JP2005345390A - Measuring method of concentration of formaldehyde in gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring method capable of continuously sampling a gas to be detected over a long time of one hr or above and capable of quantitatively measuring the concentration of formaldehyde in the gas to be detected accurately and simply. <P>SOLUTION: In the measuring method of the concentration of formaldehyde in the gas to be detected, the gas to be detected is brought into contact with a filter impregnated with 4-amino-3-phenyl-3-buten-2-on as a reagent (S1a), the filter is developed by the reaction of formaldehyde in the gas to be detected and the reagent (S1b), the surface of the developed color filter is irradiated with light to detect the reflected light from the surface of the filter by a light detection element (S2) and the concentration of formaldehyde in the gas to be detected is measured on the basis of the detection intensity of the reflected light (S3). A process for displaying the measuring result as a numerical value (S4) is included. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for measuring formaldehyde concentration in an atmosphere, and more particularly to a method and apparatus for measuring formaldehyde concentration using 4-amino-4-phenyl-3-buten-2-one as a coloring reagent.

  In recent years, problems related to allergy-like health hazards due to chemical hypersensitivity, called sick house syndrome, have been reported. Various chemical substances are considered to be the cause, but formaldehyde contained in building adhesives and adhesives for clothes is considered to be the main causative substance. Is 0.08 ppm or less.

  As a method for measuring formaldehyde contained in a gas, a measurement method using gas chromatography (GC) or high performance liquid chromatography (HPLC) or a measurement method using discoloration of a reagent is common.

  The standard measurement method by GC or HPLC can measure with high accuracy. On the other hand, however, an expensive analyzer is required, and a person who uses the analyzer is required to have high knowledge and techniques regarding measurement.

  As a measuring method using the discoloration of the reagent, formaldehyde was collected through a test gas in a collecting liquid contained in an absorption bottle, and 4-amino-3-hydrazino-5-mercapto-1,2,4- Generally, a method of chemically developing color by reacting triazole (AHMT) is used. This method is also highly accurate but requires an expensive analyzer and high technical knowledge.

  Also known is a method for detecting formaldehyde by color development of a detection paper impregnated with 4-amino-4-phenyl-3-buten-2-one (formaldehyde test strips: manufactured by Kanto Chemical Co., Inc.). This detection method is based on the reaction represented by the following formula. (See Patent Document 1)

According to the above detection method, the formaldehyde can be easily detected by leaving the detection paper in the test gas and examining the presence or absence of color development. In addition, by using 4-amino-4-phenyl-3-buten-2-one as a reagent, it is possible to sample the test gas continuously for a long time of 1 hour or more. Detects only formaldehyde with high selectivity without interference from other aldehydes, aliphatic and aromatic hydrocarbons, terpenes, halogens, esters, ketones, alcohols and other substances such as ammonia and carbon disulfide it can. However, with this method, formaldehyde is detected depending on whether the detection paper is colored or not, so that only a qualitative result can be obtained. That is, it is impossible to quantitatively detect the degree of formaldehyde concentration in the sampled sample gas.
JP 2003-207498 A

  The problem to be solved by the present invention is that the sample gas can be sampled continuously over a long time of 1 hour or more, and the formaldehyde concentration in the sample gas during that time can be accurately and without being affected by the coexisting gas. An object of the present invention is to provide a measurement method and a measurement apparatus that can be easily quantified and measured.

  In order to solve the above-mentioned problems, the measurement method of the present invention comprises contacting a test gas with an indicator containing 4-amino-4-phenyl-3-buten-2-one, and forming formaldehyde in the test gas. A first step of causing the indicator to develop a color by reaction of 4-amino-4-phenyl-3-buten-2-one, and irradiating light on the surface of the indicator and receiving reflected light from the surface A second step of detecting by the element, a third step of measuring the concentration of formaldehyde in the test gas based on the detected intensity of the reflected light by the light receiving element, and a numerical display of the measurement result of the third step And a fourth step.

  In the first step, it is desirable to attach the indicator to the clothes of a person who lives or works in test gas.

  The third step includes a fifth step of measuring a change in the detected intensity before and after the test gas is brought into contact with the indicator, and a concentration of formaldehyde in the test gas based on a measurement value obtained in the fifth step. And a sixth step of measuring

  The indicator is obtained by impregnating a filter paper selected from the group consisting of glass filter paper, silica fiber filter paper, and quartz filter paper with a 4-amino-4-phenyl-3-buten-2-one aqueous solution. Is desirable.

  The measuring device of the present invention is a measuring device for measuring the formaldehyde concentration in a test gas by utilizing a color reaction between 4-amino-4-phenyl-3-buten-2-one and formaldehyde, An indicator containing amino-4-phenyl-3-buten-2-one, a measurement chamber for accommodating the indicator after being brought into contact with a test gas in a state in which incidence of external light is blocked, and the measurement A light emitting element for irradiating light on the surface of the indicator housed in the chamber, a light receiving element for detecting reflected light from the surface of the indicator housed in the measurement chamber, and a detection intensity of the reflected light by the light receiving element It is desirable that a measurement circuit for measuring the concentration of formaldehyde in the test gas based on the above and a display device for displaying the measurement result by the measurement circuit in numerical form.

  In the measurement apparatus of the present invention, it is preferable that the measurement circuit measures a concentration of formaldehyde in the test gas based on a change in the detected intensity before and after the test gas is brought into contact with the indicator.

  It is desirable that the indicator is detachable from clothes of a person who lives or works in the test gas.

  It is desirable that the indicator is held by a holding frame that can be attached to and detached from the clothes.

  The indicator is obtained by impregnating a filter paper selected from the group consisting of glass filter paper, silica fiber filter paper, and quartz filter paper with a 4-amino-4-phenyl-3-buten-2-one aqueous solution. Is desirable.

  According to the present invention, the indicator containing 4-amino-4-phenyl-3-buten-2-one is allowed to stand in the test gas for a continuous time of 1 hour or longer. The sample gas can be sampled, and only formaldehyde can be detected with extremely high selectivity without being affected by the coexisting gas in the sample gas. The light receiving element emits light to the surface of the indicator colored by the reaction of formaldehyde and 4-amino-4-phenyl-3-buten-2-one in the test gas, and reflects the light reflected from the indicator surface. The concentration of formaldehyde in the sample gas is measured based on the detected intensity, and the measurement result is digitized and displayed. The concentration of formaldehyde contained in the detected gas can be measured accurately and in a short time.

  Embodiments of the present invention will be described below with reference to the drawings.

[Measuring method]
1 and 2 are flowcharts of a measurement method according to the present invention. In the measurement method of the present invention, an indicator holding a reagent that develops color by reaction with formaldehyde is used. As a reagent, a solution in which 4-amino-4-phenyl-3-buten-2-one is dissolved in water is used. As the indicator, an indicator that has a high solution holding performance and can sufficiently secure a contact area with the gas to be detected is used. In this example, a flat filter is used as the indicator.

  In the measurement method of FIG. 1, first, the test gas is brought into contact with the filter (S1a), and the reaction between formaldehyde in the test gas and 4-amino-4-phenyl-3-buten-2-one in the reagent is performed. By this, the filter is colored (S1b). Next, light is irradiated on the surface of the colored filter, and the reflected light from the filter surface is detected by the light receiving element (S2), and the concentration of formaldehyde in the gas to be measured is measured based on the detected intensity (S3). ), And the measurement result is digitized and displayed (S4).

  In the measurement method of FIG. 2, first, light is irradiated on the surface of the filter (or a color target having the same absorption coefficient and scattering coefficient as the filter) before contacting the test gas, and the reflected light from the filter surface is received. It detects with an element (S2-1). Next, the test gas is brought into contact with the filter (S1a), and the filter is colored by the reaction between formaldehyde in the test gas and 4-amino-4-phenyl-3-buten-2-one in the reagent ( S1b). Thereafter, the surface of the colored filter is irradiated with light, and the reflected light from the filter surface is detected by the light receiving element (S2-2). Then, a change (development degree) in the detection intensity of the reflected light before and after contacting the test gas is obtained (S3-1), and the degree of the change is converted into the concentration of formaldehyde in the test gas (S3-2). The conversion result (measurement result) is digitized and displayed (S4).

[Coloring reaction]
The color development of the filter in step S1b in FIG. 1 and FIG. 2 is that 4-amino-4-phenyl in a reagent solution obtained by dissolving 4-amino-4-phenyl-3-buten-2-one in water. This is due to the reaction between -3-buten-2-one and formaldehyde in the test gas (see Formula 1 above).

  This reaction is a substantial solution reaction in the reagent solution held in the filter, and the color development process proceeds as the test component dissolves in the reagent solution due to the contact between the solution surface and the test gas. To do. The form of the reagent retained by the filter may be a form in which the filter is moistened with a reagent solution, or the filter is left in an environment where formaldehyde is not present for a certain period of time after being wetted, or the filter is removed by an operation such as heating or decompression It may be in a dried form. When the reagent solution is dried on the filter, the color development reaction is not a solution reaction, but a color is generated by a solid-gas contact reaction between a solid reagent dried on the filter and gaseous formaldehyde. Here, “wet” means a state in which the reagent solution is filled between the fibers constituting the filter, is held by the filter, and the filter and the reagent solution are integrated to form a liquid layer.

  In the measurement method of the present invention, the reagent held on the filter and the test gas are continuously brought into contact with each other for a period of time during which color can be measured. The contact time between the filter and the test gas, that is, the measurement time is in the range of 1 to 8 hours when the formaldehyde concentration is 0.04 to 0.5 ppm. When the concentration of the reagent is lower, it can be measured for a longer time.

  The 4-amino-4-phenyl-3-buten-2-one solution used as a reagent preferably contains about 30 to 80% acetonitrile as a solvent, but the solvent is not particularly limited to acetonitrile, Any solvent that can dissolve 4-amino-4-phenyl-3-buten-2-one, which is an active ingredient, and does not inhibit the reaction with formaldehyde can be used. It is also possible to use a solvent containing only water. The concentration of 4-amino-4-phenyl-3-buten-2-one is in the range of 10 to 130 mM, but is not particularly limited and can be appropriately selected depending on the formaldehyde concentration to be measured.

  The reagent solution may be dropped and impregnated on the filter, or the filter may be put into the reagent solution and impregnated. The amount of the reagent to be retained in the filter is appropriately selected depending on the solution retention property and shape of the filter, the expected formaldehyde concentration in the test gas, and the like.

[filter]
The filter used in the measurement method of the present invention is not particularly limited in material and shape as long as it can retain a sufficient amount of reagent in the filter when it is wetted with a reagent solution. Therefore, cellulose filter paper, glass filter paper, silica fiber filter paper, quartz filter paper, or the like can be used as a filter.

  The filter can have an arbitrary shape such as a circle or a rectangle according to the measuring device. Also, the thickness of the filter can be arbitrarily selected. In order to retain a sufficient amount of reagent solution, it is also effective to use a stack of several filters.

  In addition, holding the filter with a holding frame as an inspection tab (chip) is also effective in improving the ease of handling of the filter. By holding the filter with the holding frame, the filter can be prevented from being deformed and can be easily attached to and detached from the measuring apparatus. Further, if a safety pin, a clip, or the like can be connected to the holding frame of the inspection tab, the inspection tab can be attached to the clothes of a person who lives or works in the test gas.

  3 and 4 show examples of the configuration of the inspection tab. In both figures, (a) is a plan view and (b) is a side view. The inspection tab 2 shown in this example includes a filter 21, a filter frame 22, and a filter holder 23 that fixes the filter 21 to the filter frame 22. The shape of the filter 21, the filter frame 22, and the filter holder 23 can be any shape such as a circle or a rectangle.

  Various methods can be used to impregnate the filter with the reagent solution, such as dropping directly onto the filter using a pipetman or other dispenser, or putting the filter into a container in which the reagent solution has been placed in advance and impregnating the filter. However, the method is not particularly limited as long as the reagent can be present on the filter.

  The method of drying the filter after impregnation with the reagent solution is not particularly limited, and a method of drying by leaving the filter impregnated with the reagent solution in a room temperature or warm environment or in a reduced pressure environment should be appropriately employed. Can do.

[Contact between test gas and filter]
The test gas targeted by the measurement method of the present invention is all gases that may contain formaldehyde. Specifically, indoor air, which is expected to contain low-concentration formaldehyde, kitchen room containing high-concentration formaldehyde, surrounding air, soil air, or the like is used as the test gas. Further, a gas generated by heating solid air such as ambient air and wall materials such as industrial waste water in which formaldehyde may be dissolved can be used as a test gas.

  The test gas and the filter 21 are brought into contact with each other by leaving the filter 21 in an environment where formaldehyde may exist as described above for a certain period of time. Only by leaving it in the environment, the test gas and the filter 21 come into natural contact, but the contact method is not particularly limited. For example, the test gas may be forcibly and quantitatively brought into contact with the filter 21 using an air pump or the like. When the test gas is forcibly brought into contact with the filter 21, a method of flowing the test gas parallel to the surface of the filter 21, a method of causing the test gas to collide obliquely with the surface of the filter 21, and a test gas in the filter 21. Any of the passing methods may be adopted. Considering diffusion and mixing of formaldehyde in the test gas into the reagent, a method of causing the test gas to collide obliquely with the surface of the filter 21 is desirable.

  Further, by attaching the filter 21 to the clothes of the specific person, the test gas and the filter 21 can be brought into contact with each other reliably in an environment where the specific person exists.

[Measurement of color tone or degree of color development]
When the test gas and the reagent held on the filter 21 come into contact, the surface of the filter 21 is colored yellow (discolored) when formaldehyde is present in the test gas. The absorption maximum wavelength of the coloring region on the surface of the filter 21 is 420 nm. The color development of the filter 21 that has been left in the test gas for a certain period of time is optically measured, and is compared with a calibration curve of the color development degree that is created by measuring in advance using a standard gas having a known formaldehyde concentration. Determine the concentration of formaldehyde.

  There are various methods for optically measuring the luminous intensity. A method of obtaining the degree of change in the intensity of reflected light from the filter 21 (response value%), that is, the degree of coloration, by irradiating light toward the color development region on the surface of the filter 21 Is the most accurate and simple. As a light source for irradiating the surface of the filter 21 with light, a light emitting element such as an LED can be used. A PIN photodiode can be used as the light receiving element for the reflected light.

  In the measurement method of FIG. 1, after the reflection intensity of the filter (unused filter) 21 before contacting the test gas is measured in advance and held as a reference value, the test gas is contacted. The degree of change of the intensity of the reflected light from the surface of the filter 21 (detected value in step S2) with respect to the reference value is obtained. In the measurement method of FIG. 2, the reflection from the surface of the filter 21 after contact with the test gas with respect to the intensity of the reflected light from the surface of the filter 21 before contact with the test gas (detected value in step S2-1). The degree of change in light intensity (detected value in step S2-2) is obtained.

[measuring device]
FIG. 5 is a schematic sectional view showing an embodiment of the measuring apparatus according to the present invention.

  This measuring apparatus is configured so that the inspection tab 2 shown in FIG. 3 or FIG. 4 can be detachably attached to the measuring chamber 1 a in the main body 1. More specifically, the inspection tab 2 is inserted into a slit formed on the side surface of the main body 1 and pushed along the guide frame 16 in the main body 1, thereby bringing the inspection tab 2 into a predetermined position in the measurement chamber 1 a in the main body 1. It can be installed. When the inspection tab 2 is mounted, the slit is completely closed, and the incident of external light to the filter 21 is completely blocked. The installation form of the inspection tab 2 with respect to the apparatus main body 1 is not limited to the illustrated form, and any form may be adopted as long as the optical characteristics of the surface of the filter 21 can be confirmed.

  The material of the measuring apparatus main body 1 and its internal structure may be either metal or plastic, and the filter frame 22 and the filter retainer 23 constituting the inspection tab 2 may be either metal or plastic.

  The measuring apparatus main body 1 includes an optical measurement system that optically measures the degree of color development on the surface of the filter 21 and displays it as an absolute concentration value of formaldehyde. The optical measurement system includes an LED 31 for irradiating light on the surface of the filter 21, a PIN photodiode 32 for receiving reflected light from the filter 21, and an intensity change (response) received by the PIN photodiode 32. Value), that is, a display 33 that displays the color development degree in terms of the formaldehyde concentration value. A liquid crystal display panel or electronic paper is used for the display 33. By using electronic paper, which is a non-volatile display medium, for the display 33, the display contents can be retained even after the power supply is stopped, so that the measurement result can be maintained in a display state for a long time while suppressing the power consumption of the built-in battery.

  In the case of the measurement method of FIG. 1, the response value is a filter after color development measured after gas contact with respect to the intensity of reflected light (output value of the light receiving element measured in advance) of the filter 21 before color development stored in advance in the memory. 21 shows the ratio of the intensity of reflected light 21 (the output value of the light receiving element during actual measurement). The response value% is expressed by the following equation.

Response value (%) = (V ₀ −V ₁ ) × 100 / V ₀
In this case, V ₀ is a value (reference value) stored in the memory, and V ₁ is an actual output value from the light receiving element.

  In the case of the measurement method of FIG. 2, by providing a color target (white plate) corresponding to the filter 21 before color development in the measurement apparatus main body 1, the absorption coefficient (K) and scattering coefficient of the color target are provided. With the ratio (K / S) to (S) as the reference value (0), the ratio (K / S) of the filter 21 after color development can be measured.

  The calibration curve for the formaldehyde concentration is calculated by the following Kubeluka-Munk equation.

K / S = (1-R) ² / R × 2 Equation 2
R in Formula 2 is a reflectance. The reflectance R means the ratio V ₁ / V ₀ of the output value V ₁ after contact with the test gas with respect to the output value V ₀ before contact with the test gas. FIG. 6 shows a calibration curve calculated by this equation 2.

  The part below the filter mounting part of the measuring apparatus main body 1 shown in FIG. 5 constitutes an electronic component chamber. That is, the inside of the measurement apparatus main body 1 is divided into a measurement chamber 1a and an electronic component chamber by a partition (not shown). Although not shown, the electronic component chamber includes a CUP, RAM, ROM, timer, battery, etc. An electronic component or the like necessary for displaying the voltage change measured by the PIN photodiode 32 on the liquid crystal display 33 as the formaldehyde concentration is accommodated.

An example of the procedure for measuring the formaldehyde concentration in the test gas using the above measuring apparatus will be described.
(1) The unused inspection tab 2 in which the color reagent is previously held in the filter 21 is left in an environment where formaldehyde may exist.
(2) The inspection tab 2 that has been left for a certain period of time is inserted into the slit of the measuring apparatus main body 1 and mounted at a predetermined position.
(3) The optical measurement system is operated to measure the degree of color development on the surface of the filter 21, and the formaldehyde concentration is digitized and displayed on the display 33.
(4) After confirming the formaldehyde concentration, the inspection tab 2 is taken out from the slit 15 of the measuring apparatus body 1 and discarded.

  As described above, according to the measurement apparatus of this embodiment, the measurement result of the formaldehyde concentration is digitized and displayed on the display 33, so that the conventional problem, that is, the measurement value in which the measurement result varies depending on the measurer. This makes it possible to solve the problem of difficult reading and to measure the formaldehyde concentration in the test gas with high accuracy.

  Further, according to the method and apparatus of the above embodiment, since 4-amino-4-phenyl-3-buten-2-one is used as a coloring reagent, the influence of various chemical substances existing as coexisting substances in the test gas The selectivity of formaldehyde is extremely high. The detection sensitivity is as high as 0.04 to 0.5 ppm. Further, the measurement time is 4 to 8 hours, which is longer than that of the conventional measurement method, and when measuring the formaldehyde concentration over a long time, the measurement can be performed very simply as compared with the conventional method. Furthermore, by installing the filter on clothes or the like of a person who performs business in an environment where formaldehyde may exist, the formaldehyde concentration contained in the environment in which the person exists during the time can be measured. For example, it is possible to measure the total exposure amount of formaldehyde concentration of each person throughout the working hours of a day very easily.

  The present invention will be described in more detail by reference examples and examples.

<Reference example>
6.67 ml of acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) 0.2 g of 4-amino-4-phenyl-3-buten-2-one (manufactured by Kanto Chemical Co., Inc., No. 01917-53 for environmental measurement) No. 75-05-8) for HPLC, and then 6.7 ml of this acetonitrile solution and 3.3 ml of 50 mM phosphate buffer were mixed to make 10 ml. This solution was used as a reagent solution for impregnating the filter 21.

  1 ml of the coloring solution prepared as described above and 1 ml of formaldehyde solution (300 ppm) were mixed and allowed to stand at room temperature for 2 hours, and then the absorbance was measured using a spectrophotometer at a measurement wavelength of 425 nm.

  Similarly, solutions of various chemical substances (aliphatic and aromatic hydrocarbons, terpenes, halogens, esters, ketones, alcohols and ammonia) that may coexist in the test gas with 1 ml of the color developing solution ( 1 ml of each was mixed) and left at room temperature for 2 hours, and then the absorbance was measured. Various chemical substances were dissolved and diluted with water to obtain test solutions, but water-insoluble substances were dissolved and diluted with ethanol to obtain test solutions.

  Table 1 shows the measurement results of absorbance.

  This measurement result shows that the 4-amino-4-phenyl-3-buten-2-one reagent hardly develops color even when any chemical substance except formaldehyde is present at a concentration as high as 1000 ppm. In other words, color formation with 4-amino-4-phenyl-3-buten-2-one reagent is unique to formaldehyde, and 4-amino-4-phenyl-3-buten-2-one is used as the color reagent. The measurement method according to the present invention has a very high formaldehyde selectivity.

<Example>
[Reagent solution]
6.7 ml of acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) 0.2 g of 4-amino-4-phenyl-3-buten-2-one (manufactured by Kanto Chemical Co., Inc., for environmental measurement No. 01917-53) No. 75-05-8) for HPLC, and then mixed with 3.3 ml of 50 mM phosphate buffer to make 10 ml. This solution was used as a reagent solution.

[filter]
100 μl of the test solution prepared as described above was dropped onto a cellulose filter paper having a diameter of 18 mmφ from a micropipette and impregnated. Then, after storing in a desiccator, the pressure was reduced by a vacuum pump, and it was left to stand for 10 minutes under vacuum to be dried. This was designated as a filter 21.

[Test gas]
Diluted formaldehyde solution (manufactured by Wako Pure Chemical Industries, special grade, 37%) with pure air using a calibration gas regulator (Gastech: Permeator: PD-1B) A test gas containing formaldehyde at a concentration of 2 was adjusted. The adjusted gas was filled in an airtight chamber.

[measuring device]
As a measuring device, a commercially available device (manufactured by Biomedia: portable photometer BS-01) was used. In this apparatus, a light emitting element (LED) and a light receiving element (PIN type photodiode) are arranged inside the main body so that the color of the filter 21 can be detected. A display for displaying the measurement result of the formaldehyde concentration based on the color of the filter 21 (the response value) is provided.

[Measurement of formaldehyde concentration]
The filter 21 was left in an airtight chamber filled with the test gas. The color development degree of the filter 21 was measured, and the response value (%) displayed on the display was recorded. The results are shown in FIGS.

  FIG. 7 shows the relationship between the sampling time of the test gas and the response value (%) of the coloring degree. From this measurement result, the degree of color formation due to formaldehyde increases in proportion to the contact time with the test gas from the start of measurement to around 4 hours, and the increase coefficient (slope of the curve) is also increased in the subsequent 4 hours. Although it becomes small, it turns out that it increases in proportion to contact time with test gas.

  FIG. 8 shows the relationship between formaldehyde concentration and color development response value (%). The sampling time was 8 hours. From this measurement result, it can be seen that the increase in the degree of color development depends on the concentration of formaldehyde contained in the test gas and shows a significant correlation in the range of 0.04 to 0.5 ppm.

  These measurement results indicate that the concentration of 0.08 ppm or less, which is the environmental reference value of WHO, can be measured by performing measurement for a long time of 4 to 8 hours. Further, depending on the formaldehyde concentration in the test gas, the concentration of 4-amino-4-phenyl-3-buten-2-one impregnated in the filter 21, the type of solvent used during the impregnation, and contact with the test gas This suggests that the time, color development measurement wavelength, etc. can be appropriately selected and optimized.

It is a flowchart of the measuring method concerning this invention.

It is a flowchart of the measuring method concerning this invention.

It is a schematic sectional drawing which shows embodiment of the measuring apparatus concerning this invention.

It is an example of a test | inspection tab provided with the filter holding the coloring reagent, (a) is a top view of a circular tab, (b) is a side view of a circular tab.

It is an example of a test | inspection tab provided with the filter holding the coloring reagent, (a) is a top view of a square-shaped tab, (b) is a side view of a square-shaped tab.

It is a graph which shows the calibration curve of the measuring apparatus shown in FIG.

It is the graph which showed the relationship between sampling time and the coloring degree of 4-amino-4-phenyl-3-buten-2-one by using formaldehyde concentration as a parameter.

It is a graph which shows the relationship between formaldehyde concentration and the color development degree of 4-amino-4-phenyl-3-buten-2-one.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measuring apparatus main body 1a Inspection room 2 Inspection tab 21 Filter (indicator)
31 LED (light emitting element)
32 PIN type photodiode (light receiving element)
33 Display (display device)

Claims (9)

A test gas is brought into contact with an indicator containing 4-amino-4-phenyl-3-buten-2-one, and formaldehyde in the test gas and 4-amino-4-phenyl-3-butene-2- A first step of causing the indicator to develop color by reaction with ON,
A second step of irradiating the surface of the indicator with light and detecting reflected light from the surface with a light receiving element;
A third step of measuring the concentration of formaldehyde in the test gas based on the detected intensity of the reflected light by the light receiving element;
A fourth step for quantifying and displaying the measurement result of the third step;
A method for measuring formaldehyde concentration, comprising:   The method for measuring formaldehyde concentration according to claim 1, wherein, in the first step, the indicator is attached to clothes of a person who lives or works in test gas. The third step is
A fifth step of measuring a change in the detected intensity before and after contacting the test gas with the indicator;
A sixth step of measuring the concentration of formaldehyde in the test gas based on the measurement value of the fifth step;
The method for measuring formaldehyde concentration according to claim 1, comprising:   The indicator is obtained by impregnating a filter paper selected from the group consisting of glass filter paper, silica fiber filter paper, and quartz filter paper with a 4-amino-4-phenyl-3-buten-2-one aqueous solution. Item 4. The method for measuring formaldehyde concentration according to any one of Items 1 to 3. A measuring device for measuring the formaldehyde concentration in a test gas using a color reaction between 4-amino-4-phenyl-3-buten-2-one and formaldehyde,
An indicator containing 4-amino-4-phenyl-3-buten-2-one;
A measurement chamber that accommodates the indicator after being brought into contact with the test gas in a state in which the incidence of external light is blocked;
A light emitting element for irradiating light on the surface of the indicator housed in the measurement chamber;
A light receiving element for detecting reflected light from the surface of the indicator housed in the measurement chamber;
A measurement circuit for measuring the concentration of formaldehyde in the test gas based on the detection intensity of the reflected light by the light receiving element;
A display device for digitizing and displaying the measurement result by the measurement circuit;
An apparatus for measuring formaldehyde concentration, comprising: The measurement circuit includes:
6. The formaldehyde concentration measuring apparatus according to claim 5, wherein the concentration of formaldehyde in the test gas is measured based on a change in the detected intensity before and after the test gas is brought into contact with the indicator.   The formaldehyde concentration measuring device according to claim 5 or 6, wherein the indicator is detachable from clothes of a person who lives or works in the test gas.   The said indicator is hold | maintained by the holding frame which can be attached or detached to the said clothes, The formaldehyde concentration measuring apparatus in any one of Claims 5-7 characterized by the above-mentioned.   The indicator is obtained by impregnating a filter paper selected from the group consisting of glass filter paper, silica fiber filter paper, and quartz filter paper with a 4-amino-4-phenyl-3-buten-2-one aqueous solution. Item 9. The apparatus for measuring formaldehyde concentration according to any one of Items 5 to 8.

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