Ionization device and method based on airflow hedging assistance

Abstract

The invention belongs to a mass spectrometry technology, and particularly provides an ionization device and method based on airflow hedging assistance, the ionization device comprises a vacuum cavity, a first electrospray ion source and a sample introduction cone, the first electrospray ion source and the sample introduction cone are respectively arranged in the vacuum cavity; the exhaust pipe is arranged in the vacuum cavity; the central axis of a nozzle of the first electrospray ion source is perpendicular to the central axis of the sample injection cone, the central axis of the sample injection cone penetrates through an exhaust port of the exhaust pipe, and the exhaust port, the central axis of the nozzle and a sample injection port of the sample injection cone are sequentially arranged; the air inlet pipe is arranged in the vacuum cavity, and the nozzle and an outlet of the air inlet pipe are symmetrical about the central axis of the sampling cone; the power supply applies different voltages to the spray ion source, the air inlet pipe, the exhaust port and the sample injection cone to form an electric field, and the electric field pushes sample ions to pass through the sample injection port. The invention has the advantages of high atomization efficiency, strong anti-pollution capability and the like.

Description

Technical Field

[0001] The present invention relates to mass spectrometry technology, and particularly to an ionization device and method assisted by air flow counteracting. Background Art

[0002] After ions leave the electrospray capillary in an electrospray ion source, under the action of the nebulizing sheath gas, they present a fan-shaped spray pattern. At the same time, in order to further promote the desolvation effect of droplets, heated high-temperature gas is usually applied on both sides of the spray for auxiliary atomization, so that charged droplets can form gaseous ion state as soon as possible before entering the mass spectrometry sampling port, improving the detection signal-to-noise ratio. However, due to the more significant effect of the airflow on the outermost atomized droplets, the size of the atomized droplets shows a distribution state where the droplets are larger closer to the axis and smaller farther away from the axis in the radial direction.

[0003] In order to slow down the uneven distribution of droplets caused by the airflow, existing patents use the principle of turbulence, and use two heated airflows to form a V-shaped oblique injection towards the spray airflow, thus creating irregular turbulence of the atomized droplets and reducing the non-uniformity. At the same time, in order to improve the ion signal-to-noise ratio, a non-coaxial sampling method is adopted to reduce the interference of neutral particles on charged sample ions. However, this method still does not fully turbulentize the atomizing airflow, and due to the design of the orthogonal sampling port, most of the atomizing area is not effectively sampled, and the sampling efficiency of ions is less than 10%, resulting in both the atomization efficiency and the sampling efficiency being lower than the requirements. Summary of the Invention

[0004] To solve the deficiencies in the above-mentioned prior art solutions, the present invention provides an ionization device assisted by air flow counteracting.

[0005] The object of the present invention is achieved through the following technical solutions: An ionization device assisted by air flow counteracting includes a vacuum chamber, a first electrospray ion source and an inlet cone, and the first electrospray ion source and the inlet cone are respectively arranged in the vacuum chamber; the ionization device further includes: An exhaust pipe, which is arranged in the vacuum chamber; the central axis of the nozzle of the first electrospray ion source is perpendicular to the central axis of the inlet cone, the central axis of the inlet cone passes through the exhaust port of the exhaust pipe, and the exhaust port, the central axis of the nozzle and the inlet of the inlet cone are arranged in sequence; An inlet pipe, which is arranged in the vacuum chamber, and the nozzle and the outlet of the inlet pipe are symmetrical about the central axis of the inlet cone; A power supply, which applies different voltages to the spray ion source, the inlet pipe, the exhaust pipe and the inlet cone to form an electric field, and the electric field pushes the sample ions through the inlet.

[0006] The object of the present invention also lies in providing an ionization method, and this object of the invention is achieved through the following technical solutions: An ionization method based on the ionization device of the present invention, comprising the steps of: (A1) The first electrospray ionization source operates, and the sample is ionized; meanwhile, a first gas is ejected from the intake pipe and mixed with the sheath gas ejected from the first electrospray ionization source to form a turbulent region, and the ejection directions of the sheath gas and the first gas are opposite; (A2) The neutral gas in the turbulent region flows towards the sample introduction cone and enters the exhaust pipe; Meanwhile, under the driving of the electric field between the exhaust pipe and the sample introduction cone, the sample ions in the turbulent region pass through the sample inlet of the sample introduction cone.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention proposes a droplet atomization technology and an ion repulsion sampling technology assisted by air flow counteraction. By introducing a counteracting air flow opposite to the spraying direction of the ion source, a forced turbulent mixing region is formed near the mass spectrometry sampling port, promoting sufficient atomization and desolvation of charged droplets. At the same time, an exhaust gas design coaxial with the mass spectrometry sampling port is set to ensure that the neutral particles in the forced mixing region after the turbulent effect are discharged from the vacuum chamber under the action of the second gas (discharged from the sample inlet of the sample introduction cone) and the air flow in the exhaust pipe, reducing the interference of neutral particles entering the mass spectrometry, thereby achieving: 1. Improving the atomization efficiency of the sample and increasing the ionization level; 2. Avoiding the pollution of the mass spectrometry sampling port and the pre-stage chamber caused by non-uniform atomization, reducing the desolvation pressure of the sampling port, and improving the anti-pollution ability; 3. Improving the desolvation effect of the sample ions and the sampling efficiency of the target ions; 4. Improving the detection signal-to-noise ratio and the detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Referring to the accompanying drawings, the disclosure of the present invention will become more understandable. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention. In the figures: Figure 1 is a schematic structural diagram of the ionization device of the present invention; Figure 2 is a schematic side view structural diagram of the ionization device of the present invention; Figure 3 is a schematic structural diagram of another ionization device of the present invention; Figure 4 is a schematic side view structural diagram of another ionization device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Figures 1 - 4 The following description and illustration depict alternative specific embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. To teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art should understand that variations or substitutions derived from these specific embodiments will fall within the scope of the present invention. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following alternative specific embodiments, but is only defined by the claims and their equivalents. Example 1

[0010] This example is based on an ionization device assisted by counter-flow air, such as Figures 1 - 2 shown, the ionization device includes: A vacuum chamber 61, a first electrospray ion source 21, and an inlet cone 41. The first electrospray ion source 21 and the inlet cone 41 are respectively disposed within the vacuum chamber 61. The inlet cone 41 has a gas channel, and the gas channel communicates with the inlet port 42. The second gas sequentially passes through the gas channel and the inlet port 42 and flows towards the exhaust port 12.

[0011] An exhaust pipe 11 is disposed within the vacuum chamber 61, having a plurality of through holes 13 on the outside and an exhaust port 12 at the end. The central axis of the nozzle of the first electrospray ion source 21 is perpendicular to the central axis of the inlet cone 41. The central axis of the inlet cone 41 passes through the exhaust port 12 of the exhaust pipe 11. The exhaust port 12, the central axis of the nozzle, and the inlet port 42 of the inlet cone 41 are sequentially arranged. The central axis of the exhaust pipe 11 and the central axis of the inlet cone 41 are collinear.

[0012] An inlet pipe 31 is disposed within the vacuum chamber 61, and the output end communicates with a pump. The nozzle and the outlet of the inlet pipe 31 are symmetric about the central axis of the inlet cone 41. The first gas discharged from the inlet pipe 31 uses the sheath gas of the first electrospray ion source 21 and has the same flow rate, such as using pure nitrogen. The sheath gas and the first gas flow in opposite directions, forming a turbulent region 51 at the gas intersection. The second gas flowing out of the inlet port 42 is mixed with the gas in the turbulent region 51, and then passes through the exhaust port 12 into the exhaust pipe 11 and is discharged downstream under the suction of the pump.

[0013] A power supply applies different voltages to the spray ion source 21, the exhaust port 12, and the inlet cone 41 to form an electric field, and the electric field drives the sample ions to pass through the inlet port 42.

[0014] In the positive ion mode, the voltage x applied to the spray needle 22 of the first electrospray ion source 21 is 1000V - 5000V, the voltage y applied to the exhaust port 12 is 0 - 10000V, the voltage applied to the inlet pipe 31 is 0 - 500V, and the voltage applied to the sampling cone 41 is 0 - 1000V; in the negative ion mode, the above voltages are negative voltages. The voltage x applied to the spray needle 22 of the first electrospray ion source 21 and the voltage y applied to the exhaust port 12 satisfy: y = 1.63x - 310.3, thereby forming an effective gradient electric field distributed from the turbulent region 51 to the sampling port 42 within the turbulent region 51, driving the ions within the turbulent region 51 to move towards the sampling port 42.

[0015] The ionization method of this embodiment, that is, the working method based on the ionization device of this embodiment, includes the steps: (A1) The first electrospray ion source 21 operates, and the sample is ionized.

[0016] Meanwhile, the inlet pipe 31 ejects the first gas, which mixes with the sheath gas ejected by the first electrospray ion source 21. The first gas and the sheath gas flowing in opposite directions collide, forming the turbulent region 51.

[0017] (A2) The second gas sequentially passes through the gas channel of the sampling cone 41 and the sampling port 42, flows towards the exhaust port 12, pushes the neutral gas and neutral particles within the turbulent region 51, and then passes through the exhaust port 12 and enters the exhaust pipe 11.

[0018] Meanwhile, under the drive of the electric field between the exhaust pipe 11 and the sampling cone 41, the sample ions in the turbulent region 51 pass through the sampling port 42 of the sampling cone 41. Embodiment 2

[0019] The ionization device based on air flow collision assistance in this embodiment is different from Embodiment 1 in that: As Figures 3 - 4 shown, instead of using a separate inlet pipe, a second electrospray ion source is used. The second electrospray ion source 23 and the first electrospray ion source 21 are symmetric about the central axis of the sampling cone 41, that is, the inlet pipe 31 and the sheath gas pipe of the second electrospray ion source 23 share the same pipe, thereby serving the role of providing the first gas.

[0020] In the positive ion mode, the voltage x applied to the spray needle 22 of the first electrospray ion source 21 is 1000V - 5000V, the voltage y applied to the spray needle 24 of the second electrospray ion source 23 is 1000V - 5000V, the voltage z applied to the exhaust port 12 is 0 - 10000V, and the voltage applied to the sampling cone 41 is 0 - 1000V; in the negative ion mode, the above voltages are negative voltages.

[0021] The voltage x applied to the spray needle 22 of the first electrospray ion source 21, the voltage y applied to the spray needle 24 of the second electrospray ion source 23, and the voltage z applied to the exhaust port 12 satisfy: z = 1.63·[max(x, y)] - 0.04·[min(x, y)] - 310.3, so as to form an effective gradient electric field distributed from the turbulent region 51 to the sampling port 42 in the turbulent region 51, driving the ions in the turbulent region 51 to move towards the sampling port 42.

[0022] In the ionization method of this embodiment, the working modes of the first electrospray ion source 21 and the second electrospray ion source 23 are as follows: The samples in the first electrospray ion source 21 and the second electrospray ion source 23 can be the same or different. For the same sample, all parameters need to be set to be consistent to form a symmetric counter-flow spray, enhancing the turbulence and desolvation effects. For different samples, they can be simultaneously injected through the dual electrospray ion source. On the one hand, it can improve the sample injection flux (if there are two electrospray ion sources, it is twice; if there are n electrospray ion sources, it is n times). On the other hand, according to the characteristics of the sample and the mobile phase, two or more matching mobile phases can be selected, and the samples can be injected separately from two or more ion sources, which can improve the ionization efficiency of the corresponding samples, thereby improving the signal-to-noise ratio and detection sensitivity of ion detection.

[0023] Under this condition, the first electrospray ion source 21 and the second electrospray ion source 23 can also be injected at different times. At this time, pure nitrogen gas is still sprayed in the sheath gas pipes of the ion sources that are not injecting samples and are opposite to each other. Example 3

[0024] Application of the ionization device and method based on air flow counter-flow assistance according to Embodiment 1 of the present invention in the ionization of reserpine and chloramphenicol.

[0025] For reserpine, when performing mass spectrometry detection in the positive ion mode, reserpine is first input into the ion source through the spray needle 22 of the first electrospray ion source 21. At the same time, a high voltage of 5500V is applied to the spray needle 22 of the first electrospray ion source 21 to ensure that the sample forms charged reserpine droplets. Under the action of the sheath gas, the charged droplets gradually flow towards the turbulent region 51. At the same time, due to the inlet pipe 31 discharging pure nitrogen gas with the same properties and flow rate as the first electrospray ion source 21, the two symmetric airflows collide and impact in the turbulent region 51, and the charged droplets are gradually cracked into atomized gas while the speed decreases.

[0026] To ensure the smooth entry of reserpine ions into the sampling port 42, high voltages need to be applied to the exhaust port 12, the sampling cone 41, and the intake pipe 31 simultaneously. A high voltage of 500 V is applied to the sampling cone 41, and a high voltage of 0 V is applied to the intake pipe 31. The high voltage z required for the exhaust port 12 is 1.63 * 5500 V - 310.3 V = 8654.7 V, thereby forming a relatively optimal gradient electric field from the turbulent region 51 to the sampling port 42. Under the combined action of the flow field and the electric field, the reserpine ions smoothly enter the sampling port 42, and a part of the neutral gas flow turns back after encountering the second gas (pure nitrogen gas) blown out by the sampling cone 41 and is sent into the exhaust system under negative pressure by the exhaust port 12 together with other gas flows.

[0027] For chloramphenicol, when performing mass spectrometry detection in the negative ion mode, the sampling process is the same as the above-mentioned reserpine sampling process. According to the voltage application method described in Example 1, a high voltage of -4500 V is applied to the spray needle 22 of the first electrospray ion source 21, a high voltage of -500 V is applied to the sampling cone 41, a high voltage of 0 V is applied to the intake pipe 31, and a high voltage of -7645.3 V is applied to the exhaust port 12.

[0028] The above embodiments only exemplarily show the use of two electrospray ion sources with opposite positions. Of course, there can be more, and the number is even, such as 4, 6, 8, etc., and they are opposite to each other (symmetrically arranged about the central axis of the sampling port 42).

Claims

1. An ionization device based on airflow counter-assistance comprises a vacuum chamber, a first electrospray ion source and an injection cone, wherein the first electrospray ion source and the injection cone are respectively arranged in the vacuum chamber; characterized in that: The ionization device also includes: An exhaust pipe, wherein the exhaust pipe is arranged in the vacuum chamber; the central axis of the nozzle of the first electrospray ion source is perpendicular to the central axis of the injection cone, the central axis of the injection cone passes through the exhaust port of the exhaust pipe, and the exhaust port, the central axis of the nozzle and the injection port of the injection cone are arranged in sequence; An air inlet pipe, the air inlet pipe is arranged in the vacuum chamber, and the nozzle and the outlet of the air inlet pipe are symmetrical about the central axis of the injection cone; A power supply applies different voltages to the spray ion source, the exhaust port and the injection cone to form an electric field, and the electric field pushes the sample ions to pass through the injection port.

2. The ionization device according to claim 1, characterized in that The central axis of the exhaust pipe and the central axis of the injection cone are collinear.

3. The ionization device according to claim 1, characterized in that The gas discharged from the air inlet pipe is the sheath gas of the first electrospray ion source, and the flow rate is the same.

4. The ionization device according to claim 1, characterized in that The injection cone has a gas channel connected to the injection port; the gas passes through the gas channel and the injection port in sequence, flows toward the exhaust port, mixes with the sheath gas discharged from the first electrospray ion source and the symmetrical gas discharged from the intake pipe, and then passes through the exhaust port into the exhaust pipe.

5. The ionization device according to claim 1, characterized in that In the positive ion mode, the voltage x applied to the spray needle of the first electrospray ion source is 1000V-5000V, the voltage y applied to the exhaust port is 0-10000V, the voltage 0-500V is applied to the inlet pipe, and the voltage 0-1000V is applied to the injection cone; in the negative ion mode, the above voltages are negative voltages.

6. The ionization device according to claim 5, characterized in that The voltage x applied to the spray needle of the first electrospray ion source and the voltage y applied to the exhaust port satisfy: y=1.63x-310.

3.

7. The ionization device according to claim 1, characterized in that The ionization device further comprises a second electrospray ion source, the second electrospray ion source and the first electrospray ion source are symmetrical about the central axis of the injection cone, and the air inlet pipe and the sheath air pipe of the second electrospray ion source are shared; In positive ion mode, the voltage x applied to the spray needle of the first electrospray ion source is 1000V-5000V, the voltage y applied to the spray needle of the second electrospray ion source is 1000V-5000V, the voltage z applied to the exhaust port is 0-10000V, and the voltage of 0-1000V is applied to the injection cone; in negative ion mode, the above voltages are negative voltages.

8. The ionization device according to claim 7, characterized in that The voltage x applied to the spray needle of the first electrospray ion source, the voltage y applied to the spray needle of the second electrospray ion source, and the voltage z applied to the exhaust port satisfy: z=1.63·[max(x,y)]-0.04·[min(x,y)]-310.

3.

9. An ionization method based on airflow counter-assistance, characterized in that: The ionization method comprises the steps of: (A1) The first electrospray ion source is working, and the sample is ionized; at the same time, the first gas is ejected from the gas inlet pipe and mixed with the sheath gas ejected from the first electrospray ion source to form a turbulent zone, and the sheath gas and the first gas are ejected in opposite directions; (A2) The neutral gas in the turbulent zone flows away from the injection cone and enters the exhaust pipe; At the same time, driven by the electric field between the exhaust port and the injection cone, the sample ions in the turbulent region pass through the injection port of the injection cone.

10. The ionization method according to claim 9, characterized in that: The second gas passes through the gas channel and the sampling port of the sampling cone in sequence, flows toward the exhaust port, pushes the neutral gas in the turbulent area, and then passes through the exhaust port into the exhaust pipe.

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