a immersed in the detection agent solution was placed in a drying container and dried for 24 hours by circulating a nitrogen gas stream in a light-shielded environment. Through this drying process, the disulfide compound 2,2'-dithiobis(5-nitropyridine) was supported on the porous material 103a.

[0081] Next, since the substrate is opaque, the reflected light from the detection agent support material 103b on which the detection agent is supported was measured. Specifically, incident light with light intensity I0 was reflected, the intensity I was measured using an integrating sphere, the reflectance was determined, and the Kubelka-Munk transform (KM transform) was performed.

[0082] Subsequently, as shown in Figure 1(e), the detection agent support material 103b was placed in a sample gas containing 3 ppm methyl mercaptan in a gas exposure container 104 (capacity 1000 ml), and exposed at room temperature (25°C) for 3 hours.

[0083] After exposure, the light reflectance of the detection agent-supported material 103c was measured.

[0084] Figure 4 shows the KM conversion results of the reflectance obtained before and after exposure. In Figure 4, the KM conversion spectrum of the sample gas before exposure is shown by a solid line, and the KM conversion spectra after exposure (immediately after and 1 hour later) are shown by dotted and dashed lines. The absorption maximum wavelength of the reaction starting material 2,2'-dithiobis(5-nitropyridine) is 310 nm, and the absorption maximum wavelength of the reaction product 2-thiol5-nitropyridine is 425 nm. A large difference was observed between the solid and dotted lines in the range of 380 nm to 500 nm, centered around the wavelength of 425 nm. At a wavelength of 425 nm, the conversion value before exposure was 0.488, while the conversion value immediately after exposure was 3.184, resulting in a difference of 2.696 after exposure. However, 1 hour after exposure, the conversion value decreased to 1.995, and the difference from the pre-exposure value decreased to 1.507. From the results of the above evaluation test 1, it was found that when the detection agent support material was a porous material, the detection agent initially generated reaction products upon gas exposure, but these products were not stable, and after 1 hour, the decomposition of these reaction products had progressed.

[0085] In contrast, as shown in Figure 2, when the detection agent support material was made of fiber, the reaction products generated by gas exposure of the detection agent showed no signs of decomposition even after 18 hours, indicating that the reaction products were stable.

[0086] (Evaluation Test 2) The long-term stability of reaction products was evaluated when the detection agent support material was a porous material containing silicon, such as porous glass. Similar to the comparative example, the method for producing the sulfur compound detector and its usage will be explained using Figure 1. First, detection solution 101 was prepared by dissolving 0.008 g of 2,2'-dithiobis(5-nitropyridine) and 0.12 g of sodium acetate in ethanol to a total volume of 25 ml. As shown in Figure 1(a), 25 ml of the detection agent solution 101 was placed in the detection agent immersion container 102 (100 ml beaker). As shown in Figure 1(b), a detection agent support material 103 (average pore diameter 4 mm, manufactured by Giken Kagaku Co., Ltd., AGGK-PG4-S), which is made of porous glass, was immersed in the detection agent solution 101 for 24 hours under light-shielding conditions.

[0087] The detection agent support material 103a, which had been immersed in the detection agent solution 101, was removed, and as shown in Figure 1(c), the detection agent support material 103a immersed in the detection agent solution was placed in a drying container and dried for 24 hours by circulating a nitrogen gas stream in a light-shielded state. Through this drying process, the disulfide compound 2,2'-dithiobis(5-nitropyridine) was supported on the porous glass of the detection agent support material 103a.

[0088] Next, as shown in Figure 1(d), the absorbance in the thickness direction of the detection agent-supported material 103b was measured. Specifically, the intensity I of the transmitted light transmitted through incident light with light intensity I0 was measured, and the absorbance (=log) was calculated. 10 (I0 / I)) was calculated.

[0089] Subsequently, as shown in Figure 1(e), the detection agent support material 103b was placed in a sample gas containing 3 ppm methyl mercaptan in a gas exposure container 104 (capacity 1000 ml), and the sample was exposed at room temperature (25°C) for 2 hours.

[0090] After exposure, the absorbance in the thickness direction of the detection agent-supported material 103c was measured, as shown in Figure 1(f). This absorbance measurement was performed at regular time intervals while the material was left standing in an atmosphere free of methyl mercaptan.

[0091] Figure 5 shows the results of the spectrophotometric analysis of evaluation test 3. Figure 5 shows the change over time in the spectral intensity at a wavelength of 387 nm, which indicates the absorption maximum, from the absorbance spectrum obtained by measuring the absorbance of the gas. Figure 5 shows that the decomposition of reaction products begins immediately after exposure, is halved in about 60 hours, and almost no reaction products remain supported on the porous material after about 150 hours. Therefore, it was found that when a porous material is used as the support for the detection agent in a sulfur compound detector, the longer the time until measurement, the more the reaction products decompose, making it difficult to accurately measure the absorbance.

[0092] (Evaluation Test 3) The relative sensitivity to humidity was evaluated when the sulfur compound detector's agent carrier material was a fiber (example) and a porous material (comparative example). Sulfur compound detectors were prepared using porous glass and fiber as the detection agent support material, in the same manner as in the evaluation tests and examples described above. At that time, the relative humidity (RH) in the gas exposure container 104 (capacity 1000 ml) shown in Figure 1(e) was changed from 20% to 80%, and the absorbance was measured for the porous glass and the reflectance for the fiber substrate to evaluate the sensitivity.

[0093] The results of Evaluation Test 3 are shown in Figure 6. It was found that the relative sensitivity of both porous glass and fiber changes with relative humidity. However, when measuring gases with a relative humidity exceeding 50%, such as exhaled breath, the relative sensitivity of porous glass decreased as the relative humidity increased, while the relative sensitivity of fiber increased compared to the 50% relative humidity condition, indicating its effectiveness in measuring high-humidity gases such as exhaled breath. Furthermore, it was revealed that Rayleigh scattering occurs in porous glass at high humidity, requiring scattering correction, but scattering does not occur in fiber, and therefore no correction is necessary.

[0094] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments, and any design changes, etc., that do not depart from the gist of the present invention are also included. Furthermore, the above-described embodiments can be combined by utilizing each other's technologies, as long as there are no particular contradictions or problems in their purpose and configuration.

[0095] The present invention may have the following configurations: [Section 1] Detection agent and, A detection agent support material carrying the aforementioned detection agent, Includes, The detection agent comprises a disulfide compound having a disulfide molecule and a salt of a weak acid and a strong base. The aforementioned detection agent carrier contains fibers. Sulfur compound detector. [Section 2] The disulfide compound further comprises a pyridine ring, as described in item 1 above. [Section 3] The sulfur compound detector according to item 2, wherein an electron-withdrawing group is further bonded to the pyridine ring of the disulfide compound. [Section 4] The sulfur compound detector according to any one of items 1 to 3 above, wherein the salt of the weak acid and strong base is one or more salts of sodium acetate, sodium citrate, disodium hydrogen phosphate, and sodium bicarbonate. [Section 5] The sulfur compound detector according to any one of items 1 to 4 above, wherein the detection agent support material is made of cellulose fibers and is in the form of a sheet or a flat plate. [Section 6] The sulfur compound detector described in any one of items 1 to 5 above, wherein the sulfur compound of the sulfur compound detector is a volatile sulfur compound. [Section 7] A method for producing a sulfur compound detector as described in any one of items 1 to 6 above, The process involves immersing the aforementioned detection agent support material in a detection agent solution, A step of drying the detection agent support material that has been immersed in the detection agent solution, Includes, The detection agent solution comprises the detection agent and a solvent. A method for producing a sulfur compound detector. [Section 8] The method for producing a sulfur compound detector according to item 7, wherein the solvent is ethanol, methanol, or isopropyl alcohol. [Section 9] An exposure step in which a gas is exposed to a sulfur compound detector described in any one of items 1 to 6 above, A measurement step, in which the amount of light absorbed or reflected by a sulfur compound detector exposed to the gas in the aforementioned exposure step is measured, A detection step in which the presence or absence of sulfur compounds in the gas and / or the sulfur compound content of the gas is detected from the amount of light absorbed or reflected measured in the measurement step, A method for detecting sulfur compounds, including those mentioned above. [Section 10] An exposure step in which a gas is exposed to a sulfur compound detector described in any one of items 1 to 6 above, The image acquisition step involves acquiring an image of the sulfur compound detector that has been exposed to the gas in the aforementioned exposure step, A detection step is performed to detect, from the image obtained in the image acquisition step, whether or not a sulfur compound is present in the gas, and / or the sulfur compound content of the gas. A method for detecting sulfur compounds, including those mentioned above. [Explanation of symbols]

[0096] 101: Detection agent solution 102: Container for immersion in detection agent 103: Indicator carrier material (before immersion in indicator) 103a: Indicator support material (after immersion in indicator, before drying) 103b: Inspection agent carrier (after drying), sulfur compound detector 103c: Indicator carrier (after gas exposure), sulfur compound detector (after gas exposure) 104: Containers or bags for gas exposure

Claims

1. Detection agent and, A detection agent support material carrying the aforementioned detection agent, Includes, The aforementioned detection agent consists of a disulfide compound having a disulfide and a pyridine ring in its molecule, and sodium acetate. The aforementioned detection agent carrier is made of cellulose fibers. Sulfur compound detector.

2. The sulfur compound detector according to claim 1, wherein an electron-withdrawing group is further bonded to the pyridine ring of the disulfide compound.

3. The sulfur compound detector according to claim 1, wherein the detection agent support material is in the form of a sheet or a flat plate.

4. The sulfur compound detector according to any one of claims 1 to 3, wherein the sulfur compound of the sulfur compound detector is a volatile sulfur compound.

5. A method for producing a sulfur compound detector according to claim 1, The process involves immersing the aforementioned detection agent support material in a detection agent solution, A step of drying the detection agent support material that has been immersed in the detection agent solution, Includes, The detection agent solution comprises the detection agent and a solvent. A method for producing a sulfur compound detector.

6. The method for producing a sulfur compound detector according to claim 5, wherein the solvent is ethanol, methanol, or isopropyl alcohol.

7. An exposure step of exposing a sulfur compound detector according to claim 1 to a gas, A measurement step, in which the amount of light absorbed or reflected by a sulfur compound detector exposed to the gas in the aforementioned exposure step is measured, A detection step in which the presence or absence of sulfur compounds in the gas and / or the sulfur compound content of the gas is detected from the amount of light absorbed or reflected measured in the measurement step, A method for detecting sulfur compounds, including those mentioned above.

8. An exposure step of exposing a sulfur compound detector according to claim 1 to a gas, The image acquisition step involves acquiring an image of the sulfur compound detector that has been exposed to the gas in the aforementioned exposure step, A detection step is performed to detect, from the image obtained in the image acquisition step, whether or not a sulfur compound is present in the gas, and / or the sulfur compound content of the gas. A method for detecting sulfur compounds, including those mentioned above.

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