Infrared conductivity detector

Abstract

The utility model discloses an infrared light conductivity detector which comprises an infrared light source, a light chamber, a micro-packed chromatographic column and a photoconductive detector, a gas inlet and a gas outlet are formed in the two opposite side walls of the light chamber respectively, the center line of the gas inlet and the center line of the gas outlet are not collinear, the movement distance of gas in the light chamber is increased, the gas can absorb infrared rays more sufficiently, the infrared light source and the photoconductive detector are arranged at the oppositely-arranged light through holes respectively, and the infrared light source and the photoconductive detector are arranged in the light through holes respectively. The infrared light source is a direct light source, loss of an optical path is avoided, after gas to be detected is separated by the micro-packed chromatographic column, gas with various single components is formed and enters the light chamber through the gas inlet in sequence, and compared with the mode that unseparated mixed component gas directly enters the light chamber, the detection sensitivity is improved, the detection optical path is shortened, and the detection accuracy is improved. Therefore, the size of the light chamber is reduced and a user can carry the light chamber conveniently.

Description

Technical Field

[0001] The utility model relates to the field of gas chromatography gas analysis, in particular to an infrared photoconductivity detector. Background Art

[0002] Infrared gas analysis is the mature application of non-dispersive infrared (NDIR) spectroscopy technology in gas analysis and detection. The principle of non-dispersive (non-spectral) infrared analysis is to project all rays of the continuous spectrum onto the sample gas to be analyzed, and use the selective absorption characteristics of different gases to infrared rays of different wavelengths to detect and analyze the gas components.

[0003] In existing infrared photoconductive detection devices, in order to achieve the best absorption effect of the sample gas on infrared light, the volume of the optical chamber is relatively large to increase the optical path, resulting in a larger overall volume of the detection device, which is inconvenient to carry. Summary of the invention

[0004] The utility model provides an infrared photoconductive detector to overcome the above technical problems.

[0005] In order to achieve the above purpose, the technical solution of the utility model is:

[0006] An infrared photoconductivity detector comprises an infrared light source, a light chamber, a micro-filled chromatographic column and a photoconductivity detector;

[0007] An air inlet and an air outlet are respectively arranged on two opposite side walls of the optical chamber, the center lines of the air inlet and the air outlet are not collinear, and light holes are respectively opened on the other two opposite side walls of the optical chamber, and the gas to be detected enters the interior of the optical chamber through the air inlet after passing through the micro-filled chromatographic column, and flows out through the air outlet;

[0008] The infrared light source and the photoconductive detector are respectively arranged at the light through holes arranged opposite to each other. The infrared light source is a direct light source. The infrared light emitted by the infrared light source enters the interior of the optical chamber through the light through hole on one side and is emitted to the interior of the photoconductive detector through the light through hole on the other side.

[0009] Furthermore, the photoconductive detector has an internal integrated circuit amplifier and a thermoelectric cooler.

[0010] Furthermore, it also includes an infrared filter, which is arranged between the infrared light source and the light chamber.

[0011] Furthermore, the infrared light source is an infrared light emitting resistor.

[0012] Furthermore, the inner surface roughness of the optical chamber is greater than 0.4.

[0013] Furthermore, it also includes a gas chromatography analysis workstation, and the gas chromatography analysis workstation is electrically connected to the photoconductive detector.

[0014] Beneficial effects: The utility model discloses an infrared photoconductivity detector, in which rays emitted by an infrared light source enter a light chamber through a light hole, and after the gas to be detected is separated by a micro-filled chromatographic column, various single-component gases are formed and enter the light chamber through the air inlet in turn, and the single-component gases absorb the infrared light in the light chamber and flow out through the air outlet, and the infrared light enters the photoconductivity detector through the light hole, is amplified and processed into a voltage signal, and is subsequently analyzed and processed. Compared with the mixed-component gas that has not been separated directly entering the light chamber, the present application improves the detection sensitivity, and the gas can fully absorb the infrared rays without having to travel a long distance, thereby shortening the detection optical path and reducing the volume of the light chamber; the infrared light source adopts a direct radiation mode, which avoids affecting the gas's absorption effect on infrared rays due to the loss of the optical path, and the center lines of the air inlet and the air outlet arranged on the side wall of the light chamber are not colinear, which increases the movement distance of the gas in the light chamber, makes the gas absorb the infrared rays more fully, further reduces the volume of the light chamber, and is convenient for users to carry.

[0015] The present application has a simple structure, is easy to detect, has a good response value for most substances, has fast and efficient sample analysis, has relatively accurate test results, has low test costs, and will not damage sample gases. It has broad application prospects in the fields of organic chemistry, environmental analysis, food safety, etc., and is conducive to the qualitative improvement of analytical detection technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the working principle of an infrared photoconductive detector disclosed in an embodiment of the utility model;

[0018] Figure 2 The schematic diagram of the structure of the infrared light source, the light chamber and the photoconductive detector disclosed in the embodiment of the utility model;

[0019] In the figure: 1. infrared light source; 2. light chamber; 21. air inlet; 22. air outlet; 23. light hole; 3. micro-filled chromatographic column; 4. infrared filter; 5. photoconductive detector. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] This embodiment provides an infrared photoconductivity detector, such as Figure 1-2 As shown, it includes an infrared light source 1, a light chamber 2, a micro-filled chromatographic column 3 and a photoconductive detector 5;

[0022] An air inlet 21 and an air outlet 22 are respectively provided on two opposite side walls of the optical chamber 2, and the center lines of the air inlet 21 and the air outlet 22 are not collinear. Light holes 23 are respectively opened on the other two opposite side walls of the optical chamber 2. After the gas to be detected passes through the micro-filled chromatographic column 3, it enters the interior of the optical chamber 2 through the air inlet 21 and flows out through the air outlet 22.

[0023] The infrared light source 1 and the photoconductive detector 5 are respectively arranged at the light holes 23 arranged opposite to each other. The infrared light emitted by the infrared light source 1 enters the optical chamber 2 through the light hole 23 on one side and is emitted to the photoconductive detector 5 through the light hole 23 on the other side.

[0024] In this embodiment, the rays emitted by the infrared light source 1 enter the optical chamber 2 through the light hole 23. After the gas to be detected is separated by the micro-filled chromatographic column 3, various single-component gases are formed and enter the optical chamber 2 through the air inlet 21 in turn. The single-component gas absorbs the infrared light in the optical chamber 2 and flows out through the air outlet 22. The infrared light enters the photoconductive detector 5 through the light hole 23, is amplified and processed into a voltage signal, and then undergoes subsequent analysis and processing. Compared with the mixed component gas that has not been separated directly entering the optical chamber, the present application improves the detection sensitivity, shortens the detection optical path, and thereby reduces the volume of the optical chamber. The infrared light source adopts a direct irradiation mode to avoid affecting the gas's absorption effect on infrared rays due to the loss of the optical path. The center lines of the air inlet 21 and the air outlet 22 arranged on the side wall of the optical chamber 2 are not colinear, which increases the movement distance of the gas in the optical chamber 2, makes the gas absorb infrared rays more fully, further reduces the volume of the optical chamber, and is convenient for users to carry.

[0025] In this embodiment, the volume of the optical chamber 2 is about 200 μL, which is a micro-miniature optical chamber, and the detector gas flow rate only needs 2 to 60 mL / min.

[0026] The present application has a simple structure, is easy to detect, has a good response value for most substances, has fast and efficient sample analysis, has relatively accurate test results, has low test costs, does not destroy samples, and has broad application prospects in the fields of organic chemistry, environmental analysis, food safety, etc., and is conducive to the qualitative improvement of analytical detection technology.

[0027] In a specific embodiment, the photoconductivity detector 5 has an internal integrated circuit amplifier and a thermoelectric cooler. The photoconductivity detector 5 can adopt an electrically cooled lead sulfide PbS photoconductivity detector or a lead selenide PbSe photoconductivity detector in the 2 to 14 micron band, and the photoelectric detection, circuit amplification and temperature and humidity control components are integrated in a smaller space, which simplifies the design and development of infrared optical instruments and further reduces the size of the infrared photoconductivity detector. When the photoconductivity detector 5 works at room temperature, the irradiation of infrared light will increase the temperature of the detection chamber. The thermoelectric cooler inside the photoconductivity detector 5 plays a role in regulating the temperature, so that the photoconductivity detector 5 works at room temperature. By adjusting the current of the TEC current pin, the temperature of the photoconductivity detector 5 can be kept stable, so that the measurement result is accurate and stable.

[0028] In a specific embodiment, an infrared filter 4 is also included. The infrared filter 4 is arranged between the infrared light source 1 and the light chamber 2 to filter out light other than the required wavelength to improve the detection efficiency and accuracy.

[0029] In a specific embodiment, the infrared light source 1 is an infrared light-emitting resistor, which is in the form of a wire-wound resistor. According to the characteristics of the infrared light-emitting resistor, a mathematical control model is established for real-time simulation. The power supply voltage adopts a PWM pulse width modulation power supply, and the power supply voltage is modulated according to the simulation results to ensure that the infrared spectrum of the infrared light-emitting resistor meets the measurement accuracy.

[0030] In a specific embodiment, the inner surface roughness of the optical chamber 2 is greater than 0.4, which can effectively reduce the loss of the optical path.

[0031] In a specific embodiment, a gas chromatography analysis workstation is also included. The photoconductivity detector 5 outputs a voltage signal to the gas chromatography analysis workstation. By measuring the peak height and area of ​​the signal, the peak time and relative content of each component can be obtained. After analysis and calculation, a test spectrum is output.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. An infrared photoconductivity detector, characterized in that: It comprises an infrared light source (1), a light chamber (2), a micro-filled chromatographic column (3) and a photoconductive detector (5); An air inlet (21) and an air outlet (22) are respectively provided on two opposite side walls of the optical chamber (2); the center lines of the air inlet (21) and the air outlet (22) are not collinear; and light holes (23) are respectively provided on the other two opposite side walls of the optical chamber (2); after the gas to be detected passes through the micro-filled chromatographic column (3), it enters the interior of the optical chamber (2) through the air inlet (21) and flows out through the air outlet (22); The infrared light source (1) and the photoconductive detector (5) are respectively arranged at the light through holes (23) arranged opposite to each other. The infrared light source (1) is a direct light source. The infrared light emitted by the infrared light source (1) enters the interior of the optical chamber (2) through the light through hole (23) on one side and is emitted to the interior of the photoconductive detector (5) through the light through hole (23) on the other side.

2. An infrared photoconductive detector according to claim 1, characterized in that: The photoconductive detector (5) has an internal integrated circuit amplifier and a thermoelectric cooler.

3. An infrared photoconductive detector according to claim 1, characterized in that: It also comprises an infrared filter (4), wherein the infrared filter (4) is arranged between the infrared light source (1) and the light chamber (2).

4. An infrared photoconductive detector according to claim 1, characterized in that: The infrared light source (1) is an infrared light-emitting resistor.

5. An infrared photoconductive detector according to claim 1, characterized in that: The inner surface roughness of the optical chamber (2) is greater than 0.

4.

6. An infrared photoconductive detector according to claim 1, characterized in that: It also comprises a gas chromatography analysis workstation, which is electrically connected to the photoconductive detector (5).

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