High-sensitivity and high-signal-stability membrane desolventizing and sampling system

Abstract

The invention discloses a high-sensitivity and high-signal-stability membrane desolventizing and sampling system, which comprises a sample introduction system, a heating fog chamber, a primary condensation desolventizing system, a secondary membrane gas replacement desolventizing system, a sensibilization system and an aerosol transmission pipe, and relates to the technical field of analytical chemical instruments. According to the high-sensitivity and high-signal-stability membrane desolventizing and sampling system, the sample introduction system adopts a precise electric driving motor to drive an injector to realize an accurate and stable sampling mode, and the heating fog chamber, the primary condensation desolventizing system and the secondary membrane gas replacement desolventizing system perform systematic shielding grounding anti-interference treatment. Meanwhile, the aerosol transmission pipe adopts an anti-static interference design, and the sensitization system adopts nitrogen to sensitize sample analysis. According to the invention, the problem of unstable signal caused by easy electrostatic interference of aerosol in the existing membrane desolventizing and sampling system is solved, the long-term working stability of the system is improved, and the detection sensitivity and the analysis reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of analytical chemistry instrumentation technology, specifically to a high-sensitivity, high-signal-stability membrane desolvation and sample introduction system. Background Technology

[0002] Membrane desolvation is a key sample introduction technique in modern trace element analysis, particularly in inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-OES). Its development stems from a core need: to efficiently convert liquid samples into gaseous analytes while minimizing solvent interference (especially water or organic solvents), enhancing signal intensity, and reducing interference from oxides and electrode desolvation. However, existing membrane desolvation techniques suffer from the following drawbacks: The membrane desolvation equipment itself is unstable in sample feeding and fluctuates due to static electricity.

[0003] Traditional membrane desolvation equipment largely employs self-priming micro-flow nebulizers. Low-flow self-priming sample injection inherently suffers from unstable injection rates and fluctuating injection volumes. Furthermore, self-priming micro-flow nebulizers are typically made of perfluoropolymer material, which easily generates static electricity in the atomized gas during nebulization. When researchers approach the equipment or touch the sample tube, this static electricity causes fluctuations in injection volume and nebulization efficiency, ultimately leading to fluctuations in the mass spectrometer signal, increased instability, and impacting the accuracy of analytical results.

[0004] Internal static electricity causes aerosol particles to remain in the pipeline, leading to increased residue (memory effect) between samples; Because the solvent removal efficiency is high during membrane desolvation, static electricity accumulates more easily, leading to greater negative impacts. Charged colloids adsorbed on the membrane tubes are difficult to completely rinse off, resulting in increased inter-sample residue (memory effect). This causes sample testing to be influenced by previously tested samples, gradually increasing background and affecting the accuracy of test results. Furthermore, existing membrane desolvation equipment does not consider customer replacement needs in its design; disassembly requires contacting the manufacturer or outright disposal.

[0005] External electrostatic interference affects aerosol transport and detection results.

[0006] Currently, all anti-static measures are aimed at protecting the circuit boards and electronic equipment themselves, to prevent circuit board failure and electromagnetic interference. Membrane desolvation systems, to resist acids and alkalis, extensively use materials such as PTFE, PFA, and PP. During operation, the membrane desolvation system has high solvent removal efficiency, and aerosol particles flow at high speed in the PTFE, PFA, and PP tubing, rubbing, colliding, and separating with the tubing walls. This easily generates and accumulates static electricity. The charged aerosols are highly susceptible to interference from external static electricity during transmission; for example, fluctuations in mass spectrometry detection signals when laboratory operators approach or walk near the membrane desolvation sample introduction system can affect the accuracy of analytical results.

[0007] Poor signal stability: External static electricity affects the transmission of aerosol particles in the pipeline, causing irregular adsorption and release on the inner wall of the pipeline, resulting in significant fluctuations in the test signal and a deterioration in RSD (relative standard deviation) (often exceeding 5%).

[0008] Decreased sensitivity: External static electricity can cause loss of target analytes, reduce transmission efficiency, and thus impair the method's limit of detection (LOD) and limit of quantitation (LOQ).

[0009] Low detection sensitivity: When used in aerosols, the target analyte content is low, the transmission process is long, and internal and external electrostatic interference can cause target analyte loss and low transmission efficiency, resulting in reduced detection sensitivity.

[0010] Therefore, there is an urgent need for a membrane desolvation injection system that can effectively suppress electrostatic interference and improve injection stability and signal sensitivity. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention provides a high-sensitivity, high-signal-stability membrane desolvation injection system, which solves problems such as unstable injection, large signal fluctuations, significant memory effects, and low sensitivity caused by electrostatic interference in existing technologies.

[0012] To achieve the above objectives, the present invention is implemented through the following technical solution: a high-sensitivity, high-signal-stability membrane desolvation sample introduction system, which sequentially includes a sample introduction system, a heating fog chamber, a primary condensation desolvation system, a secondary membrane gas replacement desolvation system, a sensitization system, and an aerosol transport tube along the aerosol transport path.

[0013] The sample introduction system mainly consists of a syringe, a precision electric drive motor (such as a stepper motor or servo motor), a drive circuit board, and a PTFE or PFA injection tubing. Commands are issued from a host computer (such as a computer) to control the precision electric drive motor to precisely drive the piston of the syringe, thereby achieving adjustable flow rate, high stability, and programmable control of sample solution delivery within the range of 1~500µl / min. This eliminates the susceptibility of nebulizer self-priming to interference from external static electricity, fundamentally replacing the traditional unstable self-priming injection method.

[0014] The heated atomizing chamber consists of a precision nebulizer, an atomizing chamber, a temperature control system, and a waste liquid collection port. The liquid inlet of the precision nebulizer is connected to the outlet of the sample introduction system via a pipeline, and its carrier gas interface is connected to an argon gas source. The atomizing chamber is a three-layer cylindrical closed structure installed at an angle of 15 to 60 degrees. Its innermost layer is the atomizing chamber, made of PTFE or PFA, and is a cylindrical sealed cavity with a diameter of 20 to 60 mm. The gas inlet of the atomizing chamber is connected to the aerosol outlet of the precision nebulizer, and the gas outlet is connected to the primary condensation and desolvation system via a pipeline. A makeup gas inlet is provided on the side wall, and a waste liquid discharge port is provided at the bottom. The middle layer is a metal sleeve tightly enclosing the atomizing chamber. The material is copper, aluminum, or other highly thermally conductive metals. Multiple heating rods (or heating films) and temperature sensors (such as PT100) are embedded in the metal sleeve and connected to the independent temperature control system, thereby enabling the aerosol in the atomizing chamber to be precisely heated from room temperature to a maximum of 180 degrees Celsius. The metal sleeve is provided with a first connection point for shielding and grounding. The outermost layer is an outer protective sleeve made of PTFE or PFA material for heat preservation and mechanical protection.

[0015] The primary condensation and desolvation system mainly includes a condensation chamber, a semiconductor refrigeration system, a temperature sensor, and a heat dissipation system. The condensation chamber has a three-layer structure: the inner layer is a condensation cavity made of PTFE or PFA, configured as a U-shaped pipe or a vertical serpentine pipe, with an inlet (connected to the heating mist chamber) and an outlet (connected to the secondary membrane desolvation system) at its two ends, and a waste liquid discharge port at the lowest point of the pipe; the middle layer is a heat-conducting layer tightly wrapped around the outer wall of the condensation cavity pipe, using a copper sleeve or aluminum foil, on which a precision temperature sensor and a second connection point for shielding and grounding are mounted; the cooling surface of the semiconductor refrigeration system is tightly fitted to the heat-conducting layer, while its hot surface is tightly fitted to a metal heat sink with embedded water-cooled pipes; the heat dissipation system (e.g., a fan-equipped finned water-cooled radiator) is connected to the water-cooled pipes to dissipate heat. The semiconductor refrigeration system, temperature sensor, and heat dissipation system are all connected to a temperature control system to accurately and stably control the condensation chamber temperature within a set range (e.g., 2°C) between room temperature and 0°C. As an alternative, the semiconductor cooling system and heat dissipation system can be implemented by an externally temperature-controlled circulating water chiller system. The outermost layer of the condensation chamber is a PTFE or PFA protective layer for insulation and to secure the overall structure.

[0016] The secondary membrane gas displacement desolvation system comprises a membrane tube, laminar flow orifices, a metal casing, and a gas mass flow controller. The entire system is designed as a quick-change module. The membrane tube is a double-layered structure made of selectively permeable membrane material (such as hollow fiber membrane). The inner membrane allows small molecule solvent vapors to pass through but prevents aerosol particles from passing through. During operation, moist aerosol from the primary condensation system enters the inner tube from the bottom of the membrane tube. Solvent vapor diffuses through the inner membrane to the outer casing and is carried out as waste gas by the counter-flowing purge argon. Simultaneously, some of the purge argon diffuses back into the inner tube, mixing with the dried aerosol particles to form new, drier aerosols, which flow out from the inner tube at the top of the membrane tube, thus achieving deep desolvation based on gas displacement. The outer layer of the membrane tube is an impermeable and particle-impermeable support tube. To increase the effective contact length, the membrane tube is typically designed in a spiral-ascending manner. The entire membrane tube assembly is encapsulated in a grounded metal housing, which has corresponding gas interface ports (sample gas inlet / outlet, purge gas inlet, and exhaust gas outlet).

[0017] The sensitization system includes a three-way mixer, a laminar flow orifice, and a gas mass flow controller. The main inlet of the three-way mixer is connected to the sample gas outlet of the secondary membrane desolvation system, and the second inlet is connected to the sensitizing gas source via the gas mass flow controller. The sensitizing gas is preferably high-purity nitrogen, and its flow rate is precisely controlled within the range of 0–50 ml / min using the gas mass flow controller. The outlet of the three-way mixer is sequentially connected to the laminar flow orifice and an aerosol transfer tube, and finally connected to the injection torch of the ICP-MS or ICP-OES system.

[0018] The aerosol delivery tube has a multi-layer composite structure, comprising, from the inside out: a smooth PTFE or PFA inner tube, a conductive shielding layer, and an outer protective layer. The conductive shielding layer can be implemented in any of the following forms: (1) conductive fiber cloth that has undergone electroplating (e.g., copper plating); (2) a directly wrapped metal braided mesh (e.g., stainless steel braided mesh); (3) a conductive coating (e.g., conductive paint) sprayed onto the outer wall of the inner tube. Alternatively, a structure can be used with an inner PTFE tube, a flexible shrinkable conductive layer wrapped in the middle (e.g., the aforementioned conductive fiber cloth or metal braided mesh), and an outer heat-shrinkable polyolefin tube. Heating shrinks the outer layer, thus tightly bonding the layers. The conductive shielding layer needs to be connected to the system grounding network via a wire. The inner wall of the inner tube must be smoothly processed, free of burrs and damage, to minimize aerosol delivery resistance and adsorption.

[0019] The system also includes a waste liquid discharge system, which comprises a peristaltic pump, waste liquid collection pipelines, and a waste liquid collection tank. The inlet of the peristaltic pump is connected via pipelines to the waste liquid discharge ports of the heating mist chamber and the primary condensation and desolvation system, respectively, and its outlet is connected to the waste liquid collection tank. During system operation, the peristaltic pump is controlled by a host computer via a PLC control module to promptly discharge the generated waste liquid, ensuring continuous and stable system operation.

[0020] The core innovation of this invention lies in the construction of a systematic electrostatic protection and shielding network. Specifically, the first shielding grounding connection point on the metal sleeve of the heating mist chamber, the second shielding grounding connection point on the heat-conducting layer of the primary condensation and desolvation system, the grounding point of the metal shell of the secondary membrane desolvation system, and the conductive shielding layer of the aerosol transport pipe are all interconnected by wires and connected to the metal casing of the entire membrane desolvation system. Finally, they are all connected to a dedicated grounding device with a grounding resistance of less than 4Ω via a low-impedance metal wire. This network forms an equipotential body for key components, which not only shields against interference from the external electromagnetic environment and human static electricity, but also provides an effective discharge path for the triboelectric charges generated by the aerosol flow inside the system, thereby comprehensively ensuring the stability of the aerosol transport process.

[0021] This invention provides a high-sensitivity, high-signal-stability membrane desolvation and sample introduction system. Compared with existing technologies, it has the following advantages: 1. This high-sensitivity, high-signal-stability membrane desolvation injection system employs a stepper motor-driven syringe for precise and stable sample injection, a systematic shielded anti-static design, and an anti-static interference design for the aerosol transmission tube. These features greatly improve the system's anti-interference capability and stability, ultimately enhancing the stability and reliability of the mass spectrometry signal during sample analysis.

[0022] 2. This high-sensitivity, high-signal-stability membrane desolvation injection system uses a stepper motor-driven syringe to inject samples instead of the traditional self-priming nebulizer, significantly improving the accuracy of sample introduction.

[0023] 3. This high-sensitivity, high-signal-stability membrane desolvation and sample introduction system employs multiple anti-interference and anti-static measures to significantly reduce the interference of internal and external factors on aerosol transmission, reduce aerosol loss during transmission, improve aerosol transmission efficiency and detection limit, and enhance signal stability.

[0024] 4. This high-sensitivity, high-signal-stability membrane desolvation and sample introduction system adopts a rapidly replaceable membrane replacement module, which improves equipment efficiency, reduces operating costs, and solves the memory effect of membrane tubes that traditional cleaning cannot completely resolve, i.e., the inaccuracy of analytical results caused by sample aerosol residue in the membrane tubes. This extends the service life of the equipment, improves efficiency, and enhances the long-term stability of the system.

[0025] 5. This high-sensitivity, high-signal-stability membrane desolvation and sample introduction system introduces a nitrogen sensitization system in the aerosol transmission stage to the mass spectrometer to improve the aerosol transmission efficiency and enhance the instrument's detection sensitivity. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the membrane desolvation and sample introduction system of the present invention; Figure 2 This is a schematic diagram of the secondary membrane desolvation structure of the present invention; Figure 3 This is a schematic diagram of the laminar flow hole of the present invention; Figure 4 This is a schematic diagram comparing the sensitivity of direct detection by the mass spectrometer of the present invention with that of the embodiments of the present invention; Figure 5 This is a diagram showing the sensitization factor of each element directly detected by mass spectrometer in an embodiment of the present invention; Figure 6 This is a signal fluctuation diagram of the solvent removal control test for the aerosol-free antistatic membrane of this invention; Figure 7 This is a test signal diagram from an embodiment of the present invention; Figure 8 This is a schematic diagram of the system of the present invention.

[0027] In the diagram: 100, Sample introduction system; 200, Heated mist chamber; 300, Primary condensation and desolvation system; 400, Secondary membrane gas replacement and desolvation system; 500, Sensitization system; 600, Sol transfer tube; 700, Waste liquid discharge system. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0029] Please see Figure 1-8 The present invention provides a technical solution: a high-sensitivity, high-signal-stability membrane desolvation sample introduction system, which includes, in sequence along the aerosol transport path, a sample introduction system 100, a heated mist chamber 200, a primary condensation desolvation system 300, a secondary membrane gas replacement desolvation system 400, a sensitization system 500, an aerosol transport tube 600, and a waste liquid discharge system 700.

[0030] In this embodiment, a mass spectrometry tuning solution with a concentration of 500 ppt was used as the matrix, and a multi-element mixed standard solution was added to prepare the sample to be tested. The mass spectrometer used for detection was an Agilent 7900 ICP-MS.

[0031] The specific structure and operating parameters of the system are as follows: The sample introduction system 100 mainly consists of a 1mL Teflon precision syringe, a precision electric drive motor composed of a stepper motor, a corresponding drive circuit board, and a PTFE injection tubing with an inner diameter of 0.25mm. Commands are sent via host computer software to control the drive motor to push the syringe piston at a constant speed, achieving a precise and stable sample injection rate of 100 µl / min.

[0032] Heated atomizing chamber 200: Composed of a concentric pneumatic nebulizer, atomizing chamber, temperature control system, and waste liquid collection port. The nebulizer's inlet is directly connected to the PTFE tube of the sample introduction system 100, and its carrier gas interface is connected to an argon gas source. The carrier gas flow rate is set to 0.8 L / min. The atomizing chamber is a three-layer cylindrical closed structure, installed at a 30-degree angle. The innermost layer is the atomizing cavity, made of PTFE, a cylindrical sealed cavity with a diameter of 30 mm. Its left end connects to the aerosol outlet of the nebulizer, and its right end connects to the primary condensation and desolvation system 300 via pipeline. A makeup gas inlet is provided on the side wall; the makeup gas is high-purity argon, and the flow rate is set to 0.2 L / min. L / min; The lower left of the cavity has a waste liquid discharge port. The middle layer is a metal sleeve tightly wrapping the atomizing cavity. The material is copper. Multiple heating rods and high-precision temperature sensors are embedded in the metal sleeve and connected to an independent temperature control system. The host computer uses the temperature control system to precisely control the temperature of the aerosol in the atomizing cavity at 150°C. The metal sleeve has a first shielding grounding connection point. The outermost layer is a PFA material outer protective sleeve for heat preservation and physical protection.

[0033] The primary condensation and desolvation system 300 mainly includes a condensation chamber, a semiconductor refrigeration system, a temperature sensor, and a heat dissipation system. The condensation chamber has a three-layer structure: the inner layer is the condensation cavity, which is a vertical serpentine tube made of PTFE. Its inlet and outlet are connected to the heating mist chamber 200 and the secondary membrane gas replacement and desolvation system 400, respectively. A waste liquid discharge port is provided at the lowest point of the tube. The middle layer is a copper heat-conducting layer tightly wrapped around the condensation cavity tube. A temperature sensor and a second shielding grounding connection point are installed on it. The cooling surface of the semiconductor refrigeration unit is in close contact with the heat-conducting layer, and its hot surface is in close contact with a heat sink embedded with copper water-cooled pipes. The heat dissipation system adopts a finned water-cooled radiator with a fan. Its water circuit is connected to the above-mentioned water-cooled pipes. The semiconductor refrigeration unit, temperature sensor, and cooling fan are all coordinated and controlled by the temperature control system to maintain the temperature in the condensation cavity at a stable 2°C. The outermost layer of the condensation chamber is a PTFE protective layer for heat insulation.

[0034] The 400-stage secondary membrane gas replacement desolvation system is a quickly replaceable module. Its core membrane tube consists of hundreds of selectively permeable hollow fiber membranes, assembled into a spiral-rising double-layered tube structure, entirely encapsulated in an aluminum metal shell. During operation, the aerosol, after primary condensation, enters the inner tube (sample flow path) from the bottom of the membrane tube. High-purity argon gas, used as a purge gas, enters the chamber between the outer shell and the outer layer of the membrane tube at a flow rate of 3.5 L / min from the top of the membrane tube and flows downwards along the membrane tube (countercurrent to the sample gas), carrying away the solvent vapor permeating from the inner tube and discharging it through the exhaust outlet at the bottom. The deeply dried aerosol flows out from the inner tube at the top of the membrane tube and enters the next stage. The metal shell is equipped with a third shielding grounding connection point. The membrane tube assembly is connected to the external gas path via quick-connect couplings for easy disassembly and replacement.

[0035] Sensitization system 500: includes a three-way mixer and a high-precision gas mass flow controller (MFC). The main inlet of the three-way mixer is connected to the dry sample gas outlet of the secondary membrane desolvation system, and the second inlet is connected to a high-purity nitrogen gas source through the MFC. The flow rate of the sensitizing nitrogen gas is precisely controlled at 3.2 ml / min by the MFC. The outlet of the three-way mixer is connected in sequence to a laminar flow orifice for stabilizing the gas flow and an aerosol transfer tube 600.

[0036] Aerosol transmission tube 600: It adopts a three-layer composite structure. The inner layer is a PFA tube with an extremely smooth inner wall (inner diameter 1.5mm), the middle layer is a conductive shielding layer, which in this embodiment is woven from copper-plated conductive fiber cloth, and the outer layer is a heat-shrinkable polyolefin protective layer. The lead wire of the conductive shielding layer is connected to the system grounding network.

[0037] Waste liquid discharge system 700: includes a multi-channel peristaltic pump. The inlet of each channel of the peristaltic pump is connected to the waste liquid discharge port of the heating mist chamber 200 and the first-stage condensation and desolvation system 300 through pipelines. The outlet is connected to the waste liquid collection tank through the main pipeline. When the system is running, the host computer commands the peristaltic pump to work synchronously through the control software to discharge the waste liquid in a timely manner.

[0038] Connection of the systematic electrostatic protection network: The first connection point on the metal sleeve of the heating mist chamber 200, the second connection point on the heat-conducting layer of the primary condensation and desolvation system 300, the grounding point of the metal shell of the secondary membrane gas replacement and desolvation system 400, and the conductive shielding layer lead of the aerosol transmission tube 600 are all connected together with wires and connected to the overall metal chassis of the instrument. Finally, the chassis is connected to the laboratory-specific independent grounding stake through a wire with a cross-sectional area of ​​not less than 4mm². The grounding resistance of the grounding device is measured to be 2Ω, which meets the design requirement of less than 4Ω.

[0039] Experimental verification and control test To objectively evaluate the effectiveness of this invention, the following three sets of comparative experiments were designed: Direct mass spectrometry (benchmark group): The above 500 ppt spiked sample was tested directly through the original sample introduction system (glass concentric nebulizer + cyclone chamber) of Agilent 7900 ICP-MS without any membrane desolvation system.

[0040] Test of this invention embodiment (experimental group): The same sample was processed using the membrane desolvation and sample introduction system of this invention, which was built in accordance with the above-mentioned "specific system composition and working parameters". Then, it was connected to the same Agilent 7900 ICP-MS for testing. During the test, the experimenters were specially arranged to walk back and forth around the equipment (within about 1 meter) to simulate the external electrostatic interference commonly found in real laboratory environments.

[0041] Electrostatic Discharge Protection Control Test (Control Group): This group aims to simulate the weaknesses of traditional membrane desolvation systems. To ensure a fair comparison, the same samples were used, and core conditions such as atomization chamber temperature, condensation temperature, and various gas flow rates were kept identical to the experimental group. Only the following three key modifications were made to simulate the traditional system: Remove the syringe pump drive section of the sample introduction system 100 and replace it with a conventional self-priming microflow nebulizer for sample introduction.

[0042] Cancel all electrostatic protection measures: disconnect the grounding wires of the metal casings of the heating mist chamber 200, the primary condensation and desolvation system 300, and the secondary membrane gas replacement and desolvation system 400; replace the aerosol transmission pipe 600 with a common single-layer PTFE pipe (without conductive shielding layer).

[0043] Similarly, personnel were arranged to move around and create interference during the testing process.

[0044] Test Results and Analysis: Sensitivity comparison: such as Figure 4 and Figure 5 As shown, compared with the results of "direct mass spectrometry test", the detection signal intensity of all test elements in the embodiment of the present invention (experimental group) was improved by 8 to 17.5 times, which proves the great improvement effect of the system on detection sensitivity under the synergistic effect of removing solvent interference and nitrogen sensitization.

[0045] Comparison of signal stability (interference resistance): from Figure 6 The signal fluctuation graph and data analysis of the "no electrostatic protection control test" show that, under the interference of personnel movement, the signal fluctuates drastically due to the lack of electrostatic protection. The relative standard deviation (RSD) of the signal intensity of each element was calculated. Under external electrostatic interference, the RSD of all element signals exceeded 20%, while mass spectrometry detection typically requires an RSD of less than 3%, indicating that the system is extremely unstable and has very poor anti-interference capability.

[0046] from Figure 7 The signal graphs and data analysis from the "Tests in the Embodiments of this Invention" show that, under identical external interference conditions, the signal curves are very stable. The RSD values ​​of all tested elements are below 1%, a level of fluctuation superior to conventional direct liquid injection. This irrefutably proves that the technical solution employed in this invention, combining precision injection with a systematic electrostatic protection network, can almost completely eliminate signal interference caused by injection fluctuations and internal / external electrostatic discharge, achieving excellent analytical stability and anti-interference capabilities.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-sensitivity, high-signal-stability membrane desolvation and sample introduction system, characterized in that: The aerosol transport path includes, in sequence: A sample introduction system (100) is used to provide a sample solution at a stable and programmable flow rate; A heated atomizing chamber (200), connected to the sample introduction system (100), is used to atomize the sample solution into an aerosol and heat it to vaporize the solvent; A primary condensation and desolvation system (300), connected to the heated mist chamber (200), is used to condense the heated aerosol to remove solvent vapors. The secondary membrane gas displacement desolvation system (400) is connected to the primary condensation desolvation system (300), and is equipped with a selective permeation membrane tube for deep removal of residual solvent vapors in aerosols by gas displacement. The sensitization system (500) is connected to the secondary membrane gas displacement desolvation system (400) and is used to mix a sensitization gas at a predetermined flow rate into the dried aerosol after deep desolvation. And an aerosol transport tube (600) connecting the sensitization system (500) to the sample inlet of a plasma spectrometer or mass spectrometer; The heating mist chamber (200), the primary condensation and desolvation system (300) and the secondary membrane gas replacement and desolvation system (400) are all equipped with grounded metal shielding structures, and the aerosol transmission pipe (600) is equipped with a grounded conductive shielding layer, which together form a systematic electrostatic protection and shielding network.

2. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: The sample introduction system (100) includes a syringe, a precision electric drive motor for driving the syringe, a drive circuit, and a sample inlet tube connected to the syringe outlet; the precision electric drive motor is controlled by a host computer to push the sample in the syringe, thereby achieving precise, stable and programmable sample injection in the range of 1~500 µl / min.

3. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: The heated mist chamber (200) includes: The atomizing chamber is a sealed chamber. Its inlet is connected to the inlet pipe of the sample introduction system (100), and its outlet is connected to the primary condensation and desolvation system (300). The side wall is provided with a supplementary gas interface, and the bottom is provided with a waste liquid discharge port. A metal sleeve tightly wraps around the outside of the atomizing chamber, and a heating element and a temperature sensor are embedded inside it. It is connected to a temperature control system to achieve precise heating of the aerosol inside the atomizing chamber. The metal sleeve is provided with a first shielded grounding connection point for connecting to the grounding network. An outer protective sleeve, which wraps around the metal sleeve, is used for heat insulation and mechanical protection.

4. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: The primary condensation and desolvation system (300) includes: The condensation chamber is a pipe structure made of PTFE or PFA material. Its inlet is connected to the outlet of the heating mist chamber (200), and the outlet is connected to the secondary membrane gas replacement desolvation system (400). A waste liquid discharge port is provided at the lowest point of the pipe. A heat-conducting layer tightly wraps around the outer wall of the pipe in the condensation chamber, and a second shielded grounding connection point and a temperature sensor are provided on it; A semiconductor cooler, the cold end of which is in close contact with the heat-conducting layer, is used to cool the condensation cavity; A heat dissipation unit, connected to the hot end of the semiconductor cooler, is used to dissipate heat; The semiconductor cooler, the temperature sensor, and the heat dissipation unit are all connected to a temperature control system to stably control the temperature inside the condensation chamber within a set range.

5. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: The secondary membrane gas displacement desolvation system (400) includes: The membrane tube assembly is a double-layered tube structure made of a selectively permeable hollow fiber membrane. The inner tube is used to pass aerosols from the primary condensation and desolvation system (300), and the gap between the inner and outer tubes is used to introduce purge gas. Solvent vapors can be carried away by the purge gas through the membrane wall, while aerosol particles are retained in the inner tube. At the same time, some of the purge gas can diffuse back into the inner tube and mix with the dried aerosol. The membrane tube assembly is encapsulated in a metal casing and is provided with a third shielded grounding connection point; The membrane tube assembly is connected to the system pipeline via snap-fit ​​or quick-connect couplings, forming a module that can be quickly replaced.

6. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: The sensitization system (500) includes a three-way mixer and a gas mass flow controller; one inlet of the three-way mixer is connected to the sample gas outlet of the secondary membrane gas displacement desolvation system (400), the other inlet is connected to the sensitization gas source through the gas mass flow controller, and the outlet is connected to the aerosol transfer tube (600).

7. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: The aerosol transmission tube (600) comprises, from the inside out: an inner PTFE or PFA smooth inner tube, a middle conductive shielding layer, and an outer protective layer; the conductive shielding layer is one of conductive fiber cloth, metal braided mesh, or conductive coating, and is connected to the system grounding network through a wire.

8. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: It also includes a waste liquid discharge system (700), which includes a peristaltic pump. The inlet of the peristaltic pump is connected to the waste liquid discharge port of the heating mist chamber (200) and the primary condensation and desolvation system (300) respectively through pipelines, for automatically discharging the generated waste liquid to the waste liquid collection device.

9. The high-sensitivity, high-signal-stability membrane desolvation and sample introduction system according to claim 1, characterized in that: The first shielding grounding connection point of the heating mist chamber (200), the second shielding grounding connection point of the primary condensation desolvation system (300), the third shielding grounding connection point of the secondary membrane gas replacement desolvation system (400), and the conductive shielding layer of the aerosol transmission pipe (600) are interconnected by wires and connected to the system metal shell, and then connected to a grounding device with a grounding resistance of less than 4Ω.

Images