JP4941453B2 - Odor measuring device - Google Patents

Description

  The present invention relates to an odor measuring apparatus for measuring and quantifying odors (including all fragrances and odors) used in various fields such as production of food and drink, production of various industrial products, and environmental measurement.

  In recent years, an odor measurement apparatus using an odor sensor that responds to an odor substance has been developed (see, for example, Patent Document 1). In such an odor measurement apparatus, the odor quality and the odor intensity can be expressed numerically by executing arithmetic processing using a predetermined algorithm based on detection signals acquired by a plurality of odor sensors. It has become.

  That is, in the odor measuring apparatus, based on the result of measuring a reference odor gas having a known odor, a reference axis is positioned in an m-dimensional odor space formed by detection outputs of m odor sensors, and the reference axis The odor quality is expressed by the positional relationship between the measurement point and the measurement point that is the measurement result of the unknown odor (the odor to be evaluated), specifically, the degree of similarity determined by the degree of proximity / distance between the measurement point and the reference axis. . Also, the odor intensity corresponding to a plurality of reference odor gases is calculated, and the odor index equivalent value is obtained by summing up the contribution of each odor, thereby expressing the odor intensity.

  Consider a case where a mixed odor component in which a odor component other than the measurement target is mixed with a odor component of a certain measurement target is measured. Odors that are not measured include odors of some additives, odors of mismixed substances, odors of the base material of the object to be measured, and smells of containers in which the object of measurement was stored. Things can be considered. Unless it is intentionally mixed, it can be considered that a non-measurement object is a kind of background. In the case of measuring the odor concentration of such an unknown sample in the mixture, conventionally, a standard sample with a stepwise change in the dilution of the mixture odor with a known odor concentration is prepared, and these samples are measured. Create a calibration curve. Then, with reference to the calibration curve, a quantitative value is obtained from the measurement result of the mixed odor whose odor concentration is unknown (see, for example, Patent Document 2).

  As described above, when various things are assumed to be outside the measurement target, prepare a standard sample that mixes both the measurement target and the non-measurement target, and measure the standard sample to obtain the calibration curve. is required. However, in general, the preparation of a standard sample having a mixed odor by mixing a plurality of odor components is a troublesome and time-consuming operation compared to the preparation of a single odor sample. Therefore, in the case where various types of odors that are not to be measured are assumed as described above, it is very troublesome and practically difficult to prepare a calibration curve for mixing one by one. Met.

JP 2003-315298 A Japanese Patent No. 3873491

  The present invention has been made in view of the above problems, and its main purpose is to reduce the work required to create a calibration curve in the measurement of mixed odors between the measurement object and the measurement object. Thus, an object of the present invention is to provide an odor measuring apparatus that can easily perform quantitative analysis.

An odor measuring apparatus according to the present invention, which has been made to solve the above problems, is an odor measuring apparatus for quantitatively analyzing a odor in a sample gas including a odor outside the known measurement object.
a) m (m is an integer of 2 or more) odor sensors having different response characteristics;
b) In an m-dimensional space formed by the detection outputs of the m odor sensors, a first reference line is created based on the measurement results obtained by changing the odor concentration for each of the measurement target odors, and data representing this is generated. First reference line creating means for storing;
c) in the m-dimensional space, a second reference line creating means for creating a second reference line based on the measurement results obtained by changing the concentration for each of the non-measuring odors, and storing data representing the second reference line;
d) The measurement result of the sample gas including the first odor concentration measurement object and the second odor concentration measurement object between the first reference line and the second reference line in the m-dimensional space. Is positioned as a measurement point, the first odor concentration and the second odor concentration are estimated based on the positional relationship between the position of the measurement point and the first reference line and the second reference line. Concentration estimation means;
It is characterized by having.

  In the odor measuring apparatus according to the present invention, when obtaining the odor concentration in the measurement object in the mixed odor in which the odor is mixed in the measurement object and the non-measurement object, the odor measurement apparatus is created based on a single preliminary measurement in the measurement object. Using the first reference line and the second reference line created based on the single preliminary measurement outside the measurement target, the quantitative value of the odor concentration is estimated by an arithmetic process based on data representing the reference line. The measurement point where the result of measuring the mixed odor mixed with the measurement object and the non-measurement object with m odor sensors is located in the m-dimensional space exists between the first reference line and the second reference line. It is a trap. Also, the degree of closeness / distantness between the measurement point and the two reference lines depends on the ratio of the odor concentration in the measurement target contained in the mixture and the odor concentration outside the measurement target. Can do.

  Therefore, as one embodiment of the odor measuring apparatus according to the present invention, the odor concentration estimating means includes a first reference point that is equidistant from the origin on the first reference line and the second reference line in the m-dimensional space, and Assuming a second reference point, when the odor concentration corresponding to the first reference point for the odor to be measured is A and the odor concentration corresponding to the second reference point for the odor outside the measurement target is B, the first reference point A measurement point located at a position N / (N + M) from the first reference point on the line connecting the point and the second reference point has an odor density of A × M: B × N between the measurement target and the non-measurement target. It is possible to adopt a configuration in which processing that is considered to be a mixture at a ratio of

  For example, it is assumed that the odor concentration of the odor outside the measurement target is constant, and only the odor concentration of the measurement target odor changes step by step, and the points positioned in the m-dimensional space according to the odor concentration ratio as described above are connected. And one virtual calibration curve can be drawn. Similarly, virtual calibration curves can be drawn for odors that are not measured with different odor concentrations, and one point on any calibration curve is the odor concentration (first odor) of the measurement target in the mixed odor. Odor concentration) and odor concentration (second odor concentration) outside the measurement target.

  Actually, a large number of virtual calibration curves as described above are calculated in advance, and when the measurement point of the result of measuring an unknown sample gas is positioned in the m-dimensional space, a large number of calibration curves are illuminated. Thus, the first and second odor concentrations corresponding to the measurement points can be obtained. Further, when a measurement point as a result of measuring an unknown sample gas is positioned in the m-dimensional space without obtaining a virtual calibration curve in advance, the measurement point, the first reference line, and the second reference line From the above, the first and second odor concentrations may be obtained based on the same concept as in the creation of the virtual calibration curve.

  According to the odor measuring apparatus according to the present invention, it is not necessary to prepare and measure a standard sample of mixing odor when determining the concentration of each odor in the mixing of the odor in the measuring object and the non-measuring object. It is only necessary to perform the measurement of the odor alone and the odor alone outside the measurement target. Such single odor measurement requires less labor and less time than mixed odor measurement, so that the measurement work can be saved and the burden on the operator can be reduced.

  An odor measuring apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic block diagram of the odor measuring apparatus of the present embodiment.

  The odor measuring apparatus includes a suction port 1 for sucking a sample gas, a pretreatment unit 2 for performing various pretreatments on the sucked sample gas, and a response characteristic for measuring a sample gas containing various odor components. A sensor cell 3 having a plurality of odor sensors 4 having different values, a pump 5 for drawing sample gas into the sensor cell 3, an A / D converter 6 for converting a detection signal from the odor sensor 4 into a digital signal, and digitized detection A data processing unit 7 that analyzes data, a measurement object data storage unit 8 that stores data representing a reference line created based on a measurement result of a standard sample in the measurement object, and a standard outside the measurement object The data storage unit 9 that stores data representing the reference line created based on the measurement result of the sample is stored and controls the operation of the entire apparatus. Control unit 10, an input unit 11 connected to the control unit 10 to the display unit 12 for displaying the analysis result of processing, and the like.

  In the pre-processing unit 2, removal of moisture contained in the sample gas, concentration / dilution of the target component in the sample gas, removal of interfering components, and the like are performed. The odor sensor 4 is generally a metal oxide semiconductor sensor whose resistance value changes according to the odor component, but in addition to this, a gas adsorption film is formed on the surface of a conductive polymer sensor, a crystal resonator, or a SAW device. A sensor based on another detection mechanism such as a sensor formed with the above-described sensor may be used.

  The number of odor sensors 4 is not particularly limited, but generally ten or nearly the same number (types) of odor sensors 4 are required to obtain a sufficient resolution for the odor type. For example, if the number of odor sensors 4 is 10 (that is, m = 10 in the present invention), detection signals from 10 odor sensors 4 are input to the A / D converter 6 in parallel, and the A / D converter 6 Then, each detection signal is converted into digital data and sent to the data processing unit 7 in parallel or serially. The data processing unit 7 and the control unit 10 are configured around a personal computer, and each function can be achieved by executing a predetermined processing / control program installed in the computer.

  In the odor measuring apparatus of this embodiment, a plurality of standard samples with different odor concentrations in the measurement target and a plurality of standard samples with different odor concentrations outside the measurement target are measured in advance and the results are stored. In addition, by using this, the odor concentration of each unknown odor concentration in the mixture that is known to be a mixture of the measurement object and the non-measurement object is obtained. Next, how to obtain this will be described.

  As described above, since the odor sensors 4 have different response characteristics, a 10-dimensional space formed by using detection outputs obtained from the ten odor sensors 4 as axes in different directions (directions orthogonal to each other) is considered. One measurement point can be positioned in the 10-dimensional space based on detection signals obtained from the ten odor sensors 4. The measurement results of a plurality of gases having the same odor quality and different odor concentrations are positioned as different measurement points in the 10-dimensional space, and are located away from the origin of the 10-dimensional space as the concentration increases. Therefore, it is possible to draw a single line connecting each measurement point with the increase in the odor concentration of the odor component starting from the origin.

  Since it is difficult and easy to understand the 10-dimensional space, here, the description is simplified to the 2-dimensional space formed by the detection outputs (CH1, CH2) of the two odor sensors. In the two-dimensional space shown in FIG. 2, the measurement points that are the results of measuring a plurality of gases whose odor concentrations in the measurement object are changed to 1, 10, 100 are positioned as, for example, W1, W2, and W3. A line Ta connecting these measurement points W1, W2, and W3 can be drawn. This corresponds to the reference line (first reference line) in the measurement target. On the other hand, if the odor concentration outside the measurement target is similarly measured with respect to the sample gas whose odor concentration is changed to 1, 10, 100, the measurement points are positioned as U1, U2, U3, for example. As a result, a line Tb that does not match the line Ta can be drawn, and this corresponds to a reference line (second reference line) outside the measurement target. In FIG. 2, the lines Ta and Tb are shown as straight lines. However, when the output of the odor sensor 4 has non-linearity, it may not necessarily be a straight line but may be a curved line. But that curve can be used as a reference line.

  A line that can be created when the odor concentration in a mixed odor mixed with a measurement object and a non-measurement object is changed between the two reference lines Ta and Tb. Now, as shown in FIG. 3, consider a first reference point S1 and a second reference point S2 that are equidistant from the origin on two reference lines Ta and Tb. Since each point on the reference lines Ta and Tb is associated with the concentration of the odor in the measurement object and the concentration outside the measurement object, the first reference point S1 corresponds to the concentration A of the measurement object, and the second reference point S2 is the measurement. Corresponds to the concentration B of the odor outside the target. Of course, there are cases where A = B.

  Consider a curve C connecting the two reference points S1 and S2. The curve C can be, for example, an arc or an elliptic arc passing through two reference points with the origin as the center. When a measurement point which is a result of measuring a certain odor mixed with a odor and a non-measurement odor is located on the curve C, the measurement is performed based on the position, odor concentration A and odor concentration B. Obtain the odor concentration ratio corresponding to the point. Specifically, as shown in FIG. 3, when the measurement point P1 is located on the curve C at a position N / (N + M) from the first reference point S1, the odor corresponding to this measurement point P1 has an odor concentration. It is regarded as a mixture of the odor concentration in the measurement object of [M / (N + M)] · A and the odor concentration outside the measurement object of [N / (N + M)] · B.

  For example, when the measurement point P1 is located at an intermediate point of the curve C, that is, at a location where N = M = 1, the odor corresponding to the measurement point P1 is odorous in the measurement object having an odor concentration of A / 2. It is regarded as a mixture of a non-measuring odor having a density of B / 2. Further, when the measurement point P1 is located on the curve C at a position 3/4 from the first reference point S1, that is, where N = 3 and M = 1, the odor corresponding to this measurement point P1 is It is regarded as a mixture of a measurement object having an odor concentration of (1/4) · A and a non-measurement object having an odor concentration of (3/4) · B.

  Considering the case where A and B are equal to simplify the explanation, as shown in FIG. 4, a curve connecting points of the same odor density on the two reference lines Ta and Tb can be drawn. The measurement point P1 of the mixed odor obtained by mixing the odor density outside the measurement object having the odor density of 1 and the odor density having the odor density of 1 is an addition value of the odor density on the respective reference lines Ta and Tb. It is located at an intermediate point on the curve C1 connecting points between certain odor densities 2 (that is, a point of 1: 1 for both points). Next, the measurement point P2 of the mixed odor obtained by mixing the odor concentration outside the measurement target having an odor concentration of 1 and the measurement target odor having an odor concentration of 9 is the odor concentration on the reference lines Ta and Tb. It is located at 9: 1 according to the ratio of odor density on the curve C2 connecting the points of the odor density 10 as an added value. Further, the measurement point P3 of the mixed odor obtained by mixing the odor concentration outside the measurement target having the odor concentration of 1 and the measurement target odor having the odor concentration of 99 is the addition of the odor concentration on the respective reference lines Ta and Tb. It is located at 99: 1 according to the ratio of the odor density on the curve C3 connecting the points of the odor density 100 as the value.

  In this way, a plurality of measurement points P1, P2, and P3 outside the same measurement target obtained from the points corresponding to the respective odor concentrations on the respective reference lines Ta and Tb are determined according to the increase of the odor concentration in the measurement target. A single line S is drawn by connecting. This line S is a calibration curve of a sample (mixed scent) including a odor concentration outside the measurement target of 1 and an unknown odor concentration measurement target. Although the calibration curve S is a straight line in FIG. 4, it is not always a straight line.

  In the same manner, calibration curves of, for example, 2, 3,. In principle, it is possible to draw a calibration curve without setting an upper limit for the odor concentration. However, in practice, an appropriate upper limit can be set for the odor concentration outside the measurement target. It is also possible to provide a constraint that the odor concentration of the odor is lower than the odor concentration of the odor to be measured. In any case, since each point constituting the calibration curve is a point that divides the curve drawn between the two reference lines by the ratio of odor concentration, all the calibration curves have two reference lines Ta and Tb. Exists between.

  As described above, the measurement result of an unknown sample in which a large number of calibration curves are prepared and an unknown odor concentration measurement target is mixed with an unknown odor concentration measurement target is a point on the calibration curve S. Assume that it is positioned at Q. In this case, in light of this calibration curve S, it can be determined that the odor concentration of the measurement target in the sample is 8. If the measurement result of an unknown sample does not ride on any of the calibration curves, use the calibration curve that is closest in distance, or use an interpolation process that uses two calibration curves that sandwich the measurement point. The odor concentration corresponding to the measurement result can be obtained.

  Although the above description is simplified to a two-dimensional space, it is basically the same even when it is expanded to a 10-dimensional space. A large number of calibration curves can be drawn when the odor concentration is changed, and the odor concentration of an unknown sample can be obtained based on the calibration curve. FIG. 3 assumes that A and B are equal, but it is clear that a calibration curve can be drawn by the same calculation even if A and B are not equal.

  The calculation principle of the odor concentration of the measurement target in the unknown sample in the odor measurement apparatus of the present embodiment is as described above, but it is sufficient to draw a calibration curve virtually, and such a virtual calibration curve exists. Therefore, the odor concentration of the measurement target corresponding to the measurement point is calculated from the data representing the two reference lines and the data representing the measurement point that is the result of measuring the unknown sample. Can do.

  For this purpose, first, in the odor measuring apparatus shown in FIG. 1, a gas having only the odor to be measured is introduced into the suction port 1, and the pretreatment unit 2 performs concentration so as to change the odor concentration step by step. The measurement corresponding to the odor density is executed, and the data representing the first reference line is stored in the odor data storage unit 8 to be measured. Next, a gas having only an odor that is not to be measured is introduced into the suction port 1, and the concentration corresponding to the odor concentration is changed stepwise in the pretreatment unit 2, and measurement corresponding to each odor concentration is performed. Data representing two reference lines is stored in the data storage unit 9 outside the measurement target. When there are a plurality of odors outside the measurement target, the measurement is performed in the same manner, and data representing the reference line is stored in the odor data storage unit 9 outside the measurement target.

  When an unknown sample is introduced from the suction port 1 and detection data from the odor sensor 4 is given to the data processing unit 7, the data processing unit 7 includes the odor data storage unit 8 and the odor data storage unit 9 outside the measurement target. The data representing the reference line is read out from each, and the same arithmetic processing as the quantitative calculation based on the calibration curve as described above is executed to calculate the odor concentration in the measurement target. Of course, at the same time, the odor concentration outside the measurement object is also obtained. The analysis result thus obtained may be displayed on the display unit 12 to inform the analyst.

  In addition, although the said Example is an example in case an unknown sample contains only one kind of non-measuring odor in addition to the measuring object, the odor measuring apparatus according to the present invention includes only one measuring object. On the other hand, the present invention can be extended to calculate the odor concentration of the measurement target odor and the odor concentration outside the measurement target in a mixed odor mixed with two or more non-measurement target odors.

  Moreover, the said Example is only an example of this invention, and it is clear that it will be included in the claim of this application, even if it changes suitably, amends, adds, etc. in the range of the meaning of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block block diagram of the odor measuring apparatus which is one Example of this invention. Explanatory drawing of the odor density | concentration estimation method in the odor measuring apparatus of a present Example. Explanatory drawing of the odor density | concentration estimation method in the odor measuring apparatus of a present Example. Explanatory drawing of the odor density | concentration estimation method in the odor measuring apparatus of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Suction port 2 ... Pre-processing part 3 ... Sensor cell 4 ... Odor sensor 5 ... Pump 6 ... A / D conversion part 7 ... Data processing part 8 ... Odor data memory | storage part 9 ... Measurement object odor data memory | storage part 10 ... Control unit 11 ... input unit 12 ... display unit

Claims (2)

An odor measuring apparatus for quantitatively analyzing a measurement object in a sample gas including a measurement object and a known non-measurement object,
a) m (m is an integer of 2 or more) odor sensors having different response characteristics;
b) In an m-dimensional space formed by the detection outputs of the m odor sensors, a first reference line is created based on the measurement results obtained by changing the odor concentration for each of the measurement target odors, and data representing this is generated. First reference line creating means for storing;
c) in the m-dimensional space, a second reference line creating means for creating a second reference line based on the measurement results obtained by changing the concentration for each of the non-measuring odors, and storing data representing this;
d) The measurement result of the sample gas including the first odor concentration measurement object and the second odor concentration measurement object between the first reference line and the second reference line in the m-dimensional space. Is positioned as a measurement point, the first odor concentration and the second odor concentration are estimated based on the positional relationship between the position of the measurement point and the first reference line and the second reference line. Concentration estimation means;
An odor measuring apparatus comprising: The odor measuring device according to claim 1,
The odor concentration estimation means assumes a first reference point and a second reference point that are equidistant from the origin on the first reference line and the second reference line in the m-dimensional space, respectively. When the odor density corresponding to the reference point is A and the odor density corresponding to the second reference point for the non-measurable odor is B, the first reference is on the line connecting the first reference point and the second reference point. A measurement point located at a position N / (N + M) from the point is subjected to processing that is considered to be a mixture of a measurement object and a non-measurement object at an odor concentration ratio of A × M: B × N. Odor measuring device characterized by.

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