JP2009080084A - Detection material for mercapto group-containing substance and detection device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mercapto group-containing substance detection apparatus having high discrimination with respect to mercapto group-containing substances such as methyl mercaptan and hydrogen sulfide and capable of detecting with high sensitivity.
SOLUTION: A detection material 2 in which a fluorescent substance formed on one surface of a prism 1 is fixed by a polymer film containing an aprotic polar polymer, and a detection material 2 is arranged so that excitation light 3 is irradiated. The detected light source 4, the light detection element 5 disposed opposite to the detection material 2, the measurement gas introduction tube 7 for introducing the measurement gas 6, and the fluorescence 8 emitted from the detection material 2. An optical filter 9 installed in front of the photodetecting element 5, a detection circuit 10 that processes an output signal from the photodetecting element 5, and a data processing device 11 that processes a signal from the detection circuit 10. Has been. Mercapto group-containing substances such as methyl mercaptan and hydrogen sulfide can be detected efficiently.
[Selection] Figure 1

Description

  The present invention relates to a detection material that detects a mercapto group-containing substance that is a malodorous component, and a detection device that uses the detection material.

The main malodorous components such as toilets and kitchens are substances having mercapto groups (SH groups) such as methyl mercaptan (CH ₃ -SH) and hydrogen sulfide (H-SH), and maintain a comfortable living environment. Therefore, an apparatus capable of detecting the gas concentration of these substances in the range of several ppb to several ppm is required.

  Therefore, as a detection device for detecting hydrogen sulfide and mercaptans, a device using an oxide semiconductor as a sensitive layer has been proposed (see, for example, Patent Document 1). A detection device using an oxine metal complex or a porphyrin metal complex as a fluorescent substance has also been proposed (see, for example, Patent Document 2).

JP 2004-245726 A JP-A-4-335141

  However, in the conventional detection device using the oxide semiconductor described in Patent Document 1, since the sensitivity is low, a limit concentration with respect to a mercapto group-containing substance of human olfaction, for example, about 0.7 ppb as a concentration of methyl mercaptan is set. In addition, there is a problem that the discrimination is low because the oxide semiconductor reacts with an aromatic volatile organic compound. The conventional detection device described in Patent Document 2 has a problem that the accuracy cannot be sufficiently obtained because the fluorescence intensity decreases as the malodorous substance concentration increases.

  The present invention has been made in order to solve the above-described problems, and has high discrimination with respect to mercapto group-containing substances such as methyl mercaptan and hydrogen sulfide, and can be detected with high sensitivity. It aims at obtaining the detection apparatus of the mercapto group containing substance which can be performed.

  In order to solve the above problems, the mercapto group-containing substance detection material of the present invention is a substance having a molecule containing a fluorescent functional group, and a substance that causes an increase or decrease in the amount of fluorescence due to a reaction with the mercapto group-containing substance. It is characterized by being immobilized by a polymer film. According to this problem solving means, mercapto group-containing substances such as methyl mercaptan and hydrogen sulfide can be detected efficiently.

  In order to solve the above problems, the mercapto group-containing substance detection device of the present invention includes a mercapto group-containing substance detection material, a light source that supplies excitation light to the detection material, and fluorescence emitted from the detection material. It is characterized by comprising a light detection element for detection and a detection circuit for processing an output signal from the light detection element. According to this problem solving means, it is possible to provide a detection device capable of efficiently detecting a mercapto group-containing substance such as methyl mercaptan or hydrogen sulfide.

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the detection apparatus of the mercapto group containing substance which has high discrimination with respect to mercapto group containing substances, such as methyl mercaptan and hydrogen sulfide, and can detect with high sensitivity.

  Hereinafter, the configuration and operation of a mercapto group-containing substance detection device according to an embodiment of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a schematic sectional view showing a mercapto group-containing substance detection device according to Embodiment 1 of the present invention.
As shown in FIG. 1, the detection device for a mercapto group-containing substance includes an aprotic polar polymer that has a molecule containing a fluorescent functional group formed on one surface of a prism 1 (hereinafter referred to as a fluorescent substance). The detection material 2 fixed by the polymer film, the light source 4 arranged so that the detection light 2 is irradiated with the excitation light 3 from the other surface of the prism 1, and the detection material 2 are opposed to each other. The photo-detecting element 5 arranged in this way, the gas-measuring pipe 7 for introducing the gas-to-be-measured 6 provided between the sensing material 2 and the photo-sensing element 5, and the fluorescence 8 emitted from the sensing material 2 It comprises an optical filter 9 installed in front of the light detection element 5, a detection circuit 10 that processes an output signal from the light detection element 5, and a data processing device 11 that processes a signal from the detection circuit 10. ing.

  The detection material 2 is a coumarin functional group as a fluorescent functional group and a coumarin phenylmaleimide having a maleimide group that reacts with a mercapto group (specific compound name is 7-dimethylamino-3- (4′-maleimide) (Diphenyl) -4-methylcoumarin, hereinafter abbreviated as CPM, Formula 1) is used as poly-2-methyl-2-oxazoline (hereinafter abbreviated as PMEOZO, Formula 2), which is an aprotic polar polymer. Thus, a solidified film is produced and fixed on the prism surface. A schematic diagram of a solid film cross section of the detection material 2 is shown in FIG. CPM is taken in and fixed in the polymer film of PMEOZO.

  First, an example of a method for producing the detection material 2 will be described. 10 mg of PMEOZO is weighed and 500 μL of dimethylacetamide (hereinafter abbreviated as DMAc) is added and dissolved. Weigh out 1 mg of CPM and add to it and stir well. A light yellow transparent solution is then formed. This is taken with a metal spatula, coated on a prism with a flat surface of 1 cm square, and dried as it is at room temperature to obtain a detection material.

  In the present invention, a substance in which a maleimide group that loses fluorescence is bonded to a molecule containing a fluorescent functional group is used as a detection material. As an example, the principle that a reaction product of CPM and methyl mercaptan, which is one of the detection materials, exhibits fluorescence will be described with reference to the chemical reaction formula of FIG. The coumarin functional group originally has very good fluorescence, but CPM does not have fluorescence because it is bonded to the maleimide group. The reason for this is that the excited electrons of the coumarin excited by the excitation light do not relax in the coumarin functional group when relaxed, and move to the double bond of the maleimide group. However, since the mercapto group (SH group) of methyl mercaptan is added to the double bond of the maleimide group of CPM and the double bond is lost, the excited electrons become relaxed in the coumarin functional group, so that it is fluorescent. Demonstrate. In the present invention, this principle is applied to detection of a mercapto group-containing substance.

  Next, a method for detecting a mercapto group-containing substance by the mercapto group-containing substance detection apparatus according to Embodiment 1 will be described. First, the gas to be measured 6 is flowed from the gas to be measured introduction pipe 7 toward the detection material 2 formed on the surface of the prism 1. When the gas 6 to be measured contains a mercapto group-containing substance such as methyl mercaptan, the mercapto group-containing substance reacts with CPM, and the reaction product is generated by the excitation light 3 irradiated from the light source 4. When excited, it emits fluorescence 8. The fluorescence 8 emitted here passes through the optical filter 9 and enters the light detection element 5, and the light detection element 5 outputs an electrical signal (voltage or current) corresponding to the fluorescence intensity. The electric signal output from the light detection element 5 is sent to the detection circuit 10, where it is amplified and then sent to the data processing device 11. The calculation unit of the data processing device 11 calculates the concentration of the mercapto group-containing substance in the gas to be processed based on the transmitted electric signal.

  As a method for calculating the concentration of the mercapto group-containing substance here, for example, using the fact that there is a correlation between the increase in fluorescence and the concentration of the mercapto group-containing substance in the gas to be measured, Examples include a method in which a calibration curve showing the relationship between the concentration of a substance and an increase in voltage or current is prepared in advance, and the electric signal sent is compared with the calibration curve. The increment is the difference between the value before the measurement gas flows in and the value after the reaction with the measurement gas. This is because the fluorescent CPM that has reacted once does not return to its original non-fluorescence even if the object to be detected such as methyl mercaptan disappears from the gas to be measured. The amount should be sufficiently smaller than the amount of CPM, and quantification must be performed using the increment as described above. Or you may calculate using the time differential value of a measured value. When such a calculation method is employed, it is desirable that the calculation unit of the data processing device 11 has a function of storing the transmitted electric signal, a function of comparing with a calibration curve, and the like.

  The wavelength of the light source may be selected according to the excitation wavelength of the fluorescent functional group, as long as the maleimide group can sufficiently excite the fluorescent functional group directly or through another functional atomic group. When CPM is a fluorescent material, light having a wavelength of 380 to 410 nm can be used as excitation light. The optical filter 9 is used for the purpose of improving the signal / noise (S / N) ratio, and is not necessarily required. For example, a light emitting diode (LED) can be used as the light source 4, and a photodiode (PD) can be used as the light detection element 5.

  A part of the excitation light 3 from the light source 4 is reflected or scattered from the surroundings of the detection material 2 and travels toward the light detection element 5, but is almost shielded (cut) by the optical filter 9 so that the light detection element 5 Not incident. Although the light detection element 5 generally has a wavelength dependency but outputs an electrical signal when light is incident, the optical filter 9 is disposed in the optical path of the reflected / scattered light as in the present embodiment. Thus, the intensity of the fluorescence 8 emitted from the detection material 2 can be detected with high sensitivity while suppressing the influence of the excitation light 3. In the case of using a CPM as the fluorescent material and a violet light emitting diode as the light source 4, an ultraviolet cut filter may be disposed as the optical filter 9 in front of the light detection element 5. The optical filter 9 is realized by using a dye film or a dielectric laminated film. Note that some types of light emitting diodes emit near-infrared rays of about 1000 nm. Therefore, when such a light-emitting diode is used as the light source 4, an infrared cut filter or a near infrared cut filter is used as a blue light cut filter. It is desirable that they are laminated or appropriately disposed between the light source 5 and the light detection element 5.

  In order to detect the substance to be detected in the gas to be measured using the fluorescence of the fluorescent substance, the excitation light and fluorescence must not be absorbed along with the fixation of the fluorescent substance (holding it in a solid state). It is necessary to satisfy many conditions that the fluorescent substances do not interact with each other, that the substance to be detected immediately contacts the fluorescent substance, and that the reaction between the fluorescent substance and the substance to be detected is not hindered. A detection material obtained by a method of immobilizing a fluorescent substance with a film containing an aprotic polar polymer satisfies these conditions and can efficiently detect a mercapto group-containing substance.

  As described above, according to the mercapto group-containing substance detection device according to the first embodiment, a substance having a molecule containing a fluorescent functional group (fluorescent substance) is immobilized by a film containing an aprotic polar polymer. Since the concentration of the mercapto group-containing substance is calculated from the fluorescence intensity when the reaction product of the fluorescent substance and the mercapto group-containing substance is optically excited depending on the material, the influence of substances other than the mercapto group-containing substance is hardly affected. It has a remarkable effect that the mercapto group-containing substance can be detected with high accuracy without being subjected to the above.

Embodiment 2. FIG.
FIG. 4 is a schematic cross-sectional view showing a mercapto group-containing substance detection device according to Embodiment 2 of the present invention.
As shown in FIG. 4, the detection device for a mercapto group-containing substance is formed on the surface of a substrate 12, and a substance having a molecule containing a fluorescent functional group (fluorescent substance) is formed by a polymer film containing an aprotic polar polymer. A fixed sensing material 2, a light source 4 arranged so that excitation light 3 is irradiated on the upper surface of the sensing material 2, and a light detecting element 5 arranged facing the upper surface of the sensing material 2 And a measurement gas introduction pipe 7 for introducing a measurement gas 6 provided between the detection material 2 and the light detection element 5, and a light detection element 5 for detecting fluorescence 8 emitted from the detection material 2. The optical filter 9 is further configured with a detection circuit 10 that processes an output signal from the light detection element 5 and a data processing device 11 that processes a signal from the detection circuit 10.

  Next, a method for detecting a mercapto group-containing substance by the mercapto group-containing substance detection apparatus according to Embodiment 1 will be described with reference to FIG. First, the gas to be measured 6 flows from the gas to be measured introduction pipe 7 toward the detection material 2 formed on the surface of the substrate 12. When the gas 6 to be measured contains a mercapto group-containing substance such as methyl mercaptan, the mercapto group-containing substance reacts with CPM, and the reaction product is generated by the excitation light 3 irradiated from the light source 4. When excited, it emits fluorescence 8. The fluorescence 8 emitted here passes through the optical filter 9 and enters the light detection element 5, and the light detection element 5 outputs an electrical signal (voltage or current) corresponding to the fluorescence intensity. The electric signal output from the light detection element 5 is sent to the detection circuit 10, where it is amplified and then sent to the data processing device 11. The calculation unit of the data processing device 11 calculates the concentration of the mercapto group-containing substance in the gas to be processed based on the transmitted electric signal.

  Thus, according to the mercapto group-containing substance detection device according to the second embodiment, the light source and the light detection element are both installed in the same direction with respect to the detection material via the measured gas passage. The arrangement of the light source is easy. Further, as in the first embodiment, there is a remarkable effect that the mercapto group-containing substance can be detected with high sensitivity without being affected by substances other than the mercapto group-containing substance.

  In the embodiment of the present invention, a CPM including a coumarin functional group as a fluorescent functional group has been described as an example. However, other fluorescent functional groups may be used, and the same effect can be obtained by introducing a maleimide group. I can expect.

  The detection device for a mercapto group-containing substance according to the present invention is preferably used as a rot monitor in food storage such as a refrigerator or a cold and dark room, an indoor or outdoor malodor monitor, or a leak detector for gas odorized with a mercapto group-containing substance. Furthermore, the present invention can be applied to operation control of an air purifier, an air conditioner or a ventilator that operates only when a bad odor occurs.

Since the effect of the present invention has been confirmed by experiments, the contents thereof will be specifically described below.
<Example 1>
[Preparation of sample gas]
First, a sample gas was prepared as follows. Mercaptoethanol (molecular weight 78, specific gravity 1.114), which is a mercapto group-containing substance, was dissolved in ethanol to a volume ratio of 0.1% to prepare a mercaptoethanol solution. Next, 1 μL of a mercaptoethanol solution was dropped with a microsyringe into a fluororesin odor collection bag (10 L), and then inflated to about 9 L using odorless air. Waiting for all of the mercaptoethanol solution to evaporate, odorless air was added to make the whole 10 L. The temperature was 25 ° C. Since the number of moles = pressure × volume / (gas constant × absolute temperature), the total number of moles of gas in the odor collection bag is 1 × 10 / (0.0821 × (273.15 + 25) = 0.41 mole. On the other hand, the number of moles of mercaptoethanol is 0.001 × 0.001 × 1.114 / 78 = 1.4 × 10 ⁻⁸ mol, so the mercaptoethanol concentration in this sample gas is 1 4 × 10 ⁻⁸ /0.41×10 ⁹ = 35 ppb This sample gas and odorless air are appropriately mixed by an air pump to obtain seven values of 0, 1, 2, 5, 10, 20, and 35 ppb. A sample gas was obtained.

[Mercapto group-containing substance detection experiment using a mercapto group-containing substance detection device]
The sample gas prepared above was detected using a mercapto group-containing substance detection device (light source: violet light-emitting diode capable of emitting violet light having a center wavelength of 390 nm) having the same configuration as that shown in FIG. The relationship between the mercaptoethanol concentration and the response amount (output voltage) at this time is shown in FIG. Although it responds even when the mercaptoethanol concentration is 0, this is considered to be due to excitation light transmitted through the optical filter. This is because the optical filter did not completely block violet light. However, for very dilute mercaptoethanol, a linear relationship was obtained between concentration and response. That is, by using the mercapto group-containing substance detection device according to the present invention, the concentration of the mercapto group-containing substance in the sample gas could be detected with high sensitivity. There was no response to ethanol.

  In Example 1, mercaptoethanol was used as the mercapto group-containing substance. However, even if hydrogen sulfide (which is one in which hydrogen is added to a mercapto group), which is one of the four major life malodor substances, is used. Therefore, hydrogen sulfide can be detected. Here, as hydrogen sulfide, dilute hydrochloric acid was added to 100 mg of iron (II) sulfide, and the generated hydrogen sulfide was collected by water replacement.

  Further, it is presumed that the same effect can be obtained with methyl mercaptan (which is a product obtained by adding a methyl group to a mercapto group) or other substances. In fact, even when put in the same container as the rotten food (raw saury, grilled saury, fresh cabbage, grilled cabbage, fresh cucumber, raw beef, grilled beef, rice, etc.), it fluoresced. It is thought that methyl mercaptan and hydrogen sulfide were generated from these spoiled foods.

  In Example 1, coumarin phenylmaleimide (CPM) was used as the fluorescent material, but it has been confirmed that the same effect can be obtained by using pyrenemaleimide or porphyrinmaleimide. In the case of porphyrin maleimide, an LED having an emission wavelength of 400 to 450 nm may be used. In the case of pyrenemaleimide, ultraviolet light having an excitation wavelength of about 340 nm is required, but since no light emitting diode in this wavelength region has been developed at present, it is necessary to use an ultraviolet lamp as a light source. It is necessary to use an optical filter that transmits the fluorescence emitted from the fluorescent material.

  In this example, PMEOZO was used as the aprotic polar polymer, but the same effect was obtained with the linear polysulfoxide represented by Formula 3. In this case, the longer the linear part, the lower the sensitivity, but the effect of moisture in the air decreased. Similar effects were obtained with tertiary formamide or tertiary acetamide instead of sulfoxide. The combinations of (dielectric constant, dipole moment (unit: Debye)) of dimethylformamide and dimethyl sulfoxide, which are low molecular solvents containing tertiary formamide and sulfoxide, are as follows. (36.7, 3.82), (47, 3.96). On the other hand, in the case of isopropyl alcohol in which a methyl group is sandwiched between protic polar alcohol groups (18, 1.58), in the case of diethyl ether in which a methyl group is sandwiched between aprotic and nonpolar ether groups (4.3, 1). .06). When polyalcohol or polyether, which is a polymer containing these functional groups, was used for immobilization of CPM, no response to mercaptoethanol could be observed. Acetone is an aprotic polar solvent, and a ketone group is sandwiched between methyl groups. The combination of the previous parameters is (21, 2.9). When this polyketone, which is a polymer, was used for immobilization of CPM, the response amount was about 1/3 compared to the case of PMEOZO. That is, it can be used as an immobilization material, but it is not desirable. From the above, the combination of the dielectric constant and the dipole moment is preferably 30 or more and 3.0 or more, respectively.

As described above, when the aprotic polar polymer is a functional group composed of a plurality of atoms, X contains -X- as a repeating component, and the dipole moment of the low molecule HXH is 3. The aprotic polar polymer is similarly effective when it contains 0 debye or more and a dielectric constant of 30 or more. Examples are shown in Formula 4, Formula 5, Formula 6, and Formula 7 (n1 and n2 are integers). As shown in Formulas 6 and 7, multiple types of X (X ₁ , X ₂ , X ₃ ) may be included, and the content of X may be arbitrary. As shown in Formula 6, the polymer may be branched. The molecular weight should be long enough not to dissolve in water. More desirably, the X is represented as —CH ₂ —Y—CH ₂ — when Y is a functional group composed of a plurality of atoms (for example, Formula 9 and Formula 10). A plurality of types of Y (Y ₁ , Y ₂ , Y ₃ ) may be included, and the Y content may be arbitrary. More preferably, as Y, an aprotic polar polymer having S (═O) or N—C (═O) R (R is H or a functional group) or CH—C≡N may be used ( Formula 10, Formula 11, Formula 12).

  Moreover, when a composite film in which polystyrene, which is a nonpolar polymer, was dissolved in toluene and then mixed with a mixed solution of PMEOZO and CPM was used, the response amount was reduced by about half, but long-term stability was improved. That is, the influence of moisture in the air decreased. Therefore, it is necessary to decide whether to use an aprotic polar polymer alone or to use it in combination with a nonpolar polymer according to the purpose (whether priority is given to sensitivity or stability). The same effect can be expected from polybutadiene as a nonpolar polymer. Reducing the content ratio of X in the polymer, that is, lengthening the polyethylene chain in the molecule) has the same effect. For example, Formula 10 is a polymer having a lower X content ratio than Formula 2.

<Example 2>
An experiment similar to that of Example 1 was performed using a mercapto group-containing substance detection device having the same configuration as that shown in FIG. The response amount (output voltage) at this time was about half that in the case of Example 1. In addition, the PD output in the absence of mercaptoethanol also increased. This is considered to be based on irregular reflection from the fixed film. However, it was found that the response linearity to the mercaptoethanol concentration was good, and the concentration of the mercapto group-containing substance could be quantified.

1 is a schematic cross-sectional view showing a mercapto group-containing substance detection device according to Embodiment 1. FIG. 3 is a schematic diagram of a solid film cross section of a detection material in the detection device for a mercapto group-containing substance according to Embodiment 1. FIG. It is a figure which shows the chemical reaction formula which produces | generates the reaction product of CPM and methyl mercaptan in the detection apparatus of the mercapto group containing substance which concerns on Embodiment 1. FIG. 6 is a schematic cross-sectional view showing a mercapto group-containing substance detection device according to Embodiment 2. FIG. It is a figure which shows the relationship between the density | concentration of mercaptoethanol in Example 1, and an output voltage.

Explanation of symbols

2 Sensing Material 3 Excitation Light 4 Light Source 5 Photodetection Element 6 Gas to be Measured 8 Fluorescence 10 Detection Circuit

Claims (7)

  A detection material for a mercapto group-containing substance having a molecule containing a fluorescent functional group, wherein a substance that increases or decreases in the amount of fluorescence due to a reaction with the mercapto group-containing substance is immobilized by a polymer film .   The material for detecting a mercapto group-containing substance according to claim 1, wherein the substance having a molecule containing a fluorescent functional group has a maleimide group.   The polymer film is a polymer film containing an aprotic polar polymer, and when X is a functional group composed of a plurality of atoms, it contains -X- as a repetitive component and is a dipole of low molecule HXH The material for detecting a mercapto group-containing substance according to claim 1 or 2, wherein the moment is 3.0 Debye or more and the dielectric constant is 30 or more. Sensing material mercapto group-containing material according to claim 3, characterized in that it comprises a represented by component _- X is, -CH 2 _-Y-CH 2 when the functional group obtained a Y plurality of atoms .   The mercapto group-containing substance according to claim 4, wherein Y is selected from S (= O), N-C (= O) R (R is H or a functional group), or CH-C≡N. Sensing material.   The detection material for a mercapto group-containing substance according to any one of claims 1 to 5, wherein the polymer film is prepared by mixing an aprotic polar polymer and a nonpolar polymer. . A detection material for a mercapto group-containing substance according to any one of claims 1 to 6,
A light source for supplying excitation light to the detection material;
A light detection element for detecting fluorescence emitted from the detection material;
A detection circuit for processing an output signal from the light detection element;
An apparatus for detecting a mercapto group-containing substance, comprising:

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