JP2008145271A - Odor discrimination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for separating and detecting a plurality of odor components having different movement speeds in a collector, which attains the spread of the application range of an odor discrimination device. <P>SOLUTION: In a detection step, the valve opening directions of respective valves are selected so that a carrier gas passes through a flow passage of from a carrier gas supply section C to a sensor unit 8 via a valve V1, a valve V11, a collecting tube 4, a valve 12, and a change-over valve 11. The flowing-through direction of the carrier gas in the collecting tube 4 is set to be the same as that of a sample during odor collection, that is, the carrier gas is caused to flow in the direction of from side A to side B. In this way, the separation of the odor components in the collecting tube 4 is promoted, and components having a high movement speed and those having a low movement speed are time-dependently separated to be sensed with the sensor unit 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an odor discriminating apparatus used in the field related to odor measurement, such as research and development, quality control, and environmental maintenance management in food, fragrance, and chemical product manufacturing.

  In an odor discriminating device (hereinafter abbreviated as a device in principle), the odor component to be measured is once adsorbed and collected by the collecting agent in the collecting tube, and then the collecting tube is heated again to collect the adsorbed and collected material. The collected components are desorbed, and the odor component is detected by a sensor unit including one or a plurality of sensors having the same or a plurality of operating principles (see, for example, Patent Document 1 and Patent Document 2).

  FIG. 6 shows the basic configuration of the apparatus. A sample supply unit S composed of the sample container 1 and the suction port 2 is connected to a valve V1. The valves V1 to V3 and the six-way valve 3 switch the flow path of the fluid flowing through the apparatus. The collection tube 4 contains a carbon-based adsorbent, for example, and adsorbs odor components. The collection tube 4 is heated to an appropriate temperature by a heater H for heating as necessary. The left opening of the collection tube 4 is referred to as side A, and the right opening is referred to as side B. The pump 5 sucks the sample and causes the sample to flow through a necessary flow passage in the apparatus, and discharges it from the first exhaust port.

  A carrier gas supply unit C constituted by the nitrogen cylinder 6 and the connection port 7 is connected to the valve V3. The nitrogen cylinder 6 is filled with dry nitrogen gas. The dry nitrogen gas is used as a cleaning gas for removing residual samples, residual moisture and the like in the collecting pipe 4 and the flow passage of the apparatus, and also detects odor components. Used as a carrier gas when introduced into the unit 8.

  The six-way valve 3 has six connection ports to the outside, and has a structure in which two types of positions, a first position and a second position, are selected sequentially by rotation. If the six connection ports are designated as a, b, c, d, e, and f in the clockwise direction, for example, the first position is open between ab, cd, and ef (shown by a solid line in FIG. 6). Thus, the circuit between bc, de, and fa is closed (indicated by a dotted line in FIG. 6). In the second position, the open circuit and the closed circuit are reversed from the first position.

  The sensor unit 8 incorporates a sensor using a conductive polymer, for example, and detects various odors. Some sensors use a metal oxide semiconductor as the sensitive film. This type of sensor changes the conductivity of the sensor due to an oxidation-reduction reaction between oxygen molecules adsorbed on the sensitive film and molecules of odor components. Therefore, for example, it is necessary to supply oxygen together with the sample to replenish oxygen molecules during measurement. In this case, for example, a system in which air containing oxygen is supplied as necessary from an air cylinder filled with compressed air is added to the apparatus, but the present invention is not directly related to the type of sensor. The description of the air supply system is omitted.

  FIG. 6 shows the basic structure of the odor identification device. The actual device is equipped with the above-described air supply system, molecular sieve, activated carbon, etc. for removing impurities misidentified as odor components. The used filter, pressure reducing valve, pressure gauge, flow meter, flow control valve, etc. are used, but they are not shown because they are not directly related to the present invention. As described above, the sensor unit 8 may incorporate sensors based on a plurality of principles as necessary.

  The main procedure of measurement is shown below. First, a process for collecting odor components in a sample will be described. In this step, the six-way valve 3 is selected at the first position, and the sample in the sample container 1 is drawn into the suction port 2 -the valve V 1 -the six-way valve 3 -the collection tube 4 -the six-way valve 3 -the valve V 2 -pump 5. The opening direction of each valve is selected so as to pass through the flow path. The sample passes through the flow passage by the suction force of the pump 5 and is discharged to the first exhaust port. In this step, the odor component is adsorbed and accumulated in the collecting agent in the collecting tube 4 at room temperature.

  After the collection of odor components, the process moves to a cleaning process. The opening direction of the valve V1 is switched and the direction of the suction port 2 is closed, and the dry nitrogen gas from the nitrogen cylinder 6 is connected to the connection port 7-valve V3-valve V1-hexagonal valve 3-collecting pipe 4-hexagonal valve 3-valve. V2-flow passage L is flowed through the flow passage of the first exhaust port, and residual samples, residual moisture, and the like in the flow passage are removed. At this time, the odor component in the sample adsorbed by the normal temperature collecting tube 4 is continuously adsorbed by the collecting tube 4, and only the residual moisture in the collecting tube 4 is removed. During the measurement period, the six-way valve 3, the sensor unit 8, and the flow path from the six-way valve 3 to the sensor unit 8 are usually kept at a temperature slightly higher than room temperature, for example, 40 ° C. by a heater (not shown). This prevents changes in the characteristics of the odor sensor due to fluctuations in the ambient temperature and adhesion of high-boiling compounds in the sample to the inner wall of the flow passage.

  Next, the odor detection process will be described. In the detection step, the position of the six-way valve 3 is switched from the first position to the second position, and the nitrogen gas from the nitrogen cylinder 6 is connected to the connection port 7 -the valve V3 -the six-way valve 3 -the collection tube 4 -the six-way valve 3. -Sensor unit 8-Flowed through the flow path of the second exhaust port. Moreover, the collection tube 4 is started to be heated at an ascending rate of 10 ° C./second, for example. Due to this heating, the odor component in the collection tube 4 is sequentially desorbed and conveyed to the nitrogen gas, passes through the sensor unit 8, and is detected by the odor sensor built in the sensor unit 8.

  In the detection step, nitrogen gas is used as a carrier gas that carries the odor component to the sensor unit 8 as described above. In this step, the direction of the carrier gas flow in the collection tube 4 is opposite to the sample flow during sample collection. That is, at the time of sample collection, the sample is introduced into the collection tube 4 from the side A side and discharged to the side B side. However, when the odor component is desorbed, the carrier gas is introduced from the side B side and discharged to the side A side. Is done.

  After completion of the measurement, the sample container 1 is removed from the suction port 2, a bag (not shown) filled with clean gas is connected to the suction port 2, the pump 5 is operated, and the suction port 2 and the piping in the apparatus are washed. Prepare for the next sample measurement.

  FIG. 7 shows the connections between the elements by arranging the elements at positions different from those in FIG. 6 for convenience of comparison with FIGS. 1 to 4 described later. And the interconnection is exactly the same as in FIG.

  FIG. 8 schematically shows an example of the concentration distribution of the sample in the collecting tube 4 in the odor component collecting step. That is, the odor component in the sample that has reached the collection tube 4 is first adsorbed by the collection agent in the vicinity of the side A, and then moves in the collection agent from the side A side to the side B side along the flow of the sample. As shown in the figure, the component having a high moving speed is distributed over a wide range of the collecting tube 4 and the slow component is distributed in the vicinity of the side A of the collecting tube 4. Next, when this odor component is desorbed by the carrier gas from the side B side in the detection step, the odor component moves to the side A side as shown in FIG. It is guided to the unit 8 and detected. At this time, the separation of the odor component generated in the collecting step on the collecting agent is desorbed while being lost again in the detecting step as shown in FIG.

Japanese Patent Laid-Open No. 11-218512 JP 2002-22694 A

  The configuration and operation of the conventional apparatus are as described above. However, in this configuration, in the case of a sample in which a plurality of odor components are mixed, it is difficult to separate and detect these components in terms of time. It was. That is, as described above, the plurality of odor components that flow into the collection tube 4 from the side A and are captured are located at different positions of the collection agent due to the difference in moving speed as schematically shown in FIG. Although these are distributed, these odor components are desorbed from the side A side while moving in the direction in which the components are superimposed again as shown in FIG. 9 by the carrier gas flowing in from the side B side in the detection process. The separation that occurred during the collection will be canceled again.

  Even in the conventional detection process, the discrimination power has been improved by utilizing the temperature dependence of desorption from the collection agent. Since it was not performed, the effect of improving discrimination was limited. The object of the present invention is to provide means for solving such problems.

  In order to solve the above-mentioned problems, the present invention provides a collection tube filled with a collection agent, a heating unit for heating and desorbing an odor component adsorbed to the collection agent by heating the collection tube, and a collection unit. In the odor discriminating apparatus, the flow direction of the carrier gas to the collection pipe is determined by providing a flow passage for introducing the odor component desorbed by circulating the carrier gas through the collection pipe to the sensor together with the carrier gas. A flow direction changing means for reverse rotation is provided. The flow direction changing means is composed of two or more two-way switching valves provided at both ends of the collection tube.

  According to the present invention, since it becomes possible to pass the carrier gas in the direction in which the component separation in the collection tube obtained in the odor collection step is further promoted in the detection step, the separation and detection of the odor component over time is detected. Is achieved. Further, by switching the carrier gas flow path, it is possible to obtain measurement values corresponding to all odor components as in the conventional case using a single collection tube. Furthermore, by changing and controlling the temperature gradient of the heating of the collection tube in the detection step, first, the difference in the moving speeds of a plurality of odor components having similar temperature dependences of desorption from the collection agent at the first temperature. It is also possible to perform separation detection based on this, and further change to the second temperature to perform separation detection of another composite component. By these effects, the expansion of the application range of the odor discriminating apparatus is achieved.

This will be described with reference to the illustrated example. FIG. 1 to FIG. 4 show the flow of a sample or dry nitrogen gas according to the structure and process of an embodiment of the present invention. 1 to 4, the configuration and operation of components having the same reference numerals as those in FIG. 6 are the same as those in FIG.
In FIG. 1, a valve V11 on the sample supply unit S side and a valve V12 on the carrier gas supply unit C side are respectively disposed at both ends of the collection tube 4, and the valve V1 and the valve are arranged according to each step described below. The flow of dry nitrogen gas supplied from the sample or carrier gas supply unit C is switched in cooperation with V2 and the switching valve 11.

  The switching valve 11 is a valve that switches the flow path by rotation like the six-way valve 3 in FIG. 6, but the flow path of the rotor is different from the six-way valve 3 as shown in FIG. 1. The heating / desorption condition control unit 12 includes an arithmetic unit for setting the heating condition of the heater H, a heating power source, and an input device (not shown) such as a keyboard or a mouse. The conditions for heating the collection tube 4 are appropriately changed and set according to the signal input in the field.

  FIG. 1 shows a configuration at the time of collecting odor components and a flow of a sample. A sample introduced from the sample supply unit S into the apparatus is a valve V1-valve V11-collecting tube 4-valve V12-switching valve 11-valve. An open circuit and a closed circuit of each valve are set so as to pass through the flow path of V2. In this step, the heater H cannot be energized, so that the odor component in the sample is adsorbed by the normal temperature collecting agent in the collecting tube 4. In this step, the opening and closing directions of the valve V1 and the valve V12 are selected so that the flow of dry nitrogen gas from the carrier gas supply unit C is blocked.

  FIG. 2 shows the flow of dry nitrogen gas from the carrier gas supply unit C in the cleaning process. The dry nitrogen gas passes through the flow path of valve V1-valve V11-collection pipe 4-valve V12-switching valve 11-valve V2, and the residual sample in the flow path and the residual moisture in the collection pipe 4 are removed. . In this process, since the heater H is not energized as in the previous process, the odor component in the sample is continuously adsorbed by the scavenger at room temperature.

  FIG. 3 shows a carrier gas flow path in the first detection step. The carrier gas (dry nitrogen gas) introduced from the carrier gas supply unit C passes through the flow path of the valve V1-valve V11-collecting pipe 4-valve V12-switching valve 11-sensor unit 8, and the odor component is sensor unit. The position of each valve is selected to be detected at 8. Since the carrier gas flows in from the side A side of the collection tube 4 and is discharged together with the odor component from the side B side, the separation of the odor component proceeds due to the difference in moving speed as schematically shown in FIG. First, a component having a high moving speed is detected by the sensor unit 8, and thereafter components having a low moving speed are sequentially detected.

  FIG. 4 shows a carrier gas flow path in the second detection step. The carrier gas introduced from the carrier gas supply unit C passes through the flow path of the valve V12-collecting pipe 4-valve V11-switching valve 11-sensor unit 8. In this detection step, as in the conventional apparatus described in the background art section, the carrier gas is introduced from the side B into the collection tube 4, so that the odorous components generated in the collection step as described in FIG. Separation is lost again in the detection process, and desorption corresponding to all components is mainly performed, and the same measurement result as that of the conventional apparatus is obtained.

  The present invention is not limited to the above-described embodiments, and various modified embodiments can be given. For example, in FIG. 1 to FIG. 4, one collection tube 4 is shown, but the number of collection tubes 4 is not limited to one. These valves V11 and V12 may be arranged at all times or replaceable. One or a plurality of standard heating programs may be set in advance in the heating / desorption condition control unit 12, and at the time of measurement, one of them may be selected to start measurement.

  Further, the setting condition of the heating / desorption condition control unit 12 is first raised to the first temperature and held, and then raised to the second temperature and held, so that a plurality of desorptions at the first temperature are first performed. Setting to further improve the accuracy of separation detection by separating and detecting odor components based on the difference in movement speed, and further separating and detecting a plurality of odor components desorbed at the second temperature based on the difference in movement speed. Is also possible. Operation of the apparatus including the heating / desorption condition control unit 12, data acquisition, and data analysis may be controlled by a personal computer to automate the operation of the apparatus.

  As the sensor unit 8, one or more appropriate ones of a metal oxide semiconductor sensor, a conductive polymer sensor, or a sensor having a gas adsorption film formed on the surface of a crystal resonator or a SAW device are used as necessary. can do. The present invention includes all of these.

  The present invention can be applied to an odor discriminating apparatus used in the field relating to odor measurement, such as research and development, quality control, and environmental maintenance management in food, fragrance, and chemical product manufacturing.

It is a figure which shows the flow path of the sample at the time of the smell collection in the Example of this invention. It is a figure which shows the gas flow path at the time of the washing | cleaning of a collection pipe | tube in the Example of this invention. It is a figure which shows the flow path of the carrier gas in the 1st detection process of the Example of this invention. It is a figure which shows the flow path of the carrier gas in the 2nd detection process of the Example of this invention. It is a schematic diagram which shows isolation | separation of the odor component in the collection tube at the time of the odor detection in the Example of this invention. It is a figure which shows the structure of the conventional smell identification apparatus. It is the figure which showed the connection between the main elements of the conventional smell identification apparatus by the element arrangement | positioning similar to FIGS. It is a schematic diagram which shows distribution of the component in the collection pipe | tube at the time of odor collection in the conventional odor identification apparatus. It is a schematic diagram which shows distribution of the component in the collection tube at the time of the smell detection in the conventional smell identification apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample container 2 Intake port 3 Six-way valve 4 Collection pipe 5 Pump 6 Nitrogen cylinder 7 Connection port 8 Sensor unit 11 Switching valve 12 Heating / desorption condition control part H Heater C Carrier gas supply part S Sample supply part V1 Valve V2 Valve V3 Valve V11 Valve V12 Valve

Claims (2)

  A collection tube filled with a collection agent that collects odor components in the sample, a heating unit for heating the collection tube and adsorbing the odor components adsorbed on the collection agent, and a collection tube Flow that reverses the flow direction of the carrier gas to the collecting pipe in an odor identification device that has a flow passage that guides the desorbed odor components together with the carrier gas to the sensor through the carrier gas and measures and identifies the odor gas An odor discriminating apparatus comprising a direction changing means.   2. The odor discriminating apparatus according to claim 1, wherein the flow direction changing means is composed of two or more switching valves provided at both ends of the collecting pipe.

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