JP3735982B2 - Detector cell and optical measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a detector cell for measuring absorption or emission of light in the ultraviolet or visible region, and an optical measurement apparatus using the detector cell, which are used when detecting components in a very small amount of liquid sample. About.
[0002]
[Prior art]
A detector cell for measuring the light absorption or emission of an analyte in the ultraviolet or visible region accurately and quickly analyzes trace components in the field of analytical chemistry (especially in the environmental analysis field, clinical field, pharmaceutical field, etc.). It is often used as a detector for techniques such as capillary electrophoresis (CE), liquid chromatography (LC) or flow injection analysis (FIA). This detector cell 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. Or it has a measurement chamber which becomes an interaction area | region with the light ray of a visible region, and is connected and used for the exit side of the analysis column used for the said analysis method. In addition, the measurement chamber is provided with an entrance and an exit for the measurement light. Light in the ultraviolet or visible region passes through the entrance through the liquid sample existing in the measurement chamber, and then exits from the exit for photometry. It is detected by an optical system.
[0003]
[Problems to be solved by the invention]
However, for example, the conventional detector cell used in a capillary electrophoresis apparatus generally has a large measurement chamber volume compared to a glass capillary that separates a sample. There were many cases where the separation ability of This is because the volume of the measurement chamber is large, so that the separated trace components are remixed and diffused into the medium.
[0004]
To solve this problem, for example, as described in “Analytical Chemistry, vol. 63, p. 2835 (1991)”, a laser-excited fluorescence detector using a small cell with a reduced measurement chamber volume (see FIG. Efforts have been made to reduce the measurement volume, such as the attempt of (5), but there is room for improvement in terms of resolution and accuracy because the size is not sufficient. On the other hand, a method of using the separation capillary column itself as a detection cell has been studied. In this case, the volume of the sample required for analysis and the volume of the measurement chamber can be made extremely small, but there is a problem that detection sensitivity is insufficient due to a short optical path length.
[0005]
The present invention has been devised in order to solve such problems. The object of the present invention is to use a separation capillary column itself as a detection cell in order to extremely reduce the volume of the measurement chamber, and to detect the sensitivity. In order to improve the above, it is to realize a detector cell having an optical path length capable of sufficiently allowing detection light to interact with a liquid sample to be detected.
[0006]
[Means for Solving the Problems]
The detector cell of the present invention made to solve the above problem constitutes a detector cell by arranging the divided members so as to cover the entire circumference of a part of the separation capillary column. The member is made of, for example, silicon, and the inner surface facing the capillary of the member is formed of a mirror surface that efficiently reflects detection light, for example, an Al thin film, and some of the openings are used as an entrance window and an exit window. Exists. By combining these members and covering the entire circumference of the separation capillary column, a part of the separation capillary column is used as a detection cell, and in addition, in order to improve detection sensitivity, light incident from the incident port is reflected on the inner surface of the detection cell. The optical reflection surface is configured to be multiple-reflected and output from the output window.
[0007]
Further, an optical measurement device that performs measurement using the detector cell of the present invention made to solve the above problem uses the detector cell, and a light source that irradiates detection light to an incident window of the detector cell, A photodetector for measuring the detection light from the exit window of the detector cell and means for positioning the detector cell are provided, and optical measurement is performed by the detector cell.
[0008]
In other words, by using the separation capillary column itself as a detection cell, the volume of the measurement chamber can be extremely reduced. In addition, a reflective surface is formed on the inner surface of the member, and incident light for detection is incident on the detector cell at an appropriate angle from the incident port of the member, so that a part of the separation capillary column functioning as a measurement chamber can detect a plurality of detection lights. If the cell is adjusted so as to be emitted after being reflected once, the optical path length in which the detection light and the specimen interact with each other increases with an increase in the number of reflections, and the detection sensitivity is improved as compared with the conventional case.
[0009]
Here, of the members constituting the detection cell, the shape of at least one member is concave, so that the entire circumference of the separation capillary column can be covered when the detection cell is constructed, and a gap is formed between the separation capillary column as much as possible. A shape that does not leave is desirable. The length of the measurement chamber determined by the arrangement of the entrance and exit is preferably about several tens to several hundreds of micrometers so as not to reduce the resolution.
[0010]
Further, when detecting a specimen by ultraviolet absorption, the reflective surface material is preferably Al (aluminum) having a high reflectance with respect to light in the ultraviolet region. In the case of detecting using visible light, for example, a member having a concave shape whose inner surface is mirror-finished by anisotropic etching using silicon as a material can be used as it is.
[0011]
According to the present invention, since a part of the separation capillary column is used as a measurement chamber, a sufficiently small measurement chamber can be realized, and the separation ability of various separation analysis means is not reduced. In addition, by using the reflecting surface formed on the inner surface of the member, it is possible to realize a detector cell having a configuration in which the detection light passes through the measurement chamber a plurality of times, and the detection sensitivity is substantially increased by increasing the optical path length compared to the conventional case. Can be improved. Further, when detecting a specimen by ultraviolet absorption, a multiple reflection detector cell that can be used for light absorption measurement in the ultraviolet region can be realized by using an Al reflective surface.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 2 shows a cross-sectional view of a detection cell which is an embodiment of the present invention.
[0014]
The members 6 a and 6 a ′ constituting the detection cell are overlapped to cover the entire circumference of a part of the separation capillary column 10. A silicon substrate is used for the members 6a and 6a ′. The material of the member may be any material as long as the inner surface covering the separation capillary column can be a mirror surface, and may be, for example, metal, plastic, or the like.
[0015]
At this time, a gap exists between the members 6a and 6a ′ and the separation capillary column 10, but in order to minimize light scattering, the gap 11 has a refractive index comparable to that of quartz, which is the material of the separation capillary column. Fill. These are fixed by the fixing member 12a. The fixing member is not particularly limited in shape and material as long as the members 6a and 6a ′ can be fixed in close contact with each other, but a shape and material that can be easily detached are desirable.
[0016]
With the above configuration, a sufficiently small volume measurement chamber can be realized. In addition, when the detection incident light 15 is incident at an appropriate angle from the incident port 13 of the detector cell, the detection light 16 reflects a part of the separation capillary column 10 functioning as a measurement chamber a plurality of times, and then the exit port 14 is reflected. By adjusting so as to pass through and exit, the optical path length in which the detection light and the specimen interact with each other increases as the number of reflections increases, and the detection sensitivity is improved as compared with the conventional case.
[0017]
FIG. 1 is a process diagram of an embodiment of a detection cell made of silicon as shown in FIG. In FIG. 1A, reference numeral 1 denotes a silicon substrate. A protective film 2 (for example, a SiO 2 film having a thickness of about 1.5 μm formed by thermal oxidation) functioning as an etching mask for the subsequent anisotropic etching is formed on both surfaces of the silicon substrate 1. The protective film 2 may be made of any material, film-forming method, and thickness as long as the protective film 2 functions as an etching mask for anisotropic etching. A Si3N4 film may be used. In this case, as a mask for patterning the Si3N4 film, for example, a SiO2 film formed by low pressure CVD is required.
[0018]
In FIG. 1 (2), the photoresist 3 is spin-coated with, for example, AZ4620 at 3000 rpm for 40 seconds (thickness: about 7 μm), and exposed and developed. Here, the exposure of the photoresist can be performed using an aligner or a stepper generally used in semiconductor manufacturing. Further, the material and thickness of the photoresist to be used are not particularly limited, and any material and thickness that can withstand the solution in the subsequent SiO2 film patterning step may be used. Further, the developer for developing the photoresist is not particularly limited as long as it is used for developing the photoresist to be used.
[0019]
In FIG. 1C, the SiO 2 film as the protective film 2 is patterned using an HF aqueous solution of HF: H 2 O = 1: 50 (room temperature). Thereafter, the photoresist 3 is removed. When the Si3N4 film is used as the protective film 2, the Si3N4 film may be patterned using phosphoric acid (180 ° C.).
[0020]
In FIG. 1 (4), anisotropic etching is performed to form a concave shape capable of covering the separation capillary column and a window for detection light using 40 wt% KOH (80 ° C.). In addition, TMAH (tetramethylammonium hydride), hydrazine, or the like may be used as an etchant used for anisotropic etching.
[0021]
In FIG. 1 (5), for example, an Al thin film reflective film 4 (thickness of 1000 mm or less) is formed on the inner surface of the member formed with the recesses facing the separation capillary column. Further, although not shown in the drawing, in order to prevent oxidation of the Al thin film, an Al protective film (thickness of several hundreds to several thousand mm) made of, for example, sputtered quartz may be formed thereon. FIGS. 1 (5) and 1 (6) show different cross sections from those shown in FIG. 1 (4) in order to show a cross section that does not include the detection window.
[0022]
If two members 6 and 6 ′ thus fabricated are overlapped and configured as shown in FIG. 1 (6), a detector cell that covers the entire circumference in a part of the separation capillary column is realized.
[0023]
FIG. 3 is a cross-sectional view showing a modification of the above embodiment. Although the configuration is almost the same, a recess for fixing the separation capillary column 10 is formed only on the 6b ′ side, and the members 6b and 6b ′ are overlapped to cover the entire circumference of a part of the separation capillary column 10. Similarly, the gap between the members 6a and 6a ′ and the separation capillary column 10 is filled with grease 11 having a refractive index similar to that of quartz to minimize light scattering, and is fixed by the fixing member 12b.
[0024]
FIG. 4 shows an optical measuring device using the present detector cell. In the figure, 21 is a deuterium lamp, a tungsten lamp, an ultraviolet-visible light source that sends out light of a predetermined wavelength containing a spectroscope, and 22 is a photodetector having a photometric optical system using a photodiode array detector, Both are generally used for UV-visible measurement. Reference numeral 23 denotes a stage, which is provided with a recess 24 in which the detector cell unit 20 can be positioned. Further, the light from the light source 21 can enter from the entrance window 13 of the detector cell unit, and the light from the exit window 14 can be received by the photodetector 22. Thereby, the optical measurement can be performed only by setting the detector cell unit 20 in the concave portion 24 of the stage 23. The light source and the entrance window, and the photodetector and the exit window may be on the opposite side, for example, regardless of the arrangement on the same plane.
[0025]
The embodiments of the present invention are summarized below.
[0026]
(1) In a detector cell for optically detecting a sample flowing in a capillary, two silicon substrates are arranged so as to cover the entire circumference of a part of the capillary, and the silicon substrate in a portion covering the capillary The detection cell is formed so as to form a mirror surface on the inner surface of the member, and the member has an incident port for incident measurement light on the mirror surface and an emission port for emitting the detection light reflected by the mirror surface. A detector cell characterized by being provided in
[0027]
(2) In the detector cell for optically detecting the sample flowing in the capillary, the divided member is arranged so as to cover the entire circumference of a part of the capillary, and on the inner surface of the divided member at the part covering the capillary A detection cell is formed so as to form a mirror surface using an aluminum thin film, and an incident port for allowing measurement light to enter the mirror surface, and an output port for emitting detection light after being reflected by the mirror surface A detector cell provided on the member.
[0028]
【The invention's effect】
According to the detector cell of the present invention, since a part of the separation capillary column itself can be used as the detector cell, a measurement chamber that does not impair the separation ability of various separation analysis means can be realized. In addition, by using a reflection surface formed on the inner surface of the flow path of the detector cell, and realizing a multiple reflection detector cell having a configuration in which the detection light passes through the measurement chamber multiple times, the substantial optical path length increases. The detection sensitivity is improved as compared with the conventional case.
[0029]
In addition, when the specimen contains a component having absorption in the ultraviolet region, a multiple reflection detector cell that can be used for light absorption measurement in the ultraviolet region is obtained by using an Al reflective surface that has a high reflectance for light in the ultraviolet region. realizable.
[0030]
In addition, the detector cell of the present invention is extremely easy to detach from the separation capillary column, and can greatly reduce the amount of work when replacing the capillary column.
[0031]
Furthermore, since the detector cell of the present invention is manufactured using semiconductor manufacturing technology, the members constituting the detector cell are processed with small size and high accuracy, and a plurality of members can be produced in batch. This is advantageous for cost reduction.
[0032]
Furthermore, if the optical measuring device of the present invention is used, the entrance and reflection port of the detector cell having the above characteristics can be easily positioned with the optical meter of the optical measuring device.
[Brief description of the drawings]
FIG. 1 is a diagram showing a manufacturing process of a detector cell according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view and a cross-sectional view of a detector cell according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view and a cross-sectional view of a detector cell according to another embodiment of the present invention.
FIG. 4 is a configuration diagram of an optical measuring apparatus according to an embodiment of the present invention.
FIG. 5 is an explanatory diagram of a laser-excited fluorescence detector using a conventional small cell.
[Explanation of symbols]
1: Silicon substrate 6a, 6a ': Member 10: Separation capillary column 11: Grease 12a: Fixing member 13: Entrance 14: Reflection port 15: Incident light 16: Detection light 20: Detection cell unit 21: Light source 22: Photo detector 23: Stage 24: Concave portion (positioning means)

Claims (3)

In the detector cell that optically detects the sample flowing in the capillary, the divided member is arranged so as to cover the entire circumference of a part of the capillary, and a mirror surface is formed on the inner surface of the divided member that covers the capillary In this manner, the detection cell is formed, and the member is provided with an incident port for allowing the measurement light to enter the mirror surface and an exit port for emitting the detection light after being reflected by the mirror surface. Detector cell. A light source for irradiating detection light toward the entrance of the detector cell and a photodetector for measuring the detection light from the exit of the detector cell, and positioning the light source, the photodetector, and the detector cell An optical measuring device for performing optical measurement using the detector cell according to claim 1. 2. The detector cell according to claim 1, wherein the dividing member is a silicon substrate, and a groove portion adapted to the capillary is formed on the inner surface side by anisotropic etching.

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