WO2012160941A1

WO2012160941A1 - Titration device and rice inspection method using same

Info

Publication number: WO2012160941A1
Application number: PCT/JP2012/061193
Authority: WO
Inventors: 博章鈴木; 隆顕佐竹; 暁麗邱
Original assignee: 国立大学法人筑波大学
Priority date: 2011-05-20
Filing date: 2012-04-26
Publication date: 2012-11-29
Also published as: JPWO2012160941A1

Abstract

The purpose of the present invention is to obtain a titration device which is compact and capable of performing titration on a small amount of a sample to be titrated. This titration device (10) is configured by joining a transparent resin layer (30) on a flat substrate (11). In this configuration, titrant (50) flowing through a titrant transport path (41) flows as plugs (51) in a first plug transport path (43). The sizes (volumes) of and the intervals between the plugs (51) are uneven. However, the plugs (51) are reconstructed as plugs (52) at a volume regulating section (44) so as to have even sizes, and these plugs (52) are poured into a reaction vessel (20) through a second plug transport path (45).

Description

Titration device and rice inspection method using the same

The present invention relates to a portable titration apparatus that can perform chemical analysis by titration and is portable. The present invention also relates to a rice freshness inspection method (rice inspection method) using the titration apparatus.

Food freshness is often difficult to determine by appearance alone. For this reason, a method is used in which the freshness of food is defined by some physical quantity that can be measured, and this physical quantity is measured. For example, the index indicating the freshness of rice includes the amount of fatty acid generated and the activity of the contained enzyme. Since the former increases when the rice becomes old, it can be determined using a pH meter. Since the latter decreases when the rice becomes old, the determination can be made in the same manner by measuring the enzyme activity.

In any of the determination methods, it is required that an appropriate determination result can be obtained in a short time. For example, Patent Document 1 describes a method for measuring the freshness of rice using the amount of fatty acid generated. In this method, a plurality of rice grains are stored in a color developing reaction plate with a filter that can store a plurality of rice grains independently. taking measurement. Thereby, the generation amount of fatty acid can be recognized as pH, and the freshness of rice can be measured as an objective physical quantity.

In pH measurement, a pH meter that electrochemically measures pH can be used. However, since the pH meter is expensive and does not know the absolute amount of fatty acid that directly affects freshness, titration is generally performed. Often done. In titration, it is repeated that a titrant is dropped on a sample to be titrated by a certain amount. In this case, for example, the amount of fatty acid can be determined by confirming the color change of the indicator when the indicator is added to the sample to be titrated and the titrant reaches the equivalent point. In order to drop the titrant by a fixed amount, a burette or the like is used. At the time of dropping using a burette or the like, the amount of one drop can be made minute and constant, so that the amount of drop required to reach the equivalence point can be accurately measured.

Such a pH measurement can be used to check the freshness of rice. Similarly, the freshness of other foods and the like can be inspected.

JP 2005-43097 A

The inspection device used when inspecting the freshness of food such as rice is generally large and difficult to carry. For this reason, a sample to be inspected (rice) is brought into a place where an inspection apparatus is installed, and the above measurement is performed here.

However, in order to increase the efficiency of the inspection, it is effective to carry the inspection apparatus to the place where the sample to be inspected is stored and perform the inspection on the spot. Further, since the freshness deteriorates while the sample to be inspected is moved, it is preferable that the inspection can be performed at an arbitrary place in order to perform more accurate measurement. For such applications, a small and easy-to-carry inspection apparatus is effective. In addition, such a portable inspection device is effective for enabling a non-expert consumer to perform such an inspection.

In addition, rice is often distributed as blended rice in which multiple brands are mixed. In such a case, the freshness may vary depending on the brand, so that it is required to be able to inspect rice in single grain units. That is, it is also required that a small sample to be inspected can be inspected.

In such a case, the sample to be titrated at the time of inspection using titration becomes a very small amount, and correspondingly, the amount of titrant required to reach the equivalent point becomes small. In this case, it is difficult to accurately determine the equivalence point unless the amount of dripping (injection amount) is very small.

However, in order to make such a minute input amount constant, complicated operations such as controlling the flow rate in the narrow tube are required. In order to perform such an operation, a complicated mechanism such as a flow sensor or a solenoid valve is required, so that the apparatus becomes expensive. It has also been difficult to reduce the size of the apparatus.

The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
In the titration apparatus of the present invention, a sample to be titrated is placed in a reaction tank formed in a resin layer bonded on a substrate, and a plug which is a lump of titrant is injected into the sample to be titrated multiple times. A titration apparatus for performing titration, wherein the titrant transport path into which the titrant is injected, the gas transport path into which gas is injected, the titrant transport path and the gas transport path are merged A first plug transport path for flowing the plug formed by the step toward the reaction layer, and a downstream side of the first plug transport path, and a cross-sectional area perpendicular to the flow direction is greater than that of the first plug transport path. A volume restricting portion capable of simultaneously accommodating a plurality of the plugs, a cross-sectional area perpendicular to the flow direction being larger than the first plug transport path and smaller than the volume restricting portion, the volume restricting portion A plurality of said plugs fused together A second plug transport path for introducing to the reaction vessel, characterized in that is formed at the interface between the substrate and the resin layer.
In the titration apparatus of the present invention, the resin layer is made of a transparent resin material.
In the titration apparatus of the present invention, the substrate is made of glass.
In the titration apparatus of the present invention, the groove constituting the titrant transport path, the gas transport path, the first plug transport path, the volume restricting portion, and the second plug transport path is formed on the substrate side of the resin layer. It is characterized by being formed on the surface.
The titration apparatus of the present invention is characterized in that the resin layer is composed of polydimethylsiloxane (PDMS).
In the titration apparatus of the present invention, the groove is formed by a mold.
The rice inspection method of the present invention is a rice inspection method for inspecting the freshness of rice using the titration device, wherein a liquid obtained by extracting fatty acids contained in rice is introduced into the reaction tank, and an alkaline solution is used as the titrant. It is characterized by performing titration using.

Since the present invention is configured as described above, it is possible to obtain a titration apparatus that is small in size and capable of performing titration on a small amount of a sample to be titrated.

It is a top view of the titration apparatus which becomes the 1st Embodiment of this invention. It is sectional drawing in three places of the titration apparatus used as the 1st Embodiment of this invention. It is a schematic diagram which shows the form of the plug in the flow path in the titration apparatus used as the first embodiment of the present invention. It is the result of having actually image | photographed the plug in the flow path in the titration apparatus used as an Example. It is the result of having measured the standard deviation of the volume of the plug in the titration apparatus used as an Example in the 1st plug transport path and the 2nd plug transport path. It is the result of having measured the frequency distribution of the volume of the plug in the titration apparatus used as an Example. It is the titration characteristic at the time of titrating hydrochloric acid using the titration apparatus used as an Example. It is an Example of the titration characteristic at the time of applying the rice test | inspection method used as the 2nd Embodiment of this invention with respect to the rice from which freshness differs.

(First embodiment: titration apparatus)
Hereinafter, the configuration of the titration apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a top view showing the configuration of the titration apparatus 10, and FIG. 2 is a cross-sectional view in the AA direction (a), the BB direction (b), and the CC direction (c). . In the titration apparatus 10, a small reaction tank 20 is provided on a substrate 11, and a sample to be titrated is introduced into the reaction tank 20, and a lump of titrant (plug) is discretely introduced therein. As a result, titration can be performed in the same manner as when titration is performed using a puret or the like. For example, a color change in a titration sample in the reaction vessel 20 can be confirmed, and an equivalence point can be obtained. it can.

The titration apparatus 10 is configured by bonding a transparent resin layer 30 on a flat substrate 11. The resin layer 30 is patterned so as to form a reaction tank 20 that can hold the titration sample in a state where the resin layer 30 is bonded to the substrate 11. In addition, a route through which a titrant and air flow is formed at the interface between the resin layer 30 and the substrate 11. This path is formed by a groove formed on the surface of the resin layer 30 on the side bonded to the substrate 11.

As this path, a titrant transport path 41 through which the titrant 50 flows and a gas transport path 42 through which a gas such as air flows are formed on the right side in FIG. The titrant 50 is introduced into the titrant transport path 41 and the air is introduced into the gas transport path 42 from the right side in FIG. 1 via the

silicone tubes

61 and 62, respectively. Further, the titrant transport path 41 and the gas transport path 42 merge to form a first plug transport path 43. Since the titrant 50 is mixed with gas in the first plug transport path 43, the titrant 50 becomes an intermittent mass (plug 51) and flows in the first plug transport path 43 on the left side in the figure, and the volume restricting portion. 44 is reached. Thereafter, in the volume restriction unit 44, a plurality of plugs 51 are fused to reconfigure a new plug 52, and the plug 52 flows through the second plug transport path 45 and reaches the reaction tank 20.

Although the resin layer 30 has a substantially plate shape, as shown in FIG. 2, on the lower surface side (substrate 11) side, the titrant transport path 41, the gas transport path 42, the first plug transport path 43, the volume restricting portion. 44, a groove corresponding to the second plug transport path 45 is formed. These grooves have a rectangular cross section. In addition, the sample to be titrated can be put into the reaction tank 20.

If a sample to be titrated is placed in the reaction tank 20, and the titrant 50 is introduced into the titrant transport path 41 and air is simultaneously introduced into the gas transport path 42, the titrant 50 finally becomes a plug 52 and is injected into the reaction tank 20. Therefore, titration is performed. Here, for example, if an indicator is added to the sample to be titrated, a change in the color of the indicator in the reaction tank 20 when the titrant reaches the equivalent point can be visually confirmed. Further, since the resin layer 30 is transparent, the plug flowing through the second plug transport path 45 can be visually confirmed. For this reason, the number of plugs required to reach the equivalent point can be visually confirmed.

As the substrate 11, an inexpensive glass substrate is preferably used because it has sufficient mechanical strength and chemical resistance to the titrant and the sample to be titrated.

The resin layer 30 can be patterned so as to form the reaction tank 20, the titrant transport path 41, etc., and a material that has low wettability with respect to the titrant 50 and can be bonded to the substrate 11 is preferably used. As such a material, for example, polydimethylsiloxane (PDMS) which is a kind of silicone rubber is particularly preferably used. In order to make the resin layer 30 as shown in FIGS. 1 and 2, a replica mold method is used. In this case, first, a mold having patterns corresponding to the titrant transport path 41, the gas transport path 42, the first plug transport path 43, the volume restricting portion 44, and the second plug transport path 45 in FIG. 1 is prepared. To do. After the PDMS precursor solution is poured into the mold and cured by performing a curing process, this shape can be obtained by removing the mold. As the template, for example, a photoresist formed on a flat plate can be used. In this case, the pattern on the mold can be easily formed by ultraviolet irradiation through a photomask.

Further, a through hole corresponding to the reaction tank 20 is formed in the resin layer 30 by mechanical processing. Thus, the resin layer 30 on which the patterns corresponding to the titrant transport path 41, the gas transport path 42, the first plug transport path 43, the volume restricting portion 44, the second plug transport path 45, and the reaction tank 20 are formed is a substrate. 11 is joined. The height of the first plug transport path 43, the volume restricting portion 44, and the second plug transport path 45 (the depth of the groove in the resin layer 30) is to smoothly move the plug in these flow paths. Are preferably the same. However, these widths are not constant, and details thereof will be described later.

Note that, as described above, the titrant 50 (plugs 51 and 52) flows in the region surrounded by the substrate 11 and the resin layer 30. In this case, it is preferable that the wettability of the substrate 11 and the resin layer 30 with respect to the titrant 50 is low. For this reason, it is preferable to apply a water-repellent coating with a fluororesin or the like especially on the surface of the substrate 11.

In the above configuration, the titrant 50 flowing through the titrant transport path 41 flows as the plug 51 in the first plug transport path 43. However, the size (volume) and interval of the plug 51 are not uniform. However, the plug 51 is reconfigured as a plug 52 whose size is made uniform by the volume restricting portion 44, and the plug 52 is injected into the reaction tank 20 through the second plug transport path 45.

Hereinafter, the form of the titrant (plug) from the first plug transport path 43 to the second plug transport path 45 will be described. FIGS. 3A to 3G are diagrams schematically showing this form. In FIG. 3, the titrant (plug) flows from right to left.

First, as shown in FIG. 3A, the titrant 50 is injected into the titrant transport path 41 and the air is simultaneously injected into the gas transport path 42 from the right side in FIG. Inside, the titrant 50 is plugged and proceeds to the left. However, in this state, the sizes (volumes) and intervals of the illustrated plugs 71 to 73 are not uniform. As shown in the figure, the width of the first plug transport path 43 is w ₁ , the width of the second plug transport path 45 is w ₂ , and w ₂ > w ₁ . Moreover, locally a width is wider in the flow direction by volume limiting unit 44, the maximum width is w _3, and has a _{_{_{w 3> w 2> w 1}}} . Further, in this example, one side surface in the drawing of the first plug transport path 43, the volume restricting portion 44, and the second plug transport path 45 is the same plane (in FIG. 3, it is a straight line). By changing the shape of the other side surface along the flow direction, w ₃ > w ₂ > w ₁ is satisfied. In the volume restriction portion 44, width gradually toward the downstream side becomes wider again width toward the downstream side from the point where the width becomes w ₃ is narrowed, so that the width and w ₂ Yes.

Since the wettability of the wall surface in the first plug transport path 43 is low, the plugs 71 to 73 proceed to the left without contacting each other as shown in FIG. At this time, since the inside of the first plug transport path 43 is closed by the plugs 71 to 73, the plugs 71 to 73 are kept in the air with the above-mentioned size and spacing maintained by the pressure from the right side. Proceed to the left side efficiently by pressure.

Thereafter, as shown in FIG. 3C, when the plug 71 at the foremost end reaches the volume restricting portion 44, the flow restricting portion 44 is widened at this location, and therefore the volume restricting portion 44 is a small plug. In 71, it does not become the obstruct | occluded state. The pressure from the right side is transmitted to the left side through the gap in the volume restricting portion 44, and this pressure is hardly transmitted to the plug 71. For this reason, the plug 71 is decelerated and remains in the volume restricting portion 44. On the other hand, since the

plugs

72 and 73 on the rear side are located in the first plug transporting portion 43, as in FIG. 3B, the

plugs

72 and 73 move to the left side while maintaining their sizes and intervals.

Thereafter, as shown in FIG. 3 (d), the second plug 72 also reaches the volume restricting portion 44 and fuses with the plug 71 that still remains in the volume restricting portion 44. Thereafter, similarly, the third plug 73 reaches the volume restricting portion 44 and further merges. Subsequent plugs are similarly fused in the volume restricting portion 44, and finally, as shown in FIG. 3E, one large plug 81 that closes the volume restricting portion 44 in the flow direction is formed. .

Since the volume restricting portion 44 is closed in the flow direction by the large plug 81, the pressure from the right side is efficiently transmitted to the plug 81. Therefore, the plug 81 moves to the left second plug transport path 45 as shown in FIG. 3 (f).

Thereafter, as shown in FIG. 3 (g), the plug 81 once moved to the second plug transport path 45 moves toward the left side in the same manner as in the first plug transport path 43, and then the reaction tank 20 To reach. Thereafter, when plugs having non-uniform sizes and volumes flow discretely through the first plug transport path 43, the above operation is repeated. That is, a large plug 81 is formed by the volume restricting portion 44 and flows through the second plug transport path 45.

In this flow, the size (volume) of the fused large plug 81 is determined by the volume and shape of the volume restricting portion 44. For this reason, the volume of the plug 81 formed repeatedly becomes uniform. If this plug 81 is used, a uniform amount can be injected into the reaction vessel 20 in the same manner as in the case of using a bullet or the like, so that the equivalent point can be accurately recognized. Although the volume of the plug 81 is larger than that of the plug 71 or the like, it is adjusted by setting the first plug transport path 43, the volume restricting portion 44, the second plug transport path 45, the titrant 50, the air flow rate, and the like. Is possible. With this setting, it is possible to make the amount of the sample to be titrated in the reaction tank 20 so small that titration is possible. Further, in the titration apparatus 10, such plug control is realized only by the configuration of the flow path without using an electric or mechanical flow control device.

At this time, since the resin layer 30 is made of a transparent resin material, the plugs 81 can be visually recognized, and the total number of plugs 81 required to reach the equivalent point can be easily confirmed. If the average volume of the plug 81 is known, the total amount of titrant required to reach the equivalent point can be easily calculated.

The titration apparatus 10 can be manufactured by bonding an inexpensive PDMS layer (resin layer 30) on an inexpensive glass substrate (substrate 11). In addition, the process of forming the titrant transport path 41 and the like in the resin layer 30 can be performed accurately using a mold formed by ultraviolet irradiation through a photomask, and the reproducibility is high. For this reason, this small titration apparatus 10 can be easily obtained at low cost. In this case, since the dimensional accuracy of the first plug transport path 43, the volume restricting portion 44, the second plug transport path 45, and the like can be increased, the reproducibility of the plug volume in the second plug transport path 45 is also improved. . For this reason, the reproducibility of the titration for a very small amount of the sample to be titrated can be improved. That is, the titration apparatus 10 is excellent in mass productivity.

Note that the shapes of the substrate 11 and the resin layer 30 are arbitrary as long as the above action is realized. Further, the processing method of the resin layer 30 (formation of the first plug transport path 43 and the like) is optional as long as the same shape can be obtained. Further, the material constituting the substrate 11 and the resin layer 30 can be appropriately set depending on the type of the sample to be titrated and the titrant 50. The resin layer 30 is preferably made of a transparent material so that the plug can be visually recognized from the resin layer 30 side. However, for example, if the substrate 11 is transparent, the plug can be visually observed from the substrate 11 side. The resin layer 30 does not need to be transparent. Moreover, when the plug injected into the reaction vessel 20 can be confirmed by a method other than visual observation, neither the resin layer 30 nor the substrate 11 needs to be transparent.

Also, the shape of the volume restricting portion is such that a sudden volume change occurs in the middle of the first plug transport path to the second plug transport path, and a plurality of small plugs can be retained and fused together. As long as it is optional. For this purpose, the cross-sectional area perpendicular to the flow direction from the first plug transport path to the second plug transport path is minimized in the first plug transport path and is locally increased at the volume restricting portion. Good. Specifically, for example, an optimal shape can be appropriately set according to the wettability of the resin layer to the titrant, the viscosity of the titrant, the surface tension, the volume of the plug required in the second plug transport path, and the like.

Actually, the above-described titration apparatus 10 was manufactured, and the flow of the titrant was examined. Here, a KOH aqueous solution was used as the titrant. The depths of the grooves formed in the resin layer 30 (the heights of the titrant transport path 41, the gas transport path 42, the first plug transport path 43, the volume restricting portion 44, and the second plug transport path 45) were 150 μm. The widths of the titrant transport path 41, the gas transport path 42, the first plug transport path 43, and the second plug transport path 45 were 300 μm, 600 μm, 200 μm, and 500 μm, respectively.

FIGS. 4 (a) to 4 (e) show photographs taken when the form of the plug flowing through the above-described route is shown in FIG. 4A, the plug 71 is generated at the intersection of the titrant transport path 41 and the gas transport path 42. In FIG. 4B, the plug 71 is in the first plug transport path 43. The situation to go through has been filmed. In FIG. 4C, a situation is shown in which the subsequent plug 72 travels through the first plug transport path 43 while the preceding plug 71 remains in the volume restricting portion 44. 4D, the large plug 81 is formed in the volume restricting portion 44. In FIG. 4E, the large plug 81 exits the volume restricting portion 44 and travels through the second plug transport path 45. The situation to be photographed. From this result, it is clear that the situation shown in FIG. 3 is actually occurring.

Next, the plug size (volume) distribution in the first plug transport path 43 and the second plug transport path 45 was actually examined. The volume of the plug in the first plug transport path 43, the interval, depends on the ratio of the flow rate _{V air} units of time a gas (air) in the flow rate _{V liquid} and gas transport passage 42 of the unit time of the titrant in the titrant transport path 41 _Therefore , the flow volume ratio V _air / V _liquid was changed, and the volume distribution (standard deviation) of the flowing plug was examined in the first plug transport path 43 and the second plug transport path 45. FIG. 5 shows the measurement results. Here, the standard deviation is a value normalized by an average value. From this result, the standard deviation of the volume of the plug is about half that of the first plug transport path 43 in the second plug transport path 45 regardless of the flow rate ratio, and is as small as 10% or less. That is, this is a preferable state for titration.

The standard deviation in the second plug transport path 45 was the smallest when V _air = 50 μl / min and V _liquid = 0.8 μl / min (V _air / V _liquid = 63).

Further, the volume of the plug in the second plug transport path 45 also depends on the above flow rate ratio. For example, the volume when V _air / V _liquid = 200 was 0.154 μl, and the volume when V _air / V _liquid = 63 was 0.196 μl, both of which were very small. In order to perform the titration accurately, it is preferable that the volume is small. Therefore, in the subsequent experiments, V _air / V _liquid = 200.

FIG. 6 is a frequency distribution (average value 0.154 μl) of the plug volume under these conditions. It can be confirmed that the distribution is sharp with the average value as the center. Actually, a titration experiment was performed under these conditions using a sample to be titrated in the reaction tank 20 as hydrochloric acid (HCl) and an indicator as phenolphthalein. FIG. 7 shows the result of examining the relationship (titration characteristics) between the number of injection plugs and the color index in the reaction tank 20 at this time. It can be seen that the color index gradually changes as the plug is injected. For this reason, it turns out that it can fully perform titration using this titration apparatus 10.

(Second embodiment: rice inspection method)
Such a small titration apparatus 10 is particularly preferably used when titrating a very small amount of a sample to be titrated. An example of this use is rice freshness inspection. At this time, the rice can be evaluated for each grain. As a method for evaluating the freshness of rice, a method of measuring the pH of a liquid extracted from water obtained by pulverizing rice grains is known.

Lipids contained in rice are hydrolyzed by enzymes (lipases) contained in the rice grains to become fatty acids. For this reason, the less fresh (old) rice produces more fatty acids. In the above method, the pH based on the amount of fatty acid generated is determined. That is, it is determined that the lower the pH, the more fatty acid and the lower the freshness.

Actually, the above-described titration apparatus 10 was used for this inspection. First, rice grains as the sample to be inspected were pulverized, and fatty acids were extracted with absolute ethanol. 0.4 μl of this extract and 0.1 μl of 1% phenolphthalein solution serving as an indicator were mixed in the reaction vessel 20 to obtain a sample to be titrated. A 10 mM KOH solution was used as the titrant.

When titration is performed by the above method using four types of rice with the same year of harvest (1) 2005, (2) 2006, (3) 2009, and (4) 2010. The titration characteristics are shown in FIG. It is clear that the titration characteristics are clearly different between (1) to (4). The high freshness (3) and (4) change the color sensitively with a small number of injection plugs, which corresponds to the small amount of fatty acid generated. In (2) where the freshness is lower than these, the color change appears later than (3) and (4) due to the presence of fatty acid, and in the lowest freshness (1), the number of injection plugs is 14 Even now, no major color change has been seen. That is, a difference in titration characteristics due to a difference in freshness can be observed.

Thus, it is possible to inspect the freshness of rice using the titration apparatus 10 described above. That is, using this titration apparatus 10, it is possible to precisely perform titration on a very small amount of sample to be titrated. Moreover, since this titration apparatus 10 is small, it is easy to carry it. For this reason, it is possible to precisely titrate a minute amount of the sample to be titrated at an arbitrary place.

In the above description, the example using the titration apparatus to examine the freshness of rice has been described. However, it is obvious that the titration apparatus is effective when the amount of the titrated sample is small. is there. It is also clear that the above-described titration apparatus is effective when it is necessary to carry the titration apparatus at any place with the titration apparatus. For this reason, in the inspection of foods other than rice, for example, if the pH is related to the freshness, it is obvious that the freshness can be similarly examined using this titration apparatus. The same applies when titration is effective for the inspection, even when guidelines other than pH are involved. It is also clear that it is effective in medical examinations.

DESCRIPTION OF SYMBOLS 10 Titrating apparatus 11 Substrate 20 Reaction tank 30 Resin layer 41 Titrant transport path 42 Gas transport path 43 First plug transport path 44 Volume restricting part 45 Second plug transport path 50

Titrant

51, 52, 71 to 73, 81 Plug 61 62 Silicone tube

Claims

A titration apparatus in which a sample to be titrated is placed in a reaction tank formed in a resin layer bonded on a substrate, and a titration agent plug is injected into the sample to be titrated multiple times to perform titration. Because
A titrant transport path through which the titrant is injected;
A gas transport path through which gas is injected;
A first plug transport path for flowing the plug formed by joining the titrant transport path and the gas transport path toward the reaction layer;
A volume limiting portion provided on the downstream side of the first plug transport path and having a cross-sectional area perpendicular to the flow direction larger than that of the first plug transport path and capable of simultaneously accommodating a plurality of the plugs;
A second plug transport path that has a cross-sectional area perpendicular to the flow direction larger than the first plug transport path and smaller than the volume restricting section, and introduces the plurality of plugs fused in the volume restricting section to the reaction tank. When,
Formed at the interface between the substrate and the resin layer.
The titration apparatus according to claim 1, wherein the resin layer is made of a transparent resin material.
The titration apparatus according to claim 1 or 2, wherein the substrate is made of glass.
Grooves forming the titrant transport path, the gas transport path, the first plug transport path, the volume restricting portion, and the second plug transport path are formed on the surface of the resin layer on the substrate side. The titration apparatus according to any one of claims 1 to 3, wherein
The titration apparatus according to claim 4, wherein the resin layer is composed of polydimethylsiloxane (PDMS).
The titration apparatus according to claim 5, wherein the groove is formed by a mold.
A rice inspection method for inspecting the freshness of rice using the titration device according to any one of claims 1 to 6,
A rice inspection method, wherein a liquid obtained by extracting fatty acids contained in rice is introduced into the reaction vessel, and titration is performed using an alkaline solution as the titrant.