An integrated plasma ion source with simultaneous desorption and ionization

Abstract

The present invention discloses an integrated plasma ion source for synchronous desorption and ionization, and relates to the field of ion sources. The integrated plasma ion source for synchronous desorption and ionization comprises a hollow ceramic tube, a cathode and an anode, wherein the anode is fixedly mounted on the inner bottom wall of the hollow ceramic tube, and a ceramic main body outlet is provided at the bottom end of the hollow ceramic tube, a sealing assembly is assembled between the top of the hollow ceramic tube and the cathode, and the cathode and the anode are assembled with circuit assemblies; a gas opening is provided on the outer surface of the hollow ceramic tube, and the gas opening is connected to a helium cylinder through an air pipe; a sample stage is provided below the hollow ceramic tube. The integrated plasma ion source for synchronous desorption and ionization does not require sample pretreatment for mass spectrometry detection, can simultaneously ionize non-polar to highly polar compounds, has a very small matrix effect, and is suitable for rapid broad-spectrum screening and high-throughput detection of small molecules in samples.

Description

Technical Field

[0001] The present invention relates to the technical field of ion sources, in particular to an integrated plasma ion source for synchronous desorption and ionization. Background Art

[0002] Commercial real-time direct analysis ion sources require 2-3 L / min of high-purity helium (above 99.999%). Helium is a non-renewable energy source on Earth. In my country, high-purity helium is completely dependent on imports. Therefore, there is an urgent need for an ion source with higher effective power and less helium consumption.

[0003] In 2007, Gary M. Hieftje's group at Indiana University developed this more efficient, high-power, and low-gas ion source. Initially named the FA-APGD ion source, it was renamed the FAPA ion source in 2008. This ion source discharges in the glow-arc discharge region, generating a stronger current and particle flux, increasing analyte signal tenfold under equivalent conditions. Most of the electrical energy is used to ionize the carrier gas, requiring only 0.4–1 L / min of carrier gas. This makes it more sensitive and environmentally friendly than commercial real-time direct analysis ion sources.

[0004] Because this type of ion source was previously used only for scientific research, Teflon, high-temperature polytetrafluoroethylene (PEEK), glass, or quartz was typically used as the discharge chamber material, with PEEK used as the connectors to facilitate rapid parameter changes. The core temperature of the FAPA ion source can reach nearly 1,000°C, while the PEEK connector begins to deform at around 260°C, resulting in a service life of only a few weeks, making it very inconvenient for non-professionals to use. Therefore, we proposed an integrated plasma ion source that simultaneously desorbs and ionizes. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the shortcomings of the existing technology, the present invention provides an integrated plasma ion source with simultaneous desorption and ionization, which solves the problem that the center temperature of the FAPA ion source can reach nearly 1,000 degrees Celsius, while the PEEK connector begins to deform at around 260°C, resulting in a service life of only a few weeks, which is very inconvenient for non-professionals to use.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: an integrated plasma ion source for synchronous desorption and ionization, comprising a hollow ceramic tube, a cathode, and an anode, wherein the anode is fixedly mounted on the inner bottom wall of the hollow ceramic tube, and a ceramic body outlet is opened at the bottom end of the hollow ceramic tube, one end of the cathode is inserted into the interior of the hollow ceramic tube, and the other end of the cathode extends outward, and a sealing assembly is assembled between the top of the hollow ceramic tube and the cathode, and the cathode and the anode are assembled with circuit components;

[0009] A gas opening is formed on the outer surface of the hollow ceramic tube, and the gas opening is connected to a helium cylinder through a gas pipe, and the helium cylinder injects helium into the hollow ceramic tube;

[0010] A sample stage is provided below the hollow ceramic cylinder, and a sample is placed above the sample stage.

[0011] Preferably, the circuit assembly includes a DC high-voltage power supply, the DC high-voltage power supply is connected to a ballast resistor via a wire, and a wire is installed between the ballast resistor and the top of the cathode.

[0012] Preferably, the circuit assembly also includes a conductive opening, which is opened on the side of the bottom end of the hollow ceramic tube. An M1.4 screw is screwed into the inner wall of the conductive opening, and the end of the M1.4 screw is connected to the anode. The M1.4 screw is located between the external end and the DC high-voltage power supply and is connected with a wire to form a closed loop.

[0013] Preferably, the sealing assembly includes a nut, the top of the hollow ceramic cylinder is provided with an external thread, a graphite O-ring is sleeved on the external thread, and the nut is threadedly connected to the external thread and tightly abuts against the graphite O-ring.

[0014] Preferably, the nut is provided with through holes extending through both sides, and a graphite gasket is fixedly connected to the through hole. The cathode is inserted into the inner wall of the graphite gasket and has an interference fit with the inner wall of the graphite gasket.

[0015] Preferably, the cathode is configured as a 304 stainless steel electrode rod with a diameter of 1 mm, and the diameter of the hollow ceramic cylinder is configured as 1 inch and the length is configured as 10 cm.

[0016] Preferably, the opening diameter of the gas opening is set to 1 / 4 inch;

[0017] The opening diameter of the conductive opening is set to 1.4 mm.

[0018] The present invention discloses an integrated plasma ion source for synchronous desorption and ionization, which has the following beneficial effects:

[0019] 1. The integrated plasma ion source with synchronous desorption and ionization uses the pressure difference between atmospheric pressure and the vacuum pressure inside the mass spectrometer to allow the secondary analyte ions M+ to be absorbed into the mass spectrometer for analysis and detection. The sample stage is then moved by computer or manual control. The high-energy helium gas flow primary particles can desorb and ionize the analytes on different samples one by one and enter the mass spectrometer detection. The data analyzed by mass spectrometry will be displayed in the form of signal intensity versus mass-to-charge ratio (m / z). The content of each analyte can be known by calculation. Mass spectrometry detection based on this ion source does not require sample pretreatment, can simultaneously ionize non-polar to highly polar compounds, has a very small matrix effect, and is suitable for rapid broad-spectrum screening and high-throughput detection of small molecules in samples.

[0020] 2. In the integrated plasma ion source for synchronous desorption and ionization, the helium in the hollow ceramic tube is broken down by voltage. After the breakdown, the cathode should be pink, and a lavender plasma should appear between the cathode and the anode, with light and dark stripes alternating. If the main material uses a transparent material such as quartz, the above phenomenon should be observed. The hollow ceramic tube in the present invention is opaque, so only a light pink light can be observed from the outlet of the ceramic body; and after the helium is broken down, primary particles such as He+ and Hem are first generated. The primary particles move through the outlet of the ceramic body to the external connection and react with water molecule clusters in the air to produce protonated water molecule clusters. After the protonated water molecule clusters collide with the sample, the protons are transferred to the sample to form secondary analyte ions M+.

[0021] 3. The integrated plasma ion source with synchronous desorption and ionization has a graphite O-ring, and the nut and the graphite O-ring are tightly against each other, which effectively seals the nut and the top of the hollow ceramic tube. The graphite gasket is set between the nut and the cathode, which effectively seals the nut. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a structural schematic diagram of the present invention.

[0024] In the figure: 1. DC high-voltage power supply; 2. Ballast resistor; 3. Cathode; 4. Anode; 5. Nut; 6. Graphite O-ring; 7. Graphite gasket; 8. Hollow ceramic cylinder; 9. Gas opening; 10. Helium cylinder; 11. Conductive opening; 12. Ceramic body outlet; 13. Sample stage; 14. Sample. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The embodiment of the present application solves the problem that the center temperature of the FAPA ion source can reach nearly 1,000 degrees, while the PEEK connector begins to deform at around 260°C, resulting in a service life of only a few weeks, which is very inconvenient for non-professionals to use. By providing an integrated plasma ion source with simultaneous desorption and ionization, the present application provides an ion source that uses an integrated high-temperature resistant ceramic as the discharge chamber material. The ion source of this material does not require connectors and can therefore be used for a long time without the need to replace easily deformed connectors or other materials, making it convenient for non-professionals to operate.

[0027] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0028] The embodiment of the present invention discloses an integrated plasma ion source for synchronous desorption and ionization.

[0029] According to the attached Figure 1 As shown, it includes a hollow ceramic tube 8, a cathode 3 and an anode 4, the anode 4 is fixedly mounted on the inner bottom wall of the hollow ceramic tube 8, and a ceramic body outlet 12 is opened at the bottom end of the hollow ceramic tube 8, one end of the cathode 3 is inserted into the interior of the hollow ceramic tube 8, and the other end of the cathode 3 extends outward, and a sealing component is assembled between the top of the hollow ceramic tube 8 and the cathode 3, and the cathode 3 and the anode 4 are equipped with circuit components;

[0030] A gas opening 9 is formed on the outer surface of the hollow ceramic tube 8, and the gas opening 9 is connected to a helium cylinder 10 through a gas pipe. The helium cylinder 10 injects helium into the hollow ceramic tube 8.

[0031] A sample stage 13 is provided below the hollow ceramic cylinder 8 , and a sample 14 is placed above the sample stage 13 .

[0032] The secondary analyte ions M+ are drawn into the mass spectrometer through the difference in pressure between atmospheric pressure and the vacuum pressure inside the mass spectrometer for analysis and detection. The sample stage 13 is then moved by computer or manual control, and the primary particles of the high-energy helium flow can desorb and ionize the analytes on different samples 14 one by one and enter the mass spectrometer detection. The data analyzed by mass spectrometry will be presented in the form of signal intensity versus mass-to-charge ratio (m / z), and the content of each analyte can be known by calculation. Mass spectrometry detection based on this ion source does not require sample pretreatment, can simultaneously ionize non-polar to highly polar compounds, has a very small matrix effect, and is suitable for rapid broad-spectrum screening and high-throughput detection of small molecules in samples.

[0033] The circuit component includes a DC high-voltage power supply 1, which is connected to a ballast resistor 2 through a wire, and a wire is installed between the ballast resistor 2 and the top of the cathode 3. When the DC high-voltage power supply 1 is turned on and the voltage is adjusted to 500V, the high-voltage current needs to pass through a 5000 ohm ballast resistor 2 before entering the cathode 3 to prevent excessive instantaneous current, thereby protecting the circuit.

[0034] The circuit assembly also includes a conductive opening 11, which is opened on the side of the bottom end of the hollow ceramic tube 8. An M1.4 screw is screwed into the inner wall of the conductive opening 11, and the end of the M1.4 screw is connected to the anode 4. The M1.4 screw is located between the external end and the DC high-voltage power supply 1, and a wire is connected to form a closed loop.

[0035] The helium in the hollow ceramic tube 8 is broken down by the voltage. After the breakdown, the cathode 3 should be pink, and a light purple plasma should appear between the cathode 3 and the anode 4, with alternating light and dark lines. If the main body material is made of transparent materials such as quartz, the above phenomenon should be observed. In the present invention, the hollow ceramic tube 8 is opaque, so only a light pink light can be observed from the ceramic body outlet 12;

[0036] After the helium is broken down, primary particles such as He+ and Hem are first generated. The primary particles move to the outside through the ceramic body outlet 12 to react with water molecule clusters in the air to produce protonated water molecule clusters. After the protonated water molecule clusters collide with the sample 14, the protons are transferred to the sample 14 to form secondary analyte ions M+.

[0037] The sealing assembly includes a nut 5, and the top of the hollow ceramic tube 8 is provided with an external thread, and a graphite O-ring 6 is sleeved on the external thread. The nut 5 is threadedly connected to the external thread and tightly abuts the graphite O-ring 6. Through the provision of the graphite O-ring 6, the nut 5 and the graphite O-ring 6 are tightly abutted, which effectively seals the nut 5 and the top of the hollow ceramic tube 8.

[0038] The nut 5 is provided with through holes on both sides, and a graphite gasket 7 is fixedly connected to the through hole. The cathode 3 is inserted into the inner wall of the graphite gasket 7 and has an interference fit with the inner wall of the graphite gasket 7. The graphite gasket 7 is arranged between the nut 5 and the cathode 3, which plays an effective sealing role.

[0039] The cathode 3 is set to be a 304 stainless steel electrode rod with a diameter of 1 mm, and the diameter of the hollow ceramic cylinder 8 is set to be 1 inch and the length is set to be 10 cm.

[0040] The opening diameter of the gas opening 9 is set to 1 / 4 inch; the opening diameter of the conductive opening 11 is set to 1.4 mm.

[0041] The cathode 3 in the present invention is set to a 304 stainless steel electrode rod with a diameter of 1 mm. However, according to actual conditions, the material of the cathode 3 can be any conductive material, and the shape can be pointed or non-pointed, and can be solid or hollow. The material of the anode 4 can be any conductive material, and the shape can be a perforated disc, a ring or a tube.

[0042] Working principle: First, open the helium cylinder 10 and adjust the flow rate, which is generally controlled at 0.4-1.0L / min. Inject helium into the hollow ceramic cylinder 8 through the helium cylinder 10. Then turn on the DC high-voltage power supply 1 and adjust the voltage to 500V. Before the high-voltage current enters the cathode 3, it needs to pass through a 5000 ohm ballast resistor 2 to prevent excessive instantaneous current.

[0043] The helium in the hollow ceramic tube 8 is broken down by the voltage. After the breakdown, the cathode 3 should be pink, and a light purple plasma should appear between the cathode 3 and the anode 4, with alternating light and dark lines. If the main body material is made of transparent materials such as quartz, the above phenomenon should be observed. In the present invention, the hollow ceramic tube 8 is opaque, so only a light pink light can be observed from the ceramic body outlet 12;

[0044] After the helium is broken down, primary particles such as He+ and Hem are first generated. The primary particles move to the outside through the ceramic body outlet 12 to react with water molecule clusters in the air to produce protonated water molecule clusters. After the protonated water molecule clusters collide with the sample 14, the protons are transferred to the sample 14 to form secondary analyte ions M+.

[0045] At this time, the secondary analyte ions M+ are sucked into the mass spectrometer by the pressure difference between atmospheric pressure and the vacuum pressure inside the mass spectrometer for analysis and detection. Then, the sample stage 13 is moved by computer or manual control, and the high-energy helium gas flow first-stage particles can desorb and ionize the analytes on different samples 14 one by one and enter the mass spectrometer detection. The data analyzed by mass spectrometry will be displayed in the form of signal intensity versus mass-to-charge ratio (m / z). The content of each analyte can be known by calculation. Mass spectrometry detection based on this ion source does not require sample pretreatment, can simultaneously ionize non-polar to highly polar compounds, has a very small matrix effect, and is suitable for rapid broad-spectrum screening and high-throughput detection of small molecules in samples.

[0046] Through the provided graphite O-ring 6, the nut 5 is tightly against the graphite O-ring 6, which effectively seals the nut 5 and the top of the hollow ceramic tube 8. Through the provided graphite gasket 7, the graphite gasket 7 is provided between the nut 5 and the cathode 3, which effectively seals the nut 5.

[0047] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0048] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An integrated plasma ion source for synchronous desorption and ionization, comprising a hollow ceramic cylinder (8), a cathode (3) and an anode (4), characterized in that: The anode (4) is fixedly mounted on the inner bottom wall of the hollow ceramic cylinder (8), and a ceramic body outlet (12) is provided at the bottom end of the hollow ceramic cylinder (8). One end of the cathode (3) is plugged into the interior of the hollow ceramic cylinder (8), and the other end of the cathode (3) extends outward. A sealing component is assembled between the top of the hollow ceramic cylinder (8) and the cathode (3), and the cathode (3) and the anode (4) are assembled with circuit components. A gas opening (9) is provided on the outer surface of the hollow ceramic cylinder (8), and the gas opening (9) is connected to a helium cylinder (10) via a gas pipe, and the helium cylinder (10) injects helium into the interior of the hollow ceramic cylinder (8); A sample stage (13) is provided below the hollow ceramic cylinder (8), and a sample (14) is placed above the sample stage (13).

2. The integrated plasma ion source for synchronous desorption and ionization according to claim 1, characterized in that: The circuit assembly comprises a DC high-voltage power supply (1), the DC high-voltage power supply (1) is connected to a ballast resistor (2) via a wire, and a wire is installed between the ballast resistor (2) and the top of the cathode (3).

3. The integrated plasma ion source for synchronous desorption and ionization according to claim 2, characterized in that: The circuit assembly further includes a conductive opening (11), which is opened on the side of the bottom end of the hollow ceramic cylinder (8), an M1.4 screw is screwed into the inner wall of the conductive opening (11), and the end of the M1.4 screw is connected to the anode (4), and a wire is connected between the external end of the M1.4 screw and the DC high-voltage power supply (1), forming a closed loop.

4. The integrated plasma ion source for synchronous desorption and ionization according to claim 1, characterized in that: The sealing assembly comprises a nut (5), the top end of the hollow ceramic cylinder (8) is provided with an external thread, a graphite O-ring (6) is sleeved on the external thread, and the nut (5) is threadedly connected to the external thread and tightly abuts against the graphite O-ring (6).

5. The integrated plasma ion source for synchronous desorption and ionization according to claim 4, characterized in that: The nut (5) is provided with through holes extending through both sides, and a graphite gasket (7) is fixedly connected to the through hole. The cathode (3) is plugged into the inner wall of the graphite gasket (7) and has an interference fit with the inner wall of the graphite gasket (7).

6. The integrated plasma ion source for synchronous desorption and ionization according to claim 1, characterized in that: The cathode (3) is configured as a 304 stainless steel electrode rod having a diameter of 1 mm, and the hollow ceramic cylinder (8) has a diameter of 1 inch and a length of 10 cm.

7. The integrated plasma ion source for synchronous desorption and ionization according to claim 3, characterized in that: The opening diameter of the gas opening (9) is set to 1 / 4 inch; The opening diameter of the conductive opening (11) is set to 1.4 mm.

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