JP2000121547A - Detecting meter cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the detection sensitivity of a detecting meter cell. SOLUTION: Glass substrates 1 and 2 are pasted together, and a micro channel groove is formed on the pasted surface on the side of the glass substrate 1. A sample introducing opening 9a and a sample discharge opening 9b are each passed through the glass substrate 2 at one end and the other end of the channel groove. A light shielding film for shielding detection light 11 is formed on the pasted surface of the glass substrate 1 at a location except that of the channel groove to constitute a slit 3. As a part 8a of the channel groove is a measuring chamber 8a, and a part of the micro channel groove is used as the measuring chamber 8a, it is possible to implement a measuring chamber with sufficiently micro volume. In addition, as fight which hits the shading film of the slit 3 is shielded by the shading film and does not become incident onto a detector, detection sensitivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector cell for measuring the absorption of light in the ultraviolet or visible region, and more particularly to a detector cell suitable for detecting components in a small amount of liquid sample.

[0002]

2. Description of the Related Art Such a detector cell is used in the field of analytical chemistry, for example, in the fields of environmental analysis, clinical practice, pharmaceuticals, and the like, as a method for accurately and quickly analyzing trace components, for example, by capillary electrophoresis. CE), liquid chromatography (LC) or flow injection analysis (FIA). The detector cell used in these analyzers usually has a sample inlet for introducing a liquid sample to be analyzed, a flow path for the liquid sample, and a sample outlet for discharging the liquid sample passing through the flow path. It has a sample chamber in the flow path that serves as an interaction area between the liquid sample and the detection light in the ultraviolet or visible range, and is used by being connected to the outlet of the analytical column used in the analysis method described above. Is done. A detection light is applied to a flow path portion serving as the measurement chamber, and the detection light is detected by a measurement optical system after passing through a liquid sample existing in the sample chamber.

[0003] In recent years, instead of glass capillaries which are complicated to handle, DJ Harrison et al./Science, Vol.
1, p. 895-897 (1993), there has been proposed a chip (microchip) formed by joining two substrates and used for capillary electrophoresis. The microchip uses micromachining technology based on semiconductor manufacturing technology to provide a flow path for introducing a liquid sample onto an electrophoresis member made of a glass substrate and a flow path for separating the liquid sample. It was formed. Compared to conventional capillary electrophoresis devices, microchip-based electrophoresis devices offer the advantages of high-speed analysis, extremely low solvent consumption, extremely small amounts of sample required, and the ability to downsize the device. Having. The feature of this is that it enables on-site (onside or bedside) analysis that was difficult to achieve with conventional analyzers in the field of analytical chemistry described above, and also in fields such as DNA analysis. Thus, from the viewpoint of high-speed analysis, it is promising as an advantage for screening.

[0004]

A detector cell used in a capillary electrophoresis apparatus generally has a larger measuring chamber volume than a glass capillary for separating a sample, and when analyzing a trace component, In many cases, the separation ability of capillary electrophoresis cannot be utilized. This is because the volume of the measurement chamber is large, so that the separated trace components are remixed or diffused into the medium.

To solve this problem, for example, Analytical Ch
As described in emistry, Vol. 63, p. 2835 (1991), a laser-excited fluorescence detector using a small cell with a reduced measurement chamber volume has been attempted. FIG. 1 shows the laser-excited fluorescence detector. The exit end of the capillary C is inserted into the cell D, and the laser beam from the laser device A is condensed by the lens B and irradiates the sample liquid coming out of the capillary C. The fluorescence generated from the sample solution in the cell D is condensed by the objective lens E, the excitation light component is removed by the filter C via the pinhole F, and only the fluorescence component enters the photomultiplier tube H and is detected. You. I is a computer for data processing.

However, in this laser-excited fluorescence detector, the cell D is also used, although efforts have been made to reduce the measurement volume.
Inner diameter of capillary C is larger than that of capillary C
Since the thickness of the device must be large and cannot be sufficiently miniaturized, there is room for improvement in resolution and accuracy.
On the other hand, a method of using a separation capillary column itself as a detection cell has been studied. In this case, the sample volume and the volume of the sample chamber required for the analysis can be extremely small, but the detection sensitivity is insufficient because the optical path length is short, and light that does not contribute to detection enters the detector as stray light. That is the problem.

Accordingly, the present invention provides a capillary electrophoresis apparatus and a detector cell which can be used as a detector cell for the above-described analysis method, or which can also be used as a detector of a microchip. It is an object of the present invention to provide a product with improved detection sensitivity.

[0008]

According to the present invention, the volume of the measuring chamber of the detector cell is set so as not to impair the separation ability of the various separation / analysis means, that is, the cross-sectional area of the flow channel is substantially equal to that of the separation capillary column. The detection sensitivity is improved by suppressing the light that does not interact with the liquid sample to be detected out of the detection light from entering the detector as stray light. That is, the detector cell of the present invention includes a flow path having a minute cross-sectional area formed inside the transparent plate-shaped member, and at least a part of the flow path is used as a measurement chamber so that the detection light is irradiated thereon. And a light shielding film for the detection light is formed at least in the region of the measurement chamber on both sides of the flow path as viewed from the detection light irradiation direction. In the present invention, among the detection light, stray light that does not pass through the liquid sample does not enter the detector, and only light that has interacted with the sample, for example, light that has absorbed the wavelength corresponding to the sample is detected as a signal. The detection sensitivity is improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS This detector cell can be used as a detector of various analyzers by forming only a detector cell on a transparent plate member of a substrate. In that case, the transparent plate member on which the detector cell is formed has a sample inlet for introducing a liquid sample into a flow path constituting a measurement chamber,
A sample outlet for discharging the liquid sample passing through the flow path is provided. This detector cell can also be applied as the detection unit of the microchip described above. In this case, an analysis flow path and a sample flow path intersecting the analysis flow path are formed inside the transparent plate-like member on which the detector cell is formed, and one surface of the transparent plate-like member is formed. A hole reaching the analysis flow path or the sample flow path is formed at a position corresponding to the analysis flow path and the sample flow path, and at least a part of the analysis flow path serves as a measurement chamber of the detector cell.

As a material of the transparent plate member on which the detector cell is formed, a resin plate can be used in addition to a glass plate such as quartz or Pyrex. As a light shielding film,
In addition to a Si (silicon) thin film, any film having a large absorption coefficient with respect to detection light, such as a metal thin film such as Cr (chromium) or an organic resin film such as polyimide, can be used.

[0011]

FIG. 2 shows an embodiment of the present invention.
Is a top view thereof, (b) is a sectional view taken along a line BB,
(C) is an enlarged cross-sectional view showing a central portion at the position of line AA in (a). Glass substrates 1 and 2 made of quartz are bonded together, and a fine channel groove 8 for a liquid sample flow channel having a width and a depth of several hundred μm or less is formed on the bonded glass substrate 1 side. Have been. At one end of the flow channel 8, a sample inlet 9 a is provided through the glass substrate 2, and at the other end of the flow channel 8, a sample outlet 9 b is provided through the glass substrate 2.

On the bonding surface of the glass substrates 1 and 2, a light-shielding film is formed on the glass substrate 1 to block the detection light 11 in the ultraviolet or visible region at a portion other than the flow channel of the flow channel 8. The light-shielding film forms the slit 3 through which the detection light passes only through the channel groove 8. Here, a Si thin film is used as a light shielding film constituting the slit 3. Both substrates 1,
In No. 2, a channel groove 8 is formed by bringing the surfaces to be joined into close contact with each other, and then joining them air-tight with a hydrofluoric acid solution by the method shown in FIG.

A part 8a of the flow channel 8 is a measuring chamber 8a for irradiating the detection light and measuring the absorbance. Since a part of the fine flow channel 8 is used as the measuring chamber 8a, it is sufficiently small. A volume measurement chamber can be realized. When the detection light 11 is incident on the detector cell, the detection light 11 passes only through the measurement chamber 8a which is a part of the flow channel 8, and the light hitting the light shielding film of the slit 3 is transmitted by the light shielding film. Since the light is blocked, the incidence of stray light on the detector can be reduced as compared with the related art, and the detection sensitivity is improved.

Next, a method of producing the detector cell of this embodiment will be described with reference to FIG. (A) First, after the quartz glass substrate 1 is washed, an Si film is formed to a thickness of 3000 ° as an etching protection film 5 by a thin film forming apparatus, for example, a sputtering film forming apparatus, and further an etching protection film is formed thereon. As a photoresist 6 for patterning 5, for example, AZ4620 is 3000r
Spin coat at 40 rpm for 40 seconds. At this time,
The thickness of the resist 6 is about 7 μm. The material and thickness of the photoresist used are not particularly limited,
Any material or thickness that can withstand the subsequent etching step may be used.
Also, the material and thickness of the etching protection film 5 are not particularly limited, and may be any material and thickness that can withstand the subsequent substrate etching step. Here, a Si film is used so that the etching protection film 5 also functions as a light shielding film.

(B) Next, the photoresist 6 is exposed using a photomask 7 and then developed. The exposure of the photoresist 6 can be performed using an aligner generally used in semiconductor manufacturing. The developer is not particularly limited as long as it can be used for developing the photoresist to be used.

(C) Next, the etching protection film 5 is patterned by dry etching using high-frequency plasma in SF ₆ gas. Again, the etching gas is not particularly limited, and may be any gas that can etch Si without any problem.

(D) Using the patterned etching protection film 5 and photoresist 6 as a mask, the substrate 1 is etched with, for example, a 46% hydrofluoric acid aqueous solution to form a sample channel groove 8. Again, the etchant for the substrate 1 is not particularly limited, and may be any solution that can etch quartz glass.

(E) After removing the photoresist 6, the surface of the Si film of the etching protection film 5 is oxidized to form a silicon oxide film on the surface of the Si film. (F) On the other hand, as shown in (f), through holes for the sample inlet 9a and the liquid outlet 9b are formed in the glass substrate 2 by, for example, a processing method such as a sand blast method. .

(G) Finally, the glass substrate 1 having the slit 3 formed by the light shielding film also serving as the channel groove 8 and the etching protection film 5 and the glass substrate 2 having the through holes 9a and 9b are overlapped. A 1% hydrofluoric acid aqueous solution is interposed at the interface and discarded at room temperature for 24 hours while applying a load of about 1 MPa as needed, thereby bonding the glass substrates 1 and 2 to form a detector cell. Note that the etching of the glass substrate 1 in the step (d) may be performed by dry etching.

FIG. 4 shows an example of an optical measuring apparatus using the detector cell of this embodiment. 21 is an ultraviolet-visible light source,
A deuterium lamp and a tungsten lamp as light source lamps, an optical system for selectively extracting light from any one of the lamps, and a spectroscope for selecting light having a predetermined wavelength from the selected light source light are built-in. I have. Reference numeral 22 denotes a photodetector which detects light transmitted through the measurement chamber portion of the detector cell 20, and transmits light through the photodiode array detector as a photodetector and the measurement chamber portion of the detector cell 20. And a measurement optical system for guiding detection light from the light source 21 to the photodiode array detector. Both the light source 21 and the photodetector 22 are generally used in the field of UV-visible measurement.

Reference numeral 23 denotes a stage.
Is provided with a concave portion 24 in which the detector cell 20 can be positioned. By inserting the detector cell 20 into the recess 24, the inlet channel 25 formed in the stage 23 and the sample inlet 26 of the detector cell can be brought into close contact with each other.
Outlet channel 27 formed in the chamber and sample outlet 2 of the detector cell
8 can be brought into close contact with each other. Thus, optical measurement can be performed only by setting the detector cell 20 in the concave portion 24 of the stage 23.

In the embodiment shown in FIG. 2, the light-shielding film is formed on all surfaces except the flow path portion. However, as shown in FIG. A slit may be formed only in the measurement chamber portion by forming a film. In this case, as shown in FIG. 5B, a light-shielding film forming portion of the glass substrate 1 is formed so that the light-shielding film formed only on a part of the surface of the glass substrate 1 does not hinder the bonding of the substrates 1 and 2. Preferably, a concave portion is formed by etching, and a light-shielding film is formed in the concave portion.

As another example, as shown in FIG. 6A or 6B, the light-shielding film for the slit 3 is located outside the substrate 2 or 1 as shown in FIG. Alternatively, it may be formed on the front or back glass surface.

FIG. 7 shows an embodiment in which the present invention is applied to a microchip electrophoresis apparatus. A sample flow path 34 and an analysis flow path 35 are formed on the surface of one of the transparent glass substrates 31 and 32 and cross each other on the surface of one of the substrates 32. A light-shielding film constituting the slit 3 is formed. The other substrate 31 is provided with reservoirs 33 as through holes at positions corresponding to both ends of the sample flow path 34 and the analysis flow path 35. The substrates 31 and 32 are, as shown in FIG.
The microchip is formed by laminating and adhering the light shielding films of the flow paths 34 and 35 and the slit 3 so as to be on the inner side. The microchip of this embodiment can be manufactured according to the same process as the manufacturing process of FIG.
It is preferable that the light-shielding film of the slit 3 is formed in a concave portion in the substrate 32 as shown in FIG. Further, a light-shielding film for the slit 3 may be formed on the entire surface of the substrate 32 except for the flow path on the surface where the flow path is formed, and formed on the outer surface of the substrate 31 or 32 as shown in FIG. You may.

When using this microchip, an electrophoresis buffer is injected into the sample channel 34 and the analysis channel 35 from any one of the reservoirs 33. Then, after injecting a sample into the reservoir 33 at one end of the sample flow path 34, electrodes are inserted into the respective reservoirs 33, or both ends of the sample flow path 34 are formed by using electrodes formed in the respective reservoirs 33 in advance. A predetermined high voltage is applied for a predetermined time to guide the sample to the intersection 6 between the sample flow path 34 and the analysis flow path 35. Next, a predetermined voltage for electrophoresis is applied to both ends of the analysis channel 35, and the sample present at the intersection 36 is guided into the analysis channel 35 and separated. By arranging the detector cell of the present invention having the slit 3 at the position of the detection section of the analysis channel 35, the separation component is detected.

[0026]

According to the detector cell of the present invention, a flow path having a width and a depth, which are formed with high precision by photofabrication technology, having a cross-sectional area similar to that of a separation capillary column. Since it can be used as a measurement chamber, it is possible to realize a measurement chamber having a minute volume that does not impair the separation ability of various separation and analysis means. Since the slit formed by the light shielding film that blocks incident light other than the light transmitted through the liquid sample in the measurement chamber is provided, stray light incident on the detector can be reduced, and the detection sensitivity is improved as compared with the related art. As an example, FIG. 8 shows a comparison between a case where the slit 3 made of a light-shielding film of a Si film is provided in the detector cell shown in FIG. 2 and a case where the slit 3 is not provided. Type 1 is that of the embodiment, and type 2 is that the slit of the light shielding film is not provided. In the case according to the example, the absorbance increases linearly as the concentration of the sample (uracil) increases,
Moreover, the absorbance is higher than when no slit is provided, and the detection sensitivity is improved. This is because the provision of the slit 3 suppresses stray light from entering the detector. Furthermore, since the detector cell of the present invention can be manufactured using semiconductor manufacturing technology, the entire detector cell can be processed with small size and high accuracy, and a plurality of detector cells can be produced collectively. It is also possible to reduce the cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a conventional laser-excited fluorescence detector.

FIG. 2 is a view showing one embodiment, (a) is a top view,
(B) is a sectional view taken along the line BB, (c) is (a)
FIG. 3 is an enlarged cross-sectional view showing a central portion at the position of the line AA in FIG.

FIG. 3 is a process cross-sectional view showing a method for producing a detector cell of the embodiment of FIG. 2;

FIG. 4 is a schematic sectional view showing an example of an optical measuring device using the detector cell of the embodiment in FIG. 2;

FIG. 5 is a view showing another embodiment, in which (a) is a top view,
(B) is a cross-sectional view taken along the line DD.

6 (a) and 6 (b) are views showing still another embodiment, where (a) is a top view and (b) is a sectional view corresponding to FIG. 5 (b).

FIG. 7 is a view showing an embodiment in which the present invention is applied to a microchip of a microchip electrophoresis apparatus as still another embodiment, wherein (a) and (b) are plan views each showing a glass substrate; (C) is a front view showing a state in which they are attached to each other.

FIG. 8 is a diagram showing a comparison of detection sensitivity between a detector cell of one embodiment and a conventional detector cell.

[Explanation of symbols]

 1, 2 glass substrate 3 slit 8 flow channel 8a measuring chamber 9a sample inlet 9b sample outlet 11 detection light

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihiro Arai 1 Nishinokyo Kuwaharacho, Nakagyo-ku, Kyoto City, Kyoto Prefecture Inside Shimadzu Sanjo Plant (72) Inventor Hiroaki Nakanishi 1 Nishinokyo Kuwaharacho, Nakagyo-ku, Kyoto City, Kyoto F term in Shimadzu Sanjo Works (reference)

Claims (3)

[Claims] 1. A detector having a flow path having a minute cross-sectional area formed inside a transparent plate-like member, wherein at least a part of the flow path is used as a measurement chamber and detection light is irradiated to the measurement chamber. A detector cell, wherein a light-shielding film for the detection light is formed at least in a region of the measurement chamber on both sides of the flow path when viewed from a detection light irradiation direction. 2. The transparent plate member in which the detector cell is formed has a sample inlet for introducing a liquid sample into the flow channel and a sample outlet for discharging a liquid sample passing through the flow channel. The detector cell according to claim 1, wherein the detector cell is provided. 3. The transparent plate member in which the detector cell is formed has an analysis flow path and a sample flow path intersecting the analysis flow path formed therein, and one surface of the transparent plate member. The hole which reaches the analysis flow path or the sample flow path at a position corresponding to the analysis flow path and the sample flow path is formed, and at least a part of the analysis flow path is the measurement chamber. Detector cell.