JP2000019145A - Electrochemical detector and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute analysis of sample solution accurately. SOLUTION: Working electrodes 2 and draw-out wires 3 are formed on a first layer board 1, and a circular groove 5, a ring-shaped groove 6 formed outside the circular groove 5, and a link groove for linking the circular groove 5 to the ring-shaped groove 6 are formed on a second layer board 4, and a sample solution introduction hole 7 linked to the circular groove 5 is formed on the second layer board 4, and a sample solution discharge hole 8 linked to the ring-shaped groove 6 is formed on the second layer board 4, and a radial flow cell is formed by jointing the first layer board 1 to the second layer board 4, and pipe storing grooves 9, 10 linked to the sample solution introduction hole 7 and the sample solution discharge hole 8 are formed on the second layer board 4, and a sample solution introduction pipe 11 and a sample solution discharge pipe 12 are fitted in the pipe storing grooves 9, 10, and a third layer board 13 is jointed to the second layer board 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochemical detector for flow injection analysis, liquid chromatography and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Electrochemical detection is widely used as a simple and highly sensitive method in flow injection analysis, liquid chromatography and the like. In this electrochemical detection method, a working electrode which causes an electrochemical reaction with a sample solution, a reference electrode for keeping the potential of the working electrode constant, and a counter electrode for flowing a current to the working electrode are immersed in the sample solution. In the case of flow injection analysis and liquid chromatography, a carrier liquid or eluent reservoir,
Connect the liquid sending pump and the sample solution injector with a thin tube,
In the case of liquid chromatography, a separation column for separation is further connected by a thin tube, an electrochemical detector is arranged at an outlet of the injector or the separation column, and a sample solution is injected from the injector or the separation column into the electrochemical detector,
The analysis is performed by monitoring the current generated by an electrochemical reaction between the working electrode and the sample solution when the sample solution flowing on the carrier liquid or the eluent reaches the electrochemical detector.

Such an electrochemical detector can be classified into a cylindrical type, a thin layer type, a wall jet type and the like according to the shape of the working electrode used. In addition, it can be classified into a cross-flow type that flows across the working electrode and a radial-flow type that flows from the center of the working electrode to the periphery, depending on the flow of the sample solution. Among these structures, thin-layer type and radial flow type,
That is, a radial flow cell is provided between two parallel plates separated by a minute gap, a working electrode is formed on one of the two plates, and a sample solution introduction hole (a through hole for an inlet) is provided on the other plate. An electrochemical detector having a structure in which the sample solution is introduced from the sample solution introduction hole onto the center of the working electrode and flows to the periphery along the working electrode in the radial flow cell between the flat plates has the highest detection sensitivity.

In the electrochemical detection method, since a constant potential is applied to a working electrode with respect to a reference electrode, measurement is performed. Therefore, only a sample of a reductant having an oxidation potential higher than the potential or a potential of the reduced form is measured. Only a sample of the oxidant with a low reduction potential will undergo an electrochemical reaction and will be detected as a result. Therefore, in order to simultaneously detect substances having different oxidation-reduction potentials, it is necessary to prepare a plurality of working electrodes and apply a different potential to each of the working electrodes for detection. To this end, in a thin-layer radial flow electrochemical detector, a circular working electrode is divided into sectors and different potentials are applied to each working electrode (Iwasaki et al., Analytical Chem
istry, 68, 3797, 1996).

Conventionally, in such an electrochemical detector, a joint for connecting a thin tube such as a separation column,
A first block provided with a sample solution introduction hole that passes from the joint to the radial flow cell, a sample solution discharge hole (through hole for outlet) for discharging the solution that has passed over the working electrode, and the like, and a first block in which the working electrode is embedded. The two blocks are overlapped with a thin-film separator punched out at the center.

[0006]

However, in such an electrochemical detector, a joint, a sample solution introduction hole, a sample solution discharge hole, and the like provided in the first block are dead volumes, so that the sample solution cannot be used. If the volume is extremely small, less than 1 μl (microliter), the sample solution will remain or be diluted in the dead volume, making analysis difficult and the block and the separator not adhering. If the block is not evenly stressed, gaps are likely to form and the solution may leak out. Therefore, the analysis of the sample solution cannot be performed accurately. Further, in the electrochemical detector, excellent characteristics are exhibited only when the center of the working electrode coincides with the center point where the sample solution is introduced. In particular, when a plurality of working electrodes are provided, if the center of the sector of the working electrode is displaced from the sample solution introduction hole, the amount of the sample solution flowing on each working electrode becomes uneven, so that the response differs. Therefore, the analysis of the sample solution cannot be performed accurately. For this purpose, a guide pin is set on one of the blocks so that the center of the working electrode and the sample solution introduction hole are aligned, but it is difficult to suppress a slight displacement due to play, etc. Each time you change, you need to make fine adjustments.

The present invention has been made to solve the above-described problems, and has as its object to provide an electrochemical detector capable of accurately analyzing a sample solution and a method of manufacturing the same.

[0008]

According to the present invention, there is provided an electrochemical detector comprising:
The layer substrate, the second layer substrate and the third layer substrate are laminated, a sample solution introduction pipe and a sample solution discharge pipe are provided, and a liquid flow path connecting the sample solution introduction pipe and the sample solution discharge pipe is provided. A radial flow cell is formed in the liquid flow path, and a working electrode is formed in the radial flow cell.

In this case, the working electrode is formed on the first layer substrate, the radial flow cell is formed between the first layer substrate and the second layer substrate, and the radial flow cell is formed on the second layer substrate. A third layer substrate is laminated, a sample solution introduction hole and a sample solution discharge hole communicating with the radial flow cell are formed in the second layer substrate, and the sample is placed between the second layer substrate and the third layer substrate. The sample solution introduction pipe communicating with the solution introduction hole and extending to the outside of the second layer substrate and the third layer substrate is attached, and the sample solution is inserted between the second layer substrate and the third layer substrate. The sample solution discharge pipe, which communicates with the discharge hole and extends to the outside of the second layer substrate and the third layer substrate, is attached.

In this case, the radial flow cell is formed by a circular groove provided on the second layer substrate, a ring-shaped groove provided outside the circular groove, and a communication groove connecting the circular groove and the ring-shaped groove. The sample solution introduction hole is formed at the center of the circular groove.

In the method of manufacturing an electrochemical detector, a step of forming a working electrode on a first layer substrate and a step of forming a radial electrode on a surface of the second layer substrate which is to be a bonding surface with the first layer substrate are provided. Forming a flow cell forming groove; forming a sample solution introducing hole and a sample solution discharging hole communicating with the radial flow cell forming groove in the second layer substrate; A step of forming a pipe housing groove communicating with the sample solution introduction hole and the sample solution discharge hole on a surface that is to be a bonding surface with the layer substrate, and a step of forming a center of the working electrode and a center of the sample solution introduction hole. Joining the side of the first layer substrate having the working electrode and the side of the second layer substrate having the groove for forming a radial flow cell; a pipe for introducing a sample solution and a pipe for discharging a sample solution. The above pipe collection Performing the step of attaching to the groove, and a step of bonding the side and the third layer substrate having the pipe receiving groove of the second layer substrate.

In the method for manufacturing an electrochemical detector, a step of forming a working electrode on a first layer substrate and then providing an insulating film having an opening; Forming a discharge hole, and forming a pipe housing groove communicating with the sample solution introduction hole and the sample solution discharge hole on a surface of the second layer substrate which is to be a bonding surface with the third layer substrate. And the step of aligning the center of the working electrode with the center of the sample solution introduction hole, the side of the first layer substrate having the working electrode, and the surface of the second layer substrate on which the pipe receiving groove is formed. Joining the opposite surface, attaching a sample solution introducing pipe and a sample solution discharging pipe into the pipe accommodating groove, and providing a side of the second layer substrate having the pipe accommodating groove and a third layer. And bonding the substrate.

[0013]

FIG. 1 is a schematic sectional view showing an electrochemical detector according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG.
FIG. 2 is a sectional view taken along line BB of FIG. 1. As shown in the figure, a working electrode 2 and a lead wire 3 made of gold and having a thickness of about 0.1 μm are formed on a first layer substrate 1 made of Pyrex glass, and the working electrode 2 is divided into a sector shape. A lead wire 3 is connected to each fan-shaped working electrode 2.
Further, a circular groove 5 having a depth of about several μm in the second layer substrate 4 made of Pyrex glass, a ring-shaped groove 6 provided outside the circular groove 5, and a communication connecting the circular groove 5 and the ring-shaped groove 6. A groove 14, that is, a groove for forming a radial flow cell, is provided, a sample solution introducing hole 7 communicating with the circular groove 5 is formed on the second layer substrate 4, and a sample solution discharging hole communicating with the ring-shaped groove 6 on the second layer substrate 4. 8, the sample solution introduction hole 7 and the sample solution discharge hole 8 penetrate the second layer substrate 4.
The surface of the first layer substrate 1 on which the working electrode 2 and the lead wire 3 are formed and the surface of the second layer substrate 4 on which the circular groove 5, the ring-shaped groove 6, and the communication groove 14 are formed are diluted hydrofluoric acid or A radial flow cell 15 is formed between the first layer substrate 1 and the second layer substrate 4 by a circular groove 5, a ring-shaped groove 6, and a communication groove 14, which are joined by an ultraviolet curable adhesive. The center of the working electrode 2 and the center of the sample solution introducing hole 7 coincide with each other, and the end of the lead 3 protrudes from the second layer substrate 4. Further, the second layer substrate 4 is connected to the sample solution introduction hole 7 and the sample solution discharge hole 8 on a surface opposite to the surface joined to the first layer substrate 1 and has a pipe housing having a depth of about 0.4 mm. Grooves 9 and 10 are provided, and a sample solution introduction pipe 11 and a sample solution discharge pipe 12 made of metal and having an outer diameter of 0.4 mm or less are mounted in the pipe storage grooves 9 and 10, respectively. Is also used as a counter electrode,
Further, silver is adhered inside the sample solution discharge pipe 12,
The sample solution discharge pipe 12 is also used as a reference electrode. Further, the sample solution introduction pipe 11 of the second layer substrate 4,
A third layer substrate 13 made of Pyrex glass is joined to the surface to which the sample solution discharge pipe 12 is attached. The sample solution introduction pipe 11 and the sample solution discharge pipe 12 are the second layer substrate 4 and the third layer substrate 13. To the outside of
The sample solution introduction hole 7, the radial flow cell 15, and the sample solution discharge hole 8 constitute a liquid flow path connecting the sample solution introduction pipe 11 and the sample solution discharge pipe 12.

Next, a method of manufacturing the electrochemical detector shown in FIGS. 1 to 3 will be described with reference to FIG. First, as shown in FIG. 4A, a resist mask 21 is provided on the surface of a Pyrex glass wafer by a photolithography technique, and etching is performed with a buffered hydrofluoric acid solution, so that a circular groove 5 and a ring-shaped groove 6 , Communication groove 1
4 is provided. Next, as shown in FIG. 4 (b), a sample solution introduction hole 7 and a sample solution discharge hole 8 are provided in the Pyrex glass wafer by drilling with a drill or laser. Next, the pipe storage grooves 9 and 10 are provided in the Pyrex glass wafer by cutting with a dicing saw, and then the Pyrex glass wafer is divided into the second layer substrate 4 having a desired size. FIG.
As shown in FIG. 1C, after a working electrode 2 and a lead wire 3 are formed on another Pyrex glass wafer by a lift-off method, the Pyrex glass wafer is divided into a first layer substrate 1 having a desired size. Next, the first layer substrate 1 and the second layer substrate 4 are joined by dilute hydrofluoric acid or an ultraviolet curable adhesive. In this case, bonding is performed while viewing the working electrode 2 from the sample solution introduction hole 7 with a microscope or the like, so that the center of the working electrode 2 matches the center of the sample solution introduction hole 7. Next, by using a photosensitive epoxy resin, the pipe housing grooves 9, 10 are formed.
A sample solution introduction pipe 11 and a sample solution discharge pipe 12 are attached therein. Next, the second layer substrate 4 and the third layer substrate 13 are joined by dilute hydrofluoric acid or an ultraviolet curable adhesive.

In the electrochemical detector shown in FIGS. 1 to 3, the liquid flow path is composed of the sample solution introduction hole 7, the radial flow cell 15, and the sample solution discharge hole 8, so that the shape of the liquid flow path is simple. As a result, the dead volume in which the sample solution stays or dilutes in the liquid flow path can be made extremely small. Further, pipe housing grooves 9 and 10 are provided on the surface of the second layer substrate 4 opposite to the surface bonded to the first layer substrate 1,
A pipe 11 for introducing a sample solution into the pipe storage grooves 9 and 10,
The sample solution discharge pipe 12 is attached, and the sample solution introduction pipe 11 and the sample solution discharge pipe 12 of the second layer substrate 4 are attached.
Since the third layer substrate 13 is bonded to the surface to which the is attached, the solution does not leak. Therefore, the analysis of the sample solution can be performed accurately.

In the method of manufacturing an electrochemical detector described with reference to FIG. 4, the first substrate 1 and the second substrate 4
When joining the sample solution, the sample solution introduction hole 7 is
And the center of the working electrode 2 and the center of the sample solution introduction hole 7 can be matched, so that the amount of the sample solution flowing on each working electrode 2 does not become uneven, Since the response is the same, the analysis of the sample solution can be performed accurately.

Then, a liquid feed pump (PM-100 manufactured by BAS), an injector (8125 manufactured by RHEODYNE), and an 8-channel multi-potential stat (manufactured by Fuso Seisakusho) are added to the electrochemical detector shown in FIGS. And 0, 200, 300, 400, 500, 60 with respect to the reference electrode on the working electrode 2 divided into 8 through the lead wire 3.
Voltage of 0, 700, and 800 mV, respectively,
1. Dopamine and metanephrine were mixed with the buffer solution of 1.67, and each was adjusted to a concentration of 10 μM (μmol / l), and the carrier solution (pH) was adjusted at a flow rate of 100 μl / min.
1.67 buffer solution), 10 μl of a mixed sample solution of dopamine and metanephrine was injected from an injector, and flow injection analysis was performed. Then
Immediately after the injection of the mixed sample solution, the current increased and returned to the original state. Table 1 shows the peak current obtained at this time.

[0018]

[Table 1]

As a result, when the applied voltage is 400 to 500 mV
Obtaining the concentration of dopamine from the current at 7
It was found from the current at 00 to 800 mV that the total concentration of dopamine and metanephrine could be obtained. Further, connection was only required to connect the liquid flow paths, and the same response was obtained with an error of 5% or less in any of the manufactured electrochemical detectors, and the sample solution could be accurately analyzed.

FIG. 5 is a schematic sectional view showing another electrochemical detector according to the present invention, and FIG. 6 is a sectional view taken along line CC of FIG. As shown in the figure, a working electrode 32 and a lead wire 33 made of carbon and having a film thickness of about 0.1 μm are formed on a first layer substrate 31 made of quartz, and the working electrode 32 is divided into a sector shape.
A lead wire 33 is connected to each sector-shaped working electrode 32. An insulating film 34 having a thickness of 5 μm is formed on the surface of the first layer substrate 31 on which the working electrode 32 and the lead wire 33 are formed, and the insulating film 34 has a circular opening 35 which is an opening for forming a radial flow cell. Are formed, and the working electrode 32 is located in the opening 35. In addition, the second made of quartz
A sample solution inlet 37 and a sample solution outlet 38 in the layer substrate 36
Are formed, and a sample solution introduction hole 37 and a sample solution discharge hole 38 are formed.
Penetrates through the second layer substrate 36. Also, the first layer substrate 3
The surface on which the first working electrode 32 and the lead wire 33 are formed (the insulating film 34) and the second layer substrate 36 are joined by dilute hydrofluoric acid or an ultraviolet curable adhesive. A radial flow cell 44 is formed between the second layer substrate 36 and the sample solution introducing hole 37 and the sample solution discharging hole 38 communicate with the radial flow cell 44. Further, the center of the working electrode 32 coincides with the center of the sample solution introduction hole 37, and the end of the lead 33 protrudes from the second layer substrate 36. Further, a surface of the second layer substrate 36 opposite to the surface joined to the first layer substrate 31 is communicated with the sample solution introduction hole 37 and the sample solution discharge hole 38 and has a depth of 0.1 mm.
Pipe housing grooves 39 and 40 of about 4 mm are provided, and the pipe housing grooves 39 and 40 are made of metal and have an outer shape of 0.4 mm.
A sample solution introduction pipe 41 and a sample solution discharge pipe 42 each having a size of
Is also used as a counter electrode, and silver is adhered to the inside of the sample solution discharging pipe 42 so that the sample solution discharging pipe 4
2 is also used as a reference electrode. Also, the second layer substrate 3
The third layer substrate 43 made of quartz is provided on the surface on which the sample solution introduction pipe 41 and the sample solution discharge pipe 42 of No. 6 are attached.
The sample solution introduction pipe 41 and the sample solution discharge pipe 42 extend to the outside of the second layer substrate 36 and the third layer substrate 43, and the sample solution introduction hole 37, the radial flow cell 44, and the sample solution discharge The hole 38 forms a liquid flow path connecting the sample solution introduction pipe 41 and the sample solution discharge pipe 42.

Next, a method of manufacturing the electrochemical detector shown in FIGS. 5 and 6 will be described with reference to FIG. First, as shown in FIG. 7A, a carbon thin film is formed on a quartz wafer surface by a thermal CVD (chemical vapor deposition) method, and the carbon thin film is selected by a photolithography technique and a reactive ion etching method using oxygen. Working electrode 32, lead wire 3
Form 3 Next, after a silicon oxide film having a thickness of 0.1 μm is formed on the surface of the quartz wafer on which the working electrode 32 and the lead wire 33 are formed by a plasma CVD method, an insulating film 34 is formed by a spin-on-glass method. Next, as shown in FIG. 7B, a resist mask 51 is formed by a photolithography technique, and the insulating film 3 is formed by a buffered hydrofluoric acid solution.
4. After the opening 35 is formed by selectively etching the silicon oxide film, the quartz wafer is divided into first layer substrates 31 having a desired size. Next, as shown in FIG. 7 (c), a sample solution introduction hole 37 and a sample solution discharge hole 38 are provided in another quartz wafer by drilling with a drill or laser, and cutting is performed with a dicing saw. The pipe housing grooves 39, 4
After providing 0, the quartz wafer is divided into a second layer substrate 36 having a desired size. Next, the first layer substrate 31 (insulating film 34) and the second
The layer substrate 36 is joined. In this case, joining is performed while viewing the working electrode 32 from the sample solution introduction hole 37 with a microscope or the like,
The center of the working electrode 32 is aligned with the center of the sample solution introduction hole 37. Next, a sample solution introducing pipe 41 and a sample solution discharging pipe 42 are attached in the pipe housing grooves 39 and 40 by using a photosensitive epoxy resin. Next, the second layer substrate 36 and the third layer substrate 43 are joined by dilute hydrofluoric acid or an ultraviolet curable adhesive.

In the electrochemical detector shown in FIGS. 4 and 5, the liquid flow path is composed of the sample solution introduction hole 37, the radial flow cell 44, and the sample solution discharge hole 38, so that the shape of the liquid flow path is simple. As a result, the dead volume in which the sample solution stays or dilutes in the liquid flow path can be made extremely small. Also, the first layer substrate 31 of the second layer substrate 36
Pipe receiving grooves 39, 4
0, a sample solution introduction pipe 41 and a sample solution discharge pipe 42 are mounted in the pipe storage grooves 39 and 40, and the sample solution introduction pipe 41 and the sample solution discharge pipe 42 of the second layer substrate 36 are mounted. Since the third layer substrate 43 is bonded to the surface, the solution does not leak. Therefore, the analysis of the sample solution can be performed accurately.

In the method of manufacturing an electrochemical detector described with reference to FIG. 7, when the first layer substrate 31 and the second layer substrate 36 are joined, the working electrode is inserted through the sample solution introduction hole 37 by a microscope or the like. 32 and the working electrode 3
Since the center of the sample solution 2 and the center of the sample solution introduction hole 37 can be made coincident, the amount of the sample solution flowing on each working electrode 32 does not become uneven, and the response becomes the same. Can be done accurately.

In the above-described embodiment, the working electrode 2 made of gold, the lead wire 3, and the working electrode 3 made of carbon are used.
2. Although the lead wire 33 is formed, a working electrode and a lead wire made of platinum, graphite, or the like may be formed. In the above-described embodiment, the sample solution introduction pipe 11 and the sample solution discharge pipe 12 made of metal are attached to the pipe storage grooves 9 and 10, and the metal sample solution is introduced into the pipe storage grooves 39 and 40. Although the sample pipe 41 and the sample solution discharge pipe 42 are attached, a sample solution introduction pipe and a sample solution discharge pipe made of a fused silica capillary may be attached in the pipe housing groove. In this case, a reference electrode and a counter electrode are formed on the first layer substrate, and silver is attached to the end of the reference electrode by applying silver paste, silver plating, or the like. The inner diameter and outer diameter of the sample solution introduction pipe and the sample solution discharge pipe may be uniform, but the inner diameter or the outer diameter of the sample solution introduction pipe and the sample solution discharge pipe are tapered in the pipe axis direction. May have changed. Further, in the above-described embodiment, the pipe accommodation grooves 9 and 10 are provided in the second layer substrate 4, and the pipe accommodation grooves 39 and
Although 40 is provided, a pipe storage groove may be provided in the third layer substrate, or a pipe storage groove may be provided in both the second layer substrate and the third layer substrate. In the above-described embodiment, the working electrode 2 and the lead wire 3 are formed on the first layer substrate 1, and the circular groove 5, the ring-shaped groove 6, and the communication groove 14 are provided on the second layer substrate 4. The electrode and the radial flow cell forming groove may be formed so as to face either the first layer substrate or the second layer substrate. For example, the working electrode and the radial flow cell forming groove are formed in the second layer substrate. And further forming a radial flow cell forming groove in the first layer substrate,
A working electrode may be formed on the second layer substrate.

[0025]

In the electrochemical detector according to the present invention, since the shape of the liquid flow path is simple, the dead volume in which the sample solution in the liquid flow path is retained or diluted can be made extremely small. Further, since the solution does not leak, the analysis of the sample solution can be performed accurately.

In the method of manufacturing an electrochemical detector according to the present invention, when the first layer substrate and the second layer substrate are bonded, the bonding is performed while viewing the working electrode from the sample solution introduction hole with a microscope or the like. This allows the center of the working electrode to coincide with the center of the sample solution introduction hole, so that the sample solution can be accurately analyzed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an electrochemical detector according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is an explanatory view of a method of manufacturing the electrochemical detector shown in FIGS.

FIG. 5 is a schematic sectional view showing another electrochemical detector according to the present invention.

FIG. 6 is a sectional view taken along the line CC of FIG. 5;

FIG. 7 is an explanatory diagram of a method for manufacturing the electrochemical detector shown in FIGS. 5 and 6.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... First layer substrate 2 ... Working electrode 4 ... Second layer substrate 5 ... Circular groove 6 ... Ring groove 7 ... Sample solution introduction hole 8 ... Sample solution discharge hole 9 ... Pipe storage groove 10 ... Pipe storage groove 11 ... Sample Pipe for solution introduction 12 ... Pipe for sample solution discharge 13 ... Third layer substrate 14 ... Communication groove 15 ... Radial flow cell 31 ... First layer substrate 32 ... Working electrode 34 ... Insulating film 35 ... Opening 36 ... Second layer substrate 37 ... sample solution introduction hole 38 ... sample solution discharge hole 39 ... pipe storage groove 40 ... pipe storage groove 41 ... sample solution introduction pipe 42 ... sample solution discharge pipe 43 ... third layer substrate 44 ... radial flow cell

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Osamu Niwa, Inventor: Nippon Telegraph and Telephone Corporation 3-9-1-2, Nishishinjuku, Shinjuku-ku, Tokyo (72) Inventor: Tsutomu Horiuchi 3-192-1, Nishishinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation F-term (reference) 2G058 GA12 HA00

Claims (5)

[Claims] 1. A first layer substrate, a second layer substrate and a third layer substrate are laminated, a sample solution introduction pipe and a sample solution discharge pipe are provided, and the sample solution introduction pipe and the sample solution discharge pipe are provided. An electrochemical detector comprising: a liquid flow path connecting pipes; a radial flow cell formed in the liquid flow path; and a working electrode formed in the radial flow cell. 2. The method according to claim 1, wherein the working electrode is formed on the first layer substrate, the radial flow cell is formed between the first layer substrate and the second layer substrate, and the second electrode is formed on the second layer substrate. A three-layer substrate is laminated, a sample solution introduction hole and a sample solution discharge hole communicating with the radial flow cell are formed in the second layer substrate, and the sample solution is provided between the second layer substrate and the third layer substrate. The sample solution introduction pipe communicating with the introduction hole and extending to the outside of the second layer substrate and the third layer substrate is attached, and the sample solution is discharged between the second layer substrate and the third layer substrate. 2. The electrochemical detector according to claim 1, wherein the sample solution discharge pipe, which communicates with a hole and extends to the outside of the second layer substrate and the third layer substrate, is attached. 3. 3. The radial flow cell is formed by a circular groove provided on the second layer substrate, a ring-shaped groove provided outside the circular groove, and a communication groove connecting the circular groove and the ring-shaped groove. The electrochemical detector according to claim 2, wherein the sample solution introduction hole is provided at the center of the circular groove. 4. A step of forming a working electrode on the first layer substrate, and a step of forming a radial flow cell forming groove on a surface of the second layer substrate which is to be a bonding surface with the first layer substrate. Forming a sample solution introduction hole and a sample solution discharge hole communicating with the radial flow cell forming groove in the second layer substrate; and forming a side of the second layer substrate that is to be a bonding surface with the third layer substrate. Forming a pipe housing groove communicating with the sample solution introduction hole and the sample solution discharge hole on the surface of the first layer substrate by aligning the center of the working electrode with the center of the sample solution introduction hole. Joining the side having the working electrode to the side having the groove for forming a radial flow cell of the second layer substrate, and attaching a sample solution introduction pipe and a sample solution discharge pipe in the pipe housing groove. And the second layer substrate Method for producing an electrochemical detector, which comprises a step of joining the side and the third layer substrate having the pipe receiving groove. 5. After forming a working electrode on the first layer substrate,
A step of providing an insulating film having an opening; a step of forming a sample solution introduction hole and a sample solution discharge hole in the second layer substrate; and a step of forming a bonding surface of the second layer substrate with the third layer substrate. Forming a pipe receiving groove communicating with the sample solution introducing hole and the sample solution discharging hole on the surface; and aligning the center of the working electrode with the center of the sample solution introducing hole to form the first layer substrate. Joining the side having the working electrode and the surface of the second layer substrate opposite to the surface on which the pipe storage groove is formed; and connecting the sample solution introduction pipe and the sample solution discharge pipe to the pipe storage groove. A method of manufacturing an electrochemical detector, comprising: a step of attaching the inside of the second layer substrate; and a step of joining a side having the pipe housing groove of the second layer substrate to a third layer substrate.