Atmospheric pressure ionization source with ion spatial focusing function

Abstract

The present application relates to ionization source in analytical instrument, specifically, a kind of atmospheric pressure ionization source with ion space focusing function, including hollow closed cylindrical chamber, VUV lamp is provided at the left end of cavity, the light outlet of VUV lamp faces the inside of cavity, the emission light of VUV lamp is transmitted along the axial direction of cavity from left to right inside the cavity, the light outlet near VUV lamp in cavity is as ionization reaction zone, sample inlet is provided on the cavity side wall surface near VUV lamp in ionization reaction zone, ion outlet is provided at the right end of cavity;The region in the cavity between ionization reaction zone and ion outlet is ion transmission focusing zone;Spindle-shaped metal electrode is provided in the middle of ion transmission focusing zone, the inner wall surface of ion transmission focusing zone is spindle-shaped metal electrode cylinder, gap is left between spindle-shaped metal electrode and spindle-shaped metal electrode cylinder.It can be connected with mass spectrometry sampling port through ion outlet, combined with mass spectrometry, the diameter of columnar ionization source can be reduced, it is matched with mass spectrometry sampling micropore, so as to improve ion efficiency and detection sensitivity.

Description

Technical Field

[0001] This invention relates to ionization sources in analytical instruments, specifically an atmospheric pressure ionization source with ion spatial focusing function. Specifically, it achieves efficient ion transmission through a spindle-shaped high-efficiency transmission structure design and the application of a radio frequency electric field to it, thereby focusing ions in a large-area ionization region to a small focal point and improving the ion sampling efficiency during mass spectrometry analysis. Background Technology

[0002] Ionization sources are one of the key technologies in ion-type detection instruments such as mass spectrometry and ion mobility spectrometry. Traditional ion mobility spectrometry commonly uses radioactive ionization sources. 63 Ni ionization source. 63 Ni can emit beta rays with an average energy of 17 keV. After undergoing a series of complex reactions with the carrier gas, it finally forms reagent ions H₃O. + (Positive ion detection mode) and O2 _ (Negative ion detection mode) The reagent ions react with the sample to ionize it. Radioactivity 63 Ni ionization sources are favored by scientists due to their simplicity, stability, and lack of external power supply. However, the safety inspections and special safety measures required due to their radioactivity bring many troubles to their practical application. Additionally... 63 The ion concentration produced by Ni ionization sources is not high enough, resulting in weak ion mobility spectra and a small linear range. Therefore, in recent years, researchers have been actively seeking non-radioactive ionization sources to replace traditional radioactive ones. 63 Ni ionization sources. Several atmospheric pressure ionization sources used for mass spectrometry include APCI, DART, DESI, corona discharge ionization sources, and electrospray ionization sources.

[0003] The aforementioned ionization sources are all surface ionization sources, typically exceeding 5 mm in diameter. To ensure high vacuum in mass spectrometry, sampling orifices of only a few tenths of a millimeter are usually used for sample introduction. This results in the loss of a large number of product ions generated during ionization. Furthermore, atmospheric pressure ionization sources usually contain a large number of reactant ions, which can cause ion trap mass spectrometry and quadrupole mass spectrometry storage saturation, limiting the number of target ions and affecting sensitivity. Additionally, the Coulomb repulsion generated by these ions can affect resolution. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method that can focus a large-scale surface ionization source under atmospheric pressure into a microfocus, improve ion utilization efficiency, and thus enhance mass spectrometry sensitivity and resolution.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An atmospheric pressure ionization source with ion spatial focusing function is characterized by: comprising a hollow, sealed cylindrical chamber; a VUV lamp is provided at the left end of the chamber; the light outlet of the VUV lamp faces the interior of the chamber; the emitted light from the VUV lamp is transmitted from left to right along the axis of the chamber; the area inside the chamber near the light outlet of the VUV lamp serves as an ionization reaction zone; a sample inlet is provided on the side wall of the chamber near the VUV lamp in the ionization reaction zone; and an ion outlet is provided at the right end of the chamber; the area inside the chamber between the ionization reaction zone and the ion outlet is an ion transport focusing zone; the VUV lamp, the ionization reaction zone, and the ion transport focusing zone are arranged sequentially from left to right; a spindle-shaped metal electrode is provided in the middle of the ion transport focusing zone; the inner wall of the ion transport focusing zone is a spindle-shaped metal electrode cylinder; and a gap is left between the spindle-shaped metal electrode and the spindle-shaped metal electrode cylinder.

[0007] The ionization source is characterized in that: the spindle-shaped metal electrode is formed by connecting a left frustum-shaped cone and a right cone with a common lower base surface, and the axial height of the cone closer to the VUV lamp is less than the axial height of the cone farther from the VUV lamp; the spindle-shaped metal electrode cylinder is formed by connecting a left frustum-shaped chamber and a right cone with a common lower base surface, and the axial height of the cone closer to the VUV lamp is less than the axial height of the cone farther from the VUV lamp; the spindle-shaped metal electrode and the spindle-shaped metal electrode cylinder are coaxial; the spindle-shaped metal electrode is connected to the radio frequency high voltage, while the spindle-shaped metal electrode cylinder is connected to the ground; or the spindle-shaped metal electrode is connected to the ground, while the spindle-shaped metal electrode cylinder is connected to the radio frequency high voltage.

[0008] The ionization source is characterized in that: the length of the ionization reaction zone along the axial direction is 10-20 mm; and the inner diameter of the ionization reaction zone is 5-10 mm.

[0009] The ionization source is characterized in that the ion outlet is coaxial with the spindle-shaped metal electrode cylinder.

[0010] The ionization source is characterized in that: the waveform of the radio frequency high voltage is one or more of the following waveforms: square wave, sine wave or triangular wave, the amplitudes of the positive and negative high voltages are different or the same, and the integral area of ​​the positive high voltage and the integral area of ​​the negative high voltage are the same.

[0011] The ionization source is characterized in that: the frequency of the radio frequency high voltage is between 10 kHz and 300 MHz; and the amplitude of the radio frequency high voltage is between 200 and 5000 V.

[0012] The ionization source can be connected to the mass spectrometer inlet via the ion outlet. When used in conjunction with a mass spectrometer, the diameter of the columnar ionization source can be reduced to match the sampling micropore of the mass spectrometer, thereby improving ion retrieval efficiency and detection sensitivity.

[0013] The advantages of this invention are: This invention provides an atmospheric pressure ionization source with ion spatial focusing function. By using a spindle-shaped structure design combined with a radio frequency electric field, the surface ionization source can be adjusted into a point ionization source, thereby improving the ion introduction efficiency of mass spectrometry. Attached Figure Description

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0015] Figure 1 A schematic diagram of the structure of an atmospheric pressure ionization source with ion spatial focusing function. VUV lamp (1), ionization reaction zone (2), sample inlet (3), spindle-shaped metal electrode (4), spindle-shaped metal electrode tube (5), ion transport focusing zone (6), ion outlet (7).

[0016] Figure 2 Image of ionization source coupled with mass spectrometry. Detailed Implementation

[0017] This invention utilizes VUV light to efficiently ionize samples.

[0018] An atmospheric pressure ionization source with ion spatial focusing function.

[0019] The device includes a hollow, sealed cylindrical chamber. A VUV lamp 1 is located at the left end of the chamber. The light emitted from the VUV lamp 1 faces the interior of the chamber, and the light from the VUV lamp is transmitted from left to right along the axis of the chamber. The area inside the chamber near the light outlet of the VUV lamp 1 serves as an ionization reaction zone 2. A sample inlet 3 is located on the side wall of the chamber near the VUV lamp 1 in the ionization reaction zone. An ion outlet 7 is located at the right end of the chamber. The area inside the chamber between the ionization reaction zone 2 and the ion outlet 7 is an ion transport focusing zone 6. The VUV lamp 1, the ionization reaction zone 2, and the ion transport focusing zone 6 are arranged sequentially from left to right. The VUV lamp 1 is a krypton lamp.

[0020] A spindle-shaped metal electrode 4 is provided in the middle of the ion transport focusing region 6. The inner wall of the ion transport focusing region 6 is a spindle-shaped metal electrode cylinder 5. A gap of 1 mm is left between the spindle-shaped metal electrode 4 and the spindle-shaped metal electrode cylinder 5.

[0021] The spindle-shaped metal electrode 4 is composed of a left truncated cone and a right cone connected by a common bottom surface. The axial height of the cone on the side closer to the VUV lamp 1 is less than the axial height of the cone on the side farther from the VUV lamp 1. The axial height of the cone on the side closer to the VUV lamp 1 is 3 cm, and the axial height of the cone on the side farther from the VUV lamp 1 is 6 cm.

[0022] The spindle-shaped metal electrode cylinder 5 is formed by a left frustum-shaped conical chamber and a right conical chamber connected together on their lower bottom surfaces. The axial height of the conical chamber on the side closer to the VUV lamp 1 is smaller than the axial height of the conical chamber on the side farther from the VUV lamp 1. The spindle-shaped metal electrode 4 and the spindle-shaped metal electrode cylinder 5 are coaxial. The spindle-shaped metal electrode 4 is connected to the radio frequency high voltage, while the spindle-shaped metal electrode cylinder 5 is connected to the ground; or the spindle-shaped metal electrode 4 is connected to the ground, while the spindle-shaped metal electrode cylinder 5 is connected to the radio frequency high voltage.

[0023] The length of the ionization reaction zone 2 along the axial direction is 15 mm; the inner diameter of the ionization reaction zone is 8 mm.

[0024] Ion outlet 7 is coaxial with spindle-shaped metal electrode cylinder 5.

[0025] The waveform of the radio frequency high voltage is a square wave. The amplitudes of the positive and negative high voltages are different or the same, while the integral areas of the positive and negative high voltages are the same.

[0026] The frequency of the radio frequency high voltage is 1 MHz; the positive amplitude of the radio frequency high voltage is 1600 V, and the negative amplitude is 400 V.

[0027] It can be connected to the mass spectrometer inlet through the ion outlet 7. When used in conjunction with the mass spectrometer, it can reduce the diameter of the column ionization source to match the mass spectrometer sampling micropore, thereby improving the ion transfer efficiency and detection sensitivity.

[0028] The voltage parameters applied to the spindle-shaped metal electrode 4 are as follows: the frequency of the radio frequency power supply is 1 MHz. The axial length of the ionization reaction zone 2 is 1.5 cm. The diameter of the short base of the left truncated cone of the spindle-shaped metal electrode 4 is 1.2 mm. The indirection between the spindle-shaped metal electrode 4 and the spindle-shaped metal electrode cylinder 5 is 0.5 mm, and the length of the spindle-shaped metal electrode axis is 3 cm. The opening diameter of the ion outlet 7 is 1 mm.

[0029] The ionization source described above is coupled with mass spectrometry as an ionization source for mass spectrometry, and its structure is as follows: Figure 2 As shown. This instrument mainly consists of the following parts: VUV lamp 1, ionization reaction zone 2, sample inlet 3, spindle-shaped metal electrode 4, spindle-shaped metal electrode cylinder 5, ion transport focusing zone 6, ion outlet 7, vacuum chamber 8, mass spectrometry sampling cone 9, quadrupole mass filter 10, multiplier 11, and amplifier 12. The sample detection process is as follows: the sample enters the ionization reaction zone 2 through the sample inlet 3 and is ionized. Then, under the gas flow, it passes through the ionization zone between the ion extraction electrodes to generate sample ions. The obtained sample ions pass through the ion transport focusing zone between the spindle-shaped metal electrode 4 and the spindle-shaped metal electrode cylinder 5. After passing through the ion outlet 7, it enters the quadrupole mass filter 10 through the mass spectrometry sampling cone 9 for separation, is detected on the multiplier 11, and finally amplified by the amplifier 12 for detection.

Claims

1. An atmospheric pressure ionization source with ion spatial focusing function, characterized in that: The chamber includes a hollow, sealed cylindrical cavity. A VUV lamp (1) is provided at the left end of the cavity. The light emitted from the VUV lamp (1) is directed towards the inside of the cavity. The light emitted from the VUV lamp is transmitted from left to right along the axis of the cavity. The area inside the cavity near the light outlet of the VUV lamp (1) serves as an ionization reaction zone (2). A sample inlet (3) is provided on the side wall of the cavity near the VUV lamp (1) in the ionization reaction zone. An ion outlet (7) is provided at the right end of the cavity. The area inside the cavity between the ionization reaction zone (2) and the ion outlet (7) is an ion transport focusing zone (6). The VUV lamp (1), the ionization reaction zone (2), and the ion transport focusing zone (6) are arranged sequentially from left to right. A spindle-shaped metal electrode (4) is provided in the middle of the ion transport focusing region (6), and the inner wall of the ion transport focusing region (6) is a spindle-shaped metal electrode cylinder (5), with a gap between the spindle-shaped metal electrode (4) and the spindle-shaped metal electrode cylinder (5).

2. The ionization source according to claim 1, characterized in that: The spindle-shaped metal electrode (4) is formed by connecting the left truncated cone and the right cone with their common bottom surfaces. The axial height of the cone on the side closer to the VUV lamp (1) is less than the axial height of the cone on the side farther from the VUV lamp (1). The spindle-shaped metal electrode tube (5) is formed by connecting the lower bottom surfaces of the left frustum-shaped chamber and the right conical chamber. The axial height of the conical chamber on the side closer to the VUV lamp (1) is less than the axial height of the conical chamber on the side farther from the VUV lamp (1). The spindle-shaped metal electrode (4) and the spindle-shaped metal electrode tube (5) are coaxial. The spindle-shaped metal electrode (4) is connected to the radio frequency high voltage, while the spindle-shaped metal electrode tube (5) is connected to the ground. Alternatively, the spindle-shaped metal electrode (4) is connected to the ground, while the spindle-shaped metal electrode tube (5) is connected to the radio frequency high voltage.

3. The ionization source according to claim 1, characterized in that: The length of the ionization reaction zone (2) along the axial direction is 10-20 mm; the inner diameter of the ionization reaction zone is 5-10 mm.

4. The ionization source of claim 1, wherein: The ion outlet (7) is coaxial with the spindle-shaped metal electrode cylinder (5).

5. The ionization source according to claim 1, characterized in that: The waveform of the radio frequency high voltage is one or more of the following: square wave, sine wave or triangular wave. The amplitudes of the positive and negative high voltages are different or the same, while the integral areas of the positive and negative high voltages are the same.

6. The ionization source of claim 5, wherein: The frequency of the radio frequency high voltage is from 10 kHz to 300 MHz; the amplitude of the radio frequency high voltage is from 200 to 5000 V.

7. The ionization source according to any one of claims 1-6 can be connected to the mass spectrometer inlet through the ion outlet (7) and used in conjunction with the mass spectrometer. This will reduce the diameter of the columnar ionization source to match the mass spectrometer sampling micropore, thereby improving the ion processing efficiency and detection sensitivity.

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