A method of electrospray ionization based on plasma atomization gas assistance

Abstract

The application discloses a kind of based on plasma atomization gas auxiliary electric spray ionization method, comprising the following steps: a) sample solution is introduced into electric spray needle;B) open plasma initiation device, make plasma initiation device discharge and generate plasma in plasma atomization gas gas path;C) atomization gas is introduced into plasma atomization gas gas path, and the atomization gas under the action of plasma forms plasma atomization gas;D) open high-voltage power supply, and sample solution is under the action of high-voltage electricity and plasma atomization gas and generates spray and forms sample ion, and the sample ion formed enters mass spectrometer by mass spectrometry inlet channel.This application can improve sensitivity, and under the premise that compound fragmentation dissociation does not occur, it is used for electric spray unfriendly solvent and difficult to detect low polarity compound detection, which can be compatible with normal phase liquid chromatography commonly used solvent, and can also reduce the influence of common complex matrix effect in electric spray ionization.

Description

TECHNICAL FIELD

[0001] The application relates to a method for electrospray ionization based on plasma atomization gas assistance and belongs to the technical field of mass spectrometry. BACKGROUND

[0002] Mass spectrometry (MS) is an analytical tool for measuring ion mass-to-charge ratio (mass-to-charge ratio). The excellent sensitivity, detection limit and response speed of mass spectrometry and the sample diversity make it play an important role in the analysis method. Since the appearance of the electrospray ionization technology (ESI) in the last century, due to its soft ionization characteristics of not easily causing fragmentation, the electrospray ionization technology has become the most widely used method in the field of mass spectrometry analysis.

[0003] As a most common ion source, ESI has a unique advantage in the analysis of polar small molecule substances and complex biological samples. However, the size of the charged droplet of the traditional electrospray is large, which leads to low ionization efficiency of the target compound through the electrospray device alone; at the same time, when the solvent of the sample to be measured is a poor solvent for electrospray, the sample is difficult to be ionized; when the matrix of the sample to be measured is relatively complex, the inorganic ions or other organic interfering substances in the matrix inhibit the desorption and ionization efficiency of the target analyte, and the matrix suppression effect is serious, which leads to low detection sensitivity of the traditional electrospray ionization method.

[0004] In order to improve the detection sensitivity of the electrospray ion source, nanoliter electrospray technology is developed, which can effectively improve the detection sensitivity of some drugs, but the nanoliter electrospray tip is usually below 20 mu m, which is easy to be blocked, and cannot realize long-time analysis of the sample by being combined with liquid phase.

[0005] Plasma is the fourth state of matter in addition to the three states of solid, liquid and gas. Since it was discovered in the nineteenth century, it has been widely used in people's daily life and production. The basic principle and application of in-depth research have always been a hot spot in the field of scientific research, and plasma is often used in the research in the field of mass spectrometry.

[0006] In addition, the applicant discloses a flame-assisted electrospray ionization device and a method for ionization using the device in patents CN201910665569.2 and CN201921160027.1. The device includes an electrospray channel capable of introducing a sample to be tested. The outlet end of the electrospray channel is located in front of the port of the mass spectrometry sampling channel. A flame generating device is arranged between the outlet end of the electrospray channel and the port of the mass spectrometry sampling channel. The flame generated by the flame generating device is in contact with or located around the port of the mass spectrometry sampling channel. Although the flame plasma generated by the flame generating device can assist the electrospray ionization, effectively reducing the interference of the background signal generated by the matrix, in the process of ionization of the sample using the method, the sample is directly in contact with the flame plasma, which is easy to be broken by excessive energy, and various combustion substances are easy to be generated in the combustion process of the flame plasma, which affects the ionization effect. SUMMARY

[0007] In view of the above problems existing in the prior art, the purpose of the present application is to provide an electrospray ionization method based on plasma atomized gas assistance.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] An electrospray ionization method based on plasma atomized gas assistance, comprising the following steps:

[0010] a) introducing a sample solution into an electrospray needle, the electrospray needle being connected with a high-voltage power supply through a wire, the outlet end of the electrospray needle being located in front of the port of the mass spectrometry sampling channel, the outside of the electrospray needle being sleeved with a plasma atomized gas circuit capable of introducing atomized gas, the vicinity of the electrospray needle being provided with a plasma initiation device capable of generating plasma by discharge, the discharge end of the plasma initiation device being arranged inside the plasma atomized gas circuit and not being in contact with the electrospray needle;

[0011] b) turning on the plasma initiation device to make the plasma initiation device generate plasma by discharge in the plasma atomized gas circuit;

[0012] c) introducing atomized gas into the plasma atomized gas circuit, the introduced atomized gas forming plasma atomized gas under the action of the plasma;

[0013] d) turning on the high-voltage power supply connected to the electrospray needle, the sample solution generating spray under the action of high-voltage electricity and plasma atomized gas to form sample ions, the formed sample ions entering the mass spectrometer through the mass spectrometry sampling channel.

[0014] One embodiment, the plasma initiation device comprises a Tesla coil and a discharge needle connected by a wire, the discharge needle is arranged inside the plasma atomizing gas path and does not contact the electrospray needle.

[0015] One preferred embodiment, the material of the discharge needle comprises but is not limited to metal, graphite, carbon fiber, conductive polymer material.

[0016] One preferred embodiment, the input voltage of the Tesla coil is 10-25V, and the tip voltage of the discharge needle is 2000-5000V.

[0017] One embodiment, the axis of the electrospray needle is on the same horizontal line as the axis of the mass spectrometry sampling channel.

[0018] One embodiment, the distance between the outlet end of the electrospray needle and the port of the mass spectrometry sampling channel is 5-20mm.

[0019] One embodiment, the material of the plasma atomizing gas path comprises but is not limited to quartz, metal, heat-resistant polymer material.

[0020] One embodiment, the atomizing gas comprises but is not limited to nitrogen, helium and argon.

[0021] One embodiment, the flow rate of the sample solution is 1-5000 microliters / minute.

[0022] One embodiment, the gas pressure of the atomizing gas is 0.05-0.2MPa.

[0023] One embodiment, the ionization voltage for electrospray is 2000-4000V.

[0024] Compared with the prior art, the beneficial technical effects of the present application are:

[0025] 1. Compared with the existing electrospray ionization method, the present application introduces plasma into the electrospray process, which improves the detection sensitivity for a series of compounds without changing the original electrospray device;

[0026] 2. The present application simultaneously includes both electrospray ionization and plasma ionization processes, so it can detect a series of low-polarity compounds that are difficult to detect by electrospray, as well as compounds dissolved in poor electrospray solvents;

[0027] 3. Compared with the existing plasma-based ionization method, since the plasma region in the present application does not directly contact the sample, it will not produce side reactions such as thermal cracking, oxidation and polymerization to affect the detection of the sample.

[0028] 4. In the present invention, the area where the plasma is generated by the plasma initiation device contains only atomized gas, and the gas environment is relatively stable, which does not introduce the background signal commonly seen in the plasma ionization process;

[0029] 5. The present invention can improve the sensitivity of mass spectrometry detection and at the same time suppress the matrix effect of the sample to a certain extent;

[0030] 6. The present invention can be conveniently combined with common electrospray techniques (such as desorption electrospray ionization, in situ ultrasonic spray ionization, solvent-assisted electrospray ionization, etc.) and mass spectrometers (such as triple quadrupole mass spectrometer, time-of-flight mass spectrometer, ion trap mass spectrometer, etc.), and can be extended to other mass spectrometry analyses, with a wide range of applications and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of a device provided by the present invention that can realize the electrospray ionization method based on plasma atomization gas assistance of the present invention;

[0032] Figure 2 1 is a graph comparing the signal-to-noise ratios of L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutyraldehyde, pyrethrin, fenvalerate, and stigmasterol in Example 1 of the present invention using the traditional electrospray ionization method and the electrospray ionization method provided by the present invention;

[0033] Figure 3 This is a comparison of the calibration curves obtained by using a conventional electrospray ionization method and the electrospray ionization method provided by the present invention for the standard solution and spiked matrix solution of the compound allethrin in Example 2 of the present invention, respectively. In the figure: A represents the calibration curve obtained by detecting the standard solution of allethrin using the conventional electrospray ionization method, B represents the calibration curve obtained by detecting the spiked matrix solution of allethrin using the conventional electrospray ionization method, C represents the calibration curve obtained by detecting the standard solution of allethrin using the electrospray ionization method provided by the present invention, and D represents the calibration curve obtained by detecting the spiked matrix solution of allethrin using the electrospray ionization method provided by the present invention.

[0034] Figure 4 This is a comparison chart of the signal-to-noise ratios of cholesterol compound in Example 3 of the present invention obtained by using a traditional electrospray ionization method and the electrospray ionization method provided by the present invention in different solvent systems;

[0035] The numbers in the figure are as follows: 1. Electrospray needle; 2. Plasma atomizing gas path; 3. High-voltage power supply; 4. Tesla coil; 5. Discharge needle; 6. Wire; 7. Mass spectrometer injection channel. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be further described in detail below with reference to the accompanying drawings.

[0037] Figure 1 The figure is a schematic diagram of a device structure for realizing the method of plasma atomized gas assisted electrospray ionization according to the present application, which comprises an electrospray needle 1 and a mass spectrometry sampling channel 7, the electrospray needle 1 is connected with a high-voltage power supply 3 through a wire 6, the outlet end of the electrospray needle 1 is located in front of the port of the mass spectrometry sampling channel 7, the outside of the electrospray needle 1 is sleeved with a plasma atomized gas circuit 2 capable of introducing atomized gas, a plasma initiation device capable of generating plasma by discharge is arranged near the electrospray needle 1, and the discharge end of the plasma initiation device is arranged inside the plasma atomized gas circuit 2 and does not contact the electrospray needle 1.

[0038] The mass spectrometer used in the present application can be a triple quadrupole mass spectrometer, a time-of-flight mass spectrometer, an ion trap mass spectrometer, a Fourier transform ion cyclotron resonance mass spectrometer and the like common mass spectrometers.

[0039] In the present application, the plasma initiation device comprises a Tesla coil 4 and a discharge needle 5 connected through a wire 6, and the discharge needle 5 is arranged inside the plasma atomized gas circuit 2 and does not contact the electrospray needle 1. The discharge needle 5 is equivalent to the discharge end of the plasma initiation device. The plasma generated by the discharge of the plasma initiation device can be called discharge plasma, which can avoid the defects that the flame plasma is easy to produce various combustion substances in the combustion process and affects the ionization effect compared with the flame plasma, and can effectively reduce pollution.

[0040] In the present application, the material of the discharge needle 5 includes but is not limited to metal, graphite, carbon fiber and conductive polymer material.

[0041] In the present application, the input voltage of the Tesla coil 4 is 10-25V, and the tip voltage of the discharge needle 5 is 2000-5000V.

[0042] In the present application, the axis of the electrospray needle 1 and the axis of the mass spectrometry sampling channel 7 are located on the same horizontal line, that is, the outlet end of the electrospray needle 1 is located directly in front of the port of the mass spectrometry sampling channel 7. In addition, the distance d between the outlet end of the electrospray needle 1 and the port of the mass spectrometry sampling channel 7 is 5-20mm.

[0043] In the present application, the material of the plasma atomized gas circuit 2 includes but is not limited to quartz, metal and heat-resistant polymer material. The plasma atomized gas circuit 2 is similar to a hollow sleeve, which is used to sleeve the outside of the electrospray needle 1.

[0044] In the present application, the atomized gas includes but is not limited to nitrogen, helium and argon.

[0045] The method for plasma atomized gas assisted electrospray ionization comprises the following steps:

[0046] a) introducing the sample solution into the electrospray needle 1 (using a conventional sample solution introduction method, for example, introducing the sample solution into the electrospray needle 1 by a sample pump) ;

[0047] b) starting the plasma initiation device to generate plasma in the plasma atomized gas gas path 2; specifically, starting the Tesla coil 4, and generating high-voltage discharge at the tip of the discharge needle 5, so as to generate plasma in the plasma atomized gas gas path 2;

[0048] c) introducing atomized gas into the plasma atomized gas gas path 2, and forming plasma atomized gas under the action of the plasma;

[0049] d) starting the high-voltage power supply 3 connected to the electrospray needle 1, and generating spray of the sample solution under the action of high-voltage electricity and the plasma atomized gas (the black dot between the electrospray needle 1 and the mass spectrometry sample inlet channel 7 is the sample ion), and the sample ion is introduced into the mass spectrometer through the mass spectrometry sample inlet channel 7. Figure 1

[0050] In the present application, the flow rate of the sample solution is 1-5000 microliters / minute, preferably 2-10 microliters / minute; the gas pressure of the atomized gas (i.e. the gas pressure of the atomized gas introduced in step c) is 0.05-0.2 MPa; and the ionization voltage for electrospray (i.e. the working voltage of the high-voltage power supply 3 when electrospray is performed) is 2000-4000 V.

[0051] The technical effects that can be achieved by the present application are further illustrated below in combination with specific application examples.

[0052] Example 1

[0053] The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. Figure 1 The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry. The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry.

[0054] The device shown in the figure is used in combination with a mass spectrometer (the mass analyzer is a triple quadrupole rod), and the compounds L-leucine, synthetic capsaicin, methyl salicylate, 2-methylbutanal, pyrethrin, and cypermethrin are respectively analyzed by mass spectrometry.

[0055] The above sample solutions were introduced into the electrospray needle using an injection pump at a flow rate of 5 μL / min. The nebulizer gas and high-voltage power supply were turned on. Under the action of 0.1 MPa nebulizer gas and 3000 V voltage on the electrospray needle, the sample spray was desorbed and ionized. The sample signal was detected using the MRM mode. In this mode, the signal-to-noise ratio of the traditional electrospray ionization method was obtained.

[0056] The Tesla coil 4 is turned on, and a high voltage of 4000 V is generated at the tip of the discharge needle 5, thereby generating plasma by discharge in the plasma atomizing gas path 2. The plasma ionizes the atomizing gas to produce plasma atomizing gas. Then, under the combined action of the 0.1 MPa plasma atomizing gas and the 3000 V voltage, the sample spray undergoes desorption and ionization. The sample signal is detected using the MRM mode. In this mode, the signal-to-noise ratio of the plasma atomizing gas-assisted electrospray ionization method described in the present invention is obtained.

[0057] Turn on the Tesla coil 4, and a high-voltage discharge is generated at the tip of the discharge needle 5, thereby discharging in the plasma atomizing gas path 2 to generate plasma;

[0058] Figure 2 : is a comparison chart of the signal-to-noise ratios obtained by using the electrospray ionization method provided by the present invention and the traditional electrospray ionization method to detect a series of compounds in this embodiment, wherein the signal-to-noise ratio obtained by the traditional electrospray ionization method is normalized; Figure 2 It can be seen that compared with the traditional electrospray ionization method, the electrospray ionization method provided by the present invention can significantly improve the signal-to-noise ratio for compounds with different polarities and molecular weights. In particular, for molecules such as methyl salicylate that have poor signals under ESI, the signal-to-noise ratio can also be significantly improved. This shows that the plasma atomization gas-assisted electrospray ionization method described in the present invention has higher analytical sensitivity than the traditional electrospray ionization method.

[0059] Example 2

[0060] use Figure 1 The device shown is connected to a mass spectrometer (the mass analyzer is a triple quadrupole) to analyze the compound allethrin. The standard solution and spiked matrix solution were analyzed by mass spectrometry and the quantitative curve was drawn. The specific operations are as follows:

[0061] The allyl chrysanthemum ester is configured into standard sample solution of 0.01 μg / mL, 0.025 μg / mL, 0.05 μg / mL, 0.075 μg / mL, 0.1 μg / mL, 0.25 μg / mL, 0.5 μg / mL, 0.75 μg / mL, 1 μg / mL using methanol; 2.5 g of fresh grass leaves are taken, 10 mL of methanol is added, and ultrasonic is performed for 30 minutes; the supernatant is centrifuged at 10000 rpm and 4°C for 10 minutes; the supernatant is transferred into a 25 mL volumetric flask, and methanol is added to constant volume to 25 mL to prepare a blank matrix solution; then the blank matrix solution is used to configure the allyl chrysanthemum ester sample into the standard sample solution of 0.01 μg / mL, 0.025 μg / mL, 0.05 μg / mL, 0.075 μg / mL, 0.1 μg / mL, 0.25 μg / mL, 0.5 μg / mL, 0.75 μg / mL, 1 μg / mL.

[0062] The standard sample solution is introduced into the electric spray needle using a sample pump, the flow rate is 5 μL / min, the atomization gas and the high-voltage power supply are turned on, under the action of 0.1 MPa atomization gas and 3000 V voltage on the spray needle, sample spraying desorption ionization occurs, the sample signal is detected using the MRM mode, the signal of the standard sample detected by the traditional electric spray ionization method is obtained, and the quantitative curve of the standard sample detected by the traditional electric spray ionization method is drawn according to different concentrations and signal intensities.

[0063] The Tesla coil 4 is turned on, a high voltage of 4000 V is generated at the tip of the discharge needle 5, so that plasma is generated by discharging in the plasma atomization gas gas path 2, the plasma ionizes the atomization gas to generate plasma atomization gas, under the joint action of 0.1 MPa plasma atomization gas and 3000 V voltage, sample spraying desorption ionization occurs, the sample signal is detected using the MRM mode, the signal of the standard sample detected by the electric spray ionization method based on the plasma atomization gas auxiliary according to the application is obtained, and the quantitative curve of the standard sample detected by the electric spray ionization method based on the plasma atomization gas auxiliary according to the application is drawn according to different concentrations and signal intensities.

[0064] The standard sample solution of the allyl chrysanthemum ester is detected in the same way, the signals of the standard sample detected by the traditional electric spray ionization method and the electric spray ionization method based on the plasma atomization gas auxiliary are obtained respectively, and the quantitative curves of the standard sample detected by the traditional electric spray ionization method and the electric spray ionization method based on the plasma atomization gas auxiliary according to the application are drawn according to different concentrations and signal intensities respectively.

[0065] Figure 3: The quantitative curves obtained by detecting the standard sample solution and the spiked matrix sample solution of allethrin using the conventional electrospray ionization method and the plasma atomization gas-assisted electrospray ionization method of the present invention respectively in this embodiment; Figure 3 It can be seen that using the plasma atomizer-assisted electrospray ionization method described in the present invention, the detection results for the standard solution and the spiked matrix solution are similar, and the matrix effect is less than 5%. When the traditional electrospray ionization method is used to detect the standard sample and the spiked matrix sample, the signal is relatively lower and the matrix effect is more obvious. This shows that the plasma atomizer-assisted electrospray ionization method described in the present invention can effectively suppress the matrix effect problem that is common in the ionization of compounds with low proton affinity.

[0066] Example 3

[0067] use Figure 1 The device shown is coupled with a mass spectrometer (the mass analyzer is a triple quadrupole) to analyze the compound cholesterol. The samples were tested using the mobile phase commonly used in normal phase liquid chromatography as the solvent. The specific operation is as follows:

[0068] Cholesterol was prepared into a 1 mg / mL sample solution using n-hexane and propanol, respectively;

[0069] The sample solution was introduced into the electrospray needle using an injection pump at a flow rate of 5 μL / min. The nebulizer gas and high-voltage power supply were turned on. Under the action of 0.1 MPa nebulizer gas and 3000 V voltage on the spray needle, the sample spray was desorbed and ionized. The sample signal was detected using the MRM mode to obtain the signal-to-noise ratio of the sample detected using the traditional electrospray ionization method.

[0070] The Tesla coil 4 was turned on, and a high voltage of 4000 V was generated at the tip of the discharge needle 5, thereby generating plasma by discharge in the plasma atomizing gas path 2. The plasma ionized the atomizing gas to produce plasma atomizing gas. Under the combined action of the 0.1 MPa plasma atomizing gas and the 3000 V voltage, the sample spray was desorbed and ionized. The sample signal was detected using the MRM mode, and the signal-to-noise ratio of the sample detected using the plasma atomizing gas-assisted electrospray ionization method of the present invention was obtained.

[0071] Figure 4is a signal-to-noise ratio comparison chart of the cholesterol sample detected by the conventional electrospray ionization method and the plasma atomized gas assisted electrospray ionization method described in the present application under the mobile phase commonly used in normal phase liquid chromatography. When using the less polar n-hexane solvent, the signal is very low under the conventional electrospray ionization method, and the sample signal is not detected, while the signal can be detected by the plasma atomized gas assisted electrospray ionization method described in the present application. And when using the more polar propanol as the solvent, the signal-to-noise ratio detected by the electrospray ionization method described in the present application is also obviously improved. By Figure 4 It can be seen that the plasma atomized gas assisted electrospray ionization method described in the present application can also achieve good detection for compounds dissolved in poorly conductive electrospray solvents, and can improve the sensitivity of electrospray detection, indicating that the plasma atomized gas assisted electrospray ionization method described in the present application can also be combined with normal phase liquid chromatography.

[0072] As can be seen from the above, the plasma atomized gas assisted electrospray ionization method described in the present application can improve the sensitivity of electrospray mass spectrometry detection on the basis of the original electrospray ionization, and has good signal-to-noise ratio improvement ability for most compounds, and has wide application range. Because the present application simultaneously includes the processes of electrospray ionization and plasma ionization, it can also achieve good detection for some compounds that are difficult to detect by electrospray method and some compounds dissolved in some poorly conductive electrospray solvents, and can also solve the matrix effect problem commonly encountered in electrospray method. And unlike the conventional plasma ionization (such as flame plasma ionization) method, the plasma in the present application does not contact the sample, which not only reduces pollution, but also avoids the sample denaturation problem that easily occurs in plasma ionization, and also has the advantage of low matrix effect of plasma ionization, which can adapt to the detection of complex matrix samples.

[0073] Finally, it is necessary to point out here that the above described is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A plasma atomization gas-assisted electrospray ionization method, characterized in that: The steps include: a) introducing a sample solution into an electrospray needle, the electrospray needle being connected to a high-voltage power supply via a wire, the outlet end of the electrospray needle being located in front of a port of a mass spectrometer injection channel, the exterior of the electrospray needle being provided with a plasma atomizing gas path capable of introducing atomizing gas, and a plasma initiating device capable of discharging and generating plasma being provided near the electrospray needle, the plasma initiating device comprising a Tesla coil and a discharge needle connected by a wire, the discharge needle being located within the plasma atomizing gas path and not in contact with the electrospray needle; b) turning on the plasma initiation device so that the plasma initiation device discharges in the plasma atomizing gas path to generate plasma; c) introducing the atomized gas into the plasma atomized gas path, whereby the introduced atomized gas forms plasma atomized gas under the action of the plasma; d) Turn on the high-voltage power supply connected to the electrospray needle. The sample solution is sprayed under the action of the high-voltage power and the plasma atomizing gas to form sample ions. The formed sample ions enter the mass spectrometer through the mass spectrometer injection channel.

2. The plasma atomization gas-assisted electrospray ionization method according to claim 1, characterized in that: The input voltage of the Tesla coil is 10-25 V, and the tip voltage of the discharge needle is 2000-5000 V.

3. The plasma atomization gas-assisted electrospray ionization method according to claim 1, characterized in that: The axis of the electrospray needle and the axis of the mass spectrometer injection channel are located on the same horizontal line.

4. The plasma atomization gas-assisted electrospray ionization method according to claim 1, characterized in that: The distance between the outlet end of the electrospray needle and the port of the mass spectrometer injection channel is 5 to 20 mm.

5. The plasma atomization gas-assisted electrospray ionization method according to claim 1, characterized in that: The flow rate of the sample solution was 1 to 5000 μl / min.

6. The plasma atomization gas-assisted electrospray ionization method according to claim 1, characterized in that: The pressure of the atomizing gas is 0.05~0.2 MPa.

7. The plasma atomization gas-assisted electrospray ionization method according to claim 1, characterized in that: The ionization voltage for electrospray was 2000-4000 V.

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