JP2005337816A - Odor measuring method and odor measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an odor measuring method and an odor measuring device capable of measuring accurately, even when the concentration of an odor component included in sample gas is low. <P>SOLUTION: This odor measuring method has a collection process for supplying the sample gas including the odor component to a container 11 filled with a collection agent 11a for collecting the odor component, a desorption process for desorbing the odor component collected by the collection agent 11a and supplying carrier gas for transferring the desorbed odor component to the container 11, and a measuring process for measuring the odor component included in the carrier gas passing the container 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an odor measuring method and an odor measuring apparatus.

  Conventionally, for example, an odor measuring apparatus described in Patent Document 1 is known. This odor measuring apparatus is a container for enclosing a sample that emits odor, a carrier gas supply means for supplying a carrier gas composed of dry air to the container, and a measurement for detecting an odor component contained in the carrier gas that has passed through the container. And means.

  By the way, bad breath is caused by three types of odor components (hydrogen sulfide; dimethyl sulfide; methylmercaptan). It depends on the inspection by the measuring device (bad breath measuring device). In the present specification, hydrogen sulfide, dimethyl sulfide, and methyl mercaptan are sometimes collectively referred to as volatile sulfur compounds.

  The sensory test is a subjective halitosis evaluation method and cannot provide an objective index to the patient. Therefore, it is difficult to convince a patient suffering from self-odor based on the result of the sensory test. On the other hand, according to the examination by the odor measuring apparatus, it is possible to provide an objective index to the patient.

JP 11-271204 A (FIG. 1)

  However, since the concentration of the volatile sulfur compound contained in the bad breath is very low, the odor measuring device according to Patent Document 1 cannot improve the sensitivity, and identifies the type of the volatile sulfur compound. It's also difficult.

  Such a problem is not limited to the measurement of bad breath, and is a problem that is commonly applied when the concentration of the odor component contained in the gas to be measured (hereinafter referred to as “sample gas”) is low. .

  Therefore, an object of the present invention is to provide an odor measuring method and an odor measuring apparatus capable of measuring with high accuracy even when the concentration of an odor component contained in a sample gas is low.

  The odor measurement method according to the present invention, which was created to solve such a problem, is a collection step of supplying a sample gas containing an odor component to a container loaded with a collection agent for collecting the odor component; A desorption step of desorbing the odor component collected by the scavenger and supplying a carrier gas for transferring the desorbed odor component to the container, and measuring the odor component contained in the carrier gas that has passed through the container And a measuring step.

  According to such an odor measurement method, since the odor component contained in the sample gas is concentrated and measured, it is possible to accurately measure even when the concentration of the odor component contained in the sample gas is low. Become. In addition, as an odor component contained in sample gas, the volatile sulfur compound contained in a bad breath is mentioned, for example.

  An odor measuring apparatus according to the present invention includes a concentration unit having a container loaded with a collection agent for collecting an odor component, a desorption unit for desorbing the odor component collected by the collection agent, and an odor component. A sample gas supply path from the sample gas supply source to the container, a carrier gas supply means for supplying a carrier gas to the container, a measuring means for measuring an odor component contained in the carrier gas that has passed through the container, It is characterized by providing.

  According to such an odor measuring apparatus, it is possible to measure the concentrated odor component after concentrating the odor component contained in the sample gas. That is, according to this odor measuring apparatus, even when the concentration of the odor component contained in the sample gas is low, it can be measured with high accuracy.

  In the odor measuring apparatus according to the present invention, the measuring means may include a plurality of gas sensors having different characteristics. In this way, when the sample gas includes a plurality of odor components, the type of the odor component can be identified by pattern recognition.

  The odor measuring apparatus according to the present invention may further include pattern recognition means for recognizing sensor response patterns of the plurality of gas sensors. If the odor measuring device is provided with a pattern recognition means, it is possible to easily and quickly identify the type of odor component.

  In the odor measuring apparatus according to the present invention, it is preferable that each of the gas sensors is an electrochemical gas sensor. Note that an electrochemical gas sensor is not easily affected by humidity, and is suitable, for example, for measuring bad breath containing a lot of humidity. If each gas sensor responds to a volatile sulfur compound contained in bad breath, the presence / absence or strength of bad breath and the quality of bad breath can be objectively evaluated.

  According to the odor measuring method according to the present invention, even when the concentration of the odor component contained in the sample gas is low, it can be measured with high accuracy.

  Further, according to the odor measuring apparatus of the present invention, it is possible to measure the concentrated odor component after concentrating the odor component contained in the sample gas. That is, according to the odor measuring apparatus according to the present invention, even when the concentration of the odor component contained in the sample gas is low, it can be measured with high accuracy.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

(Odor measuring device)
As shown in FIG. 1, the odor measuring apparatus according to the present embodiment includes a concentration unit 10 that concentrates odor components contained in a sample gas, a sample gas supply unit 20 that supplies sample gas to the concentration unit 10, and a concentration unit. A carrier gas supply means 30 for supplying a carrier gas to the means 10 and a measurement means 40 for measuring an odor component are provided.

  In the odor measuring apparatus according to this embodiment, the inlet valve V1 provided at the front stage of the concentrating means 10, the outlet valve V2 provided at the rear stage of the concentrating means 10, the inlet valve V1 and the carrier gas supply means 30. A discharge valve V3 provided between the outlet valve V2 and the suction valve V4 provided between the pump 22 of the sample gas supply means 20, the means 10 to 40 and the valves V1 to V4. And a computer 50 to be controlled.

Here, each of the inlet valve V1 and the outlet valve V2 is an electromagnetically driven three-way valve, and the inlet valve V1 has a state in which the first flow path R1 and the third flow path R3 communicate with each other, the first flow path R1 and the first flow path R1. The outlet valve V2 is configured to be able to switch between a state in which the six flow paths are communicated, and the outlet valve V2 is in a state in which the second flow path R2 and the fourth flow path R4 are in communication with each other. The state in which the road R9 is communicated is configured to be switchable.
Each of the discharge valve V3 and the suction valve V4 is also an electromagnetically driven three-way valve. The discharge valve V3 communicates with the seventh flow path R7 and the sixth flow path R6, and discharges with the seventh flow path R7. The suction valve V4 is configured to be able to switch between a state in which the passage R11 communicates with the passage R11, and the suction valve V4 has a state in which the fourth passage R4 and the fifth passage R5 communicate with each other, a suction passage R12, and a fifth passage R5. Is configured to be switchable with a state of communicating with each other.
Each valve V1 to V4 is electrically connected to the computer 50 and is driven based on a command from the computer 50.

  The concentrating means 10 concentrates the odor component contained in the sample gas, and includes a cylindrical container 11, a heating unit 12 disposed around the container 11, and a temperature sensor 13 that measures the temperature of the container 11. And a temperature controller 14 for controlling the heating unit 12.

  One end of the container 11 is connected to the inlet valve V1 via the first flow path R1, and the other end is connected to the outlet valve V2 via the second flow path R2. As shown in FIG. 2, the container 11 is loaded with a collection agent 11a for collecting odor components, and the openings at both ends of the container 11 have sealing materials 11b and 11b (one in FIG. 2). Only is shown). Examples of the collecting agent 11a include an adsorbent made of a porous material such as activated carbon, a heat-resistant resin having a 2,6-diphenyl-p-phenylene oxide structure, and ODPN (β, β′-oxydipropionitrile) held by a carrier. These mixed materials are used.

  The heating unit 12 heats the collection agent 11 a through the container 11, and includes a nichrome wire 12 a wound around the outer periphery of the container 11. That is, the heating unit 12 volatilizes (evaporates) the odor component collected by the collection agent 11a, and functions as a desorption means for desorbing the odor component collected by the collection agent 11. The nichrome wire 12a is inserted into the insulating silicon tube 12b.

  The temperature sensor 13 includes thermocouples 13a and 13a having one end connected to the outer peripheral surface of the container 11 and the other end connected to the temperature controller 14 (see FIG. 1).

  The temperature controller 14 shown in FIG. 1 is electrically connected to a computer 50, and based on the temperature of the container 11 measured by the temperature sensor 13 and the desorption temperature and temperature increase rate set by the computer 50. The magnitude of the current flowing through the line 12a (see FIG. 2) is controlled. That is, the temperature controller 14 controls the temperature of the container 11 (collecting agent 11 a), and can raise the temperature of the container 11 (collecting agent 11 a) at a temperature increase rate set by the computer 50. Furthermore, the temperature of the container 11 (collecting agent 11a) can be kept at the desorption temperature set by the computer 50.

  As shown in FIG. 1, the sample gas supply means 20 includes a sampling bag 21 in which a sample gas containing an odor component is sealed, and a pump 22.

  The sampling bag 21 is a sample gas supply source, and is connected to one end of the container 11 via a sample gas supply path including a third flow path R3, an inlet valve V1, and a first flow path R1.

  The pump 22 is connected to the other end of the container 11 via the fifth flow path R5, the suction valve V4, the fourth flow path R4, the outlet valve V2, and the second flow path R2, and is connected to the fifth flow path R5 side. The gas is sucked and discharged to the discharge path R13 side.

  The carrier gas supply means 30 includes a cylinder 31 in which a carrier gas is sealed, and a mass flow controller 32 that controls the flow rate of the carrier gas flowing out from the cylinder 31. For example, dry air is used as the carrier gas.

  The cylinder 31 is connected to a mass flow controller 32 via an eighth flow path R8, and the mass flow controller 32 includes a seventh flow path R7, a discharge valve V3, a sixth flow path R6, an inlet valve V1, and a first flow path R1. Is connected to one end of the container 11. The mass flow controller 32 may be electrically connected to the computer 50, and the computer 50 may be configured to control the mass flow controller 32.

The measuring means 40 measures odor components contained in the carrier gas that has passed through the container 11, and has a plurality of gas sensors 41, 42,..., 4n having different characteristics (hereinafter referred to as 4n when the gas sensors are not distinguished). It is attached.) Each gas sensor 4 n is electrically connected to the computer 50 and outputs the sensor response to the computer 50. As each gas sensor 4n, for example, an oxide semiconductor sensor, a QCM sensor, a SAW sensor, a conductive polymer sensor, or the like can be used. However, when a sample gas such as bad breath contains a lot of moisture, an electrochemical type sensor can be used. A gas sensor is preferred. Here, the electrochemical gas sensor is a constant potential electrolytic type, and the relationship of “I _A ∝C ₀ ” is established between the output voltage I _A and the gas concentration C ₀ .

  The computer 50 controls the driving of the valves V1 to V4, sets the desorption temperature, sets the rate of temperature rise, monitors the temperature of the container 11, sets the flow rate of the carrier gas, collects sensor responses output from the gas sensors 4n, and the like. Is to do. In the present embodiment, the computer 50 functions as a pattern recognition unit that recognizes sensor response patterns of a plurality of gas sensors. That is, the computer 50 creates a sensor response pattern for the odor component measured from the sensor responses of the plurality of gas sensors 4n, and compares the measured odor with the sensor response pattern for each odor component stored in advance. Identify the type of ingredient. Examples of pattern recognition methods include multivariate analysis methods and neural networks.

Next, an odor measuring method using the odor measuring apparatus will be described.
(Collection process)
First, a sample gas containing an odor component is supplied to the container 11 of the concentration means 10. Specifically, as shown in FIG. 3A, the inlet valve V1 is switched so that a flow path (sample gas supply path) from the sampling bag 21 to one end of the container 11 communicates, and the other end of the container 11 is switched. The outlet valve V2 and the suction valve V4 are switched so that the flow path from the pump to the pump 22 communicates, and then the pump 22 is operated. If it does so, the sample gas in the sampling bag 21 will be introduce | transduced into the container 11, and the odor component contained in the said sample gas will be collected by the collection agent 11a. During the supply of the sample gas, the discharge valve V3 is switched so that the seventh flow path R7 and the discharge path R11 communicate with each other. In this way, even if the carrier gas is released from the cylinder 31, it is discharged from the discharge path R11. Therefore, excess pressure is applied to the sixth flow path R6 to the eighth flow path R8 and the mass flow controller 32. Does not work.

(Desorption process)
After supplying the sample gas for a predetermined time, the collection agent 11 a is heated through the container 11 to desorb (volatilize) the odor component collected in the collection agent 11 a, and the carrier gas is supplied to the container 11. Specifically, an electric current is passed through the nichrome wire 12b (see FIG. 2) of the heating unit 12 to heat the container 11 (collecting agent 11a), and after the temperature of the container 11 reaches the desorption temperature, FIG. ), The inlet valve V1 and the discharge valve V3 are switched so that the flow path from the cylinder 31 to one end of the container 11 communicates, and the flow path from the other end of the container 11 to the measuring means 40 communicates. After switching the outlet valve V2, the cylinder 31 is opened to release the carrier gas. Then, the concentrated odor component is detached from the collecting agent 11a and flows into the measuring means 40 together with the carrier gas. During the supply of the carrier gas, the suction valve V4 is switched so that the suction path R12 and the fifth flow path R5 communicate with each other. In this way, even if the pump 22 is activated, air is supplied from the suction path R12, so that the pump 22 is not overloaded. In the present embodiment, the carrier gas is supplied to the container 11 after the temperature of the container 11 (collecting agent 11a) reaches the desorption temperature. The temperature of the collecting agent 11a) may be raised.

(Measurement process)
Then, each gas sensor 4n of the measuring means 40 measures the odor component contained in the carrier gas that has passed through the container 11. The sensor response of each gas sensor 4n is sent to the computer 50 and collected by the computer 50. Further, the computer 50 creates a sensor response pattern for the odor component contained in the sample gas from the collected sensor responses of each gas sensor 4n, and compares it with a sensor response pattern for each odor component stored in advance. Identify the types of odorous components contained in the sample gas.

  As described above, when the odor is measured by the procedure described above using the odor measuring apparatus according to the present embodiment, the odor component contained in the sample gas is concentrated, so that the concentration of the odor component contained in the sample gas is low. Even in this case, it becomes possible to measure with high accuracy.

  Next, the results of experiments conducted to confirm the effects of the odor measuring method and the odor measuring apparatus described above will be shown. The odor components to be measured are hydrogen sulfide, dimethyl sulfide, and methylmercaptan, which are the causes of bad breath (hereinafter collectively referred to as “volatile sulfur”). Compound ").

  Here, in this embodiment, the container 11 (see FIG. 1) is a stainless steel cylindrical tube having an outer diameter of 3.06 (mm), an inner diameter of 2.64 (mm), and a length of 50 (mm). The collection agent 11a (see FIG. 1) is 40 (mg) of activated carbon (30/60 (mesh)), and the sealing agents 11b and 11b are glass fibers. The capacity of the sampling bag 21 (see FIG. 1) is 20 (l).

  In order to collect the sample gas into the sampling bag 21 (see FIG. 1), for example, a volatile sulfur compound solution diluted to 0.1% (w / w) is placed in a sample bottle having a volume of 14 (ml). (Ml) is introduced and the headspace gas is introduced into the sampling bag 21. Hydrogen sulfide is diluted with water, and dimethyl sulfide and methyl mercaptan are diluted with ODO (Octyl Decil Oil).

In this example, the following three types of electrochemical gas sensors 4n (see FIG. 1) responding to volatile sulfur compounds contained in bad breath were used.
(I) Hydrogen sulfide sensor (Dragel Safety; XS RH ₂ S 100)
(Ii) Sulfur dioxide sensor (Dragel Safety; XS SO ₂ )
(Iii) Gas concentration measuring sensor (Dragel Safety; XS odorant (measuring gas concentration such as dimethyl sulfide or methyl mercaptan)

  In addition, each gas sensor (i)-(iii) has an interference characteristic with respect to a volatile sulfur compound, for example, the sensor for hydrogen sulfide responds also to gases other than hydrogen sulfide, and the sensor for sulfur dioxide is Although it responds also to gas other than sulfur dioxide, since the response pattern (response pattern of a sensor array) of three types of sensors differs, it is possible to identify the kind of volatile sulfur compound. Further, for example, a filter for removing hydrogen sulfide may be attached to one or both of the sulfur dioxide sensor and the gas concentration measurement sensor.

  Moreover, it was confirmed that each gas sensor (i)-(iii) does not respond with respect to the gas of relative humidity 70 (% RH). That is, the electrochemical gas sensor is suitable for measurement in an environment with high relative humidity, such as measurement of bad breath.

  In the collection step, the pump 22 (see FIG. 1) was controlled so that the flow rate of the sample gas was 800 (ml / min). The sample gas supply time was 180 (sec).

  In the desorption process, the heating unit 12 was controlled by the temperature controller 14 so that the temperature increase rate of the container 11 was 300 (° C./min). The desorption temperature was 250 (° C.).

  The carrier gas was dry air, and the mass flow controller 32 was controlled so that the flow rate was 500 (ml / min).

  FIG. 4 shows a response waveform of the sulfur dioxide sensor when the collection step and the desorption step are performed under the above-described conditions (in the figure, symbol p), and the case where the collection step and the desorption step are not performed (that is, the sample gas) It is a graph which shows the response waveform (in the figure, code | symbol q) of the sensor for sulfur dioxide of (when measuring directly). The sensor response value is an arbitrary scale.

  As shown in this graph, the peak of the response waveform of the sensor for sulfur dioxide when the collection process and the desorption process are performed is approximately 7% of the response waveform of the sensor for sulfur dioxide when the collection process and the desorption process are not performed. It turns out that it is 5 times. That is, according to the odor measurement method described above, since the odor component is concentrated by the collection process, even when the concentration of the odor component contained in the sample gas is low, it is possible to measure with high accuracy. . In FIG. 4, the odor component contained in the sample gas is only hydrogen sulfide, and its concentration is 3.8 (ppm).

  FIG. 5 is a graph showing the relationship between the concentration of the sample gas and the maximum response value of each of the gas sensors. FIG. 5A shows a case where the odor component contained in the sample gas is only hydrogen sulfide. 5 (b) shows a case where the odor component contained in the sample gas is only dimethyl sulfide, and FIG. 5 (c) shows a case where the odor component contained in the sample gas is only methyl mercaptan. In addition, the collection process and the desorption process were performed on the said conditions, respectively. The sensor response value is an arbitrary scale.

  As shown in each graph of FIG. 5, the maximum response value of each gas sensor (i) to (iii) (that is, the amount of the odor component desorbed from the trapping agent 11a (see FIG. 1)) and the concentration of the sample gas It can be seen that there is a roughly proportional relationship. Moreover, if the collection process and desorption process are the said conditions, it turns out that it can measure to the density | concentration of 0.5 (ppm) or less about each odor component.

  FIG. 6 is a graph showing the results of principal component analysis performed on the maximum response values of the gas sensors (i) to (iii) measured for each odor component. Here, the principal component analysis is a method of displaying data by compressing multidimensional information into a small number of dimensions so that there is no loss of information.

  As shown in this graph, it can be seen that the response patterns of each odor component can be separated. That is, according to the odor measuring apparatus described above, it is possible to identify the type of odor component when the sample gas includes a plurality of odor components. It can also be seen from this graph that the type of odor component can be identified even if the minimum concentration of each odor component is about 0.5 (ppm). That is, according to the above-described odor measuring method, it is understood that a low concentration odor component having a bad breath level can be identified. That is, according to the odor measuring apparatus and the odor measuring method described above, it is possible to objectively evaluate the presence / absence or strength of bad breath and the quality of bad breath.

(Examination of sample gas supply time)
FIG. 7A is a graph showing the relationship between the sample gas supply time and the sensor response. As shown in this graph, the sensor response increases as the sample gas supply time increases, but the increase rate tends to gradually decrease. In FIG. 7 (a), the odor component contained in the sample gas is only dimethyl sulfide, and its concentration is 5.7 (ppm). Further, the flow rate of the dry air as the carrier gas is set to 500 (ml / min), and the desorption temperature of the container 11 (see FIG. 1) is set to 250 (° C.).

(Examination of carrier gas flow rate)
FIG. 7B is a graph showing the relationship between the flow rate (ml / min) of the carrier gas and the sensor response. As shown in this graph, it can be seen that the sensor response increases as the flow rate of the carrier gas increases. The sensor response value is an arbitrary scale. In FIG. 7B, the odor component contained in the sample gas is only dimethyl sulfide, and its concentration is 1.2 (ppm). The sample gas supply time is 180 (sec), and the desorption temperature of the container 11 (see FIG. 1) is 200 (° C.).

(Examination of desorption temperature)
FIG. 8 is a graph showing the relationship between the desorption temperature and the sensor response pattern. This sensor response pattern is standardized by the following equation.

  As shown in this graph, it can be seen that the sensor response pattern changes depending on the desorption temperature. In FIG. 8, the odor component contained in the sample gas is only dimethyl sulfide, and its concentration is 1.4 (ppm). Further, the supply time of the sample gas is 180 (sec), and the flow rate of the dry air as the carrier gas is 500 (ml / min).

It is a block diagram of the odor measuring apparatus which concerns on this invention. It is sectional drawing for demonstrating a concentration means. (A), (b) is a figure for demonstrating the smell measuring method which concerns on this invention. It is a graph which shows the response waveform of the sensor for sulfur dioxide at the time of implementing the odor measuring method which concerns on this invention, and the response waveform of the sensor for sulfur dioxide when not implementing the said odor measuring method. FIG. 5 is a graph showing the relationship between the concentration of the sample gas and the maximum response value of the gas sensor. FIG. 5A shows a case where the odor component contained in the sample gas is only hydrogen sulfide, and FIG. When the odor component contained in the gas is only dimethyl sulfide, (c) is the case where the odor component contained in the sample gas is only methyl mercaptan. It is a graph which shows the result of having performed the principal component analysis with respect to Fig.5 (a)-(c). (A) is a graph showing the relationship between the sample gas supply time and the sensor response, and (b) is a graph showing the relationship between the flow rate of the carrier gas and the sensor response. It is a graph which shows the relationship between desorption temperature and a sensor response pattern.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Concentration means 11 Container 11a Collection agent 12 Heating part (desorption means)
20 Sample gas supply means 30 Carrier gas supply means 40 Measurement means

Claims (7)

A collection step of supplying a sample gas containing the odor component to a container loaded with a collection agent for collecting the odor component;
A desorption step of desorbing the odor component collected by the scavenger and supplying a carrier gas for transferring the desorbed odor component to the container;
And a measurement step of measuring an odor component contained in the carrier gas that has passed through the container.   The odor measuring method according to claim 1, wherein the odor component is a volatile sulfur compound contained in bad breath. A concentration means having a container loaded with a collecting agent for collecting the odorous component and a desorption means for desorbing the odorous component collected by the collecting agent;
A sample gas supply path from a sample gas supply source containing an odor component to the container;
A carrier gas supply means for supplying the container with a carrier gas for transferring the desorbed odor component;
An odor measuring device comprising: measuring means for measuring an odor component contained in the carrier gas that has passed through the container.   The odor measuring apparatus according to claim 3, wherein the measurement unit includes a plurality of gas sensors having different characteristics.   The odor measuring apparatus according to claim 4, further comprising pattern recognition means for recognizing sensor response patterns of the plurality of gas sensors.   6. The odor measuring apparatus according to claim 4, wherein each of the gas sensors is an electrochemical gas sensor.   The odor measuring device according to any one of claims 4 to 6, wherein each of the gas sensors responds to a volatile sulfur compound contained in bad breath.

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