JP3197841B2 - Measurement method of odor intensity in aqueous solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fragrance of a flower of cosmetics and a liquid food, and a fragrance of a flower.
The present invention relates to a method for measuring odor intensity in an aqueous solution, which can be applied to monitoring of odor pollution which requires monitoring of the intensity of ur.

[0002]

2. Description of the Related Art Conventionally, odors of cosmetics and liquid foods or odors of drainage have been measured by an instrumental analysis method in which odor components are analyzed by a detector tube, an absorption spectrophotometer, a gas chromatograph method or a mass spectrometer. There is a sensory test method that uses the human sense of smell. Evaluation by the sensory test method
Objectivity is poor because it differs depending on individual differences, that is, lifestyles, ages, health conditions, and the like. Further, the gas chromatograph method or the instrument analysis method using the mass spectrometer has drawbacks such as not only that the instrument is expensive, but also that it cannot be easily carried. For this reason, at present, there is a strong demand for a method for simply and more objectively measuring the odor intensity.

[0003] Recently, an apparatus for easily measuring the odor molecular intensity using a semiconductor gas sensor or a quartz oscillator has been put into practical use. In a semiconductor gas sensor, an electric resistance type semiconductor gas sensor utilizing the fact that the electric resistance of an oxide semiconductor is changed by a gas, and a field effect transistor using a Si semiconductor, including a Pb thin film as a gate metal and including a Pb thin film. There are a transistor-type semiconductor gas sensor that uses the fact that hydrogen gas changes the gate action, and a diode-type semiconductor gas sensor that uses that the rectification action of a diode in which an oxide semiconductor and a metal are brought into contact is changed by gas.

[0004] Among the semiconductor gas sensors, the most widely used electric resistance type semiconductor gas sensors are classified into a bulk-sensitive type and a surface-sensitive type depending on whether the interaction with the gas reaches the semiconductor bulk or stops at the semiconductor surface. Divided. Bulk-sensitive semiconductor gas sensors are mainly used for air-fuel ratio control of boilers and automobile engines. Further, the surface-sensitive semiconductor gas sensor has a very wide range of applications, utilizing the fact that the electrical resistance of the porous low antibody changes due to gas adsorption and reaction on the oxide semiconductor surface.

[0005] Surface-sensitive semiconductor gas sensors include general flammable gases such as city gas and LP gas, toxic gases such as CO, breath gases such as alcohol and H ₂ S, malodorous gases such as merumptan and amine, and amines. And various gases such as food-based gases such as aldehydes and environmental polluting gases such as NOx, O3, and chlorofluorocarbon. As a semiconductor material, SnO ₂ , ZnO, γ-Fe ₂ O ₃ , α-Fe
Many n-type semiconductor oxides such as ₂ O ₃ , In ₂ O ₃ , TiO ₂ , and WO ₃ are used, and a noble metal or metal oxide is supported thereon as a surface decoration agent for improving sensitivity and selectivity. It is a thing.

As an odor detecting device using a surface-sensitive semiconductor gas sensor supporting a metal oxide, for example, an alkaline earth metal (Be, Mg, C
a, Sr, Ba) An odor detection device including a sensor carrying a metal oxide containing at least one of the following: an odor detection device (Japanese Unexamined Patent Publication No. No. 259250) has been proposed.

[0007]

An odor detection apparatus using the above-mentioned surface-sensitive semiconductor gas sensor measures, via air, odor molecules which are volatilized and diffused from the surface of a substance containing odor into the atmosphere. It is a measurement in a gas phase, and a measurement in a liquid is impossible for a surface-sensitive semiconductor gas sensor due to its characteristics. In addition, an odor detection device using a quartz oscillator sensor can measure in liquids in principle, but it is necessary to strictly unify the contact area with the liquid every time it is measured. It has the drawback that there are many problems in its properties.

On the other hand, the intensity of odor molecules in an aqueous solution is not always the same as the intensity of odor molecules volatilized from its surface. The intensity of odor molecules volatilized from its surface is measured, and the intensity of odor molecules dissolved in the solution is measured. At present, only the intensity is estimated, and the method for measuring the odor intensity in an aqueous solution has not yet been put to practical use.

An object of the present invention is to provide a method for measuring odor intensity in an aqueous solution, which can measure the odor intensity of odor molecules dissolved in a solution.

[0010]

According to a first aspect of the present invention, there is provided a method for measuring odor intensity, comprising immersing an odor introduction portion provided with a porous polymer film in an aqueous solution, and introducing the odor through the porous polymer film. The odor molecules transmitted through the portion are introduced into the odor detection portion of the electric resistance type semiconductor gas sensor, and the odor intensity is measured, and the odor intensity is displayed on the display portion.
As described above, the odor introducing section provided with the porous polymer film is immersed in the aqueous solution, and the odor molecules transmitted to the odor introducing section via the porous polymer film are detected by the odor detecting section of the electric resistance type semiconductor gas sensor. Then, the odor intensity is measured, and the odor intensity is displayed on the display unit, whereby the odor intensity of the odor molecules in the aqueous solution, which has been conventionally difficult, can be easily measured.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The porous polymer membrane used in the odor introducing portion of the present invention has the property of allowing gas-permeable molecules to pass therethrough but is mainly used as a breathable waterproof clothing. In addition to the Teflon porous membrane and polyethylene porous membrane used in the above, a porous membrane of cellulose, polyimide or polysulfone can be used. In order to allow all the odor molecules dissolved in the aqueous solution to pass, the untreated porous polymer membrane is used as it is, but it has a selective permeability that selectively allows only the odor molecules to be detected. A porous polymer membrane can also be used.

[0012] The odor molecules in the odor introduction portion that have passed through the porous polymer membrane are introduced into the odor detection portion of a conventionally known electric resistance type semiconductor gas sensor, and the odor intensity is measured, and the odor intensity is displayed on the display portion. . Examples of the electric resistance type semiconductor gas sensor include SnO ₂ , ZnO, and γ-Fe _{2.
O 3, α-Fe 2 O} 3, In 2 O 3, the n-type semiconductor oxides of TiO _2, WO _3, but which was supported like precious metals and metal oxides can be used, alkali SnO _2, ZnO What carries a metal oxide containing at least one of the earth metals is preferable because various odors can be detected with high sensitivity.

[0013] The measurement of the odor concentration by the electric resistance type semiconductor gas sensor is performed by sucking the odor molecules permeating the porous polymer membrane in the odor introduction section with a suction pump and bringing the odor molecules into contact with the sensor in the odor detection section. A change in electric resistance due to gas adsorption or reaction on the surface is measured by a measurement circuit including a bridge circuit including, for example, a sensor of the odor detection unit, and the odor intensity is digitally or analogly displayed on a display unit. As the odor display portion of the electric resistance type semiconductor gas sensor, a device having a peak hold function, a buzzer, a lamp display, or a device having various display functions can be used. The smell molecule is
Odor molecules that naturally pass through the porous polymer membrane without being suctioned by a suction pump can be measured over time.

[0014]

【Example】

Example 1 The details of the odor concentration measuring method of the present invention will be described below with reference to FIGS. FIG. 1 shows an odor molecule introducing portion provided with a porous polymer film used in the odor concentration measuring method of the present invention. FIG. 1 (a) shows a side cross section of the odor molecule introducing portion having a porous polymer film provided at one end of a cylinder. Figure, (b) is a side sectional view of the odor molecule introduction part of the porous polymer tube,
FIG. 2 is an explanatory diagram of the odor concentration measuring method of the present invention, and FIG. 3 is an example of a measuring circuit of the odor detecting section.

In FIG. 1 (a), reference numeral 1 denotes a porous Teflon membrane 3 having a hole of 0.02 to 15 μm at one end of a plastic cylinder 2 and a membrane fixing ring 5
The other end of the cylinder 2 is provided with an odor molecule suction tube 6, and the porous Teflon film 3 of the odor molecule introduction portion 1 is immersed in an aqueous solution in which odor molecules are dissolved. The odor molecules in the aqueous solution are configured to permeate through the porous Teflon membrane 3 and enter the odor molecule introduction section 1.

In FIG. 1B, reference numeral 11 denotes a diameter of 10 m.
m, an odor molecule introduction part made of a Teflon porous tube 12 having a length of 5 mm, which is sealed with a plastic cap for fixing the shape of a plastic tube for preventing intrusion of a solution from one end of the porous tube 12. The other end of the porous tube 12 is provided with a plastic cap having a odor molecule suction tube 14 and also serving as a tube-shaped fixing cap. When immersed in an aqueous solution, the odor molecules in the aqueous solution are converted into a porous tube 1
2 to penetrate into the odor molecule introduction part 11.

In FIGS. 2 and 3, reference numeral 21 denotes a glass beaker, 22 denotes an aqueous solution 22 in which odor molecules contained in the glass beaker 21 are dissolved, and the aqueous solution 22 contains the pores of the odor molecule introduction portion 11 shown in FIG. The quality tube 12 is immersed. Reference numeral 23 denotes a sensor of an odor detection unit 24 of an electric resistance type semiconductor gas sensor connected to the odor molecule suction tube 14 of the odor molecule introduction unit 11, and the sensor 23 constitutes a measurement circuit 25 together with the resistors R ₀ , R ₁ , and R _2. are doing. 2
Reference numeral 6 denotes an odor display section, which digitally or analogly displays odor intensity. Reference numeral 27 denotes a power supply, which uses a rectifier circuit for obtaining an appropriate DC voltage from a battery or a commercial power supply.
Reference numeral 28 denotes a suction pump. When the suction pump 28 is driven, the odor molecules permeated into the odor molecule introduction part 11 through the porous tube 12 are sucked. The aspirated odor molecules are configured so that the sensor 23 reduces the resistance value in proportion to the concentration, and outputs from the measurement circuit 25 to be displayed on the odor display unit 26.

When the odor intensity in the aqueous solution 22 in which the odor molecules are dissolved is measured by the above configuration, the porous tube 12 of the odor molecule introduction part 11 is immersed in the aqueous solution 22 in the glass beaker 21. And
An electric resistance type semiconductor gas sensor is connected to the odor molecule suction pipe 14 of the odor molecule introduction section 11, and a suction pump 28 is connected to the electric resistance type semiconductor gas sensor. After a while
By driving the suction pump 28, the odor molecules permeated into the odor molecule introduction section 11 from the aqueous solution 22 through the porous tube 12 are suctioned, and the sensor 23 of the odor detection section 24 is used.
Then, the sensor 23 reduces the resistance value in proportion to the concentration, the odor intensity is measured by the measuring circuit 25 and displayed on the odor display section 26.

Therefore, according to the method of the present invention, the odor intensity in the aqueous solution 22, which was conventionally difficult to measure and had to be estimated from the odor intensity of the odor molecules volatilized from the aqueous solution 22, is added to the odor molecule introduction part in the aqueous solution 22. 11 by immersing the porous tube 12 portion, it is possible to easily measure using a conventionally known electric resistance type semiconductor gas sensor, it is possible to more accurately measure the odor intensity of odor molecules in the aqueous solution 22 .

Embodiment 2 As shown in FIG. 4, coffee 41 extracted from coffee powder is put into a coffee cup 42, and a porous Teflon membrane 44 is attached to the mouth of a wide-mouth medicine bottle 43 via a packing (not shown) with a membrane fixing ring 45. The portion of the porous Teflon film 44 of the odor molecule introduction part 46 fixed by the above is immersed in the coffee 41 in the coffee cup 42 when the sample temperature drops to 26.0 ° C., and immediately after the immersion, the ZnO A suction port of a portable electric resistance type semiconductor gas sensor 48 comprising a n-type metal oxide semiconductor sensor, a measuring circuit, an odor display unit, a power supply and a suction pump, and a peak hold and an output to a recorder 47. Insert 49,
By driving a suction pump (not shown),
The odor molecules are further attracted and brought into contact with an n-type metal oxide semiconductor sensor mainly composed of ZnO to form a porous Teflon film 4.
The manner in which the electric resistance value changed in proportion to the change in the odor intensity of the odor molecules transmitted through the four portions was measured as a voltage change. The result is shown as A in FIG. Also,
The measurement was performed again 60 minutes after the measurement. The result is shown as B in FIG. As shown in FIG. 5, in the case of B after a lapse of 60 minutes, the smell of coffee is volatilized and diffused, and the odor intensity is reduced in comparison with A immediately after the extraction.

Example 3 Tap water was placed in a glass beaker having a capacity of 500 ml, and an appropriate amount of a bathing agent was dissolved as an odor substance. Immediately thereafter, the porosity of the odor molecule introduction part 11 shown in FIG. The porous tube 12 is immersed in tap water, and SnO ₂ —CaO _{2 is} introduced into the odor molecule suction tube 14 of the odor molecule introduction unit 11.
The suction port of a portable electric resistance type semiconductor gas sensor having an n-type metal oxide semiconductor sensor is connected, and the suction pump of the electric resistance type semiconductor gas sensor is driven to remove odor molecules from the odor molecule introduction section 11. Aspirate for 3.5 minutes,
A state in which the electric resistance value changes in proportion to the change in the odor intensity of the odor molecules transmitted through the porous tube 12 and measured as a voltage change when brought into contact with an SnO ₂ -CaO-based n-type metal oxide semiconductor sensor. did. The result is shown as A in FIG. After the same sample is left for 2 hours, the suction pump is driven again and the odor molecule introducing section 11 is turned on.
The odor molecules are aspirated for about 3.5 minutes, and SnO ₂ -Ca
The state in which the electric resistance value changed in proportion to the change in the odor intensity of the odor molecules transmitted through the porous tube 12 and brought into contact with an O-based n-type metal oxide semiconductor sensor was measured as a voltage change. The result is shown as B in FIG.

As shown in FIG. 6, in the measurement immediately after dissolving the bath agent indicated by A, the voltage increases in proportion to the increase in the odor intensity of the odor molecules. In addition, it can be seen that the odor intensity of odor molecules remaining in the tap water after being left for 2 hours indicated by B is quantified, and at the same time, knowledge about odor persistence can be obtained.

Example 4 A commercially available Coca-Cola was placed in a glass beaker having a capacity of 500 ml, and the change in odor intensity was measured in the same manner as in Example 2. The results are shown in FIG. 7 as A immediately after opening and B as 30 minutes after opening. As shown in FIG. 7, as compared with A immediately after opening, in the case of B 30 minutes after opening, the odor molecules volatilize and diffuse, and the odor intensity is reduced.

[0024]

According to the method for measuring odor intensity in an aqueous solution of the present invention, the odor intensity in an aqueous solution, which has conventionally been difficult to measure and can only be estimated from the odor intensity of odor molecules volatilized from the aqueous solution, is measured using a porous polymer membrane. By allowing the odor molecules in the aqueous solution to pass through the odor introduction portion provided with the, a simple and accurate measurement can be performed using a conventionally known electric resistance type semiconductor gas sensor. Therefore, if the correlation between the odor intensity and the odor concentration is determined in advance, the odor concentration can be calculated from the odor intensity.

[Brief description of the drawings]

FIG. 1 is an odor molecule introducing portion provided with a porous polymer film used in the odor concentration measuring method of the present invention. FIG. 1 (a) is a side of an odor molecule introducing portion having a porous polymer film provided at one end of a cylinder. The cross-sectional view is a side cross-sectional view of the odor molecule introduction portion of the porous polymer tube.

FIG. 2 is an explanatory diagram of an odor concentration measuring method of the present invention.

FIG. 3 is an example of a measurement circuit of an odor detection unit.

FIG. 4 is a schematic explanatory view of an experimental apparatus used in the odor concentration measurement method of Example 2.

FIG. 5 is a graph showing a relationship between a suction time and a voltage proportional to a change in odor intensity in Example 2.

FIG. 6 is a graph showing a relationship between a suction time and a voltage proportional to a change in odor intensity in Example 3.

FIG. 7 is a graph showing a relationship between a suction time and a voltage proportional to a change in odor intensity in Example 4.

[Explanation of symbols]

1, 11, 46 Odor molecule introduction part 2 Cylinder 3 Porous Teflon film 4 Packing 5, 45 Membrane fixing ring 6, 14 Odor molecule suction tube 12 Porous tube 13, 15 Fixing cap 21 Glass beaker 22 Aqueous solution 23 Sensor 24 Smell Detection unit 25 Measurement circuit 26 Odor display unit 27 Power supply 28 Suction pump R ₀ , R ₁ , R ₂ resistor 41 Coffee 42 Coffee cup 43 Wide-mouthed medicine bottle 44 Porous Teflon film 47 Recorder 48 Electric resistance type semiconductor gas sensor 49 Suction mouth

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-259250 (JP, A) JP-A-7-83879 (JP, A) JP-A-7-83880 (JP, A) JP-A-5-83880 256814 (JP, A) JP-A-6-11501 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/12

Claims (1)

(57) [Claims] 1. An odor introducing section provided with a porous polymer film is immersed in an aqueous solution, and an odor molecule transmitted to the odor introducing section via the porous polymer film is detected by an electric resistance type semiconductor gas sensor. A method for measuring odor intensity in an aqueous solution, wherein the odor intensity is measured by introducing the odor intensity into a part.