CN117457470B - Novel ultraviolet ionization high-resolution mass spectrometer - Google Patents
Novel ultraviolet ionization high-resolution mass spectrometer Download PDFInfo
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- 239000004205 dimethyl polysiloxane Substances 0.000 claims abstract description 19
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- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims abstract description 19
- 235000013870 dimethyl polysiloxane Nutrition 0.000 claims abstract description 18
- CXQXSVUQTKDNFP-UHFFFAOYSA-N octamethyltrisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C CXQXSVUQTKDNFP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001514 detection method Methods 0.000 claims abstract description 11
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- 238000010884 ion-beam technique Methods 0.000 claims description 7
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J49/0422—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components for gaseous samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
- G01N27/66—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber and measuring current or voltage
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- H—ELECTRICITY
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- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J49/0468—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components with means for heating or cooling the sample
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- H—ELECTRICITY
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- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/10—Ion sources; Ion guns
- H01J49/16—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission
- H01J49/161—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission using photoionisation, e.g. by laser
- H01J49/162—Direct photo-ionisation, e.g. single photon or multi-photon ionisation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/24—Vacuum systems, e.g. maintaining desired pressures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/26—Mass spectrometers or separator tubes
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Abstract
The invention discloses a novel ultraviolet light ionization high-resolution mass spectrometer, which comprises an instrument composition module, a heating module and a capillary tube, wherein the instrument composition module comprises a sample injection module, an ionization source, a linear ion trap and an electrostatic ion trap, the sample injection module is used for introducing sample gas and isolating the internal and external air pressure of a cavity, heating the heating module, and the sample gas sequentially passes through a PDMS film and a sample to be introduced into the linear ion trap; the linear ion trap is used for trapping, accumulating and cooling sample ions, and then ejecting the sample ions to form ion groups; the deflection lens deflects the ion group and introduces the ion group into the electrostatic ion trap; the image current detection signal of the electrostatic ion trap is converted into a high-resolution mass spectrogram through FFT conversion, mass axis correction and data processing. The invention can realize compact miniaturization of the instrument, ultraviolet ionization, film sample injection or quick sample injection and small-volume electrostatic ion trap mass analyzer, and has compact structure, and can be used for field detection in a real-time and portable manner.
Description
Technical Field
The invention relates to the technical field of mass spectrometry, in particular to a novel ultraviolet ionization high-resolution mass spectrometer.
Background
According to chemical structures, VOCs can be classified into 8 major types of alkanes, aromatic hydrocarbons, alkenes, halohydrocarbons, esters, aldehydes, ketones and other compounds, the detected VOCs have the characteristics of complex sources, various types, low concentration (pptv-ppbv magnitude) and rapid space-time change, most of the VOCs are distributed in a range of 40-350 amu, the number of VOCs only in the exhaled breath of a human body is as many as two to three thousand, for the VOCs ultraviolet ionization mass spectrum commonly used in the market at present, an ion trap, a four-stage rod or a resolution is often adopted in a mass spectrum with a flight time of thousands, ultraviolet ionization mass spectrum adopting a quadrupole and an ion trap is easy to carry, but the resolution is poor, the ultraviolet ionization mass spectrum adopting a flight time mass analyzer is higher in resolution but huge in volume and is not suitable for portable detection, and for portable detection, the volume of the flight time analyzer is often reduced, so that the conventional ultraviolet ionization mass spectrum has higher false positives in the VOCs analysis and cannot be used as gold standard.
Disclosure of Invention
The invention aims to provide a novel ultraviolet ionization high-resolution mass spectrometer so as to solve the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a novel ultraviolet light ionization high resolution mass spectrometer comprising:
the sample injection module is used for introducing sample gas, heating the sample gas and heating the heating module, so that sample residues (in the cavity) can be reduced, the sample gas is isolated from vacuum, the sample gas containing an object to be detected is selectively transmitted to serve as the sample of the object to be detected, and the sample of the object to be detected is introduced into the linear ion trap;
the ionization source is used for ionizing the sample to be detected entering the linear ion trap so as to enable the sample to be detected to generate characteristic ions;
the linear ion trap emits characteristic ions to form an ion group;
the deflection lens deflects the ion groups entering and leaving the deflection lens through the aperture, so that the air flow with higher pressure of the linear ion trap cannot directly reach the electrostatic ion trap, and then the ion beam is introduced into the electrostatic ion trap;
the electrostatic ion trap is used for acquiring mass number and ion concentration information of sample ions of an object to be detected, and a high-resolution mass spectrogram is obtained by carrying out data processing on mirror image current of the electrostatic ion trap.
Further, the sample injection module comprises a sample injection pipe, a PDMS film, a sample outlet, a heating module and a mounting cavity, wherein the sample injection pipe and the sample outlet are connected with the mounting cavity, the sample injection pipe is used for introducing sample gas into the mounting cavity, the sample outlet is used for releasing the linear ion trap gas, the PDMS film and the heating module are arranged in the mounting cavity, the heating module is used for heating the mounting cavity, and the sample gas containing an object to be detected is isolated in vacuum, selectively transmitted and enriched through the PDMS film and then introduced into the linear ion trap.
Further, the sample introduction module further comprises a sample introduction capillary for communicating the mounting cavity with the linear ion trap.
Furthermore, the two ends of the linear ion trap are respectively provided with a front end cover of the linear ion trap and a rear end cover of the linear ion trap, the sample introduction capillary is used for introducing the sample of the object to be detected into the linear ion trap through the aperture of the rear end cover of the linear ion trap, and ultraviolet rays emitted by the ionization source ionize the sample of the object to be detected entering the linear ion trap through the front end cover of the linear ion trap so as to enable the sample of the object to be detected to generate characteristic ions.
Further, a focusing transmission lens for focusing the ion group is arranged between the linear ion trap and the deflection lens, and a vacuum isolation valve is arranged on the ion path between the focusing transmission lens and the deflection lens.
Further, the device also comprises a vacuum pump set, wherein the vacuum pump set is used for providing and maintaining the multistage vacuum pressure of the cavity for the sample injection module, the vacuum isolation valve and the electrostatic ion trap.
Further, the ionization source adopts a krypton lamp, the ionization energy of the krypton lamp is 10.6eV, the vacuum isolation valve is a normally closed electromagnetic valve, and the electrostatic ion trap adopts an orbitrap.
Further, a group of radio frequency voltages are added to four electrodes of the linear ion trap and used for trapping characteristic ions of a sample to be detected, the characteristic ions are cooled under the background air pressure of the linear ion trap, then a group of pulse high voltages are given to the electrodes of the linear ion trap, and the characteristic ions enter the electrostatic ion trap along an ion path through a focusing transmission lens.
Further, by detecting the mirror image differential current on the electrostatic ion trap, the detected differential current time domain signal is subjected to fast Fourier transform to obtain a frequency spectrum, and then is converted into a high-resolution mass spectrogram through a formula and mass correction, wherein the formula is thatWhere ω is the frequency obtained by the fast fourier transform, q is the charge amount, m is the ion mass, and k is the electrostatic ion trap coefficient.
In order to achieve the above purpose, the present invention further provides the following technical solutions:
a novel detection method of an ultraviolet light ionization high-resolution mass spectrometer comprises the following steps:
introducing sample gas into a sample injection module, heating the sample gas through the sample injection module, isolating vacuum from the sample gas, selectively transmitting the sample gas containing the to-be-detected object as a to-be-detected object sample, and introducing the to-be-detected object sample into a linear ion trap;
ionizing an object sample to be detected entering the linear ion trap through an ionization source to generate characteristic ions;
ejecting the generated characteristic ions through a linear ion trap to form an ion group;
the deflection lens deflects the ion groups entering and leaving the deflection lens through the aperture, so that the high-pressure air flow of the linear ion trap cannot directly reach the electrostatic ion trap, and then the ion beam is introduced into the electrostatic ion trap;
the electrostatic ion trap is used for acquiring mass number and ion concentration information of sample ions of an object to be detected, and a high-resolution mass spectrogram is obtained by carrying out data processing on mirror image current of the electrostatic ion trap.
Compared with the prior art, the invention has the beneficial effects that:
the sample gas is introduced into a sample injection module, and the sample gas is subjected to isolated vacuum, selective permeation and enrichment under a heating state by the sample injection module to form a sample of an object to be detected, and the sample of the object to be detected enters a linear ion trap; ionizing an object sample to be detected entering the linear ion trap through an ionization source to generate characteristic ions; ejecting the generated characteristic ions through a linear ion trap to form an ion group; the deflection lens deflects the ion group so that the ion group reaches the electrostatic ion trap in a buffer mode; the electrostatic ion trap analyzes and corrects the mass of the ion group and converts the mass into a high-resolution mass spectrogram.
According to the invention, the background noise can be reduced, the detection sensitivity of specific molecules can be improved, and the load of the pump set can be effectively reduced by the vacuum isolation valve, so that the pump set module with smaller pumping speed and smaller volume can be used in the vacuum pump set, a compact structure type mass spectrum device is realized, and the volume of the whole device is effectively reduced. The device has compact structure, and the vacuum isolation valve can further reduce the volume of the cavity and the volume of the pump group, so that the portability of the ultraviolet ionization high-resolution mass spectrometer can be realized.
The invention adopts an ultraviolet lamp (usually krypton lamp) as an ion source, a linear ion trap and an electrostatic ion trap as a mass analyzer, and combines the characteristics of soft ionization of the ultraviolet lamp and high resolution of the electrostatic ion trap: characteristic ions generated by soft ionization of the ultraviolet lamp are mostly molecular ion peaks, so that less fragment ions exist, and the sample to be detected is more easily and qualitatively analyzed; the electrostatic ion trap can be used as a high-resolution spectrogram of a mass analyzer to easily identify organic molecules with similar mass numbers and various types; the high-resolution characteristic ion peak mass spectrogram with high recognition degree obtained by the mass spectrometer and the method provided by the invention provides accurate qualitative semi-quantitative data, and solves the problem of insufficient data recognition in the fields of field analysis, medical diagnosis, rapid screening and the like.
Drawings
FIG. 1 is a block diagram of a UV ionization high-resolution mass spectrometer system according to the present invention.
Fig. 2 is a schematic diagram of the operation of the linear ion trap electrode voltage according to the present invention.
Fig. 3 shows a mass spectrum of an electrostatic ion trap for measuring VOCs generated inside a heated mounting cavity.
Fig. 4 shows a detailed view of the actual peak mass spectrum of VOCs.
FIG. 5 shows a block diagram of a sample injection module according to the present invention.
FIG. 6 shows a schematic diagram of a path of a rotating sample designed on the outer surface of a PDMS film according to the present invention.
In the figure: the device comprises a 1-ionization source, a 2-linear ion trap front end cover, a 3-linear ion trap, a 4-linear ion trap rear end cover, a 5-sample introducing capillary, a 6-heating module, a 7-sampling tube, an 8-PDMS film, a 9-sample outlet, a 10-vacuum isolation valve, an 11-electrostatic ion trap, a 12-deflection lens, a 13-vacuum pump group, a 14-focusing transmission lens, a 15-sampling module, a 16-mounting cavity, a 17-ion path and an 18-rotary sample path.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the terms "upper end," "lower end," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like indicate an azimuth or a positional relationship based on that shown in the drawings, merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "configured," "sleeved," "connected," and the like are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Referring to fig. 1 to 6, the present invention provides a technical solution:
the vacuum ultraviolet ionization source (Vacuum TUV Photoionization, VUV-PI for short) is a universal mass spectrum soft ionization source, which utilizes vacuum ultraviolet light (the wavelength is usually between 10 and 200 nm) to ionize molecules in a sample, the ionization source uses a krypton lamp which emits 10.6eV photons as a light source, VOCs which can ionize less than 10.6eV ionization energy can be ionized, and characteristic ion peaks are generated, the characteristic is convenient for spectrogram identification and high flux analysis, and the vacuum ultraviolet ionization mass spectrum has no fragments, is easy to analyze, has high sensitivity and is suitable for on-line rapid analysis and portable navigation detection.
The resolution of the electrostatic ion trap mass spectrum is as high as hundreds of thousands, the mass accuracy is in the PPM level, and the smaller the mass number is, the higher the resolution is, the soft ionization of the ultraviolet ionization source is combined with the ultrahigh resolution of the electrostatic ion trap, and the extremely high VOCs fixing capability and a certain semi-quantitative capability can be realized in a narrower mass range, so that the ultraviolet ionization electrostatic ion trap mass spectrum has extremely high potential as a gold standard for online VOCs detection.
The invention is a ultraviolet ionization high-resolution mass spectrometer with a compact supporting structure, the mass spectrometer has the characteristics of on-site analysis, quick response, real-time monitoring, suitability for complex environments and wider contact permission, and allows a user to perform real-time or near real-time analysis, so that sample degradation or pollution caused by sample transportation and storage is avoided, in case of emergency, such as chemical leakage or other environmental disasters, the portable mass spectrometer can quickly provide data, timely decision making is facilitated, and the invention is further introduced by combining the embodiments:
the novel ultraviolet ionization high-resolution mass spectrometer comprises an ionization source 1, a linear ion trap front end cover 2, a linear ion trap 3, a linear ion trap rear end cover 4, a sample introducing capillary 5, a heating module 6, a sample injection tube 7, a PDMS film 8, a sample outlet 9, a vacuum isolation valve 10, an electrostatic ion trap 11, a deflection lens 12, a focusing transmission lens 14 and a vacuum pump set 13.
Specifically, as shown in fig. 5, the sample injection module 15 is composed of a sample injection tube 7, a PDMS film 8, a sample outlet 9, a heating module 6 and a sample introducing capillary 5, wherein an ultraviolet lamp is ionized and combined with one other mass spectrum, the heating module 6 heats the whole sample injection module to 60-100 ℃ through a heating rod or a heating sheet, so that sample residues can be reduced, the PDMS film 8 has the functions of isolating vacuum, selectively penetrating and enriching sample gas containing a to-be-detected object (gas containing a target component), the sample gas flows through the surface of the PDMS film 8 through the sample injection port, and the sample is enriched through the film and introduced into the sample introducing capillary 5 and then enters the linear ion trap 3.
An ionization source 1 for generating ultraviolet light is used, and an ionization energy of a krypton lamp is 10.6eV. When the sample molecules of the object to be detected are lower than the ionization energy, the sample can be ionized, the characteristic ions are mainly generated, the fragment ions are few, and the energy is insufficient for ionizing most of background gas in the atmosphere, so that the sample has the advantage of selective ionization. Helping to reduce background noise and improve detection sensitivity of specific molecules.
Specifically, krypton lamp can ionize most organic molecules, mainly generates molecular ion characteristic peaks, has few fragment ions, and has the advantage of selective ionization because the energy is insufficient to ionize most background gases such as nitrogen, oxygen, carbon monoxide, water vapor and the like in the atmosphere. Helping to reduce background noise and improve detection sensitivity of specific molecules.
Specifically, as shown in fig. 6, the PDMS film 8 has functions of isolating vacuum, selectively penetrating and enriching samples, and a rotary sample passage 18 is generally designed on the outer surface of the PDMS film 8, and makes the air flow in a serpentine shape (S curve shape) flow, so that the contact time and contact area of the sample gas and the PDMS film 8 are increased as much as possible, the sample gas flows through the surface of the PDMS film 8 through a sample inlet, the impact of the sample gas on the PDMS film 8 is reduced, and simultaneously the sample is permeated through the film and introduced into the sample introducing capillary 5, and then enters the linear ion trap 3.
The sample is ionized by ultraviolet lamp 1 in linear ion trap 3, a group of radio frequency voltage is added to four electrodes of linear ion trap 3 to trap sample ion, sample ion is cooled by repeatedly collision of linear ion trap 3 with background gas under the air pressure condition of 0.1pa of linear ion trap 3, so that ions with different mass numbers have the same low initial kinetic energy, then a group of pulse high voltage is provided for ion trap electrode, the ions enter electrostatic ion trap 11 along track through focusing transmission lens 14, focusing transmission lens 14 is used for focusing ion group (ion beam) emitted from linear ion trap 3, and then deflecting under the action of deflecting lens 12.
The purpose of the deflection lens 12 is to deflect the ion beam entering and leaving the deflection lens 12 through the aperture, the deflection lens 12 has a Z-shaped air pressure of about 10E-5pa, the deflection lens 12 prevents the higher pressure air flow of the linear ion trap 3 from reaching the electrostatic ion trap 11 directly, so that the vacuum of the electrostatic ion trap 11 reaches a better vacuum degree (the process is that the ion group reaches the electrostatic ion trap 11 in a buffer manner), and then the ion beam is introduced into the electrostatic ion trap mass analyzer, and the voltage operation mode of the linear ion trap 3 is shown in fig. 2.
The electrostatic ion trap 11 is used for acquiring mass number and ion concentration information of an ion to be detected, and a high-resolution mass spectrogram can be obtained by performing data processing on mirror current of the electrostatic ion trap. The actual effect diagram is shown in fig. 3 and 4, fig. 3 shows mass spectrograms of electrostatic ion traps for measuring VOCs generated in the heating installation cavity, and mass spectrogram information of samples with different concentrations is clearly shown in the diagram; fig. 4 shows a detailed diagram of actual peak mass spectrum of VOCs, in which isotope and low concentration sample information can be kept in a low concentration region, the dynamic range of a single spectrogram exceeds 5000, the dynamic range can reach 106 after a plurality of spectrograms are processed, meanwhile, the excellent resolution of an electrostatic ion trap is combined with the capability of real-time full spectrum, and in a conventional 30-400 mass number interval, thousands of VOCs can be simultaneously analyzed in theory, so that extremely strong qualitative capability can be provided for VOCs measurement. The abscissa (m/z) in fig. 3 and 4 represents the number of masses, and the ordinate (Intensity) represents the signal Intensity.
The linear ion trap front end cap 2, the linear ion trap rear end cap 4, the deflection lens 12 and the transmission focusing lens 14 are all aperture-bearing.
The electrostatic ion trap 11 is preferably a rail as a mass analysis deviceThe track trap has the characteristic of high resolution, the frequency spectrum is obtained by detecting mirror image differential current on the electrostatic ion trap through fast Fourier transform on the detected differential current time domain signal, and then the frequency spectrum is converted into a high resolution mass spectrogram through a formula and mass correction, wherein the formula is thatWhere ω is the frequency obtained by FFT (fast fourier transform), q is the charge amount, m is the ion mass, k is the electrostatic ion trap 11 coefficient, the orbitrap can achieve ultra-high resolution, and under normal ion trap volumes, the ion path 17 (shown by the dashed line in fig. 1) is the ion trajectory in this case.
The important technical points of the invention are as follows: the vacuum pump stack 13 is required to provide and maintain a multi-stage vacuum pressure of the chamber, wherein the linear ion trap 3 needs to operate at a pressure of 10E-2 to 10E-3pa, the pressure of the electrostatic ion trap 11 is generally below 10E-7pa, and it should be noted that, since the sample introducing capillary 5 is connected to the linear ion trap 3, the internal pressure of the linear ion trap 3 (around 0.1 pa) is higher than the external pressure of the linear ion trap 3 (10E-2 to 10E-3 pa), and a PDMS film 8 of suitable thickness and size and a sample introducing capillary 5 of suitable size need to be selected to maintain the pressure of the linear ion trap 3 around 0.1pa, which is important because (in order to do so, the background gas can cool the sample ions well, so that the sample ions leave the linear ion trap 3 under the action of the pulsed high pressure and have uniform kinetic energy when entering the electrostatic ion trap 11).
Another unique design of the present invention is that a vacuum isolation valve 10 is added, which is a normally closed electromagnetic valve, for isolating the external air pressure 10E-2 to 10E-3pa of the linear ion trap 3 to the next stage, i.e. the air pressure of the deflection lens 12 is 10E-5pa vacuum (degrees), when the power is on, an ion path 17 can be formed, when the power is off, the path between the linear ion trap 3 and the deflection lens 12 is closed, and an ion running track cannot be formed. The vacuum isolation valve 10 is preferably a vacuum pinch valve or a flapper valve, with a response time in the order of ms, the valve operating time being several milliseconds before and after the sample ions exit the linear ion trap 3, the main functions of the valve being:
1. maintaining a higher gas pressure required by the sample during ionization and cooling of the linear ion trap 3 and a lower gas pressure of sample ions during spectrogram analysis of the electrostatic ion trap 11;
2. the vacuum isolation valve 10 is added, so that a vacuum cavity in which the electrostatic ion trap 11 is positioned can be protected when the whole machine is suddenly powered off or stopped, and the time for recovering vacuum is effectively reduced;
3. the vacuum isolation valve 10 can effectively reduce the burden of the vacuum pump set 13, so that the vacuum pump set 13 can use a pump set module with smaller pumping speed and smaller volume, thereby realizing the ultraviolet ionization high-resolution mass spectrometer with compact structure and effectively reducing the volume of the whole machine;
an important feature of the present invention is that it can achieve compact and small size of the apparatus, and the electrostatic ion trap mass analyzer for ultraviolet ionization, film sample injection or rapid sample injection and small volume has compact structure, and as mentioned above, the vacuum isolation valve 10 can further reduce the volume of the cavity and the volume of the vacuum pump group 13, so that the present invention can achieve portability of the ultraviolet ionization high resolution mass spectrometer.
The invention adopts an ultraviolet lamp (usually krypton lamp) as an ion source, a linear ion trap 3 and an electrostatic ion trap 11 as a mass analyzer, and combines the characteristics of soft ionization of the ultraviolet lamp and high resolution of the electrostatic ion trap:
1. characteristic ions generated by soft ionization of the ultraviolet lamp are mostly molecular ion peaks, so that less fragment ions exist, and the sample to be detected is more easily and qualitatively analyzed;
2. the electrostatic ion trap 11 can easily identify organic molecules with similar mass numbers and various types as a mass analyzer high-resolution spectrogram;
3. the high-resolution characteristic ion peak mass spectrogram with high recognition degree obtained by the mass spectrometer and the method provided by the invention provides accurate qualitative semi-quantitative data, and has great potential to solve the pain points with insufficient data recognition in the fields of field analysis, medical diagnosis, rapid screening and the like.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (9)
1. A novel ultraviolet light ionization high resolution mass spectrometer, comprising:
the sample injection module (15) is used for introducing sample gas, heating the sample gas, isolating the sample gas from vacuum, selectively transmitting the sample gas containing the to-be-detected object as the to-be-detected object sample, and introducing the to-be-detected object sample into the linear ion trap (3);
an ionization source (1), wherein the ionization source (1) is used for ionizing an object sample entering the linear ion trap (3) so as to enable the object sample to generate characteristic ions;
the linear ion trap (3) emits characteristic ions to form an ion group;
a deflection lens (12), the deflection lens (12) deflects the ion groups entering and leaving the deflection lens (12) through an aperture, so that the high-pressure air flow of the linear ion trap (3) cannot directly reach the electrostatic ion trap (11), and then the ion beam is introduced into the electrostatic ion trap (11);
the electrostatic ion trap (11) is used for acquiring mass number and ion concentration information of sample ions of an object to be detected, and a high-resolution mass spectrogram is obtained by carrying out data processing on mirror image current of the electrostatic ion trap (11);
a focusing transmission lens (14) for focusing the ion group further is arranged between the linear ion trap (3) and the deflection lens (12), and a vacuum isolation valve (10) is arranged on an ion path (17) between the focusing transmission lens (14) and the deflection lens (12).
2. The novel ultraviolet ionization high-resolution mass spectrometer according to claim 1, wherein the sample injection module (15) comprises a sample injection tube (7), a PDMS film (8), a sample outlet (9), a heating module (6) and a mounting cavity (16), the sample injection tube (7) and the sample outlet (9) are connected with the mounting cavity (16), the sample injection tube (7) is used for introducing sample gas into the mounting cavity (16), the sample outlet (9) is used for releasing gas of the linear ion trap (3), the PDMS film (8) and the heating module (6) are arranged in the mounting cavity (16), the heating module (6) is used for heating the inside of the mounting cavity (16), and the sample gas containing a to-be-detected object is isolated from vacuum and selectively transmitted through the PDMS film (8) and then introduced into the linear ion trap (3).
3. A novel uv ionisation high resolution mass spectrometer as claimed in claim 2 wherein said sample injection module (15) further comprises a sample introduction capillary (5) for communicating the mounting cavity (16) with the linear ion trap (3).
4. A novel ultraviolet ionization high-resolution mass spectrometer as claimed in claim 3, wherein the linear ion trap (3) is provided with a linear ion trap front end cover (2) and a linear ion trap rear end cover (4) at two ends respectively, the sample introducing capillary (5) introduces the sample of the object to be detected into the linear ion trap (3) through the aperture of the linear ion trap rear end cover (4), and ultraviolet rays emitted by the ionization source (1) ionize the sample of the object to be detected entering the linear ion trap (3) through the linear ion trap front end cover (2) so as to enable the sample of the object to be detected to generate characteristic ions.
5. A novel ultraviolet ionisation high resolution mass spectrometer as claimed in claim 1 further comprising a vacuum pump unit (13), the vacuum pump unit (13) being arranged to provide and maintain a multi-stage vacuum pressure in the chamber for the sample injection module (15) and the electrostatic ion trap (11).
6. The novel ultraviolet light ionization high-resolution mass spectrometer according to claim 1, wherein the ionization source (1) adopts a krypton lamp, the ionization energy of the krypton lamp is 10.6eV, and the vacuum isolation valve (10) is a normally closed electromagnetic valve.
7. A novel uv ionisation high resolution mass spectrometer as claimed in claim 1 wherein a set of rf voltages is applied to the four electrodes of the linear ion trap (3) for trapping sample characteristic ions of the analyte, the characteristic ions are cooled at the background air pressure of the linear ion trap (3) and subsequently pulsed at a high voltage to the electrodes of the linear ion trap (3) to pass the characteristic ions along the ion path (17) through the focussing transfer lens (14) into the electrostatic ion trap (11).
8. A novel uv ionization high resolution mass spectrometer as claimed in claim 1, wherein the frequency spectrum is obtained by fast fourier transform of the detected differential current time domain signal by detecting mirror differential current on the electrostatic ion trap (11), and then converted into a high resolution mass spectrogram by the formula and mass correction, the formula beingWhere ω is the frequency obtained by the fast fourier transform, q is the charge amount, m is the ion mass, and k is the electrostatic ion trap (11) coefficient.
9. The novel detection method of the ultraviolet light ionization high-resolution mass spectrometer is characterized by comprising the following steps of:
introducing sample gas into a sample injection module (15), heating the sample gas through the sample injection module (15), isolating vacuum from the sample gas, selectively transmitting the sample gas containing an object to be detected as an object sample to be detected, and introducing the object sample to be detected into a linear ion trap (3);
ionizing an object sample entering the linear ion trap (3) through an ionization source (1) to generate characteristic ions;
ejecting the generated characteristic ions through a linear ion trap (3) to form ion groups;
the deflection lens (12) deflects the ion groups entering and leaving the deflection lens (12) through the aperture, so that the high-pressure air flow of the linear ion trap (3) cannot directly reach the electrostatic ion trap (11), and then the ion beam is introduced into the electrostatic ion trap (11);
the electrostatic ion trap (11) is used for acquiring mass number and ion concentration information of sample ions of an object to be detected, and a high-resolution mass spectrogram is obtained by carrying out data processing on mirror image current of the electrostatic ion trap (11).
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