Dual-optical-path dual-mode detection system for capillary electrophoresis

Abstract

The utility model discloses a dual-optical path dual-mode detection system for capillary electrophoresis, which comprises a quartz capillary, an ultraviolet absorption detector, a laser-induced fluorescence detector and an upper computer, a detection window is prefabricated on the quartz capillary, and the ultraviolet absorption detector and the laser-induced fluorescence detector are respectively positioned in two mutually perpendicular planes. Detection light paths of the ultraviolet absorption detector and the laser-induced fluorescence detector are respectively vertical to the detection window; the ultraviolet absorption detector and the laser-induced fluorescence detector are respectively in signal connection with the upper computer, and a detection signal is analyzed and processed by the upper computer and then is output outwards. The detection system integrates an ultraviolet absorption detection mode and a laser-induced fluorescence detection mode, and a light source can be flexibly replaced so as to realize detection of components with different properties in a complex sample.

Description

Technical Field

[0001] This utility model belongs to the technical field of capillary electrophoresis detection equipment, and particularly relates to a vertical dual-optical-path dual-mode detection system with replaceable light source for capillary electrophoresis. Background Technology

[0002] Capillary electrophoresis (CE) is a microseparation technique for analyzing charged chemical substances under a high-voltage electric field, with wide applications in food safety, environmental pollution, and pharmaceutical analysis. A CE device includes a capillary, a high-voltage power supply, a detection system, and data acquisition and processing components. The detection system is an indispensable part of a CE device. Various detection modes are available for CE, commonly including optical detection (such as laser-induced fluorescence detection and UV-Vis absorption detection), electrochemical detection (such as amperometric and conductivity detection), and mass spectrometry. CE optical detectors typically have only one detection mode, with different modes selected for specific analytes. For example, laser-induced fluorescence detection can be used for fluorescent substances due to its high sensitivity. When analytes contain chromophores or auxochromes, UV absorption detection can be used, offering moderate sensitivity. However, when samples are complex, a single detection mode often cannot meet the requirements for simultaneous detection of multiple types of compounds; therefore, there is an urgent need to develop CE detection systems that integrate different detection modes.

[0003] Currently, there are few CE detection systems that integrate laser-induced fluorescence detection and ultraviolet-visible absorption detection modes. Existing research has shown that systems integrating both optical detection modes either use fiber optic guidance, which results in some light energy loss and reduced detection sensitivity; or they rely on a single light source and optical path, limiting the detectable analytes to the wavelength of that single source; or they use special, delicate structures, which are inconvenient for capillary replacement and use. Based on these reasons, this invention provides a CE detection system integrating dual optical paths and dual detection modes, which can meet the analytical requirements of complex samples with different properties, without requiring special, delicate structures or optical fibers, resulting in low cost and ease of use. Utility Model Content

[0004] The purpose of this invention is to provide a low-cost, easy-to-use vertical dual-optical-path dual-mode capillary electrophoresis detection system. This system integrates ultraviolet absorption detection mode and laser-induced fluorescence detection mode, and the light source can be flexibly replaced to achieve the detection of different components in complex samples.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A dual-optical-path, dual-mode detection system for capillary electrophoresis includes a quartz capillary, an ultraviolet absorption detector, a laser-induced fluorescence detector, and a host computer. A detection window is pre-formed on the quartz capillary. The ultraviolet absorption detector and the laser-induced fluorescence detector are located in two mutually perpendicular planes, and their detection optical paths are perpendicular to the detection window. The ultraviolet absorption detector and the laser-induced fluorescence detector are respectively connected to the host computer for signal processing. The detection signals are analyzed and processed by the host computer before being output.

[0007] The ultraviolet absorption detector includes an ultraviolet light-emitting diode, a first quartz focusing lens, a second quartz focusing lens, a quartz filter, a slit, and a first photoelectric converter arranged in a straight line along the direction of ultraviolet light propagation. The first quartz focusing lens and the second quartz focusing lens are located on both sides of the detection window, and the first photoelectric converter is connected to the host computer for signal transmission.

[0008] The laser-induced fluorescence detector includes a laser diode, a collimating lens, and a dichroic mirror arranged in a straight line along the laser's direction of propagation. The bottom of the dichroic mirror is tilted towards the laser diode, and the central axis of the dichroic mirror forms a 45° angle with the emission direction of the laser diode. A focusing lens is arranged above the dichroic mirror near the detection window. The focusing lens, along with a filter and a second photoelectric converter arranged below the dichroic mirror, are arranged vertically in a longitudinal direction. The second photoelectric converter is connected to a host computer for signal transmission.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1) A dual-optical-path approach is adopted, with two detectors perpendicular to the capillary on different planes, ensuring no interference between the detection modes;

[0011] 2) The dual-mode optical detector, consisting of an ultraviolet absorption detector and a laser-induced fluorescence detector, can work independently or simultaneously, and the detection mode can be flexibly selected;

[0012] 3) The laser-induced fluorescence detection mode and the ultraviolet absorption detection mode use light sources of different wavelengths, which can be adapted to different analytes and are flexible and convenient to use;

[0013] 4) A single run can simultaneously detect fluorescent substances and substances that produce ultraviolet absorption in complex samples, improving analytical detection efficiency. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the vertical dual-optical-path dual-mode detection system of this utility model.

[0015] Figure 2 This is the electrophoretic spectrum used for detection by the vertical dual-optical-path dual-mode detection system of this utility model.

[0016] In the diagram: 1. Detection window, 2. Quartz capillary, 3. Ultraviolet absorption detector, 4. Ultraviolet light-emitting diode, 5. First quartz focusing lens, 6. Second quartz focusing lens, 7. Quartz filter, 8. Slit, 9. First photoelectric converter, 10. Focusing lens, 11. Dichroic mirror, 12. Filter, 13. Second photoelectric converter, 14. Laser diode, 15. Collimating lens, 16. Laser-induced fluorescence detector, 17. Detection circuit. Detailed Implementation

[0017] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, the dual-optical-path dual-mode detection system of this utility model includes a quartz capillary tube 2, an ultraviolet absorption detector 3, a laser-induced fluorescence detector 16, and a host computer 17. A detection window 1 is pre-formed on the quartz capillary tube 2. The ultraviolet absorption detector 3 and the laser-induced fluorescence detector 16 are located in two mutually perpendicular planes, and the detection optical paths of the ultraviolet absorption detector 3 and the laser-induced fluorescence detector 16 are perpendicular to the detection window 1. The ultraviolet absorption detector 3 and the laser-induced fluorescence detector 16 are respectively connected to the host computer 17 for signal transmission. The detection signal is analyzed and processed by the host computer 17 and then output.

[0019] The ultraviolet absorption detector 3 includes an ultraviolet light-emitting diode 4, a first quartz focusing lens 5, a second quartz focusing lens 6, a quartz filter 7, a slit 8, and a first photoelectric converter 9 arranged in a straight line in the direction of ultraviolet light propagation. The first quartz focusing lens 5 and the second quartz focusing lens 6 are located on both sides of the detection window 1, and the first photoelectric converter 9 is connected to the host computer 17 via signal.

[0020] The laser-induced fluorescence detector 16 includes a laser diode 14, a collimating lens 15, and a dichroic mirror 11 arranged in a straight line along the laser propagation direction. The bottom of the dichroic mirror 11 is tilted towards the laser diode 14, and the central axis of the dichroic mirror 11 forms a 45° angle with the emission direction of the laser diode 14. A focusing lens 10 is arranged above the dichroic mirror 11 near the detection window 1. The focusing lens 10, the filter 12, and the second photoelectric converter 13 arranged below the dichroic mirror 11 are arranged vertically in the longitudinal direction. The second photoelectric converter 13 is connected to the host computer 17 via signal.

[0021] The working principle of this utility model is as follows:

[0022] 1. Ultraviolet absorption detection mode

[0023] The ultraviolet light emitted by the ultraviolet light-emitting diode 4 is focused by the first quartz focusing lens 5 onto the detection window 1 on the quartz capillary 2. After being absorbed by the sample inside the quartz capillary 2, it is collected by the second quartz focusing lens 6. After passing through the quartz filter 7 and the slit 8, it is converted into a photoelectric signal by the first photoelectric converter 9 and the signal is sent to the host computer 17 for analysis and processing before being output.

[0024] 2. Laser-induced fluorescence detection mode

[0025] The light beam emitted by the laser diode 14 is collimated by the collimating lens 15, reflected by the dichroic mirror 11 placed at 45° to it, and focused by the focusing lens 10 to the detection window 1, causing the sample in the quartz capillary 2 to be excited and emit a fluorescence signal. The fluorescence signal is focused by the focusing lens 10 and passes through the dichroic mirror 11 and the filter 12. It is then converted into a photoelectric signal by the second photoelectric converter 13 and the signal is sent to the host computer 17 for analysis and processing before being output.

[0026] In the two detection modes described above, the analysis and processing of the detection signal using a host computer 17 (such as a computer) is existing technology and will not be elaborated further. The ultraviolet light-emitting diode 4 can be selected from various wavelengths between 200 nm and 400 nm to meet the detection requirements of different analytes, and the laser diode 14 can be selected from various wavelengths and matched with appropriate filters.

[0027] The dichroic mirror 11 and the filter 12 correspond to the wavelength of the laser diode 14; the quartz filter 7 corresponds to the wavelength of the ultraviolet light-emitting diode 4, and the wavelength that can be transmitted cannot exceed the wavelength of the laser diode 14, so as to filter out part of the light emitted by the laser diode 14 that enters the optical path of the ultraviolet absorption detector, so as to avoid its interference with the ultraviolet absorption detection.

[0028] The first photoelectric converter 9 uses a photovoltaic cell, while the second photoelectric converter 13 can use a photomultiplier tube or a photodiode.

[0029] In summary, this novel dual-optical-path, dual-mode detection system integrates two detection modes: an ultraviolet absorption detector and a laser-induced fluorescence detector. Each detection mode has an independent light source and optical path. In use, the two detection modes share a single detection site (detection window 1), and can operate independently or simultaneously. When operating simultaneously, it can achieve synchronous detection of multiple target analytes without interference between the two detection modes. Furthermore, using ultraviolet light-emitting diodes and laser diodes as light sources offers advantages such as low cost, stability, and ease of integration.

[0030] Another embodiment of the detection using the dual-optical-path dual-mode detection system of this utility model is given to illustrate the detection effect and reliability of this utility model.

[0031] The sample to be detected consisted of 500 nM sodium fluorescein and 2 mM tryptophan. In the dual-mode detection system, the ultraviolet light-emitting diode wavelength was 275 nm, and the laser diode wavelength was 445 nm. Capillary electrophoresis was used to separate the sample, with a background buffer solution of 20 mM tris(hydroxymethyl)aminomethane and 20 mM 2-cyclohexylaminoethanesulfonic acid. The capillary electrophoresis separation voltage was 15 kV, the capillary length was 40 cm, the capillary inner diameter was 50 μm, and the effective separation length was 25 cm. Figure 2 This is an electrophoretic spectrum of the two signals obtained from the same electrophoresis run of the sample in this embodiment. The spectrum shows that sodium fluorescein in the sample has a fluorescent group, and a fluorescent signal can be detected in the laser-induced fluorescence detection mode; in the ultraviolet absorption detection mode, the ultraviolet absorption signal of tryptophan can be obtained, and the two signals do not interfere with each other, proving that the dual-mode detection system of this invention can simultaneously detect samples with different properties without interference between the components.

Claims

1. A dual-optical-path, dual-mode detection system for capillary electrophoresis, characterized in that: The system includes a quartz capillary (2), an ultraviolet absorption detector (3), a laser-induced fluorescence detector (16), and a host computer (17). The quartz capillary (2) has a pre-fabricated detection window (1). The ultraviolet absorption detector (3) and the laser-induced fluorescence detector (16) are located in two mutually perpendicular planes, and the detection optical paths of the ultraviolet absorption detector (3) and the laser-induced fluorescence detector (16) are perpendicular to the detection window (1). The ultraviolet absorption detector (3) and the laser-induced fluorescence detector (16) are connected to the host computer (17) for signal transmission. The detection signal is analyzed and processed by the host computer (17) and then output to the outside.

2. The dual-optical-path dual-mode detection system for capillary electrophoresis as described in claim 1, characterized in that: The ultraviolet absorption detector (3) includes an ultraviolet light-emitting diode (4), a first quartz focusing lens (5), a second quartz focusing lens (6), a quartz filter (7), a slit (8), and a first photoelectric converter (9) arranged in a straight line in the direction of ultraviolet light propagation. The first quartz focusing lens (5) and the second quartz focusing lens (6) are located on both sides of the detection window (1), and the first photoelectric converter (9) is connected to the host computer (17) via signal.

3. The dual-optical-path dual-mode detection system for capillary electrophoresis as described in claim 1, characterized in that: The laser-induced fluorescence detector (16) includes a laser diode (14), a collimating lens (15), and a dichroic mirror (11) arranged in a straight line along the laser propagation direction. The bottom of the dichroic mirror (11) is tilted towards the side closer to the laser diode (14), and the central axis of the dichroic mirror (11) forms a 45° angle with the emission direction of the laser diode (14). A focusing lens (10) is provided above the dichroic mirror (11) near the detection window (1). The focusing lens (10), the filter (12) arranged below the dichroic mirror (11), and the second photoelectric converter (13) are arranged vertically in the longitudinal direction. The second photoelectric converter (13) is connected to the host computer (17) via signal.

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