Online desalting method and system for preventing macromolecular target compound from losing

Abstract

The invention discloses an online desalting method and system for preventing macromolecular target compound loss. The system comprises a chromatographic separation unit, a detector, a desalination module, a molecular sieve separation module and a flow path switching module, the flow path switching module comprises at least one multi-port switching valve; the desalination module comprises an anion suppressor and a cation suppressor, and sample flow output by the chromatographic separation unit selectively flows to the cation suppressor and / or the anion suppressor through a port switching valve; the molecular sieve separation module comprises a hollow fiber membrane assembly of a hollow fiber membrane with a specific molecular weight threshold value, a flat plate type ultrafiltration membrane bag and a micro-fluidic chip screening structure, the chromatographic separation unit is provided with exclusion filler with a specific size threshold value, and a desalted sample is divided into permeate flow and intercepted flow in the module; the intercepted stream enters a detector for analysis and then is stored. According to the invention, interference of various salts can be eliminated, and nondestructive on-line desalination of valuable target analytes can be ensured.

Description

Technical Field

[0001] This invention relates to the field of analytical chemistry instrumentation technology, and more specifically to an online desalination method and system for preventing the loss of macromolecular target compounds. Background Technology

[0002] Chromatography-mass spectrometry (CMS) has become an indispensable tool in modern analytical chemistry, especially in the analysis of complex samples. However, many efficient chromatographic separation methods, such as the buffer salts used in ion chromatography and reversed-phase chromatography, rely on non-volatile salts as the mobile phase. This can severely affect the efficiency of electrospray ionization (ESI) in mass spectrometry and may contaminate the ion source. To address this issue, the traditional approach is to use membrane-based electrolytic suppressors, or desalters, to remove these interfering salts online.

[0003] Although existing patents, such as CN217212484U, propose methods for continuous desalination using electrolytic membrane suppressors, their desalination modes are singular and cannot be optimized based on specific salt compositions such as cations or anions, leading to increased energy consumption or unsatisfactory desalination results. More importantly, the working principle of existing membrane suppressors is mainly based on ion exchange or electric field migration. This not only removes small molecule salt ions but may also cause some macromolecules of significant analytical value or charged target analytes with certain polarity, such as peptides, oligonucleotides, specific sugar compounds, or nanoparticles, to be partially captured, adsorbed, or lost with the regeneration waste liquid, thereby reducing sample recovery rate and detection sensitivity. This is particularly important for fields such as proteomics, metabolomics, and biopharmaceuticals. Although some improvements, such as patent CN223042203U introducing conductivity monitoring and flow path switching to protect the detector, and patent CN116298022A using ion-selective sensors for fault monitoring, have not fundamentally solved the problem of non-specific losses during the desalination process.

[0004] Therefore, it is necessary to design a new system that can efficiently and flexibly remove various salt interferences while ensuring non-destructive online desalination of valuable target analytes such as macromolecular components. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an online desalination system and method to prevent the loss of macromolecular target compounds.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an online desalting system for preventing the loss of macromolecular target compounds, comprising: a chromatographic separation unit, a detector, a desalting module, a molecular sieving module, and a flow path switching module;

[0007] The flow path switching module includes at least one multi-port switching valve; The desalting module includes an anion suppressor and a cation suppressor, and the sample output from the chromatographic separation unit flows selectively to the cation suppressor and / or anion suppressor through a multi-port switching valve; The molecular sieving module includes a hollow fiber membrane assembly, a flat-plate ultrafiltration membrane pack, and a microfluidic chip sieving structure. The hollow fiber membrane assembly is equipped with a hollow fiber membrane with a specific molecular weight threshold. The chromatographic separation unit is equipped with exclusion packing material with a specific size threshold. The sample flow after being processed by the desalting module is divided into a permeate flow and a cut-off flow after passing through the molecular sieving module. The permeate flow is discharged through a waste liquid outlet, and the cut-off flow is input into a detector for analysis and then stored.

[0008] The further technical solution is as follows: the specific molecular weight threshold and the specific size threshold are adjustable according to user settings, the permeate flow is a fluid smaller than the specific molecular weight threshold and the specific size threshold, and the intercepted flow is a fluid greater than or equal to the specific molecular weight threshold and the specific size threshold.

[0009] The further technical solution includes a control module, which controls the flow direction of the multi-port switching valve in the flow path switching module based on the sample flow parameters output by the chromatographic separation unit.

[0010] A further technical solution is as follows: the outlet of the multi-port switching valve is also connected to the molecular sieving module, and the sample stream output by the chromatographic separation unit can directly flow into the molecular sieving module.

[0011] The further technical solution includes sensors located at the outlet of the chromatographic separation unit and the outlet of the desalting module, and the control module adjusts the desalting path according to the fluid parameters before and after desalting.

[0012] The further technical solution is as follows: the control module is also used to discharge the sample stream directly to the waste liquid outlet when the ion signal of the desalted fluid exceeds the preset safety threshold.

[0013] The further technical solution is as follows: the molecular sieving module is integrated into the desalination module and placed in the waste liquid channel of the desalination module.

[0014] This invention also provides an online desalination method to prevent the loss of macromolecular target compounds, the method using the above-mentioned online desalination system, comprising: Receives a sample stream containing the target analyte and salts from the chromatographic separation unit; Based on the specific information about the salt content in the sample stream, the control module selects the corresponding desalination path through the control flow path switching module. In the selected desalination path, the corresponding salt ions in the sample stream are removed by the desalination module; The desalted sample stream is directed to the molecular sieving module, where it is divided into a permeate stream and a cut-off stream. The permeate stream is discharged through the waste outlet, while the cut-off stream is input into the detector for analysis and storage.

[0015] Its further technical solutions include: The sample stream that has not undergone desalination is directly directed to the molecular sieving module, where it is divided into a permeate stream and a cut-off stream. The permeate stream is discharged through the waste outlet, while the cut-off stream is input into the detector for analysis and storage.

[0016] The advantages of this invention compared to existing technologies are as follows: By integrating a chromatographic separation unit, detector, desalting module, molecular sieving module, and flow path switching module, this invention achieves efficient and flexible online desalting. The sample stream is first pre-processed by the chromatographic separation unit, and then selectively flows to anion or cation suppressors for targeted desalting via a multi-port switching valve in the flow path switching module. The desalted sample then enters the molecular sieving module, which consists of a hollow fiber membrane assembly, a flat-plate ultrafiltration membrane packing, and a microfluidic chip sieving structure. It features hollow fiber membranes with specific molecular weight thresholds and exclusion packing with specific size thresholds, ensuring that large molecular components are not lost while effectively removing small molecule salts. Finally, the permeate stream is discharged as waste liquid, while the intercepted stream is sent to the detector for analysis and storage, thus ensuring non-destructive detection and preservation of the target analyte. In this way, the entire system can efficiently remove various salt interferences while protecting valuable organic macromolecules from loss.

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

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of an online desalination system for preventing the loss of macromolecular target compounds, provided in an embodiment of the present invention. Figure 2 Schematic diagram of the desalination mode flow path provided in the embodiments of the present invention Figure 1 ; Figure 3 Schematic diagram of the desalination mode flow path provided in the embodiments of the present invention Figure 2 ; Figure 4 Schematic diagram of the desalination mode flow path provided in the embodiments of the present invention Figure 3 ; Figure 5 Schematic diagram of the desalination mode flow path provided in the embodiments of the present invention Figure 4 ; Figure 6 This is a schematic diagram of the molecular sieving module built into the desalination module according to an embodiment of the present invention; Figure 7 A schematic diagram of the structure of the plug-and-play independent unit molecular sieving module provided in an embodiment of the present invention, which is disposed between the desalination module and the detector; Figure 8 This is a schematic flowchart of an online desalination method for preventing the loss of macromolecular organic matter via membrane separation, provided in an embodiment of the present invention. Figure 9 A schematic diagram of the experimental curve of KH2PO4 provided in an embodiment of the present invention; Figure 10 A schematic diagram of the experimental curve of (NH4)2HPO4 provided in the embodiments of the present invention; Figure 11 A schematic diagram of an experimental curve for another content of KH2PO4 provided in an embodiment of the present invention; Explanation of the markings in the image: 10. Chromatographic separation unit; 20. Control module; 30. Flow path switching module; 40. Desalting module; 41. Cation suppressor; 42. Anion suppressor; 50. Molecular sieving module; 60. Detector; 70. Sensor. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0023] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0024] Chromatography-mass spectrometry (CMS), a key tool in modern analytical chemistry, plays a crucial role in the analysis of complex samples. However, its efficiency is often negatively impacted by non-volatile salts. These salts, when used in high-efficiency chromatographic separation methods such as ion chromatography and reversed-phase chromatography, reduce electrospray ionization (ESI) efficiency and contaminate the ion source. Although existing technologies, such as membrane-based electrolytic suppressors, attempt to remove these interfering salts online, they generally suffer from a lack of optimization based on specific salt compositions, leading to increased energy consumption or unsatisfactory desalination results. Furthermore, the working principles based on ion exchange or electric field migration may cause the loss of large molecular target analytes (such as peptides and oligonucleotides), thereby reducing sample recovery and detection sensitivity. While improvements have been made by introducing conductivity monitoring and flow path switching or using ion-selective sensors, the problem of non-specific losses during desalination has not been completely solved, especially in proteomics, metabolomics, and biopharmaceutical fields.

[0025] Therefore, embodiments of the present invention provide an online desalting system to prevent the loss of macromolecular target compounds, so as to achieve efficient and flexible removal of various salt interferences, while ensuring non-destructive online desalting of valuable target analytes such as macromolecular components, thereby enhancing the application potential of CMS technology in complex sample analysis.

[0026] Specifically, this system integrates modules for chromatographic separation, intelligent flow path switching, targeted desalting, and molecular sieving to achieve efficient removal of various salts from samples and effective protection of macromolecular organic compounds. First, the sample stream undergoes preliminary processing in the chromatographic separation unit 10. Then, based on the specific salt information, the control module 20 intelligently selects the optimal desalting path, utilizing anion suppressors 42 and cation suppressors 41 to specifically remove salt ions from the sample. Next, the sample stream enters the molecular sieving module 50, where it passes through hollow fiber membranes with specific molecular weight thresholds and exclusion packing with specific size thresholds, separating the sample stream into a permeate stream (small molecule waste liquid) and a cutoff stream (large molecule target analytes), ensuring that macromolecular components remain undamaged and can be further analyzed and stored. Furthermore, the system's multi-port switching valves and sensors 70 allow for direct or indirect adjustment of the processing flow according to sample characteristics, increasing flexibility and adaptability, thus ensuring efficient removal of salt interference while protecting valuable macromolecular organic compounds from loss.

[0027] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0028] Figure 1 This is a schematic diagram of an online desalination system for preventing the loss of macromolecular target compounds provided in an embodiment of the present invention. Specifically, the membrane separation online desalination system for preventing the loss of macromolecular organic matter includes: a chromatographic separation unit 10, a detector 60, a desalination module 40, a molecular sieving module 50, and a flow path switching module 30; The flow path switching module 30 includes at least one multi-port switching valve; The desalting module 40 includes anion suppressor 42 and cation suppressor 41. The sample output from the chromatographic separation unit 10 flows through a multi-port switching valve to selectively flow to cation suppressor 41 and / or anion suppressor 42. The molecular sieving module 50 includes a hollow fiber membrane assembly, a flat-plate ultrafiltration membrane pack, and a microfluidic chip sieving structure. The hollow fiber membrane assembly is equipped with a hollow fiber membrane with a specific molecular weight threshold. The chromatographic separation unit 10 is equipped with exclusion packing with a specific size threshold. After the sample is processed by the desalting module 40, it is divided into a permeate stream and a cut-off stream after passing through the molecular sieving module 50. The permeate stream is discharged through the waste liquid port, and the cut-off stream is input into the detector 60 for analysis and storage.

[0029] In this embodiment, the core principle of the molecular sieving module 50 is nanoscale size sieving. Molecules with molecular weights ranging from 200 to 5000 (or even higher) are all at the nanoscale, while the membrane pore size is controlled to be around a few nanometers. This size matching is the basis for precise sieving—when the membrane pore size is smaller than the target molecule size, protein molecules are physically blocked from passing through; when the pore size is large enough, molecules can pass through. This achieves precise classification based on molecular weight thresholds (such as 200, 500, 1000, 2000, 3000, and 5000 Daltons).

[0030] The traditional sieving method involves separating NaCl and small protein molecules in the sample at an anion exchange membrane. - Proteins flowed out, while NaOH and Cl... - The bound protein flows out. However, this traditional method has a key drawback—the lack of a fine molecular weight fractionation mechanism. The separation of large protein molecules from NaCl relies on ion exchange rather than size sieving, which results in the inability to effectively distinguish proteins of different molecular weights, ultimately yielding only a coarsely separated product (NaOH + Cl). -(And the mixed outflow of large protein molecules). Traditional membrane separation often has uneven pore size distribution, making it impossible to achieve precise fractionation such as allowing passage below 1000 and retaining 1000-2000. Therefore, traditional methods cannot screen, meaning that ions and proteins will be excluded together. Here, proteins refer to zwitterions with one amino group and one carboxyl group.

[0031] This application employs a multi-stage, tandem precision sieving architecture: the sample first passes through an anion exchange membrane (or molecular sieve membrane / chromatographic packing material), and then through a hollow fiber membrane or size exclusion packing material with a specific molecular weight threshold. NaCl and small molecule proteins pass directly through and are discharged (waste liquid), while the required large molecule proteins are retained and enter subsequent detection. The core of this design lies in the precise pre-fractionation: by selecting membrane components with different pore sizes, such as hollow fiber membranes with molecular weight cutoffs of 500, 2000, 5000, 20000, 50000, 100000 Daltons or even larger, or chromatographic packing materials with specific size size size size and size of size exclusion limit, it is possible to precisely control which molecules pass through and which remain.

[0032] Specifically, the molecular sieving module 50 includes three specific implementation forms: Hollow fiber membrane module: This module contains hollow fiber membranes with specific molecular weight thresholds (specifically, molecular weights higher than 200 Daltons, such as 500, 2000, 5000, 20000, 50000, 100000 Daltons or larger), utilizing their nanoscale pore size (2nm level) for sieving. When the desalted sample flows through the membrane module, molecules smaller than the pore size permeate through the membrane wall as permeate (discharged through the waste outlet), while molecules larger than the pore size are retained within the fiber cavity as trap flow.

[0033] Flat-sheet ultrafiltration membrane packs: These employ a multi-layer flat-sheet membrane stacked structure, with each membrane having a precise molecular weight cutoff (MWCO). Multi-stage sieving is achieved through parallel or series connections. Samples flow through the membrane pack under pressure and are separated according to molecular weight.

[0034] Microfluidic chip sieving structure: Integrating nanochannels or sieving arrays at the chip level, using micro-nano fabrication technology to precisely control pore size (2nm accuracy), achieving high throughput and low sample consumption for precise sieving.

[0035] The chromatographic separation unit 10 is equipped with size exclusion packing material with a specific size threshold, forming a complementary separation system with the molecular sieving module 50. The chromatographic unit 10 is based on the principle of size exclusion chromatography (SEC), utilizing the stereochemical size exclusion effect of the packing material pores to separate molecules; while the molecular sieving module 50 employs membrane separation or microfluidic sieving. When combined, the sample processed by the desalting module 40 can first undergo preliminary fractionation in the chromatographic unit 10, then enter the molecular sieving module 50 for fine fractionation, and finally, the extracted stream is input into the detector 60 for analysis and storage, while the permeate is discharged as waste liquid. This dual sieving mechanism of "chromatography + membrane separation" ensures high resolution and high recovery rate for molecular weight fractionation.

[0036] Therefore, the sieving accuracy of the molecular sieving module 50 depends on three core parameters: the uniformity of membrane pore size (controlled at the 2nm level), the selection of molecular weight thresholds (setting fractionation points of 500 / 2000 / 5000 / 20000 / 50000 / 100000 Daltons), and the optimization of operating conditions (flow rate, pressure, temperature, etc.). When processing proteins or other biomolecules with molecular weights of 200-5000 Daltons, by selecting membrane components with appropriate cutoff values, precise separation can be achieved, with molecules above the cutoff value being retained and those below the cutoff value permeating. This is precisely the technical advantage of the system in this embodiment compared to traditional methods—upgrading from coarse separation to precise sieving.

[0037] In this embodiment, the membrane separation online desalting system for preventing the loss of macromolecular organic matter is a highly integrated sample processing platform designed to efficiently remove salts from samples while retaining target macromolecular organic matter. The system mainly includes core modules: a chromatographic separation unit 10, a detector 60, a desalting module 40, a molecular sieving module 50, and a flow path switching module 30. First, the chromatographic separation unit 10, as the first step in the entire system, is responsible for the preliminary separation of components in the sample. It utilizes exclusion packing material with a specific size threshold to classify the mixture according to molecular size, ensuring more accurate processing of target analytes in subsequent steps. Next, the chromatographically separated sample flows into the desalting module 40. This module includes anion suppressors 42 and cation suppressors 41. Through the selective conduction of a multi-port switching valve, the sample flow can be guided to the corresponding suppressor as needed to remove excess anions and cations, achieving the desalting purpose.

[0038] Subsequently, the processed sample enters the molecular sieving module 50, which integrates a hollow fiber membrane module, a flat-sheet ultrafiltration membrane pack, and a microfluidic chip sieving structure. The hollow fiber membrane module is specially designed with a specific molecular weight threshold, effectively screening out target macromolecules while allowing small molecule impurities to permeate and be discharged as waste. Simultaneously, the flat-sheet ultrafiltration membrane pack provides high-throughput processing capacity, ensuring efficient system operation. Finally, the molecularly sieved sample is divided into two parts: a permeate stream and a trap stream. The former contains small molecule impurities and is discharged through the waste outlet; the latter contains valuable analytes and will be sent to the detector 60 for detailed analysis and evaluation. The entire process is coordinated and controlled by the flow path switching module 30, which includes at least one multi-port switching valve to ensure seamless connection between each processing step, thereby maximizing the protection of target analytes from loss and providing a high-quality sample basis for subsequent scientific research or industrial applications.

[0039] Furthermore, the inlets of the independent anion suppressor 42 and cation suppressor 41 can be selectively connected to the outlet of the flow path switching module 30 as needed to perform specific desalting tasks. This design allows the system to selectively remove anions and cations from the sample stream, thereby improving the overall desalting efficiency. Finally, the molecular sieving module 50, located downstream of the desalting module 40, operates based on the size exclusion principle. It further filters the desalted sample, ensuring that small molecules below a specific molecular weight threshold (such as salt ions and small molecule impurities), i.e., the permeate stream, can pass through and be discharged, while large molecular target analytes above this threshold, i.e., the intercepted stream, are blocked and guided to the detector 60 via another path. This design effectively avoids the loss of large molecular target analytes, ensuring that they can enter subsequent analysis stages without damage. In summary, this system not only solves the problems of high energy consumption, poor desalting effect, and non-specific loss in traditional methods, but also significantly enhances the application potential of chromatography-mass spectrometry in the analysis of complex samples, especially in the life sciences. In addition, the system supports intelligent operation, making operation more convenient and results more reliable, which greatly meets the needs of modern laboratories for efficient and accurate analysis.

[0040] Each suppressor has a specific function designed to remove the corresponding type of ions from the sample to ensure that the sample that finally enters detector 60 has a low salt content, thereby improving the quality and accuracy of subsequent analyses (such as mass spectrometry).

[0041] Anion suppressor 42 is mainly used to remove anionic components from the sample, such as chloride ions (Cl). - ), sulfate ions (SO4²) - Under the influence of an electric field, the anion reacts with the hydroxide ions (OH-) inside the suppressor. -( ) exchange, producing water or other volatile acids.

[0042] Cation suppressor 41 is mainly used to remove cationic components from the sample, such as sodium ions (Na+). + ), potassium ions (K) + Similarly, under the influence of an electric field, cations will react with hydrogen ions (H+) inside the suppressor. + The exchange of substances produces water or other volatile bases.

[0043] In one embodiment, the multi-port switching valve is one of the key components of the entire online desalination system, playing a crucial role in controlling the analyte flow path. Specifically, the multi-port switching valve, through its multiple inlets and outlets, enables precise control of the sample flow path, thereby guiding the sample to different desalination paths as needed. This design allows the system to flexibly respond to various desalination requirements.

[0044] By controlling the state of this valve, the sample can be guided to different desalination paths. Specifically, the inlets of anion suppressor 42 and cation suppressor 41 can be selectively connected to the outlet of flow path switching module 30 as needed, thereby achieving the following desalination modes: Full desalination mode: Please refer to Figure 2 The sample stream passes sequentially through cation suppressor 41 and anion suppressor 42 to remove all types of cation and anion salts, making it suitable for high-concentration complex salt situations.

[0045] Decation-only mode: Please refer to Figure 3 The sample flow passes only through the cation suppressor 41, which is suitable for situations where the mobile phase mainly contains cation salts, such as sodium phosphate or sodium acetate.

[0046] Deionization mode only: Please refer to Figure 4 The sample flow passes only through the anion suppressor 42, which is suitable for use with ion-pairing reagents containing anionic salts, such as tetrabutylammonium hydroxide.

[0047] Bypass mode: Please refer to Figure 5 The sample stream bypasses the two suppressors and flows directly to subsequent modules for rinsing samples or systems that do not contain interfering salts.

[0048] To achieve the above functions, the design of the anion suppressor 42 and the cation suppressor 41 is crucial. Each suppressor is equipped with a dedicated channel structure, where the analyte channel is used for sample passage, while the regeneration waste liquid channel is used for discharging the waste liquid generated in the reaction. In actual operation, the multi-port switching valve dynamically adjusts the connection between the channels according to the current state of the system and the preset desalination strategy, ensuring that the sample can be processed according to the predetermined path.

[0049] In this way, by utilizing the flow path switching module 30 and independent anion suppressors 42 and cation suppressors 41, the system can select the most suitable desalination mode according to the specific composition of the sample, ensuring the accuracy and reliability of the processing results. Simultaneously, combined with an intelligent control system, the entire process achieves automated management, reducing operational difficulty and improving work efficiency.

[0050] Furthermore, the multi-port switching valve can be a ten-way valve or a combination of two six-way valves or other valves. This design offers greater connectivity options, allowing the system to switch quickly and seamlessly between different desalination modes. For example, in full desalination mode, the sample stream can be sequentially passed through cation suppressor 41 and anion suppressor 42 via valve settings to remove all types of salts; while in cases where only specific types of salts need to be removed, such as those containing only sodium ions (Na+), the flow can be diverted to other modes. + ) or chloride ions (Cl - If the position of the multi-port switching valve is adjusted, the sample flow can be made to pass only through the cation suppressor 41 or the anion suppressor 42, thereby saving energy and reducing the wear of the suppressors.

[0051] Furthermore, the multi-port switching valve is closely connected to the system's control module 20, which is responsible for receiving information from the sensor 70 and issuing commands accordingly to adjust the valve's state. This means that, based on real-time monitored data such as conductivity, pH value, or specific ion concentration, the control module 20 can dynamically select the optimal desalination mode, ensuring ease of operation and consistency of results.

[0052] Furthermore, to improve the system's adaptability and maintainability, the multi-port switching valve is designed for easy replacement and upgrades. This is reflected not only in the hardware—the valve itself is easy to disassemble and replace—but also in the software—allowing for switching between different operating modes through simple parameter settings. This design greatly enhances the system's flexibility and practicality, enabling users to quickly adjust the system configuration according to actual needs and meet diverse experimental requirements.

[0053] In summary, the multi-port switching valve, as the core component of the flow path switching module 30, not only supports multiple desalination modes but also significantly improves the intelligence level and efficiency of the entire online desalination system through its collaborative work with the control module 20 and other system components. This design is crucial for ensuring the quality and efficiency of sample processing, especially in complex sample sequence analysis and high-precision detection tasks.

[0054] In one embodiment, the specific molecular weight threshold and the specific size threshold are adjustable according to user settings, the permeable flow is fluid with a specific molecular weight threshold and the specific size threshold, and the intercepted flow is fluid with a specific molecular weight threshold and the specific size threshold.

[0055] This means that users can set these parameters according to the specific requirements of the sample being processed in order to achieve the best separation results.

[0056] Specifically, a specific molecular weight threshold refers to the boundary between large and small molecules that a membrane or sieving medium can effectively distinguish. For example, in the biopharmaceutical industry, when it is necessary to extract a target protein with a specific molecular weight range from a mixture, this threshold can be adjusted to ensure that only the target protein or molecules of similar size are retained, while all other components smaller than this threshold are rejected as permeate. This not only improves the purity of the target product but also reduces the complexity of subsequent processing steps.

[0057] Similarly, a specific size threshold refers to the pore size or channel size used for physical sieving, which determines which substances can pass through the membrane or sieving medium. In practical applications, to separate particles or polymers larger than a certain size, the corresponding size threshold can be set. Particles or molecules larger than or equal to this size threshold will be retained in the capture stream, becoming valuable products; while impurities or solvents smaller than the size threshold will be discharged from the system with the permeate stream.

[0058] This flexibility makes the system suitable for a variety of applications, from scientific research to sample pretreatment in industrial production processes. Users can easily customize operating procedures for different sample types and separation requirements by simply adjusting parameters, greatly enhancing the system's adaptability and practicality. Furthermore, because these thresholds can be adjusted in real time according to changes in experimental conditions or production processes, the efficiency and economy of the entire processing are also improved.

[0059] In this embodiment, the intercepted stream consists of large molecular target analytes (such as proteins, peptides, etc.) in the sample, while the permeated stream consists of small molecular substances (such as salt ions and small molecular impurities).

[0060] More specifically, the molecular sieving module 50 operates based on the principle of physical sieving, with its core mechanism being size exclusion. This means it distinguishes different types of molecules based on their size, thereby achieving effective separation. The following is a detailed explanation of how this module works: The molecular sieving module 50 sets two key thresholds—a specific molecular weight threshold and a specific size threshold. This ensures that all molecules smaller than the specific molecular weight threshold and specific size threshold (mainly salt ions and small molecule impurities) can pass through the sieving membrane smoothly, while large molecular target analytes (such as proteins or peptides) that are greater than or equal to the specific molecular weight threshold and specific size threshold are retained.

[0061] Substances with molecular weights below a specific molecular weight threshold and a specific size threshold (e.g., Na) + Cl - Salt ions, small molecule solvents, and impurities can pass through the sieving membrane, forming a "permeate flow," and are eventually discharged as waste liquid. Target analytes with molecular weights greater than or equal to specific molecular weight thresholds and specific size thresholds (such as biomacromolecules like peptides and proteins) cannot pass through the sieving membrane, but are instead guided along the "retention flow" path to detector 60 for subsequent analysis.

[0062] Therefore, by precisely controlling the threshold, only molecules smaller than a certain size are allowed to pass through, while important macromolecular target analytes are retained in the flow path and guided to detector 60. This design not only improves desalination efficiency but also minimizes the loss of target analytes, ensuring the accuracy and reliability of analytical results. Furthermore, the modular structural design enhances the system's adaptability and operability, making it an efficient, flexible, and easy-to-use online desalination solution.

[0063] In one embodiment, please refer to Figure 1 The above-mentioned membrane separation online desalination system for preventing the loss of macromolecular organic matter also includes a control module 20, which is used to control the flow direction of the multi-port switching valve in the flow path switching module 30 according to the sample flow parameters output by the chromatographic separation unit 10.

[0064] In this embodiment, the control module 20 receives information from the sensor 70 (such as conductivity, pH value, specific ion concentration, etc.) and operator instructions, and determines which desalination mode to use based on this information. For example, when a high concentration of cations is detected, the cation-only desalination mode is selected; if it is found that all types of salts need to be removed, the full desalination mode is activated.

[0065] By sending control commands to the multi-port switching valve in the flow path switching module 30, the control module 20 can automatically adjust the valve state to ensure that the sample is processed along the predetermined optimal path. This improves the system's flexibility and adaptability, making the desalination process more precise and efficient.

[0066] During the desalination process, the control module 20 continuously monitors changes in key parameters. Once an abnormality is detected (such as the ion signal in the flow path after desalination exceeding the preset safety threshold), measures are immediately taken, such as switching the flow path to the detector 60 to waste liquid, to protect downstream equipment from damage.

[0067] Furthermore, the outlet of the multi-port switching valve is also connected to the molecular sieving module 50. Besides connecting to the desalting module 40, the sample stream output from the chromatographic separation unit 10 can directly flow into the molecular sieving module 50. This means that in certain situations (such as when the sample does not contain interfering salts or has already undergone preliminary desalting), the desalting step can be skipped, allowing the sample stream to directly enter the molecular sieving module 50 for further purification. This design not only simplifies the system structure and reduces unnecessary steps but also improves overall efficiency. It provides significant convenience, especially for applications requiring rapid screening of small molecule impurities without deep desalting.

[0068] In summary, in this embodiment, by integrating an advanced control module 20, a flexible flow path switching mechanism, and efficient molecular sieving technology, the entire online desalination system achieves intelligent and automated management. This not only significantly reduces operational complexity but also substantially improves the consistency and repeatability of experimental results, making it particularly suitable for analyzing complex samples. Furthermore, the system supports user-defined settings, allowing for rapid configuration adjustments to meet diverse research requirements.

[0069] In one embodiment, please refer to Figure 1 The aforementioned online desalting system for preventing the loss of macromolecular target compounds also includes sensors 70 located at the outlet of the chromatographic separation unit 10 and the outlet of the desalting module 40, and the control module 20 adjusts the desalting path according to the fluid parameters before and after desalting.

[0070] Sensor 70 is a key component of the entire system, used to monitor critical parameters in the flow path before and after desalination in real time. Specifically: Conductivity sensor 70: Used to detect changes in ion concentration in fluids. This is crucial for determining whether a sample requires desalination.

[0071] pH Sensor 70: Helps monitor the acidity or alkalinity of the solution, ensuring that the desalination process does not cause unnecessary chemical effects on the sample.

[0072] Specific ion concentration sensor 70: capable of accurately measuring specific ions (such as Na+). + , Cl - The concentration of (etc.) is used to guide the selection of the most suitable desalination mode.

[0073] The data collected by sensor 70 is transmitted in real time to control module 20 for analysis and decision-making. For example: If sensor 70 detects extremely low conductivity in the sample stream, it may mean that the sample does not contain interfering salts. In this case, the system can automatically switch to bypass mode to avoid unnecessary energy consumption.

[0074] If high conductivity or the presence of specific ions is detected, the system will select the most suitable desalination mode according to a preset logic algorithm to achieve the best desalination effect.

[0075] In one embodiment, the control module 20 is further configured to discharge the sample stream directly to the waste liquid outlet when the ion signal of the desalted fluid exceeds a preset safety threshold.

[0076] Based on different types of analytical tasks and the characteristics of target molecules, users can preset a safety threshold in the control module 20. This threshold is usually a critical point determined based on experience or experimental requirements. Once this point is exceeded, the ion content in the sample stream is considered too high, which may affect subsequent analytical results or damage expensive detectors 60 (such as mass spectrometers).

[0077] Adaptive adjustment: In some cases, the control module 20 can automatically adjust this threshold based on historical data analysis to ensure optimal operating conditions.

[0078] If sensor 70 detects that the ion signal in the desalted fluid exceeds a preset safety threshold, it indicates that the current desalination effect is poor, and there may be incompletely removed salt or other interfering substances. At this time, control module 20 will immediately issue a command to adjust the state of the multi-port switching valve in flow path switching module 30, redirecting the sample flow from its original path to the waste liquid outlet instead of continuing to flow to detector 60. This step effectively avoids damage to detector 60 from high ion concentration samples and ensures the quality of subsequent analyses.

[0079] In addition to physical flow path switching, control module 20 can also activate an alarm mechanism to notify operators to pay attention to the current situation and check the system status. This early warning function helps to detect potential problems in a timely manner and reduce unnecessary losses. Control module 20 will also further analyze the factors causing the exceedance and dynamically adjust the operating parameters of the desalination mode or suppressor according to the specific situation, attempting to reprocess the sample stream until the ideal effect is achieved.

[0080] For example, in the presence of high concentrations of Na + and Cl -During the online desalting of complex proteomics samples, if a high ion signal is still detected in the desalted sample stream, it indicates that the desalting efficiency under the current settings is insufficient. In this case, the control module 20 will respond quickly, switching this unqualified sample stream to the waste liquid outlet to prevent it from entering the mass spectrometer. Simultaneously, the system will record this event and prompt the operator to check or adjust the desalting parameters, such as increasing the operating intensity of the cation suppressor 41 or the anion suppressor 42, or changing the desalting mode to full desalting mode, to ensure that the next run achieves the expected purification effect.

[0081] In one embodiment, please refer to Figure 6 The molecular sieve module 50 is integrated within the desalination module 40 and located at the waste liquid channel of the desalination module 40. Taking the cation suppressor 41 as an example, it has an analyte channel and a waste liquid channel inside, separated by a cation exchange membrane. Under normal operating conditions, cations in the salt (such as Na+) are sieved. + Under the influence of an electric field, it passes through the membrane into the waste liquid channel and reacts with the H₂ present therein. + Exchange. In traditional designs, waste liquid is discharged directly.

[0082] A molecular sieving module 50 is integrated at the outlet of the waste liquid channel. This unit contains an ultrafiltration membrane. Tiny amounts of large molecular targets (such as proteins) that diffuse or migrate from the analyte channel, if entering the waste liquid channel, will be retained by the membrane and guided back to the main analytical flow path or a dedicated collection loop through a separate retentate outlet. The waste liquid (containing Na+)... + H + (etc.) are discharged from the permeate outlet. This design minimizes any possible loss path of the target material, achieving “zero-loss” desalination.

[0083] In one embodiment, please refer to Figure 7 The aforementioned molecular sieving module 50 is a replaceable unit externally mounted on the desalination module 40. In this embodiment, the molecular sieving module 50 is not only an independent unit, but also a replaceable unit, which means that it can be customized and replaced based on different size exclusion principles.

[0084] Multiple sieving mechanisms: The molecular sieving module 50 can take one of the following forms: Hollow fiber membrane modules: with specific molecular weight cutoff (MWCO), suitable for efficient screening of molecules of different sizes.

[0085] Flat-sheet ultrafiltration membrane packs: offer high throughput and good physical strength, suitable for large-scale sample processing.

[0086] Microcolumns filled with size exclusion chromatography packing material: Utilizing the principle of size exclusion chromatography, precise molecular weight separation is achieved.

[0087] Physical sieving structure based on microfluidic chip: Combining microfluidic technology to achieve highly integrated and automated small-volume sample processing.

[0088] Users can select the most suitable sieving mechanism according to specific experimental needs to ensure optimal separation results. This module is easy to change and adjust quickly, improving the system's adaptability and efficiency.

[0089] As can be seen from the description of the above embodiments, the online desalination system and method of this embodiment not only provide a highly efficient desalination solution, but also achieve effective protection and efficient separation of target analytes through innovative design. Whether it is the molecular sieving module 50 built into the waste liquid flow path or the replaceable unit used as an independent unit, both demonstrate the system's significant advantages in flexibility, accuracy, and practicality. These features collectively promote the widespread application and development of online desalination technology in life sciences and other high-end fields.

[0090] Users can quickly switch between molecular sieving modules 50 to select sieving components suitable for specific molecular weight ranges according to different experimental needs. For example, when processing peptide samples, a sieving component with a molecular weight cutoff (MWCO) of 500 Da can be selected, while when processing protein samples, a component with a MWCO of 5 kDa can be used.

[0091] Users can easily replace different molecular sieving modules 50 as needed to adapt to different types of analytical tasks. As they are independent units, they are easy to clean, maintain, and upgrade, improving the system's operability and versatility.

[0092] By integrating sensor 70 and control module 20, this embodiment achieves the following optimizations: Users can complete complex desalination processes without manual intervention, lowering the technical threshold. Since all steps are automatically executed and recorded by the system, consistency of experimental conditions is ensured for each experiment, improving the reliability and repeatability of results. Real-time monitoring and early warning functions promptly identify and resolve problems, reducing the possibility of equipment failure and extending service life.

[0093] In summary, by introducing sensor 70 and advanced control module 20, the system of this embodiment can not only effectively remove salts of different compositions but also significantly improve the recovery rate of target analytes, making it particularly suitable for the analysis of complex samples. At the same time, its intelligent design greatly simplifies the operation process, providing strong support for researchers.

[0094] In this embodiment, the effluent (containing the target analyte and salts) from the chromatographic separation unit 10 (e.g., a chromatographic column) enters a multi-port switching valve through the inlet. This valve is controlled by an electric actuator driven by the control module 20. A regenerator source (e.g., deionized water) supplies regenerators to both suppressors. By switching the control valve, the system can achieve four basic modes: Full desalination mode: The sample stream flows sequentially through the cation suppressor 41 and the anion suppressor 42 to remove all cation and anion salts, which is suitable for high-concentration complex salts.

[0095] Decation-only mode: The sample stream passes only through the cation suppressor 41, which is suitable for situations where the mobile phase is mainly sodium phosphate, sodium acetate, etc. (the anions acetate and phosphate have relatively little or tolerable interference with mass spectrometry).

[0096] Deionization-only mode: The sample stream passes only through anion suppressor 42, suitable for use with tetrabutylammonium hydroxide plasma-paired reagents.

[0097] Bypass mode: The sample stream bypasses the two suppressors and flows directly to the subsequent modules for rinsing samples or systems that do not contain interfering salts.

[0098] The core of the molecular sieving module 50 can be a hollow fiber membrane module with a molecular weight cutoff (MWCO) of 5 kDa, ensuring that peptides or proteins with a molecular weight greater than 5 kDa are retained, while salt ions (Na+) are excluded. + K + Cl - (etc.) were removed.

[0099] In addition, the control module 20 integrates a microprocessor and a user interface, allowing users to directly select specific analysis modes, such as "protein / peptide analysis mode," and input the target molecular weight range (e.g., greater than 10 kDa). The system defaults to "full desalting mode" to ensure complete salt removal. Simultaneously, if the molecular sieving module 50 is an adjustable or associated waste liquid diversion valve, the control module 20 will automatically adjust it to the optimal operating point corresponding to the 10 kDa cutoff value.

[0100] Furthermore, conductivity sensors 70 are installed before and after the desalting module 40. At the start of the analysis, the control module 20 monitors the conductivity of the flow path before desalting using these sensors 70. If the conductivity is extremely low, the system will automatically switch to "bypass mode". If the conductivity is mainly contributed by one ion (through analysis of signal characteristics or comparison with a preset database), the system may suggest or automatically switch to "cation desalination only" or "anion desalination only" mode to save energy. During operation, if the conductivity after desalting exceeds a set threshold, it indicates that the suppressor may be inefficient or malfunctioning. In this case, the control module 20 will trigger an alarm and automatically switch the flow path to detector 60 to waste liquid to protect the expensive mass spectrometer.

[0101] Compared with the prior art, the system of this embodiment has the following significant advantages: The system allows selection of the most direct and efficient desalination path based on the actual composition of the mobile phase salts, avoiding unnecessary energy consumption and suppressor wear associated with "full-mode" desalination. This makes it particularly suitable for method development and complex sample sequence analysis. By integrating the molecular sieving module 50, small molecule interfering substances such as salt ions are physically separated from the target macromolecular analytes, ensuring near 100% recovery of valuable biological samples such as peptides, proteins, and nucleic acids. This significantly improves the sensitivity and accuracy of subsequent mass spectrometry detection, expanding the application of online desalination technology in high-end life science fields. Through the combination of sensor 70 feedback and intelligent control algorithms, the system can automatically diagnose salt types, assess desalination effectiveness, select and switch to the optimal mode, and optimize operating parameters, lowering the technical threshold for operators and ensuring the reproducibility and reliability of the analytical process. Both the molecular sieving module 50 and the suppressor can be designed as plug-and-play devices, allowing users to quickly replace them according to different analytical needs (target analyte molecular weight range, salt type), enhancing the system's versatility and practicality.

[0102] Please see Figure 9 , Figure 10 as well as Figure 11 Under different C-components (i.e., different phosphate compounds), the conductivity was observed to decrease to tens of microsiemens after treatment by the desalination device. This indicates that the salt concentration in the treated solution has been significantly reduced, and the original salt has been almost completely removed, thus verifying the effectiveness of the system and its positive role in improving water quality.

[0103] Specifically, Figure 9 The experimental data are as follows: Flow rate: 0.3 mL / min; Mobile phase: A: pure water; B: acetonitrile; C: 50mM KH2PO4, pH=6.5; Detector: Conductivity detector; The details are shown in Table 1.

[0104] Table 1 Experimental Data

[0105] Under these mobile phase gradient conditions, the salt is essentially removed through the system of this embodiment.

[0106] Figure 10 The experimental data are as follows: Flow rate: 0.3 mL / min; Mobile phase: A: pure water; B: acetonitrile; C: 100 mM (NH4)2HPO4, pH=6.0; Detector: Conductivity detector; The specifics are shown in Table 2.

[0107] Table 2 Experimental Data

[0108] Under these mobile phase gradient conditions, the salt is essentially removed through the system of this embodiment.

[0109] Figure 10 The experimental data are as follows: Flow rate: 0.3 mL / min; Mobile phase: A: 50 mL M KH2PO4, pH=2.3; B: 50 mL M KH2PO4, pH=4.5; C: Acetonitrile; Detector: Conductivity detector; The specifics are shown in Table 3.

[0110] Table 3 Experimental Data

[0111] Under these mobile phase gradient conditions, the salt is essentially removed through the system of this embodiment.

[0112] The aforementioned online desalting system for preventing the loss of macromolecular target compounds integrates a chromatographic separation unit 10, a detector 60, a desalting module 40, a molecular sieving module 50, and a flow path switching module 30, achieving efficient and flexible online desalting. The sample stream is first pre-processed by the chromatographic separation unit 10, and then selectively flows to either the anion suppressor 42 or the cation suppressor 41 for targeted desalting via a multi-port switching valve in the flow path switching module 30. The desalted sample then enters the molecular sieving module 50, which consists of a hollow fiber membrane assembly, a flat-plate ultrafiltration membrane packing, and a microfluidic chip. It features hollow fiber membranes with specific molecular weight thresholds and exclusion packing with specific size thresholds, ensuring that macromolecular components are not lost while effectively removing small molecule salts. Finally, the permeate stream is discharged as waste liquid, while the intercepted stream is sent to the detector 60 for analysis and storage, thus ensuring non-destructive detection and preservation of the target analyte. In this way, the entire system can efficiently remove various salt interferences while protecting valuable organic macromolecules from loss.

[0113] In one embodiment, please refer to Figure 8 Furthermore, an online desalination method for preventing the loss of macromolecular target compounds is provided. This method uses the online desalination system described in the above embodiments, comprising: S110, Receives a sample stream containing the target analyte and salt from the chromatographic separation unit 10; S120. Based on the specific information of salt content in the sample stream, the control module 20 selects the corresponding desalination path through the control flow path switching module 30. S130. In the selected desalination path, the corresponding salt ions in the sample stream are removed by the desalination module 40; S140. The desalted sample stream is directed to the molecular sieving module 50 and divided into a permeate stream and a cut-off stream. The permeate stream is discharged through the waste liquid outlet, and the cut-off stream is input into the detector 60 for analysis and storage.

[0114] In addition, the above methods also include: S150. The sample stream that has not undergone desalination is directly directed to the molecular sieving module 50, where it is divided into a permeate stream and a cut-off stream. The permeate stream is discharged through the waste liquid outlet, while the cut-off stream is input into the detector 60 for analysis and storage.

[0115] For the system in this embodiment, the online desalination process includes: First, the system receives a sample stream containing the target analyte and salts from the chromatographic separation unit 10. This step is fundamental to the entire process, ensuring that subsequent processing is targeted at the actual sample containing the target molecule and interfering salts.

[0116] Based on information about the salt content in the sample stream—either preset information (e.g., salt content predetermined according to sample type or experimental design) or real-time detection information (data acquired instantly by sensor 70)—the system determines which desalination path to direct the sample stream through the flow path switching module 30. This system supports multiple desalination modes, including but not limited to full desalination, cation-only desalination, anion-only desalination, and bypass modes, to adapt to different analytical needs and sample characteristics.

[0117] In the selected desalination pathway, the system applies anion suppressor 42 and / or cation suppressor 41 to specifically remove the corresponding salt ions from the sample. Specifically: Cation suppressor 41 is used to suppress cations (e.g., Tris) + It is converted into volatile neutral molecules, making it easy to remove from the sample.

[0118] Anion suppressor 42 is responsible for suppressing anions (such as Cl-). - It can be converted into volatile acids such as HCl, thus achieving the same removal purpose.

[0119] This selective removal strategy not only improves desalination efficiency but also reduces the impact on the target analyte, ensuring the accuracy of the analytical results.

[0120] After or during desalting, the sample stream passes through molecular sieving module 50. This step is crucial because it further refines the sample quality. Salt ions and small molecules with molecular weights below a preset threshold (e.g., 500 Da or 10 kDa, depending on the specific application) are effectively separated and removed.

[0121] Conversely, target analytes with molecular weights higher than a preset threshold are retained in the sample stream and eventually delivered to detector 60 for analysis.

[0122] The role of molecular sieving is to provide a physical barrier that allows only large molecules that meet the size requirements to pass through, thereby achieving the collection of highly pure target analytes and laying the foundation for subsequent high-sensitivity mass spectrometry analysis.

[0123] As an application example, this embodiment demonstrates how to use the system to perform online desalting of complex proteomics samples (containing 1M urea and 50mM Tris-HCl buffer) after enzymatic digestion and then feed them into a mass spectrometer.

[0124] First, the user selects "Biomacromolecule Mode" through the user interface and sets the target molecular weight range to 500-5000 Da (i.e., peptide range). The system then selects "Full Desalting Mode" based on this setting.

[0125] After the sample enters the system, it first passes through the cation suppressor 41, in which Tris + (Cations) are converted into volatile neutral molecules; subsequently, the sample flows through anion suppressor 42, Cl - The anion is converted into HCl (a volatile acid). It is noteworthy that urea, as a neutral molecule, is unaffected in this process.

[0126] The desalted mixture flows into a molecular sieve microcolumn with a molecular weight cutoff (MWCO) of 500 Da. During this process, salt ions (Na+)... + K + Cl - ), extra H + / OH - Small molecule impurities (molecular weight <500 Da) are retained on the column or enter the waste stream. However, the target peptide (molecular weight >500 Da) passes through the microcolumn rapidly due to size exclusion effect and enters the mass spectrometer in a high concentration and low salt state with almost no retention for electrospray ionization.

[0127] Compared to traditional solid-phase extraction desalting columns, the system in this embodiment achieves an online, continuous, and automated operation process, avoiding sample loss and human error associated with offline desalting. Furthermore, through precise mode selection, the system ensures complete removal of Tris and HCl salts, resulting in a cleaner background and stronger peptide mass spectrometry signals.

[0128] In summary, the system in this embodiment not only provides a flexible and efficient desalting mode selection mechanism, but also minimizes sample loss and improves the sensitivity and accuracy of subsequent mass spectrometry detection through intelligent control and optimized design. This innovative technology is particularly suitable for the analysis of complex samples in life science research, providing researchers with an efficient and reliable tool.

[0129] Therefore, the system design objectives of this embodiment include: based on the specific composition of the salt in the mobile phase (e.g., containing only Na), + Contains only Cl - (Or both), selecting the most direct and efficient desalination path improves desalination efficiency and reduces energy consumption. During the desalination process, the molecular sieving module 50 effectively separates small molecule impurities and salt ions while preventing the passage of target macromolecular analytes, ensuring they are directed to the detector 60 to avoid loss. By integrating sensors 70 and intelligent control algorithms, the system automatically diagnoses the salt type, judges the desalination effect, selects the optimal desalination mode, optimizes operating parameters, and improves operational convenience and result reproducibility.

[0130] It should be noted that those skilled in the art will clearly understand that the specific implementation process of the above-mentioned membrane separation online desalination method for preventing the loss of macromolecular organic matter can be referred to the corresponding description in the aforementioned system embodiments. For the sake of convenience and brevity, it will not be repeated here.

[0131] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An online desalination system for preventing the loss of macromolecular target compounds, characterized in that, include: Chromatographic separation unit, detector, desalting module, molecular sieving module, and flow path switching module; The flow path switching module includes at least one multi-port switching valve; The desalting module includes an anion suppressor and a cation suppressor, and the sample output from the chromatographic separation unit flows selectively to the cation suppressor and / or anion suppressor through a multi-port switching valve; The molecular sieving module includes a hollow fiber membrane assembly, a flat-plate ultrafiltration membrane pack, and a microfluidic chip sieving structure. The hollow fiber membrane assembly is equipped with a hollow fiber membrane with a specific molecular weight threshold. The chromatographic separation unit is equipped with exclusion packing material with a specific size threshold. The sample flow after being processed by the desalting module is divided into a permeate flow and a cut-off flow after passing through the molecular sieving module. The permeate flow is discharged through a waste liquid outlet, and the cut-off flow is input into a detector for analysis and then stored.

2. The online desalination system for preventing the loss of macromolecular target compounds according to claim 1, characterized in that, The specific molecular weight threshold and the specific size threshold are adjustable according to user settings. The permeate flow is a fluid with a molecular weight threshold and a specific size threshold lower than the specific molecular weight threshold and the ... size threshold.

3. The online desalination system for preventing the loss of macromolecular target compounds according to claim 1, characterized in that, It also includes a control module, which controls the flow direction of the multi-port switching valve in the flow path switching module based on the sample flow parameters output by the chromatographic separation unit.

4. The online desalination system for preventing the loss of macromolecular target compounds according to claim 1, characterized in that, The outlet of the multi-port switching valve is also connected to the molecular sieving module, and the sample stream output by the chromatographic separation unit can flow directly into the molecular sieving module.

5. The online desalination system for preventing the loss of macromolecular target compounds according to claim 1, characterized in that, It also includes sensors located at the outlet of the chromatographic separation unit and the outlet of the desalting module, and the control module adjusts the desalting path according to the fluid parameters before and after desalting.

6. The online desalination system for preventing the loss of macromolecular target compounds according to claim 3, characterized in that, The control module is also used to discharge the sample stream directly to the waste liquid outlet when the ion signal of the desalted fluid exceeds a preset safety threshold.

7. The online desalination system for preventing the loss of macromolecular target compounds according to claim 1, characterized in that, The molecular sieving module is integrated into the desalination module and is located in the waste liquid channel of the desalination module.

8. An online desalination method for preventing the loss of macromolecular target compounds, characterized in that, The method uses an online desalination system as described in any one of claims 1 to 7 to prevent the loss of macromolecular target compounds, comprising: Receives a sample stream containing the target analyte and salts from the chromatographic separation unit; Based on the specific information about the salt content in the sample stream, the control module selects the corresponding desalination path through the control flow path switching module. In the selected desalination path, the corresponding salt ions in the sample stream are removed by the desalination module; The desalted sample stream is directed to the molecular sieving module, where it is divided into a permeate stream and a cut-off stream. The permeate stream is discharged through the waste outlet, while the cut-off stream is input into the detector for analysis and storage.

9. The online desalination method for preventing the loss of macromolecular target compounds according to claim 8, characterized in that, Also includes: The sample stream that has not undergone desalination is directly directed to the molecular sieving module, where it is divided into a permeate stream and a cut-off stream. The permeate stream is discharged through the waste outlet, while the cut-off stream is input into the detector for analysis and storage.

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