Ionization device and method based on airflow counter-assistance

Abstract

The present invention relates to mass spectrometry technology and specifically provides an ionization device and method based on airflow counterflow assistance. The ionization device includes a vacuum chamber, a first electrospray ion source, and an injection cone, wherein the first electrospray ion source and the injection cone are respectively disposed within the vacuum chamber; an exhaust pipe is disposed within 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 sequentially disposed; an intake pipe is disposed within the vacuum chamber, and the nozzle and the outlet of the intake pipe are symmetrical about the central axis of the injection cone; and a power supply applies different voltages to the spray ion source, the intake pipe, the exhaust port, and the injection cone to form an electric field, which propels sample ions through the injection port. The present invention has the advantages of high atomization efficiency and strong anti-contamination capability.

Description

Technical Field

[0001] The present invention relates to mass spectrometry technology, and in particular to an ionization device and method based on airflow counter-flow assistance. Background Art

[0002] After the ions leave the electrospray capillary, the electrospray ion source presents a fan-shaped spray pattern under the action of the atomizing sheath gas. At the same time, to further promote the desolvation effect of the droplets, heated high-temperature gas is usually applied on both sides of the spray to assist in atomization, so that the charged droplets can quickly form a gaseous ion state before entering the mass spectrometer sampling port, thereby improving the detection signal-to-noise ratio. However, because the interaction between the atomized droplets at the periphery and the airflow is more significant, the size of the atomized droplets in the radial direction shows a distribution pattern in which the droplets are larger the closer to the axis and the smaller the droplets are farther away from the axis.

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

[0004] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides an ionization device based on airflow counter-flow assistance.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] An ionization device based on airflow counter-flow assistance includes 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; the ionization device also includes:

[0007] an exhaust pipe disposed in the vacuum chamber; a 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 disposed in sequence;

[0008] 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;

[0009] A power supply applies different voltages to the spray ion source, the air inlet pipe, the exhaust pipe and the injection cone to form an electric field, and the electric field pushes the sample ions to pass through the injection port.

[0010] The present invention also aims to provide an ionization method, which is achieved through the following technical solutions:

[0011] The ionization method based on the ionization device of the present invention comprises the steps of:

[0012] (A1) The first electrospray ionization source operates to ionize the sample; simultaneously, the first gas is ejected from the gas inlet pipe and mixed with the sheath gas ejected from the first electrospray ionization source to form a turbulent region, with the sheath gas and the first gas ejected in opposite directions;

[0013] (A2) The neutral gas in the turbulent region flows away from the injection cone and enters the exhaust pipe;

[0014] At the same time, driven by the electric field between the exhaust pipe and the injection cone, the sample ions in the turbulent region pass through the injection port of the injection cone.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] This invention proposes a droplet atomization technology and ion repulsion injection technology based on airflow counterflow. By introducing a counterflow airflow opposite to the ion source spray direction, a forced turbulent mixing zone is formed near the mass spectrometer inlet, promoting sufficient atomization and desolvation of the charged droplets. A coaxial exhaust gas design is also provided with the mass spectrometer inlet to ensure that neutral particles in the forced mixing zone after turbulent flow are discharged from the vacuum chamber by the airflow of the second gas (exhausted from the injection cone inlet) and the exhaust pipe, thereby reducing the interference of neutral particles entering the mass spectrometer. This achieves the following:

[0017] 1. Improve sample atomization efficiency and increase ionization level;

[0018] 2. Avoid the contamination of the mass spectrometer inlet and front stage cavity caused by non-uniform atomization, reduce the desolvation pressure of the inlet, and improve the anti-pollution ability;

[0019] 3. Improve the desolvation effect of sample ions and improve the sampling efficiency of target ions;

[0020] 4. Improve the detection signal-to-noise ratio and improve the detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that these drawings are merely used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] Figure 1 It is a simplified structural diagram of the ionization device of the present invention;

[0023] Figure 2 is a schematic side view of the ionization device of the present invention;

[0024] Figure 3 is a simplified structural diagram of another ionization device of the present invention;

[0025] Figure 4 It is a side view schematic diagram of another ionization device of the present invention. DETAILED DESCRIPTION

[0026] Figures 1-4 The following description describes optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations or substitutions derived from these embodiments will be within the scope of the present invention. Those skilled in the art will 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 optional embodiments, but is limited only by the claims and their equivalents. Example 1

[0027] This embodiment is based on an ionization device assisted by airflow counter-flow, such as Figure 1-Figure 2 As shown, the ionization device includes:

[0028] The vacuum chamber 61, the first electrospray ion source 21, and the injection cone 41 are respectively disposed within the vacuum chamber 61. The injection cone 41 has a gas channel therein, which is connected to the injection port 42. The second gas flows through the gas channel and the injection port 42 in sequence toward the exhaust port 12.

[0029] An exhaust pipe 11 is disposed within the vacuum chamber 61 and has a plurality of through-holes 13 extending therethrough on its outer side. An exhaust port 12 is formed at its end. The central axis of the nozzle of the first electrospray ion source 21 is perpendicular to the central axis of the injection cone 41. The central axis of the injection 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 injection port 42 of the injection cone 41 are disposed sequentially, and the central axes of the exhaust pipe 11 and the injection cone 41 are collinear.

[0030] The air inlet pipe 31 is disposed within the vacuum chamber 61, with its output end connected to a pump. The nozzle and the outlet of the air inlet pipe 31 are symmetrical about the central axis of the injection cone 41. The first gas discharged from the air inlet pipe 31 uses the sheath gas of the first electrospray ion source 21, and has the same flow rate, such as pure nitrogen. The sheath gas and the first gas flow in opposite directions, forming a turbulent zone 51 at the intersection of the gases. The second gas flowing out of the injection port 42 mixes with the gas in the turbulent zone 51, then passes through the exhaust port 12 into the exhaust pipe 11, and is discharged downstream under suction by the pump.

[0031] The power supply applies different voltages to the spray ion source 21 , the exhaust port 12 and the injection cone 41 to form an electric field, which pushes the sample ions to pass through the injection port 42 .

[0032] In 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 injection cone 41 is 0-1000V. In negative ion mode, the above voltages are negative. 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 the following relationship: y = 1.63x - 310.3, thereby forming an effective gradient electric field within the turbulent region 51 extending from the turbulent region 51 to the injection port 42, driving ions within the turbulent region 51 toward the injection port 42.

[0033] The ionization method of this embodiment, that is, the working method of the ionization device of this embodiment, includes the following steps:

[0034] (A1) The first electrospray ion source 21 operates and the sample is ionized.

[0035] At the same time, the first gas ejected from the gas inlet pipe 31 is mixed with the sheath gas ejected from the first electrospray ion source 21 , and the first gas and the sheath gas in opposite directions collide with each other to form a turbulent zone 51 .

[0036] (A2) The second gas passes through the gas channel and the sampling port 42 of the sampling cone 41 in sequence, flows toward the exhaust port 12 , pushes the neutral gas and neutral particles in the turbulent zone 51 , and then passes through the exhaust port 12 into the exhaust pipe 11 .

[0037] At the same time, driven by the electric field between the exhaust pipe 11 and the injection cone 41 , the sample ions in the turbulent region 51 pass through the injection port 42 of the injection cone 41 . Example 2

[0038] This embodiment is based on an ionization device assisted by airflow counter-flow, and is different from the first embodiment in that:

[0039] like Figure 3-Figure 4 As shown, a separate air inlet pipe is no longer used, but a second electrospray ion source is used. The second electrospray ion source 23 and the first electrospray ion source 21 are symmetrical about the central axis of the injection cone 41, that is, the air inlet pipe 31 and the sheath gas pipe of the second electrospray ion source 23 are shared, thereby providing the first gas.

[0040] 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 of 0-1000V is applied to the injection cone 41; in the negative ion mode, the above voltages are negative voltages.

[0041] 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, thereby forming an effective gradient electric field distributed from the turbulent zone 51 to the injection port 42 in the turbulent zone 51, driving the ions in the turbulent zone 51 to move toward the injection port 42.

[0042] In the ionization method of this embodiment, the first electrospray ion source 21 and the second electrospray ion source 23 operate as follows:

[0043] 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 symmetrical counter-spray spray to enhance turbulence and desolvation effects. For different samples, dual electrospray ion sources can be used for simultaneous injection. On the one hand, the sample injection flux can be increased (twice if there are two electrospray ion sources, and n times if there are n electrospray ion sources). On the other hand, two or more matching mobile phases can be selected based on the characteristics of the sample and the mobile phase. Injecting the samples separately from two or more ion sources can improve the ionization efficiency of the corresponding sample, thereby improving the detection signal-to-noise ratio and detection sensitivity of the ions.

[0044] Under this condition, the first electrospray ion source 21 and the second electrospray ion source 23 can also be used to inject samples at different times. In this case, no sample is injected and the relative ion source sheath gas pipes are still spraying pure nitrogen. Example 3

[0045] According to Example 1 of the present invention, an ionization device and method based on airflow counterflow assistance are used in the ionization of reserpine and chloramphenicol.

[0046] When mass spectrometry is performed in positive ion mode for reserpine, reserpine is first introduced into the ion source via the spray needle 22 of the first electrospray ion source 21. Simultaneously, 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 influence of the sheath gas, the charged droplets gradually flow toward the turbulent region 51. Simultaneously, because the inlet pipe 31 discharges pure nitrogen gas with the same properties and flow rate as the first electrospray ion source 21, the two symmetrical gas flows collide in the turbulent region 51, gradually pyrolyzing the charged droplets into atomized gas while simultaneously decreasing in velocity.

[0047] To ensure smooth entry of reserpine ions into the injection port 42, high voltage must be applied simultaneously to the exhaust port 12, the injection cone 41, and the inlet pipe 31. A high voltage of 500V is applied to the injection cone 41, and 0V is applied to the inlet pipe 31. The high voltage required at the exhaust port 12 is z = 1.63 * 5500V - 310.3V = 8654.7V, thereby creating an optimal gradient electric field from the turbulent region 51 to the injection port 42. The combined effects of the flow and electric fields allow reserpine ions to smoothly enter the injection port 42. A portion of the neutral gas flow, upon encountering the second gas (pure nitrogen) expelled from the injection cone 41, is then deflected and, along with the rest of the gas flow, is delivered into the exhaust system at negative pressure through the exhaust port 12.

[0048] For chloramphenicol, when mass spectrometry detection is performed in negative ion mode, the injection process is consistent with the reserpine injection process described above. 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 injection cone 41, a high voltage of 0 V is applied to the air inlet pipe 31, and a high voltage of -7645.3 V is applied to the exhaust port 12.

[0049] The above embodiment is merely an example of using two electrospray ion sources positioned opposite to each other. Of course, there can be more, an even number such as 4, 6, 8, etc., which are positioned opposite to each other (symmetrically arranged about the central axis of the injection port 42).

Claims

1. An ionization device based on airflow counter-flow assistance, comprising 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 further comprises: an exhaust pipe disposed in the vacuum chamber; a 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 disposed 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, wherein the power supply applies different voltages to the spray ion source, the exhaust port, and the injection cone to form an electric field, which pushes the sample ions through the injection port; A gas channel is provided in the injection cone, which is 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.

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, wherein 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, wherein 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 applied to the inlet pipe is 0-500V, and the voltage applied to the injection cone is 0-1000V; in the negative ion mode, the above voltages are negative voltages.

5. The ionization device according to claim 4, 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.

6. The ionization device according to claim 1, characterized in that The ionization device also includes a second electrospray ion source, which is symmetrical with the first electrospray ion source 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 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 spray needle of the second electrospray ion source is 1000V-5000V, the voltage z applied to the exhaust port is 0-10000V, and the injection cone is applied with a voltage of 0-1000V; in the negative ion mode, the above voltages are negative voltages.

7. The ionization device according to claim 6, 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.

8. An ionization method based on airflow counter-flow assistance implemented by the ionization device according to claim 1, characterized in that: The ionization method comprises the steps of: (A1) The first electrospray ionization source is operating, and the sample is ionized. Simultaneously, the first gas is ejected from the gas inlet pipe and mixes with the sheath gas ejected from the first electrospray ionization source, forming a turbulent region. The sheath gas and the first gas are ejected in opposite directions. (A2) the second gas sequentially passes through the gas channel and the injection port of the sampling cone and flows toward the exhaust port of the exhaust pipe, pushing the neutral gas in the turbulent region to flow away from the injection cone, and then passes through the exhaust port 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.

9. The ionization method according to claim 8, 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 applied to the inlet pipe is 0-500V, and the voltage applied to the injection cone is 0-1000V; in the negative ion mode, the above voltages are negative voltages.

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