High-dynamic-range online absorbance detection system and method

Abstract

The invention discloses an online absorbance detection system with a high dynamic range. The online absorbance detection system comprises a flow cell, a multi-light source assembly, a detection assembly and an electronic control unit, the multi-light-source assembly comprises at least two light sources and at least two incident optical fibers, the front ends of the incident optical fibers are arranged in the flow cell at different insertion depths, and the incident optical fibers and the emergent optical fibers form different optical path lengths; the electronic control unit is lightened by driving the light source in a time-sharing manner, and optical signals under different optical paths are synchronously acquired by using the same detection assembly. Through the structural design without a mechanical moving part, a multi-optical-path detection system is constructed by utilizing the difference of the depth of the optical fiber inserted into the flow cell, and by combining a data processing algorithm in the electronic control unit, the optimal optical path is automatically selected according to the signal intensity to calculate the absorbance. The system has the advantages of wide dynamic range, simple structure, high response speed and the like, and effectively solves the problems of limited high and low concentration detection caused by a fixed optical path and abrasion and lag caused by mechanical switching of the optical path in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of analytical chemistry instrument technology, and specifically relates to an absorbance detection system for online monitoring of liquid samples, and more particularly to an absorbance analysis technique capable of achieving wide dynamic range concentration detection. Background Technology

[0002] Ultraviolet-visible absorption spectroscopy (UV-Vis) is a widely used quantitative analysis technique in analytical chemistry. Its basic principle is based on the Lambert-Beer law, which states that when a beam of parallel monochromatic light passes through a homogeneous, non-scattering sample solution, the absorbance (A) of the solution is directly proportional to the concentration (c) of the absorbing substance and the path length of the light in the solution (i.e., the optical path length L), expressed as A = εLc, where ε is the molar absorptivity, an inherent physical property of the substance at a specific wavelength.

[0003] In modern industrial production, environmental monitoring, biopharmaceuticals, and clinical diagnostics, the demand for automated online absorbance detection is increasingly urgent. However, practical applications often face the challenge of detecting multiple analytes in a single sample, or the concentration range of the same analyte varying significantly under different conditions. For example, in water quality monitoring, the concentrations of ammonia nitrogen, nitrate, and nitrite can range from micrograms per liter to milligrams per liter. In bio-fermentation processes, the concentrations of substrates, intermediates, and target products dynamically change over time across 3-4 orders of magnitude. In continuous chemical production, the formation of target products also involves continuous changes from low to high concentrations, requiring online monitoring of the product formation rate to necessitate absorption spectrometers with cross-range detection capabilities. Furthermore, the colorimetric principles of different analytes vary across these detection scenarios. Some substances (such as permanganates) possess inherent color and absorbance properties; others (such as ammonia nitrogen in water) require the addition of specific chromogenic agents (such as Nessler's reagent) to undergo a chemical reaction, forming colored complexes for detection. For the determination of enzyme activity, a chromogenic substrate is typically added, and the absorbance change is monitored by tracking the substrate consumption or product formation rate. These ultimately detected colored substances exhibit vastly different molar absorptivity (ε), potentially differing by thousands or even tens of thousands of times. Traditional UV-Vis spectrophotometers or online detection modules typically employ 10 mm fixed-path cuvettes or flow cells. According to the Lambert-Beer law, the effective measurement range of the detector is typically 0.01 to 2.0 AU. This results in a concentration detection dynamic range of approximately two orders of magnitude for fixed-path systems. Furthermore, based on logarithmic calculations and error propagation theory in the definition of absorbance, combined with electronic circuit noise, the range of absorbance values ​​with high signal-to-noise ratio is 0.2–0.8 AU; outside this range, the signal-to-noise ratio decreases.

[0004] Therefore, when the concentration of the sample after color development is too high and the absorbance exceeds the detector's upper limit, the sample must be precisely diluted before detection, or a cuvette / flow cell with a shorter optical path (e.g., 1 mm or 2 mm) should be used. Conversely, when the sample concentration is too low and the absorbance signal is weak, the sample needs to be pre-concentrated, or a cuvette / flow cell with a longer optical path (e.g., 25 mm or 50 mm) should be used to enhance the signal. Some studies have used a motor to move a window in the flow cell to change the optical path according to the detection solution; another approach is to place a moving mirror in the flow cell and adjust the optical path length by changing the position of the mirror. These mechanically driven solutions generally have inherent technical drawbacks. First, the introduction of precision mechanical moving parts (such as motors, lead screws, and guide rails) significantly increases the complexity and cost of the system, and also becomes a major source of system failure and wear, reducing the long-term reliability of the instrument. Second, the mechanical adjustment process takes time, and the optical path switching speed is slow, making it difficult to meet the real-time monitoring requirements of rapid chemical reaction kinetics. Furthermore, mechanical movement may introduce vibrations, affecting the stability of the optical path and increasing measurement noise. Therefore, developing an absorbance detection system with a simple structure, no moving mechanical parts, fast response, and the ability to achieve a large dynamic range measurement is of significant application value for promoting the automation and intelligentization of absorbance photometric analysis technology. Summary of the Invention

[0005] This invention provides a high dynamic range online absorbance detection system.

[0006] A high dynamic range online absorbance detection system has a core architecture consisting of four organically coupled functional modules: a flow cell, a multi-source light source assembly, a detection assembly, and an electronic control unit.

[0007] A high dynamic range online absorbance detection system includes: a flow cell with a sample inlet and outlet for carrying a flowing sample to be tested; a multi-light source assembly including at least two light sources and correspondingly connected incident optical fibers; the front ends of each incident optical fiber are inserted into the flow cell at different depths, forming different preset distances with the receiving end face of the exiting optical fiber, thus constructing at least two different detection optical paths; a detection component including an exiting optical fiber and a photodetector for receiving the transmitted light signal after the incident light from the incident optical fiber is absorbed by the solution to be tested and converting it into an electrical signal; and an electronic control unit connected to each component, controlling the light sources to be turned on alternately in a time-division manner and synchronously acquiring signals, and calculating the absorbance under different optical paths.

[0008] The flow cell, serving as the physical carrier for sample analysis, is equipped with precise sample inlets and outlets, and its main structure must meet stringent chemical and optical requirements. Therefore, the main body of the flow cell is made of corrosion-resistant material to support the flowing sample solution, which may possess strong acidic, alkaline, or organic solvent properties. In a preferred embodiment, the corrosion-resistant material is selected from quartz or optical glass with excellent ultraviolet-visible light transmittance, or polytetrafluoroethylene, stainless steel, or composite materials thereof with excellent chemical inertness.

[0009] The multi-light source assembly constitutes the core mechanism of this invention for achieving multi-optical-path detection without mechanical movement. This assembly includes at least two independently controlled light sources and at least two corresponding incident optical fibers. Its innovation lies in the fact that the front ends of the at least two incident optical fibers are positioned at precisely set, differentiated insertion depths at the front end of the flow cell. This spatial arrangement creates different preset physical distances between the end face of each incident optical fiber and the end face of the exit optical fiber in the flow cell. These physical distances directly define the path length of the light beam through the liquid being tested, thereby constructing multiple detection optical paths of varying lengths within the same flow cell. The specific light source can be a light-emitting diode, a laser, or a broadband light source supporting millisecond-level switching, such as a scintillation xenon lamp. The at least two light sources are correspondingly connected to the rear ends of the at least two incident optical fibers and are controlled by a high-precision electronic control system. This electronic control system employs time-division multiplexing technology, enabling millisecond-level time-division alternating illumination of the light sources. This ensures that at any given instant, only a single path of light beam exists within the flow cell, effectively avoiding optical crosstalk between different optical path signals and guaranteeing measurement accuracy.

[0010] The detection component consists of an outgoing optical fiber and a photodetector, responsible for capturing and converting optical signals. The front end of the outgoing optical fiber is precisely fitted to the end of the flow cell, opposite to the multiple incident optical fibers, and is used to collect the transmitted light signal after the light emitted by the incident optical fibers is absorbed by the sample solution. The input end of the photodetector is connected to the rear end of the outgoing optical fiber, responsible for linearly converting the received weak optical signal into a processable electrical signal. Photodetectors include photodiodes, avalanche diodes, photomultiplier tubes, and fiber optic spectrometers. Depending on the selected photodiode, avalanche diode, or photomultiplier tube, a pre-spectral absorbance detection system can be constructed using monochromatic light sources such as LEDs or lasers, while a post-spectral absorbance detection system can be constructed using a broadband light source such as a xenon scintillation lamp. As a more compact alternative, the detection component can also omit the outgoing optical fiber, replacing it with a transparent window at the T-junction, allowing the photodetector to be installed directly against the window, improving system integration.

[0011] The electronic control unit is electrically connected to both the light source driver and the photodetector, responsible for regulating the on / off timing of different light sources and synchronously acquiring the photodetector signal within the corresponding time window. The electronic control unit typically consists of a light source driver circuit, a microcontroller, and a computer system. The light source driver circuit controls the on / off of the light source, working with the microcontroller to achieve timing control of the light source. The computer system, in conjunction with the microcontroller, enables the acquisition and processing of the photodetector signal. The electronic control unit can analyze absorbance values ​​measured at different optical paths in real time according to preset logic. A built-in algorithm filters absorbance data within the detector's optimal linear response region (high signal-to-noise ratio region) based on the absorbance value, and then, combined with the corresponding optical path parameters, calculates the absorbance value of the sample under a 10 mm standard optical path. The specific criteria for selecting high signal-to-noise ratio values ​​are as follows: select absorbance values ​​that are relatively large and fall within the range of 0.2–0.8. If the absorbance of both the long and short optical paths is greater than 0.8, then take the smaller absorbance value; if the absorbance of both the long and short optical paths is less than 0.2, then take the larger absorbance value. After selecting the value, convert the absorbance under the 10 mm standard optical path according to the Lambert-Beer law and its corresponding optical path.

[0012] The present invention provides a method for high dynamic range online absorbance detection using the above-described system, comprising:

[0013] (1) Absorbance zeroing: A blank solution is introduced into the flow cell, and the electronic control unit controls the two light sources to turn on sequentially to obtain the blank light intensity I under long optical path. 0L and blank light intensity I under short optical path 0S And record it;

[0014] (2) Absorbance detection: The sample to be tested is introduced into the flow cell, and the electronic control unit controls the two light sources to be turned on in sequence to obtain the measured light intensity I under long optical path. L Measurement of light intensity I under short optical path S And record it;

[0015] (3) Absorbance calculation: The electronic control unit calculates the corresponding long-path photometric value A according to Formula 1 and Formula 2 based on the recorded blank light intensity and the collected measured light intensity. L and short optical path absorbance value A S ;

[0016] A L = -Lg(I L / I 0L )... Formula 1

[0017] A S = -Lg(I S / I 0S )... Formula 2

[0018] (4) Absorbance screening: The electronic control unit selects the calculated A... L and A S Perform multi-level logical discrimination; theoretically, long optical path A L Always greater than A S Therefore, when A L When it is less than 0.2, the current A L That is, it is determined to be the preferred value A. Opti , when A S When it is greater than 0.8, the current A S That is, it is determined to be the preferred value A. Opti , when A L and A S Only when one of the absorbance values ​​falls within the range of 0.2-0.8 is the absorbance value A preferred. Opti , when A L and A S If all values ​​are within the range of 0.2-0.8, then the larger value is preferred, A. Opti ;

[0019] (5) Absorbance conversion: According to the Lambert-Beer law, which states that optical path length L is proportional to absorbance, the optimal value in step (4) is combined with the actual optical path length to obtain the absorbance value A of the test solution at a standard optical path length of 10 mm. STD The calculation process is shown in Formula 3 below;

[0020] A STD = A Opti × 10 mm / L …… Formula 3

[0021] When performing continuous measurements, step (1) can be omitted, and step (3) can be calculated by directly calling the blank light intensity data pre-stored in the electronic control unit.

[0022] In a preferred embodiment, to balance system complexity and detection range, two incident optical fibers are configured: a first incident optical fiber and a second incident optical fiber. The first incident optical fiber has a shallower insertion depth, forming a longer first optical path (i.e., long optical path L1, where L1 is set to 5 mm to 100 mm, preferably 20 mm) between its end face and the front end of the exiting optical fiber. The second incident optical fiber has a deeper insertion depth, forming a shorter second optical path (i.e., short optical path L2, where L2 is 0.5 mm to 5 mm, preferably 1 mm) between its end face and the front end of the exiting optical fiber. According to the Lambert-Beer law, absorbance is proportional to optical path. The long optical path L1 is suitable for detecting trace or low-concentration samples, significantly enhancing the absorbance signal and greatly improving detection sensitivity, thus solving the problem of poor signal-to-noise ratio at low concentrations. The short optical path L2 is suitable for detecting high-concentration samples, effectively preventing detector signal saturation or deviation from the linear range due to excessively high absorbance by shortening the optical path. Furthermore, the detection of long and short optical paths is performed almost simultaneously, and the data is automatically selected based on the range of absorbance data after being measured at the same time. Thus, through the synergistic combination of L1 and L2, the dynamic range of the absorbance photometric detection system can be easily expanded by more than ten times, covering a wide concentration range from micrograms to milligrams.

[0023] As an alternative, the selection of the light source is highly flexible. Narrowband light sources such as light-emitting diodes (LEDs) and laser diodes (LDs) can be used. The selection of the light source wavelength depends strictly on the characteristic absorption peak of the substance to be measured to ensure the sensitivity and specificity of the measurement. At the same time, the back end can be combined with photodiodes, avalanche diodes, and photomultiplier tubes to realize a system structure similar to pre-spectral dispersion. Alternatively, broadband light sources such as scintillation xenon lamps can be used in conjunction with a fiber optic spectrometer as a detector to realize a post-spectral absorbance detection scheme.

[0024] This invention integrates multiple optical paths of different lengths within a single flow cell, utilizing the rapid electrical switching of the light source to replace traditional mechanical moving parts. This achieves wear-free, highly reliable, and millisecond-level synchronous detection. The design not only automatically covers a concentration dynamic range of more than four orders of magnitude with intelligent optical path selection, eliminating the cumbersome steps of sample pretreatment, but also significantly improves the detection efficiency and stability of automated analysis systems due to its simple structure, low cost, and ease of integration.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. This invention significantly broadens the dynamic range of detection by integrating a multi-path design and a built-in screening algorithm within a single flow cell, effectively avoiding cumbersome sample pretreatment operations.

[0027] 2. The system adopts a fully electrical switching mechanism with no mechanical moving parts. This fundamentally eliminates mechanical wear and improves operational stability while achieving extremely high response speed and signal synchronization, thus meeting the needs of rapid response monitoring.

[0028] 3. The present invention has a compact structure, low cost and easy integration. It can automatically optimize the optical path selection according to the signal strength, which greatly improves the automation level of the system and significantly reduces the development difficulty and the total system cost.

[0029] In summary, this invention utilizes a structural design without mechanically moving parts to construct a multi-optical-path detection system based on the difference in optical fiber insertion depth within the flow cell. Combined with data processing algorithms within the electronic control unit, it automatically selects the optimal optical path to calculate absorbance based on signal strength. This system offers advantages such as a wide dynamic range, simple structure, and fast response speed, effectively solving the limitations of high and low concentration detection caused by fixed optical paths in existing technologies, as well as the wear and lag problems resulting from mechanical switching of optical paths. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the device structure in Example 1.

[0031] Figure 2 This is a schematic diagram of the wide dynamic range absorbance flow in Example 1.

[0032] Figure 3 This is a schematic diagram of the device structure in Example 2.

[0033] 1. Flow cell; 2. Incident tee port; 3. Outgoing tee port; 4. First incident optical fiber; 5. First incident light source; 6. Second incident optical fiber; 7. Second incident light source; 8. Outgoing optical fiber; 9. Photodetector; 10. Electronic control unit; 11. Liquid inlet pipe; 12. Liquid outlet pipe; 13. Liquid to be tested; 21. Through bolt; 22. Sealing blade ring; 51. First light-emitting diode; 52. Second light-emitting diode; 81. Transparent light window; 91. Photodiode. Detailed Implementation

[0034] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflict. It should be noted that the terms "left," "center," "right," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0035] Example 1

[0036] like Figure 1 As shown, Example 1 is a high dynamic range absorbance detection system designed in a preferred embodiment of the present invention. The absorbance detection optical path adopts a post-splitting overall design. The light source is a scintillation xenon lamp broadband light source with a wavelength coverage of 200 nm–800 nm, which meets the absorbance detection requirements from ultraviolet to visible light bands. The incident fiber and the outgoing fiber are quartz optical fibers, which meet the light transmission requirements of 200 nm–1200 nm. The photodetector is a fiber optic spectrometer with a detection wavelength coverage of 200 nm–950 nm, which meets the detection requirements of post-splitting. The composite light emitted by the first incident light source 5 (selected as a scintillation xenon lamp light source) and the second incident light source 7 (selected as a scintillation xenon lamp light source) is introduced into the flow cell 1 through the first quartz incident fiber 4 and the second quartz incident fiber 6, respectively, through the incident tee interface 2. After being absorbed by the test liquid 13 in the flow cell, the light reaches the quartz outgoing fiber 8, and then the detection light is coupled to the photodetector 9 of the fiber optic spectrometer connected to the end of the fiber.

[0037] Example 1 describes the flow path configuration as follows: the flow cell is made of transparent perfluoroethylene propylene (FEP) material, with an inner diameter of 2.0 mm, an outer diameter of 3.18 mm, and a length of 5 cm; the inlet tee port 2 and outlet tee port 3 are made of polyetheretherketone (PEEK) material, with a thread specification of 1 / 4-28 mm and a nominal diameter of 1.5 mm; all through bolts 21 that mate with the tee are made of PEEK material, with a thread specification of 1 / 4-28 mm; the sealing ring 22 that seals the pipeline and tee is made of ethylene-tetrafluoroethylene copolymer (ETFE) material, with an inverted conical structure; the liquid inlet pipeline 11 and the liquid outlet pipeline 12 are made of FEP material, with an inner diameter of 1 mm and an outer diameter of 1.6 mm; all liquid connection parts selected in this fluid passage are made of corrosion-resistant materials, thereby ensuring that the pipeline is corrosion-free and leak-free during operation.

[0038] The key components of the absorbance detection optical path in Example 1 are as follows: the first incident fiber 4, the second incident fiber 6, and the exit fiber are all made of quartz fiber. The first incident fiber 4 is an all-quartz fiber with a length of 20 cm and a core diameter of 0.8 mm; the second incident fiber 6 is an all-quartz fiber with a length of 15 cm and a core diameter of 0.2 mm; and the exit fiber 8 is an all-quartz fiber with a length of 25 cm and a core diameter of 1.0 mm. The numerical aperture (NA) of both incident fibers and the exit fiber is 0.22, and the divergence angle or reception angle in the aqueous solution is 19°. The small divergence angle and reception angle help the detection light to propagate in a collimated manner in the flow cell aqueous solution, reducing the influence of stray light from the flow cell wall. The distance between the front end of the first incident fiber 4 and the front end of the exiting fiber 8 is 20 mm, that is, the effective long optical path L1 is 20 mm. The distance between the front end of the second incident fiber 6 and the front end of the exiting fiber 8 is 1 mm, that is, the effective long optical path L2 is 1 mm. The optical path ratio between the two is 20. Thus, the 20-fold optical path ratio of the present invention, combined with the two orders of magnitude detection range of absorbance detection itself, can realize a wide dynamic range absorbance measurement of more than three orders of magnitude.

[0039] In the specific operation of the preferred embodiment 1, the high dynamic range online absorbance detection system of the present invention regulates the opening timing of the first and second incident optical fibers through the electronic control unit 10 (generally including a light source driving circuit + microcontroller + computer system, etc.) to simultaneously acquire the optical signals of the long optical path L1 of 20 mm and the short optical path L2 of 1 mm; and simultaneously refers to Figure 2 The detection process first establishes a blank baseline, that is, obtains the blank light intensity I of the blank solution under two optical paths. 0L I 0S Subsequently, the measured light intensity I of the sample under test was acquired in real time. L and I S The long-path absorbance A is calculated in parallel according to the formula A = -lg(I / I0). L With short optical path absorbance A S To ensure that the measurement data has both a high signal-to-noise ratio and excellent linearity, the system executes automatic filtering logic based on a preset optimal response range (0.2 - 0.8): when A L Choose A when < 0.2 L As the preferred absorbance A Opti , when A S Choose A when > 0.8 S As the preferred absorbance A Opti If only one of the two values ​​falls within the interval, select that value; otherwise, select A. L As the preferred absorbance A Opti Ultimately, the system uses Lambert-Beer's law to determine A. Opti Normalized absorbance A at a standard optical path length of 10mmSTD (The calculation formula is A) STD = A Opti (× 10 mm / L), thereby expanding the dynamic detection range by more than 20 times without the need for sample dilution, effectively covering a wide concentration range from micrograms to milligrams.

[0040] Example 2

[0041] like Figure 3 As shown, Embodiment 2 is a structural modification of Embodiment 1, employing a pre-splitting structure. This means the light incident into the flow cell is monochromatic light that meets the absorbance detection requirements, and the selected light source is a light-emitting diode (LED). Light emitted from the first LED 51 (as the first incident light source) and the second LED 52 (as the second incident light source) passes through the first incident fiber 4 and the second incident fiber 6, respectively, and is introduced into the flow cell via the incident tee interface 2. The end of the flow cell is connected to the exit tee interface 3. A transparent window 81 is installed on the right side of the exit tee interface 3 to guide the light from the first incident fiber 4 and the second incident fiber 6 out of the flow cell. A photodetector, a high-sensitivity photodiode 91, is installed on the right side of the transparent window 81. Photodiodes are small, simple in structure, and lack wavelength energy discrimination capability, making them suitable for absorbance detectors using monochromatic light as the light source. The usage method of this embodiment is similar to Embodiment 1, but the improvement lies in using a smaller light source and detector, directly replacing the exit fiber with a transparent window, resulting in a more compact overall structure. Meanwhile, the effective long optical path L1 of the system is the distance from the flow cell end of the first incident fiber 4 to the transparent optical window 81, and the effective short optical path is the distance from the flow cell end of the second incident fiber 6 to the transparent optical window 81.

[0042] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A high dynamic range online absorbance detection system, characterized in that, include: A flow cell, with sample inlet and outlet, is used to hold the flowing sample to be tested; A multi-source component, comprising at least two light sources and corresponding connected incident optical fibers; Each incident fiber is inserted into the flow cell at a different depth and forms a different preset distance with the receiving end face of the outgoing fiber, thus constructing at least two different detection optical paths; the detection component, including the above-mentioned outgoing fiber and photodetector, is used to receive the transmitted light signal after the incident light from the incident fiber is absorbed by the solution to be tested and convert it into an electrical signal. The electronic control unit connects all components, controls the light source to turn on alternately in a time-sharing manner and synchronously collects signals, and calculates the absorbance under different optical paths.

2. The system according to claim 1, characterized in that, The flow cell is made of corrosion-resistant materials such as quartz, glass, polytetrafluoroethylene or stainless steel, and its diameter is adapted to the fiber optic installation size.

3. The system according to claim 1, characterized in that, The incident optical fiber includes a first incident optical fiber forming a long optical path and a second incident optical fiber forming a short optical path, the long optical path length being 5 mm to 100 mm and the short optical path length being 0.5 mm to 5 mm.

4. The system according to claim 1, characterized in that, The light source is selected from light-emitting diodes, lasers, or broadband light sources that support millisecond-level switching, such as flashing xenon lamps.

5. The system according to claim 1, characterized in that, The photodetector includes a photodiode, an avalanche diode, a photomultiplier tube, and a fiber optic spectrometer.

6. In the system according to claim 4 or 5, a pre-spectral absorbance detection system is constructed by using a photodiode, avalanche diode, photomultiplier tube, and a monochromatic light source such as a light-emitting diode, and a post-spectral absorbance detection system is constructed by using a fiber optic spectrometer and a scintillation xenon lamp broadband light source.

7. The system according to claim 1, characterized in that, The electronic control unit connects to each component, controls the light source to turn on alternately in a time-sharing manner and synchronously collects the light signal of the detection component, and calculates the absorbance under different optical paths.

8. A method for online absorbance detection with high dynamic range based on the system described in any one of claims 1-7, characterized in that, include: S1 Sample Introduction: The sample to be tested is continuously or intermittently pumped into the flow cell; S2 Time-sharing detection: The electronic control unit illuminates different light sources at different times and synchronously collects the transmitted light intensity of each optical path. S3 data processing: Calculate the absorbance A for each optical path, select the preferred absorbance value according to the built-in filtering program, and convert it to the absorbance value under the 10 mm standard optical path length based on its actual optical path length. S4 Cyclic Detection: Repeated time-division detection and data processing, with a single cycle time of less than 100 milliseconds, enabling real-time continuous monitoring.

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