Self-absorption-free concentric parallel flow atomizer

Abstract

The invention belongs to the field of trace analysis, and particularly relates to a non-self-absorption concentric parallel flow atomizer which comprises a gas conveying pipe, a liquid conveying pipe and a connecting pipe. The side wall of the connecting pipe is connected with a liquid inlet pipe, the liquid inlet end of the liquid conveying pipe is inserted into one end of the connecting pipe, and the liquid conveying pipe communicates with the liquid inlet pipe. One part of the air delivery pipe is inserted into the other end of the connecting pipe and extends into the infusion pipe; the gas conveying pipe and the liquid conveying pipe are coaxially arranged, and the outlet end of the gas conveying pipe is flush with the outlet end of the liquid conveying pipe; an inlet of the gas conveying pipe is connected with an atomization gas source and used for providing atomization gas. Atomized gas is conveyed to the outlet end through the gas conveying pipe and then atomizes a sample solution flowing out of the liquid conveying pipe, and self-absorption is avoided. The atomizer provided by the invention is detachable, can tolerate high salt and insoluble particles, is relatively high in atomization efficiency, and is superior to an existing commodity atomizer in analysis performance.

Description

Technical Field

[0001] This invention belongs to the field of trace analysis, specifically relating to a non-self-priming concentric parallel flow atomizer. Background Technology

[0002] ICP-AES and ICP-MS are mature and mainstream technologies for trace element analysis, widely used in geology, food, environment, industry, and life sciences. Pneumatic nebulizer solution injection is the primary sample introduction method for ICP-AES and ICP-MS instruments, with concentric nebulizers and cross-flow nebulizers being the most common. Their sample lift rates are typically 0.5 mL / min to 2 mL / min, and the actual sample consumption for a single analysis is 1 mL to 10 mL. However, traditional concentric nebulizers often employ an inner tube for liquid inlet and an outer tube for gas inlet. During operation, they heavily rely on the Venturi effect, where high-speed atomizing gas ejected from the annular gap creates a strong negative pressure at the sample liquid outlet. While this allows for self-aspiration injection, it also triggers a series of chain reactions. After the liquid stream is drawn away from the nozzle by the negative pressure, it must travel a distance to interact with the atomizing gas. Furthermore, the flow field of the gas-liquid interaction is unstable, resulting in most samples failing to be effectively atomized, instead impacting the walls as liquid films or large droplets, forming waste liquid. This leads to a generally low atomization efficiency (below 2%) and low sample utilization. Furthermore, the sample flow path is limited by an extremely fine capillary tube, which easily traps high-salt or insoluble particles, causing nebulizer blockage. Simultaneously, its inherently high self-absorption flow rate is severely imbalanced with the nanoliter output of micro-flow separation technologies such as capillary electrophoresis. When these technologies are coupled, a large amount of replenishing fluid must be introduced to maintain stable sample injection, which not only dilutes the sample and reduces sensitivity but also induces laminar flow at the coupling interface, disrupting the banding of separated components and leading to peak broadening and decreased resolution. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a non-self-priming concentric parallel flow atomizer. The atomizer provided by this invention is easy to manufacture, detachable, can tolerate high salt and insoluble particles, has extremely low or even no self-priming flow rate, high atomization efficiency, and superior analytical performance compared to existing commercial atomizers.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A non-self-priming concentric parallel flow nebulizer includes a gas delivery pipe, a liquid delivery pipe, and a connecting pipe. A liquid inlet pipe is connected to the side wall of the connecting pipe. The liquid inlet end of the liquid delivery pipe is inserted into one end of the connecting pipe and is connected to the liquid inlet pipe. A portion of the gas delivery pipe is inserted into the other end of the connecting pipe and extends into the liquid delivery pipe. The gas delivery pipe and the liquid delivery pipe are coaxially arranged, and the outlet end of the gas delivery pipe is flush with the outlet end of the liquid delivery pipe. An nebulizing gas source is connected to the inlet of the gas delivery pipe to provide nebulizing gas. After the nebulizing gas is delivered to the outlet end through the gas delivery pipe, it atomizes the sample solution flowing out of the liquid delivery pipe.

[0005] This invention constructs a concentric structure with the gas delivery tube and liquid delivery tube coaxial and flush at their outlet ends. This allows the nebulized gas in the gas delivery tube and the sample solution in the annular channel to flow in the same axial direction, forming a parallel flow. The nebulized gas directly atomizes the sample solution at the outlet end of the gas delivery tube, avoiding negative pressure within the annular channel. Combined with a rational structural design, this achieves no self-priming, high atomization efficiency, and anti-clogging effects. Specifically, the flush outlet ends of the gas delivery tube and liquid delivery tube ensure the nebulized gas has maximum kinetic energy at the outlet end, and the sample solution has a large effective atomization area as it flows through the annular channel, significantly improving atomization efficiency and sample utilization. This solves the problems of low atomization efficiency, low sample utilization, and unsuitability for micro-sample analysis. The liquid delivery tube uses an appropriate size to accommodate high-salt crystals and insoluble particles in the sample, preventing nebulizer clogging. The co-current flow of the nebulized gas and sample solution eliminates negative pressure, achieving no self-priming and eliminating the need for large amounts of replenishing liquid, reducing laminar flow and improving sensitivity. This solves the problems of large amounts of replenishing liquid, laminar flow, and low sensitivity when using interfaces for micro / nano separation technologies.

[0006] Furthermore, the gas delivery pipe is a pointed capillary inner tube, which is formed by heating and drawing molten quartz capillary tubes. The inner diameter of the molten quartz capillary tube is 150μm~320μm and the outer diameter is 365μm~450μm.

[0007] Furthermore, the method for drawing the pointed capillary inner tube includes the following steps: The molten quartz capillary is locally heated to soften, and then stretched in two opposite directions away from the center of the heated section to form a narrow diameter region. After the narrow diameter region is cooled, it is heated again to soften and then stretched rapidly in two opposite directions until it breaks, resulting in a pointed capillary inner tube.

[0008] Furthermore, the outer diameter of the outlet end of the pointed capillary inner tube is 21.6 μm to 78.9 μm, and the wall thickness is 6 μm to 10 μm.

[0009] Furthermore, the infusion tube is a capillary outer tube, which is made by cutting fused silica capillary tubes. The inner diameter of the capillary outer tube is 450μm to 530μm and the outer diameter is 690μm.

[0010] Furthermore, the connecting tube includes a first interface, a second interface, and a third interface. The first interface and the second interface are coaxially arranged. The gas delivery tube passes through the first interface, the liquid delivery tube passes through the second interface, and the third interface is connected to the liquid inlet tube.

[0011] Furthermore, it also includes a first connector and a second connector. The first connector is coaxially sleeved on the outside of the infusion tube. One end of the second connector is connected to the first connector, and the other end of the second connector forms a supplementary gas passage with the outside of the infusion tube, which is used to deliver the aerosol generated after atomization to the atomization chamber.

[0012] Furthermore, the side wall of the second connector is connected to a supplementary air intake line for providing supplementary air.

[0013] Furthermore, the first connector is a through connector, which is made of polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK) material, and has an inner diameter of 1.55 mm and an outer diameter of 3.6 mm.

[0014] Furthermore, the second connector is a glass connecting tube, which is formed by two glass tubes with an inner diameter of 4mm and an outer diameter of 6mm perpendicularly intersecting each other.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a self-priming concentric parallel flow nebulizer that utilizes a coaxial parallel flow structure with an inner tube for air intake and an outer ring for liquid intake, fundamentally solving the bottleneck problem of traditional concentric nebulizers. Specifically, the atomizing gas is directly ejected from the tapered inner capillary tube, while the sample solution is smoothly transported through the annular channel between the inner and outer tubes. Both tubes remain flush at the outlet, achieving zero-distance contact and parallel flow in the same direction. This design completely eliminates the Venturi effect, allowing the atomizing gas to act on the sample liquid flow instantaneously at the tube opening where kinetic energy is greatest. This avoids energy attenuation and flow field instability caused by negative pressure suction and delayed atomization in traditional structures, thus efficiently atomizing most of the sample into usable aerosols, significantly improving atomization efficiency and sample utilization. Simultaneously, the sample flow path is changed from the traditional ultra-fine capillary tube to an annular channel with a larger cross-sectional area, capable of accommodating high-salt crystals and insoluble particles, preventing clogging of the nebulizer.

[0016] Furthermore, since the atomization process does not rely on negative pressure self-absorption, it achieves active control of sample introduction. Its self-absorption flow rate is extremely low, which can be precisely matched with the nano-level output of micro-flow separation technologies such as capillary electrophoresis. When used in conjunction with other technologies, it requires no or only a very small amount of replenishing liquid, which not only prevents sample dilution and sensitivity reduction, but also eliminates laminar flow interference caused by replenishing liquid flow, ensuring that the bands of the separated components do not broaden during transmission and maintaining high resolution.

[0017] The concentric parallel flow nebulizer provided by this invention has the advantages of high nebulization efficiency, good nebulization stability, low sample volume, near-zero self-absorption flow rate, easy clogging of the sample inlet tube, and tolerance to high salt and particulate matter. In addition, its detachable structure makes it easy to maintain. Its components are easy to process and any component can be easily replaced, so the use and maintenance costs are low. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only 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 The diagram and physical image of the concentric parallel flow atomizer are shown below. (a) is a structural diagram of the concentric parallel flow atomizer, and (b) is a physical image of the concentric parallel flow atomizer.

[0020] Figure 2 The images shown are micrographs of the outlet end of the pointed capillary inner tubes prepared in Examples 1 to 3, wherein (a) is a micrograph of the outlet end of the pointed capillary inner tube prepared in Example 1, (b) is a micrograph of the outlet end of the pointed capillary inner tube prepared in Example 2, and (c) is a micrograph of the outlet end of the pointed capillary inner tube prepared in Example 3.

[0021] Figure 3 The images show the atomization plume diagrams of the concentric parallel flow nebulizer and the conventional concentric nebulizer at different sample flow rates. (a.1) to (a.9) are the atomization plume diagrams of the concentric parallel flow nebulizer prepared in Example 4 at different sample flow rates, and (b.1) to (b.6) are the atomization plume diagrams of the conventional concentric nebulizer at different sample flow rates.

[0022] Figure 4 The signal strengths of the concentric parallel flow nebulizer prepared in Example 4 are shown under different nebulizing gas pressures, sample inlet flow rates, and relative distances between the outlet ends of the inner and outer tubes. Among them, (a) is the signal strength under different nebulizing gas pressures, (b) is the signal strength under different sample inlet flow rates, and (c) is the signal strength under different relative distances between the outlet ends of the inner and outer tubes.

[0023] Figure label: 1-Gas delivery tube, 2-Infusion tube, 3-Connecting tube, 31-Infusion inlet tube, 4-First connector, 5-Second connector. Detailed Implementation

[0024] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

[0025] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature and the second feature are in direct contact, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0030] Currently, researchers have developed and commercialized a series of novel nebulizers. For example, microfluidic nebulizers such as the High-Efficiency Nebulizer (HEN), Microconcentric Nebulizer (MCN), Microdroplet Nebulizer (MMN), and Direct Injection High-Efficiency Nebulizer (DIHEN) can efficiently atomize liquid samples in the range of 5–200 μL / min, and are applied to the analysis and speciation studies of trace samples. Other nebulizers, such as the SeaSpray concentric nebulizer, OneNeb flow field focusing nebulizer, MiraMist parallel flow nebulizer, and ultrasonic nebulizer, can directly atomize high-salt samples with a concentration of up to 20%, and the MiraMist parallel flow nebulizer has a near-zero self-aspiration flow rate. However, no single nebulizer can currently solve all of these problems simultaneously. Based on this, the present invention provides a self-priming concentric parallel flow nebulizer. The outlet end of the gas supply pipe 1 is flush with the outlet end of the liquid supply pipe 2, forming an annular channel between the gas supply pipe 1 and the liquid supply pipe 2 for transporting the sample solution. The nebulizing gas and the sample solution flow in the same axial direction to form a parallel flow, and the nebulizing gas directly atomizes the sample solution at the outlet end of the gas supply pipe 1, without creating negative pressure in the annular channel, thus achieving self-priming-free operation. Because the atomization of the sample solution occurs at the outlet end of the gas supply pipe, the nebulizing gas has the maximum kinetic energy at this point, resulting in a larger effective atomization area and thus higher atomization efficiency. Simultaneously, since the liquid sample flows out from the concentric large outer tube (with an inner diameter of 450μm to 530μm), pipe blockage caused by larger particles and high-salt crystals can be avoided.

[0031] A schematic diagram of the concentric parallel flow atomizer of the present invention is shown below. Figure 1 As shown in (a), it includes a gas delivery tube 1, a liquid delivery tube 2, and a connecting tube 3; the side wall of the connecting tube 3 is connected to a liquid inlet tube 31, the liquid inlet end of the liquid delivery tube 2 is inserted into one end of the connecting tube 3, and the liquid delivery tube 2 is connected to the liquid inlet tube 31; a part of the gas delivery tube 1 is inserted into the other end of the connecting tube 3 and extends into the liquid delivery tube 2; the gas delivery tube 1 and the liquid delivery tube 2 are coaxially arranged, and the outlet end of the gas delivery tube 1 is flush with the outlet end of the liquid delivery tube 2, forming a concentric structure; an annular channel is formed between the gas delivery tube 1 and the liquid delivery tube 2 for transporting the sample solution; the inlet of the gas delivery tube 1 is connected to an atomizing gas source for providing atomizing gas; the atomizing gas in the gas delivery tube 1 and the sample solution flow in the same direction along the axial direction to form a parallel flow; after the atomizing gas is transported to the outlet end through the gas delivery tube 1, it directly atomizes the sample solution flowing out of the liquid delivery tube 2, achieving non-self-absorption.

[0032] The gas delivery pipe 1 is a pointed capillary inner tube, which is formed by heating and drawing fused silica capillary tubes. The inner diameter of the fused silica capillary tube is 150μm to 320μm, and the outer diameter is 365μm or 450μm. The outer diameter of the outlet end of the pointed capillary inner tube is 21.6μm to 78.9μm, and the wall thickness is 6μm to 10μm.

[0033] The method for drawing the pointed capillary inner tube includes the following steps: A portion of a molten quartz capillary is heated in a flame until softened, while simultaneously being stretched in two opposite directions away from the center of the heated section to form a narrow diameter region. After the molten quartz capillary is removed from the flame and cooled, the narrow diameter region is heated in the flame again and rapidly stretched in two opposite directions until it breaks, resulting in a pointed capillary inner tube.

[0034] The infusion tube 2 is a capillary outer tube, which is a fused silica capillary tube (Hebei Yongnian Ruifeng Chromatography Devices Co., Ltd.). It is cut from a fused silica capillary tube with an inner diameter of 450μm or 530μm and an outer diameter of 690μm. The outlet end is polished to a symmetrical flat end with 600-grit sandpaper.

[0035] The connecting pipe 3 is a three-way connector, including a first interface, a second interface and a third interface. The first interface and the second interface are coaxially arranged. The first interface and the second interface are respectively provided with PEEK pipes. The gas supply pipe 1 passes through the first interface, the liquid supply pipe 2 passes through the second interface, and the third interface is connected to the liquid inlet pipe 31.

[0036] The outer diameter of the PEEK tube of the first interface of the tee connector is 1 / 16in, and the inner diameter is 0.4mm or 0.5mm. The outer diameter of the PEEK tube of the second interface of the tee connector is 1 / 16in, and the inner diameter is 0.75mm.

[0037] It also includes a first connector 4 and a second connector 5. The first connector 4 is coaxially sleeved on the outside of the infusion tube 2. One end of the second connector 5 is connected to the first connector 4, and the other end of the second connector 5 forms a supplementary gas passage with the outside of the infusion tube 2, used to deliver the aerosol generated after nebulization to the nebulization chamber. The first connector 4 is a straight connector made of plastic materials such as PTFE or PEEK, with an inner diameter of 1.55 mm and an outer diameter of 3.6 mm. The second connector 5 is a glass connecting tube, which is formed by two glass tubes with an inner diameter of 4 mm and an outer diameter of 6 mm perpendicularly intersecting. At the connection between the first connector 4 and the second connector 5, there are two annular grooves, each 1.4 mm wide and deep, for installing plastic O-rings to provide a seal and prevent leakage.

[0038] The second connector 5 has a supplementary air intake pipe connected to its side wall for providing supplementary air. The second connector 5 is a glass connecting tube.

[0039] Example 1 A method for preparing a pointed capillary inner tube: The pointed capillary inner tube is made from a fused silica capillary tube (Hebei Yongnian Ruifeng Chromatography Devices Co., Ltd.) with an inner diameter of 150 μm and an outer diameter of 365 μm through a two-step flame heating process. The specific process is as follows: a 10 cm long section of commercial fused silica capillary tube is cut, and a portion 2 cm from one end is placed in a n-butane flame to burn off the polyimide coating. Then, the heated portion of the fused silica capillary tube is moved into the outer flame of the n-butane flame to heat the fused silica capillary tube until it softens. At the same time, the fused silica capillary tube is stretched in two opposite directions away from the center of the heated section to form a narrow diameter region with an outer diameter of 150 μm (the narrowest point). Next, the fused silica capillary tube is removed from the n-butane flame and cooled for 5 seconds. The narrow diameter region is then moved back into the outer flame generated by an alcohol lamp to heat until it softens, and the fused silica capillary tube is quickly stretched in two opposite directions until it breaks. The fused silica capillary tube is split in two from the narrowest point to obtain the pointed capillary inner tube.

[0040] Example 2 A method for preparing a pointed capillary inner tube, prepared according to the method described in Example 1, the difference being that: the pointed capillary inner tube is formed by two steps of flame heating by drawing a fused quartz capillary tube with an inner diameter of 250 μm and an outer diameter of 365 μm.

[0041] Example 3 A method for preparing a pointed capillary inner tube, prepared according to the method described in Example 1, the difference being that: the pointed capillary inner tube is formed by two steps of flame heating by drawing a fused quartz capillary tube with an inner diameter of 320 μm and an outer diameter of 450 μm.

[0042] Figure 2 The pointed capillary inner tubes obtained by the above method using 150μm×365μm capillary tubes (a), 250μm×365μm capillary tubes (b), and 320μm×450μm capillary tubes (c) are, i.e. Figure 2 (a), (b), and (c) in the figures correspond to the pointed capillary inner tubes prepared in Examples 1 to 3, respectively. Five sets of repeated experiments were conducted, and the average value was taken. Based on the scale, their outer diameters were estimated to be 21.6±1.7μm, 41.6±3.6μm, and 78.9±8.6μm, respectively, and their wall thicknesses were approximately 8μm, 6μm, and 10μm.

[0043] Example 4 A non-self-priming concentric parallel flow atomizer includes a tapered capillary inner tube, a capillary outer tube, a PEEK tee connector, a PTFE straight connector (first connector 4, PTFE connector), and a glass connecting tube (second connector 5) as shown in Example 1. A physical image of the concentric parallel flow atomizer is shown below. Figure 1As shown in (b) of the diagram. With the concentric axis as the horizontal reference, PEEK tubes are provided on both the left and right horizontal ports of the PEEK tee connector. The left horizontal port is the first interface, and the right horizontal port is the second interface. The pointed capillary inner tube (i.e., the pointed capillary tube in the figure) passes sequentially through the PEEK tube (outer diameter is 1 / 16in, inner diameter depends on the pointed capillary inner tube, which is made of capillary tube with an outer diameter of 365μm and PEEK tube inner diameter of 0.4mm), the PEEK tee connector, and the capillary outer tube on the left side of the tee connector. Then, PEEK screws are used to fix and seal the left horizontal port of the PEEK tee connector to ensure that the outlet ends of the capillary outer tube and the pointed capillary inner tube are flush. The inlet end of the pointed capillary inner tube is connected to the argon cylinder for the flow of high-pressure atomized gas. The vertical port of the PEEK tee connector connects to one end of a PTFE tube of suitable length (1 / 16in outer diameter, 0.25–0.5mm inner diameter), secured and sealed with a PEEK screw. The other end of the PTFE tube connects to the peristaltic pump tubing or syringe pump standard for inductively coupled plasma mass spectrometry (ICP-MS). A capillary tube (450μm inner diameter, 690μm outer diameter fused silica capillary) passes through the PEEK tube (1 / 16in outer diameter, 0.75mm inner diameter, slightly shorter than the capillary tube) on the right side of the PEEK tee connector, secured and sealed to the right horizontal port of the PEEK tee connector with a PEEK screw. The inlet of the capillary tube connects to the vertical inlet of the PEEK tee for the flow of standard or sample solutions, which are introduced through the vertical inlet of the PEEK tee. The PEEK tube on the outside of the capillary outer tube (i.e., the PEEK tube on the right side of the PEEK tee connector) passes through the PTFE straight connector and is sealed and fixed. The PTFE straight connector is connected to the glass connecting tube. A layer of PTFE sealing film is wrapped around the O-ring of the PTFE straight connector for sealing and fixing, ensuring that the outlet ends of both the capillary outer tube and the pointed capillary inner tube extend outwards outwards through the glass connecting tube. The glass connecting tube is formed by two glass tubes with an inner diameter of 4mm and an outer diameter of 6mm perpendicularly intersecting each other: the total length of the vertical and horizontal tubes does not exceed 5cm. The vertical tube intersects the horizontal tube perpendicularly and does not penetrate the horizontal tube. The vertical tube is located at about 1 / 4 of the front end of the horizontal tube (i.e., the end closest to the PTFE straight connector). One end of the horizontal tube is connected to the PTFE straight connector, and the other end is connected to the nebulizer and the nebulization chamber of the plasma mass spectrometer. One end of the vertical tube is connected to the inside of the horizontal tube, and the other end is connected to another argon cylinder for the flow of low-pressure supplementary gas (carrier gas). Argon gas cylinders, peristaltic pumps, and other components and their connections can be made using conventional techniques in this field.

[0044] In this invention, parallel flow refers to the parallel flow direction of the atomizing gas flow and the sample liquid flow; concentricity refers to the concentric arrangement of the inner tube of the atomizing gas flow and the outer tube of the sample liquid flow. Since the atomizing gas flow exits from the inner tube, it does not create negative pressure around it (e.g., Venturi effect), thus eliminating self-absorption.

[0045] Example 5 A non-self-priming concentric parallel flow atomizer is prepared according to the method described in Example 4, with the difference being that: the pointed capillary inner tube is formed by two steps of flame heating from a fused silica capillary tube with an inner diameter of 320 μm and an outer diameter of 450 μm; the PEEK tube on the left side of the three-way connector has an inner diameter of 0.5 mm and an outer diameter of 1 / 16 in; and the capillary outer tube is a fused silica capillary tube with an inner diameter of 530 μm and an outer diameter of 690 μm.

[0046] Example 6 Microscopic observation of the atomization effect (atomized plume): The concentric parallel flow nebulizer prepared in Example 4 was fixed under a microscope. The nebulizing gas cylinder was opened, and the argon pressure was adjusted to 1 MPa. Distilled water was delivered to the capillary tube using a syringe pump. Videos of the aerodynamic nebulization were taken sequentially before spraying and at flow rates of 0.25 mL / min, 0.5 mL / min, 1.0 mL / min, 1.5 mL / min, 2.0 mL / min, 5.0 mL / min, 10 mL / min, and 15 mL / min. Images of stable nebulization were extracted using video processing software to obtain nebulization plume diagrams at different sample flow rates (e.g., ...). Figure 3 (As shown in (a.1) to (a.9)). For comparison, pneumatic nebulization videos of a conventional concentric nebulizer (TR-30-A1, Meinhard Glass Products, USA) were taken sequentially at sample flow rates of 0.1 mL / min, 0.25 mL / min, 0.5 mL / min, 1.0 mL / min, 1.5 mL / min, and 2.0 mL / min. Images of stable nebulization were extracted using video processing software to obtain nebulization plume diagrams at different sample flow rates (e.g., ...). Figure 3 (As shown in (b.1) to (b.6)).

[0047] Depend on Figure 3 It can be seen that the pneumatic atomization of samples by the concentric parallel flow nebulizer has three characteristics: 1. The atomizing gas is ejected from the nozzle of the pointed inner tube, and atomization occurs at the outlet, where the aerodynamic energy is the greatest; 2. The sample flows out from the concentric outer tube, resulting in a larger effective atomization area, which promotes atomization; 3. The atomization does not change with the increase of the sample inlet flow rate, and the stability is good. In contrast, the pneumatic atomization of conventional concentric nebulizers occurs in a region far from the nozzle (approximately five times the outer diameter of the inlet capillary), with lower aerodynamic energy, a smaller effective atomization area, and poorer atomization efficiency. Furthermore, as the sample inlet flow rate increases, the atomization center moves further away from the nozzle, and the atomization stability and efficiency gradually decrease.

[0048] Example 7 Optimization of conditions for concentric parallel flow atomizers: 1. Optimization of atomizing gas pressure and supplemental gas flow rate: The atomization efficiency of the concentric parallel flow atomizer of the present invention depends on the atomizing gas pressure, while the transmission efficiency of the atomized aerosol depends on the atomizing gas pressure and the supplementary gas flow rate. The concentric parallel flow atomizer prepared in Example 4 was inserted into the atomization chamber of a plasma mass spectrometer and the supplementary gas was connected. A 10 μg / L multi-element mixed standard solution (SPEX CertiPrep, USA) was introduced at a flow rate of 0.55 mL / min. The nebulizer gas pressure was sequentially fixed at 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, and 1.1 MPa. The supplementary gas flow rate was then increased or decreased (0.6–1.1 L / min) in the instrument control software to maximize the mass spectrometric signals of 12 mass numbers (7Li, 9Be, 55Mn, 59Co, 107Ag, 111Cd, 115In, 138Ba, 205Tl, 208Pb, 209Bi, and 238U). Their mass spectrometric signals were then acquired. Figure 4 The mass spectrometry signal shown in (a) is a result of the mass spectrometry signal versus the nebulizer gas pressure and the feed gas velocity. The nebulization efficiency is higher when the nebulizer gas pressure is ≥0.9 MPa, while the transmission efficiency is highest when the feed gas velocity is 0.77 L / min. The results indicate that the nebulizer gas pressure is much higher than that of conventional concentric nebulizers (typically below 0.3 MPa), and the nebulizer gas and carrier gas can be independently adjusted to achieve optimal nebulization and transmission.

[0049] 2. Optimization of injection flow rate: Using the nebulizer prepared in Example 4, with a fixed nebulizing gas pressure of 0.9 MPa and a supplementary gas flow rate of 0.77 L / min, a 10 μg / L multi-element mixed standard solution was introduced sequentially using the instrument's built-in peristaltic pump at flow rates of 0.15 mL / min, 0.28 mL / min, 0.41 mL / min, 0.55 mL / min, 0.68 mL / min, 0.82 mL / min, 1.09 mL / min, 1.37 mL / min, and 1.65 mL / min (corresponding to peristaltic pump speeds of 5, 10, 15, 20, 25, 30, 40, 50, and 60 rpm, respectively). Mass spectrometry signals of 12 mass numbers (7Li, 9Be, 55Mn, 59Co, 107Ag, 111Cd, 115In, 138Ba, 205Tl, 208Pb, 209Bi, and 238U) were collected. Figure 4 The mass spectrometry signal shown in (b) is a result of the mass spectrometry signal changing with the nebulizer gas pressure and the supplemental gas flow rate. When the injection flow rate is below 0.55 mL / min, the mass spectrometry signal increases linearly with the increase of the injection flow rate; when the injection flow rate is ≥0.55 mL / min, the mass spectrometry signal increases slowly. The results indicate that the concentric parallel flow nebulizer can obtain a good mass spectrometry signal at a relatively low injection flow rate, further demonstrating its high nebulization efficiency.

[0050] 3. Optimization of the relative distance between the inner and outer pipes: Using the nebulizer prepared in Example 4, with a fixed nebulizing gas pressure of 0.9 MPa and a supplementary gas flow rate of 0.77 L / min, a 10 μg / L multi-element mixed standard solution was introduced at a flow rate of 0.55 mL / min. The relative distance between the outlet ends of the pointed capillary inner tube and the outer capillary tube was changed sequentially (-0.25 mm, i.e., the pointed capillary inner tube retracts 0.25 mm into the outer capillary tube; +0.15 mm, i.e., the pointed capillary inner tube extends 0.15 mm out of the outer capillary tube). Mass spectrometry signals of 12 mass numbers (7Li, 9Be, 55Mn, 59Co, 107Ag, 111Cd, 115In, 138Ba, 205Tl, 208Pb, 209Bi, and 238U) were obtained. Figure 4 The mass spectrometry signal shown in (c) varies with the relative distance between the two components. The results indicate that the concentric parallel flow nebulizer has the highest atomization efficiency when the two components are aligned, but the mass spectrometry signal decreases slightly when the distance between them varies from -0.15 mm to +0.1 mm.

[0051] Example 8 Performance analysis of concentric parallel flow atomizers: Using the nebulizer prepared in Example 4, under optimal conditions (nebulizing gas pressure 0.9 MPa, supplemental gas flow rate 0.77 L / min, relative distance between inner and outer tubes 0), a 10 μg / L multi-element mixed standard solution was introduced at a flow rate of 0.55 mL / min. The sensitivity, detection limit (with ultrapure water as blank, S / N=3), and precision (n=10) of the concentric parallel flow nebulizer were determined at 12 mass numbers (7Li, 9Be, 55Mn, 59Co, 107Ag, 111Cd, 115In, 138Ba, 205Tl, 208Pb, 209Bi, and 238U). The results were compared with those of a conventional concentric nebulizer and a PFA nebulizer (PFA-400, Elemental Scientific) (all under their optimal experimental conditions). The results are shown in Table 1. The results show that the analytical performance of the concentric parallel flow atomizer is significantly better than that of the conventional concentric atomizer and the PFA atomizer, and the sample consumption is also lower than the latter two, proving that the concentric parallel flow atomizer of the present invention has better atomization efficiency and atomization stability.

[0052] Table 1. Performance Comparison of the Concentric Parallel Flow Atomizer of the Present Invention with Conventional Concentric Atomizers and PFA Atomizers Using the nebulizer prepared in Example 4, under optimal conditions (nebulizing gas pressure 0.9 MPa, supplemental gas flow rate 0.77 L / min, relative distance between inner and outer tubes 0), distilled water was used as the sample. The PTFE sample tube connected to the vertical port of the three-way connector was placed in a beaker containing distilled water. The concentric parallel flow nebulizer was operated in self-lift mode (without using a peristaltic pump or syringe pump to deliver the sample). The weight difference of the distilled water in the beaker before and after spraying (spraying time was 30 minutes) was measured, and the self-lift flow rate of the concentric parallel flow nebulizer (also called self-absorption flow rate, which is equal to the ratio of weight difference to spray time) was calculated. The measured self-lift flow rate of the concentric parallel flow nebulizer was less than 0.01 mL / min, which is far lower than that of conventional concentric nebulizers (1.0 mL / min), PFA nebulizers (0.5 mL / min), and other commercial nebulizers. This is beneficial for the coupling of chromatography (especially electrophoresis and electrochromatography) and inductively coupled plasma mass spectrometry.

[0053] Using the nebulizer prepared in Example 4, under optimal conditions (nebulizing gas pressure 0.9 MPa, supplementary gas flow rate 0.77 L / min, relative distance between inner and outer tubes 0), 10% m / m saline solution was pumped into the concentric parallel flow nebulizer at a flow rate of 1.65 mL / min using a peristaltic pump for spraying. The spray stability and nozzle condition were observed under a microscope. Observations showed that even after continuous spraying for 2 hours, the concentric parallel flow nebulizer could still stably atomize 10% m / m saline solution into an aerosol, and no visible salt crystals were observed at the nozzle.

[0054] Using the nebulizer prepared in Example 4, under optimal conditions (nebulizing gas pressure 0.9 MPa, supplementary gas flow rate 0.77 L / min, relative distance between inner and outer tubes 0), 10 mg / mL micron-sized silica gel (particle size less than 5 μm) was pumped into the concentric parallel flow nebulizer at a flow rate of 1.65 mL / min using a peristaltic pump. The spray stability and nozzle condition were observed under a microscope. Observations showed that even after 2 hours of continuous spraying, the concentric parallel flow nebulizer maintained stable spraying, and there was no clogging in the nozzle or capillary inner tube.

[0055] In summary, this invention relates to solution injection methods for inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS), particularly their interfaces for analyzing high-salt, suspended, or trace samples, and for coupling with micro / nano separation techniques such as capillary liquid chromatography, nano-liquid chromatography, capillary electrophoresis, and capillary electrochromatography. The concentric parallel flow nebulizer provided by this invention offers advantages such as high nebulization efficiency, good nebulization stability, low injection volume, near-zero self-absorption flow rate, resistance to clogging of the injection tube, and tolerance to high salt and particulate matter. Furthermore, its detachable structure facilitates maintenance, and its components are easy to manufacture and replace, resulting in low usage and maintenance costs.

[0056] It should be noted that the connection relationships of components not specifically mentioned in this invention are all assumed to be based on existing technology. Since they do not involve the inventive point and are commonly used in existing technology, the structural connection relationships are not described in detail.

[0057] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the inventive concept of this invention, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0058] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A non-self-priming concentric parallel flow atomizer, comprising an air supply pipe (1), an infusion pipe (2), and a connecting pipe (3), characterized in that, The side wall of the connecting pipe (3) is connected to the inlet pipe (31), the inlet end of the infusion pipe (2) is inserted into one end of the connecting pipe (3), and the infusion pipe (2) is connected to the inlet pipe (31); A portion of the gas delivery tube (1) is inserted into the other end of the connecting tube (3) and extends into the infusion tube (2); the gas delivery tube (1) and the infusion tube (2) are coaxially arranged, and the outlet end of the gas delivery tube (1) is flush with the outlet end of the infusion tube (2); the inlet of the gas delivery tube (1) is connected to an atomizing gas source to provide atomizing gas; after the atomizing gas is delivered to the outlet end through the gas delivery tube (1), it atomizes the sample solution flowing out of the infusion tube (2).

2. The non-self-priming concentric parallel flow atomizer according to claim 1, characterized in that, The gas transmission pipe (1) is a pointed capillary inner tube, which is made by heating and drawing molten quartz capillary tube.

3. The non-self-priming concentric parallel flow atomizer according to claim 2, characterized in that, The outer diameter of the outlet end of the pointed capillary inner tube is 21.6μm to 78.9μm, and the wall thickness is 6μm to 10μm.

4. The non-self-priming concentric parallel flow atomizer according to claim 2, characterized in that, The inner diameter of the fused silica capillary is 150μm to 320μm, and the outer diameter is 365μm to 450μm.

5. The non-self-priming concentric parallel flow atomizer according to claim 1, characterized in that, The infusion tube (2) is a capillary tube, which is made by cutting fused silica capillary tubes. The inner diameter of the capillary tube is 450μm~530μm and the outer diameter is 690μm.

6. The non-self-priming concentric parallel flow atomizer according to claim 1, characterized in that, The connecting pipe (3) includes a first interface, a second interface and a third interface. The first interface and the second interface are coaxially arranged. The gas delivery pipe (1) passes through the first interface, the liquid delivery pipe (2) passes through the second interface, and the third interface is connected to the liquid inlet pipe (31).

7. The non-self-priming concentric parallel flow atomizer according to claim 1, characterized in that, It also includes a first connector (4) and a second connector (5). The first connector (4) is coaxially sleeved on the outside of the infusion tube (2). One end of the second connector (5) is connected to the first connector (4), and the other end of the second connector (5) forms a supplementary gas passage with the outside of the infusion tube (2) to deliver the aerosol generated after atomization to the atomization chamber.

8. The non-self-priming concentric parallel flow atomizer according to claim 7, characterized in that, The first connector (4) is made of polytetrafluoroethylene or polyetheretherketone.

9. The non-self-priming concentric parallel flow atomizer according to claim 7, characterized in that, The side wall of the second connector (5) is connected to a supplementary air intake pipe for providing supplementary air.

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