JP2014092487A - Detecting tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detecting tube capable of promptly and simply detecting a material to be detected at high sensitivity without using a mercury compound.SOLUTION: A detection part 14 is arranged inside a detecting tube 2. The detection part 14 is charged with a detection agent in which a reactant obtained by selecting at least one or more kinds of compounds from a group composed of p-toluenesulfonic-acid silver, p-toluenesulfonic-acid zinc or p-toluenesulfonic-acid iron, an alkali reagent and a coloring agent are arranged on the surfaces of carrier-particles. The reactant reacts on a material to be detected in sample gas when the sample gas flows into the detection part 14, and p-toluenesulfonic acid is generated as a result; the pH of the detection part 14A is changed by the generated p-toluenesulfonic acid; and a coloring agent undergoes a color change by the pH change. The concentration of the material to be detected included in the sample gas is obtained by the length of a portion having undergone the color change by the pH change.

Description

  The present invention relates to a detector tube that can measure the concentration of a substance to be detected in a sample gas with high sensitivity without using a mercury compound.

  Among the gas detectors, gas detectors for detecting hydrogen sulfide, phosphine, hydrogen cyanide, diborane, etc. use mercuric chloride as the reactant, and mercuric chloride and their detection targets. Some have the principle that hydrogen chloride is generated by reaction with a substance.

Mercury, which is an important component of these gas detectors, is a harmful substance that causes many health problems including Minamata disease, and its use is being severely regulated. Currently, international efforts to prevent mercury pollution are being strengthened, and the Mercury Convention, which includes restrictions on the distribution of products containing mercury, is under consideration by the Intergovernmental Negotiations Committee for adoption in 2013. After the treaty is concluded, it will be difficult to manufacture and sell products containing mercury.
Under such circumstances, gas detectors using inorganic salts such as lead acetate, silver sulfate, palladium sulfate and ammonium molybdate, copper sulfate in place of mercury compounds as reactive agents have been studied.

  FIG. 7 to FIG. 11 are graphs showing the relationship between the concentration of a substance to be detected and the length of a discolored portion by a conventional product using lead acetate, silver sulfate, palladium sulfate and ammonium molybdate, copper sulfate, and mercuric chloride. . However, as shown in FIGS. 7 to 11, an apparatus using mercuric chloride can measure a hydrogen sulfide gas having a low concentration of 1 ppm or less, whereas the reaction between these inorganic salts and a substance to be detected is used. In the conventional apparatus, measurement is possible only with hydrogen sulfide gas having a concentration of 1 ppm or more.

  Among these, it is known that an apparatus using silver p-toluenesulfonate as a reactant reacts relatively stably even with a low concentration detection target substance. [Patent Documents 1 to 5] However, in the method using the discoloration due to the silver colloid as a reaction product for the measurement, since the color of the silver colloid is slight, it is difficult to visually confirm.

Therefore, in these apparatuses using silver p-toluenesulfonate as a reactant, reaction traces of silver colloid generated when silver p-toluenesulfonate is reduced by the detection target substance as shown in the following reaction formula (1). This is based on the principle of measuring the concentration of the target gas by measuring the above by a photometric method.
_{H 2 -X + 2CH 3 C 6} H 4 SO 3 Ag → Ag 2 -X + 2CH 3 C 6 H 4 SO 3 H
...... (1)

  In the photoelectric photometry method, light is measured by transmitting light having a certain wavelength and comparing the transmitted light with a reference substance. Therefore, in the measurement using the photoelectric photometry, a power source is required, and it is difficult to measure in a dangerous place where the power source cannot be used. Furthermore, since measurement in an environment where the battery and power supply cannot be used, such as during a disaster, becomes impossible, a method that can measure without depending on the power supply is desirable. In addition, since a device for generating light of a certain wavelength and measuring transmitted light is required, the device tends to be large, and the cost for installation or operation tends to increase.

Japanese Patent Laid-Open No. 06-018510 Japanese Patent Laid-Open No. 06-186166 JP 2008-020285A JP 2008-139239 A Japanese Patent Laid-Open No. 10-239303

In the measurement using the detection tube, since the concentration is visually confirmed, the measurement can be easily performed. However, as described above, since the color of the silver colloid, which is a reaction product of silver p-toluenesulfonate and the detection target substance, is slight, it is difficult to visually confirm the color of the silver colloid. Therefore, the inventors of the present invention focused on the residue p-toluenesulfonic acid, not the precipitated silver colloid.
The present invention was created based on the above idea, and an object of the present invention is to provide a detection tube capable of detecting a detection target substance with high sensitivity, speed and simplicity without using a mercury compound. .

In order to solve the above problems, the present invention provides a detection tube for detecting a detection target substance, which is a cylindrical detection tube main body and a detection agent disposed at a position of a detection unit inside the detection tube main body. And p-toluenesulfonic acid, which is contained in the detection agent and which makes the detection agent alkaline, and p-toluenesulfonic acid which is contained in the detection agent and reacts with the detection target substance to form p-toluenesulfonic acid A reactant comprising at least one compound selected from the group consisting of silver, zinc p-toluenesulfonate, and iron p-toluenesulfonate; A colorant that changes color when the pH value of the detection unit decreases due to the generation of toluenesulfonic acid, the detection tube has a transparent part at least partially transparent, and the detection part is inside the transparent part In It is location, a sensing tube which is to be visually recognized color of the detecting agent.
Further, in the present invention, the detection agent has a plurality of carrier particles, and each of the carrier particles includes a drug group composed of the reactive substance, the colorant, and the alkaline reagent. At least a detection tube to which each of the reactants is attached.
Further, in the present invention, the detection agent includes fine porous particles, and a plurality of the fine porous particles are respectively disposed on the surfaces of the carrier particles,
Each fine porous particle is a detection tube in which at least the colorant and the alkaline reagent are attached from the group of drugs.

The detection tube of the present invention is configured as described above, and the silver colloid that is a reaction product of silver p-toluenesulfonate and the detection target substance is not used as a colorant, but is released by reaction. -The acidic property of toluene sulfonic acid is used, the colorant is discolored by pH change due to p-toluenesulfonic acid, and the discoloration of the colorant can be detected instead of the change in transmitted light due to silver colloid. Yes.
The reaction between silver p-toluenesulfonate and the substance to be detected causes a change in reflected light that is significantly easier to detect than a change in transmitted light due to the silver colloid. The position of the boundary between the part that has been changed and the part that has not changed color can be easily confirmed visually.
Further, by arranging the agent to be contained in the detection agent on the carrier particles, the detection agent can be stably held in the detection unit while providing air permeability by appropriately selecting the particle size of the carrier particles.
In addition, by arranging a plurality of fine porous particles to which the drug is attached on the surface of the detection agent, the area of the surface to which the drug is attached increases, so that the reagent is directly attached to the carrier particles. In comparison, the reactivity between the detection target substance and the surface of the carrier particles can be improved, and the boundary position between the discolored portion and the undiscolored portion of the colorant can be made clearer.
Furthermore, the detection tube main body of the detection tube can be made of glass, and both ends can be melted and sealed. This detection tube can hold the detection agent disposed inside the detection tube main body in a state where it is not exposed to the atmosphere, and can stably hold the detection agent for a long period of time. The expiration date can be extended.

  The detector tube of the present invention makes it possible to measure the concentration of a substance to be detected contained in the air at a specific location in a short time with higher sensitivity, speed and convenience without using a mercury compound.

(A): Front view showing the appearance of the detector tube of the present invention (b): Cut-off cross-sectional view for explaining the inside (A): Cut cross-sectional view for explaining the internal structure of the first sub-particle (b): Cut cross-sectional view for explaining the internal structure of the first main particle (c): Detection agent particles Cutaway cross-sectional view for explaining the internal structure : A graph showing the relationship between the concentration of the substance to be detected and the length of the color changing region for the detector tube according to the example of the present invention : A graph comparing the effect of humidity on the detection agent with and without the dehumidifying part : A graph showing the effect of temperature on detector tube readings : Graph showing the influence of the humidity on the detector tube indication (0 ° C, 20 ° C, 40 ° C) : Graph showing the relationship between the concentration of the substance to be detected and the length of the discolored part using a conventional product using lead acetate : Graph showing the relationship between the concentration of the substance to be detected and the length of the discolored part by conventional products using silver sulfate : Graph showing the relationship between the concentration of the substance to be detected and the length of the discolored part using a conventional product using palladium sulfate and ammonium molybdate : Graph showing the relationship between the concentration of the substance to be detected and the length of the discolored part by the conventional product using copper sulfate : Graph showing the relationship between the concentration of substances to be detected by conventional products using mercuric chloride and the length of discolored parts

  Hereinafter, a detection tube according to a first example of an embodiment of the present invention will be described with reference to the drawings using hydrogen sulfide as a detection target substance.

  Fig.1 (a) is an external view of the detection tube 2 of this invention, The same figure (b) is the AA sectional view taken on the line. As shown in FIGS. 1A and 1B, the detection tube 2 of the present invention has a tube body 10. Inside the tube body 10, a filter 11, a dehumidifying unit 12, and a protection unit are provided. 13, a detection unit 14, and a plug unit 15 are provided.

The tube body 10 is a tube of a transparent member such as glass, for example, and a part thereof is made transparent so that at least the detection unit 14 can be observed in the length direction. Here, a glass tube having an inner diameter of 2.9 mm to 3.0 mm was used.
When the detection tube 2 is stored, both ends of the tube body 10 are sealed so as not to come into contact with the atmosphere. Here, both ends of the tube body 10 are sealed by melting glass.

  A scale portion 22 is provided on a portion of the surface of the tubular body 10 located on the detection unit 14. The scale portion 22 is provided with a visible mark (indicator) at an interval according to a predetermined rule along the direction in which the tubular body 10 extends, and when the detection portion 14 changes color as will be described later. Further, the position of the boundary between the non-discolored portion and the discolored portion is specified by a mark adjacent to the boundary so that the length of the discolored portion, the density obtained from the length, and the like can be known.

When the sealing of both ends of the tube body 10 is released, the sample gas can flow from the inlet side toward the outlet side, and inside the tube body 10 from the inlet side toward the outlet side, The filter 11, the dehumidifying part 12, the protection part 13, the detection part 14, and the plug part 15 are arranged in this order.
When the detection tube 2 is used, first, sealing at both ends of the tube body 10 is released. Here, sealing is released by notching both ends of the tube 10 and opening the inside of the detection tube 2 at both ends.

  The filter 11 is fibrous, the plug portion 15 is a polyethylene sintered body, and the detection target substance, which is a gas to be detected, does not react and allows gas to pass through. The filter 11 and the plug portion 15 A hygroscopic substance and a detection agent, which will be described later, disposed in the dehumidifying unit 12 and the detection unit 14 are prevented from falling.

  After the sealing of both ends is released, the outlet side of the tube body 10 is attached to the suction device, and the inlet side is inserted into the sample gas. For example, a sample gas partially taken out from the atmosphere to be measured is stored in a bag-like container, and the tip on the inlet side of the detection tube 2 is inserted into the container. Here, a vacuum gas collector was used as the suction device.

  In the dehumidifying unit 12, the protective unit 13, and the detecting unit 14, the detection target substance does not react and has air permeability. In this state, when the suction device is operated and the pressure on the outlet side is reduced, the sample Gas is sucked into the tube body 10 from the inlet side of the tube body 10. The sucked sample gas passes through the filter 11 and first reaches the dehumidifying unit 12.

The dehumidifying part 12 has a hygroscopic substance that reacts with or adsorbs moisture in the sample gas and removes moisture from the sample gas, and the hygroscopic substance is included in the detection tube 2. The detection target substance to be detected is a powder or fibrous substance that does not react or adsorb.
The dehumidifying part 12 is a part in which a certain range of the tubular body 10 is filled with the hygroscopic substance. Here, the filling length of the dehumidifying part 12 was 15 mm.

  The detection target substance of the detection tube of the present invention is a compound that reacts with silver p-toluenesulfonate to liberate p-toluenesulfonic acid, specifically, a compound such as hydrogen sulfide, phosphine, hydrogen cyanide, diborane, And it is a compound which has a substituent in the compound. The detection target substance detected by the detection tube 2 is hydrogen sulfide, and the hygroscopic substance is lithium bromide that does not react with hydrogen sulfide.

A detection unit 14 is arranged on the downstream side of the dehumidification unit 12 via a protection unit 13.
The protection part 13 is comprised with the inorganic material, and is filled with the granular glass smaller than the internal diameter of the tubular body 10 here. Here, the filling length was 7 mm.

  Here, glass particles having an average particle size of 150 μm to 250 μm are filled, and by providing the protection unit 13 in the upstream region of the detection unit 14, the detection unit 14 is stably held, and concentration measurement by the scale unit 22 described later is performed. Has been made to be accurate.

  At least a portion of the tubular body 10 surrounding the detection unit 14 has a constant inner diameter, and a scale portion 22 is provided on the surface thereof, and a plurality of particulate detection agents are present in the portion having the constant inner diameter. The detection unit 14 is configured to be filled with a uniform density. Here, the filling length of the detection unit 14 is 65 mm.

As shown in FIG. 2C, one particle of the detection agent has carrier particles 36 and a drug arranged on each carrier particle 36. The drug contains silver p-toluenesulfonate, an alkaline reagent, and a colorant, and when the detection agent particles are filled in the tube 10, there is a gap between the detection agent particles. Is formed, and the air permeability of the detection unit 14 is expressed. Here, the carrier particles 36 have an average particle diameter of 250 μm to 350 μm.
An arrangement process for arranging silver p-toluenesulfonate, an alkaline reagent, and a colorant on the carrier particles 36 will be described later.

The sucked sample gas is dehumidified when passing through the dehumidifying unit 12, passes through the protection unit 13, and reaches the detection unit 14.
Silver p-toluenesulfonate (2CH ₃ C ₆ H ₄ SO ₃ Ag) reacts with the detection target substance H ₂ -X as shown in the following reaction formula (2) in contact with the detection target substance in the sample gas. Liberate p-toluenesulfonic acid. At this time, a silver salt as a reaction product is also generated.

_{H 2 -X + 2CH 3 C 6} H 4 SO 3 Ag → Ag 2 -X + 2CH 3 C 6 H 4 SO 3 H ...... (2)
The structural formula of silver p-toluenesulfonate is shown below.

The color former has a color change region that is in a certain pH range in the acidic region, and the color when the pH of the atmosphere in contact with the colorant is on the alkaline side of the color change region, and the pH moves into the color change region. It is a compound that is different from the color when it is used, and can observe discoloration. Here, cresol red is used. Cresol red has a color change region from pH 0.4 to pH 2.2, exhibits red in the color change region from pH 0.4 to pH 2.2, and yellow in the alkaline side region above pH 2.2.
An alkaline reagent is a compound that positions the pH of the detection agent on the alkali side of the color change region of the colorant. Here, sodium hydroxide was used as the alkali reagent.

When the sample gas passes through the protection unit 13 and contacts the detection agent in the detection unit 14, the silver p-toluenesulfonate disposed inside the detection unit 14 reacts with hydrogen sulfide in the sample gas, and p-toluene. Generate sulfonic acid.
The generated p-toluenesulfonic acid reacts with an alkali reagent located around the p-toluenesulfonic acid, and moves the pH of the surface of the detection agent in the acidic direction from the alkali side. When the pH of the surface of the detection agent enters the color change region of the colorant, the color of the colorant changes and the color of the detection agent changes.

  Since the p-toluenesulfonate silver is consumed by the reaction between the detection target substance in the sample gas and the silver p-toluenesulfonate, if the sample gas is further sucked after the color change occurs, the color of the colorant is changed. The position where the occurs occurs moves toward the exit.

There is a certain relationship between the length of the discolored portion of the detection unit 14 and the amount of the substance to be detected introduced into the detection unit 14 from the inlet side, and this relationship is obtained in advance by experiments. ing.
Therefore, when the length of the discolored portion is measured, the amount of the detection target substance that has reacted can be found, and if the amount of the sample gas that has been sucked is known, the concentration of the detection target substance contained in the sample gas can be found.

In this detection tube 2, the amount of sample gas to be sucked is determined in advance, and when the suction device sucks that amount of sample gas, the suction is stopped.
Since the suction device sucks a certain amount of sample gas, the concentration of the detection target substance contained in the sample gas can be obtained from the length of the discolored portion. Near the mark at a predetermined position in the scale part 22, a numerical value of the concentration of the detection target substance when the boundary of discoloration is located at the mark is provided.
Accordingly, by observing the scale portion 22 after a certain amount of sample gas is sucked, the relative position between the position of the boundary between the discolored portion and the undiscolored portion and the mark can be observed, and the detection target Obtain the concentration of the substance and finish the measurement work.

[Production method of detecting agent particles]
Hereinafter, the manufacturing method of the detection agent particle | grains 30 used for the detection tube which concerns on the Example of this invention is demonstrated in detail based on drawing. FIG. 2C is a cross-sectional view for explaining the internal structure of the detection agent particle 30.

As shown in FIG.2 (c), as for the detection agent particle | grains 30, 2nd subparticle 31 'is arrange | positioned on the particle | grain surface of 2nd main particle 32'.
In order to describe these configurations, first, the manufacturing method and the configuration of the first sub-particles 31 and the first main particles 32 will be described.

  An aqueous dispersion of fine porous particles 34, a colorant is added to an alkaline hydrophilic colloidal silica sol (pH 9.5 to pH 10.0) to which an alkali reagent is added, and the mixture is stirred and mixed. An alkali reagent and a colorant are attached to the surface of the porous particles 34. The 1st subparticle 31 of Fig.2 (a) was obtained. Reference numeral 33 in the figure denotes an adherent (first sub-adhesive) composed of an alkali reagent and a colorant attached to the surface of the fine porous particles 34. The first subparticle 31 is converted into the second subparticle 31 ′ by a process described later. Here, the fine porous particles 34 are silica fine particles having a particle diameter of 10 nm to 20 nm.

  Apart from that, silver p-toluenesulfonate was made into an aqueous solution and then mixed with the carrier particles 36 to obtain the first main particles 32 of FIG. Reference numeral 35 in FIG. 5B is an attached matter (first main attached matter) having silver p-toluenesulfonate attached to the surface of the carrier particle 36. The first main particles 32 are converted into second main particles 32 ′ by a process described later. Silica sand having an average particle size of 250 μm to 350 μm was used for the carrier particles 36.

  When the aqueous dispersion of the first sub-particles 31 and the aqueous dispersion of the first main particles 32 are mixed, the alkali reagent, the colorant, and the silver p-toluenesulfonate are mixed using water as a medium. In addition, fine porous particles 34 are attached to the carrier particles 36. Further, an alkali reagent, a colorant, and p-toluenesulfonic acid are formed on the surfaces of the carrier particles 36 and the fine porous particles 34. A second main deposit 35 'and a second sub deposit 33' made of silver are formed. By drying this, the detection agent particle 30 of FIG.2 (c) was obtained.

  The addition amount of the hydrophilic colloidal silica sol to which the alkali reagent is added is preferably 0.12 mL to 0.13 mL per 100 g of the carrier, and the addition amount of cresol red is preferably 1.2 to 1.8 mg per 100 g of the carrier. For example, when 0.1 ppm of hydrogen sulfide gas is used as the minimum concentration to be detected, the optimum amount of silver p-toluenesulfonate is 2.4 mg per 100 g of carrier.

By using silica sand for the carrier particles 36, air permeability is ensured, and it is possible to stably hold the silver p-toluenesulfonate, the alkali reagent, and the colorant as the reactants.
Further, by attaching the fine porous particles 34 to the carrier particles 36, the surface area of the detection agent particles 30 is increased, and the reactivity between hydrogen sulfide and the single substance surface is improved.

  In addition, by using silver p-toluenesulfonate as the reactant, it is possible to obtain a stable reaction for a trace amount of the substance to be detected as compared with the case of using an inorganic salt. Since the addition amount of silver p-toluenesulfonate greatly affects the sensitivity of the detection tube according to the present invention, the addition amount is appropriately determined according to the concentration, type or amount of the detection target substance contained in the sample gas to be detected. There is a need.

  Here, hydrophilic colloidal silica sol to which sodium hydroxide is added is used as the alkali reagent, but potassium hydroxide may be used instead of sodium hydroxide as the alkali reagent. Moreover, when ammonia is used as the alkaline reagent, it has been found that when the detection agent reacts with the detection target substance, the state of discoloration is different from the case where sodium hydroxide or potassium hydroxide is used. In addition, since the direction where sodium hydroxide or potassium hydroxide is used is more vividly discolored, it is easier to check the discolored portion.

  Further, here, cresol red was used as the color former, but as described above, the acidic region has a color change region that is in a certain pH range, and the pH of the atmosphere in contact with the colorant is in the color change region. The color when it is on the alkaline side is different from the color when the pH moves from the alkaline side to the color change region, and any compound that can observe the color change may be used. It can also be used as a colorant.

Moreover, although p-toluenesulfonic acid silver was used as a reactive substance here, it is estimated that not p-toluenesulfonic acid silver but p-toluenesulfonic acid zinc or p-toluenesulfonic acid iron may be sufficient. . That is, using a reactant obtained by selecting at least one compound from the group consisting of silver p-toluenesulfonate, zinc p-toluenesulfonate, or iron p-toluenesulfonate. Expected to be possible.
The hygroscopic substance may be any substance that does not react with or adsorb to the detection target substance for detection, and a substance other than lithium bromide can be substituted.

  In addition, the detection agent particles 30 used in the detection tube 2 of the first example contained the fine porous particles 34, but instead of the detection agent particles 30, the fine detection particles 30 did not contain the fine porous particles 34. A detector tube of a second example using carrier particles 36, and detector particles arranged on each carrier particle 36, each having an alkali reagent, a colorant, and a drug containing silver p-toluenesulfonate. May be created.

When the detection tube of the second example was used, the color was changed when the detection agent reacted with the detection target substance. The boundary between the discolored portion and the undiscolored portion could be recognized.
However, the detection tube 2 of the first example has better color developability at the discolored portion than the detection tube of the second example, and it is easier to recognize the boundary between the discolored portion and the non-discolored portion. The detection agent used in the detection tube of the second example was replaced with the hydrophilic colloidal silica sol to which the alkaline reagent used in the first example was added. It was manufactured using the aqueous solution.

[Discoloration confirmation experiment]
A standard gas containing a constant concentration of hydrogen sulfide gas was passed through the detector tube 2 shown in FIG. 1 from the inlet side to the outlet side, and the color change of the detector 14 was observed. The detection agent filled in the detection unit 14 was pale yellow before the standard gas was ventilated, and a certain area on the inlet side changed to pink after venting. The change in color before and after ventilation could be easily observed with the naked eye, and the position of the boundary between the discolored portion and the undiscolored portion could be clearly confirmed.

  Further, for the detection tube 2 shown in FIG. 1, the detection agent filled in the detection unit 14 is made by adhering only silver p-toluenesulfonate to the carrier particles without attaching the alkali reagent and the colorant. A modified comparison detector tube was made. A standard gas having a constant amount and a constant concentration was passed through the detection tube for comparison and hydrogen sulfide was reacted with silver p-toluenesulfonate. After the standard gas was ventilated, the comparative detector tube with silver p-toluenesulfonate attached to the carrier particles was very light brown, but the color change between before and after venting was negligible. It was very difficult to observe with the naked eye. Therefore, the position of the boundary between the discolored portion and the non-discolored portion could not be confirmed.

[Effect of dehumidifier]
FIG. 4 is a graph showing the effect on the length of the discolored portion due to humidity change when the dehumidifying unit 12 is provided and when the dehumidifying unit 12 is not provided for the detection tube 2 shown in FIG. It is. By providing the dehumidifying part 12, it becomes possible to measure stably in the range of 0% RH to 90% RH.

[Calibration curve]
<Measurement condition>
The detection tube 2 shown in FIG. 1 was used as the detection tube. The measurement environmental conditions were 25 ° C. and 50% RH.
<sample>
Hydrogen sulfide gas calibrated to various hydrogen sulfide concentrations by the permeation tube method was used as a standard gas. The permeation tube method is one of the methods for calibrating the standard gas. A method of obtaining a calibration gas with a constant concentration using the property that a certain amount of liquefied gas permeates and diffuses through the wall of the permeation tube at a constant temperature. It is. Since the concentration is determined by the basic physical quantity of the weight reduction amount of the permeation tube and the dilution gas amount, it is known that a calibration gas having a high reliability and a stable concentration can be obtained.
<Detection operation>
The outlet side of the detection tube 2 shown in FIG. 1 with both ends cut off is attached to a gas sampling device, and the inlet side is inserted into a standard gas container. Aspirate 50 mL and 100 mL of standard gas using a gas collector and measure the length of the discolored portion.
<result>
A calibration curve showing the relationship between the hydrogen sulfide concentration and the length of the discolored portion is shown in FIG.
It was confirmed that when the air flow rate was 100 mL, accurate detection was possible when the hydrogen sulfide concentration in the standard gas was in the range of 0.1 ppm to 3.0 ppm. Further, it was confirmed that detection was possible from 0.2 ppm to 6.0 ppm at an air flow rate of 50 mL. The measurement time when 100 mL was vented was as short as 1 minute.

[Influence of temperature]
The temperature characteristics were examined using different detector tubes with the same structure as in FIG. The temperature conditions of the measurement environment were set to 0 ° C., 20 ° C., and 40 ° C., and the lengths of the discolored portions when a standard gas having a constant amount and a constant concentration was passed were measured and compared. Humidity was kept constant at 50% RH.
FIG. 5 is a graph showing the influence of temperature. FIG. 5 shows that the color change length becomes longer as the temperature becomes lower, and the color change length becomes shorter as the temperature becomes higher. Accurate measurement can be performed by appropriately correcting the value indicating the density read from the scale according to the temperature of the use environment.

[Influence of humidity]
Similarly, humidity characteristics were examined using a detector tube 2 having the same structure as that of FIG. Standard gas of constant amount and constant concentration (2.45 ppm and 0.21 ppm) with humidity conditions of 0% RH, 50% RH, and 95% RH under the respective temperature conditions of 0 ° C., 20 ° C. and 40 ° C. The values indicating the concentration read from the scale when flowing were compared. The values measured at 0 ° C. and 40 ° C. were corrected by a predetermined method based on the relationship between the temperature and the length of the discolored portion.
FIG. 6 is a graph showing the influence of humidity on the indicated value. It was found that stable measurement can be performed within the range of 0 to 90% RH at each temperature. The detector tube according to the invention can be used in a wide range of humidity.

2 …… Detection tube 10 …… Tube 11 …… Filter 12 …… Dehumidification part 13 …… Protection part 14 …… Detection part 15 …… Plug part 22 …… Scale part 30 …… Detection agent particle 31 …… First Sub-particles 32 …… first main particles 31 ′ …… second sub-particles 32 ′ …… second main particles 33 …… first sub-adhesives 33 ′ …… second sub-adhesives 34 ... … Fine porous particles 35 …… first main deposit 35 ′ …… second main deposit 36 …… carrier particles

Claims (3)

A detection tube for detecting a substance to be detected,
A cylindrical detector tube body;
A detection agent disposed at the position of the detection unit inside the detection tube body;
An alkaline alkaline reagent contained in the detection agent to make the detection agent alkaline;
Consists of silver p-toluenesulfonate, zinc p-toluenesulfonate, or iron p-toluenesulfonate that is contained in the detection agent and reacts with the substance to be detected to produce p-toluenesulfonic acid. A reactant comprising selecting at least one compound from a group of
A colorant that is contained in the detection agent and changes color when the pH value of the detection unit decreases due to generation of the p-toluenesulfonic acid;
The detection tube has a transparent part that is at least partially transparent;
The detection section is arranged inside the transparent section, and is a detection tube that can visually recognize the color of the detection agent. The detection agent has a plurality of carrier particles,
The detection tube according to claim 1, wherein at least the reactive substance is attached to each of the carrier particles from a chemical group composed of the reactive substance, the colorant, and the alkaline reagent. . The detection agent includes fine porous particles,
A plurality of the fine porous particles are respectively disposed on the surfaces of the carrier particles,
The detection tube according to claim 2, wherein at least the colorant and the alkali reagent are attached to each of the fine porous particles from the drug group.

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