CN114724919B - A composite ionization source device for simultaneous mass spectrometry analysis of substances with different polarities - Google Patents
A composite ionization source device for simultaneous mass spectrometry analysis of substances with different polaritiesInfo
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- CN114724919B CN114724919B CN202210365104.7A CN202210365104A CN114724919B CN 114724919 B CN114724919 B CN 114724919B CN 202210365104 A CN202210365104 A CN 202210365104A CN 114724919 B CN114724919 B CN 114724919B
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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
- H01J49/10—Ion sources; Ion guns
- H01J49/107—Arrangements for using several ion sources
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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
- H01J49/10—Ion sources; Ion guns
- H01J49/16—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission
- H01J49/165—Electrospray ionisation
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Abstract
The invention discloses a composite ionization source device for simultaneous mass spectrometry of substances with different polarities, which comprises an electrospray extraction ionization source device and a dielectric barrier discharge device, wherein an inlet of the dielectric barrier discharge device is connected with an outlet of the electrospray extraction ionization source device, and the outlet is connected with an inlet of a mass spectrometer, wherein a solvent electrospray part of the electrospray extraction ionization source device comprises polar solvent electrospray and weak polar solvent electrospray. In the scheme, the serial connection design of the two ionization source devices, namely the electrospray extraction ionization device and the dielectric barrier discharge device, is convenient for respectively completing the high-efficiency ionization of the polar substances and the weak-polarity and nonpolar substances of the sample spray drop, thereby being beneficial to improving the coverage range of mass spectrum analysis.
Description
Technical Field
The invention relates to the technical field of mass spectrometry, in particular to a composite ionization source device for simultaneous mass spectrometry of substances with different polarities.
Background
The mass spectrometer is an instrument for separating and analyzing charged ions under the action of an electromagnetic field and mainly comprises an ionization source, a mass analyzer, a detector and the like. Ionization of a substance to be measured into a charged state by an ionization source is also a critical step in mass spectrometry, and thus the ionization source is called the heart of a mass spectrometer.
Various ionization source arrangements have been developed but the ionization mechanism of these ionization sources results in a bias for the applicable species in operation. Such as the usual electrospray ionization sources (electrospray ionization, ESI), electrospray extraction ionization sources (extractive electrospray ionization, EESI), etc., suitable for ionization analysis of polar molecules, atmospheric pressure chemical ionization (atmosphere pressure chemical ionization, APCI), dielectric barrier discharge (DIELECTRIC BARRIER DISCHARGE IONIZATION, DBDI), etc., suitable for ionization of weakly polar and nonpolar molecules. Most commercial instruments are provided with a plurality of ion sources such as an electrospray ionization source, an atmospheric pressure chemical ionization source and the like, the ion sources are often required to be replaced when analyzing substances with different polarities, the cost is high, and the simultaneous mass spectrometry analysis of polar, weak-polar and nonpolar substances by single sample injection cannot be realized, so that the commercial instruments have limitations.
To overcome the limitations described above, composite ionization source devices have been developed. In the existing composite ionization source technology, most of the technologies are the combination of atmospheric pressure photo ionization and atmospheric pressure chemical ionization. However, existing composite ionization sources still have the following drawbacks:
1. The two ionization technologies are suitable for ionization of weak polar and nonpolar substances, and lack ionization analysis capability on polar substances, and meanwhile, the polar substances are important parts in mass spectrometry and occupy a high proportion;
2. the sample must be atomized and heated to be gaseous, and the sample purity requirement is high, so that the sample is not suitable for complex matrix sample analysis and is not suitable for ionization analysis of thermally unstable substances.
Disclosure of Invention
In view of the above, the invention provides a composite ionization source device for simultaneous mass spectrometry of substances with different polarities, which is designed in series by using an electrospray extraction ionization device and a dielectric barrier discharge device, so that high-efficiency ionization of polar substances and low-polarity and nonpolar substances of a sample spray drop is conveniently completed, and the coverage of mass spectrometry is improved.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a compound ionization source device for mass spectrometry of substances with different polarities simultaneously comprises an electrospray extraction ionization source device and a dielectric barrier discharge device;
the inlet of the dielectric barrier discharge device is connected with the outlet of the electrospray extraction ionization source device, and the outlet is used for being connected with the inlet of the mass spectrometer, wherein the solvent electrospray part of the electrospray extraction ionization source device comprises polar solvent electrospray and weak polar solvent electrospray.
Preferably, the dielectric barrier discharge device comprises a dielectric tube, an electrode tube and a ring electrode;
the medium pipe is provided with an inlet for connecting a gas conveying pipe to be ionized;
The first end of the electrode tube is inserted into the first end of the medium tube, and the second end of the electrode tube is positioned outside the medium tube and connected with the outlet of the electrospray extraction ionization source device;
the ring electrode is sleeved on the outer wall of the medium pipe and is electrically connected with the electrode pipe through an alternating-current high-voltage power supply.
Preferably, the dielectric barrier discharge device further comprises:
and the carbon fiber is positioned in the medium tube and arranged on the outer wall of the first end of the electrode tube.
Preferably, the insulating tube is further included;
one end of the insulating tube is connected with the outlet of the electrospray extraction ionization source device, and the other end of the insulating tube is connected with the second end of the electrode tube.
Preferably, the device also comprises a T-shaped transmission pipe and an air pump;
the first end of the T-shaped transmission pipe is connected with the second end of the medium pipe, the second end is used for being connected with an inlet of the mass spectrometer, and the third end is connected with an air inlet end of the air pump.
Preferably, the electrospray extraction ionization source device comprises a sample spraying device, a polar solvent electrospray device, a weak polar solvent electrospray device and an extraction ionization cavity;
The extraction ionization cavity is provided with a sample spray droplet inlet, a polar solvent spray droplet inlet, a weak polar solvent spray droplet inlet and an outlet respectively, wherein the extension line of the sample spray droplet inlet to the inner cavity of the extraction ionization cavity is intersected with the extension line of the polar solvent spray droplet inlet to the inner cavity of the extraction ionization cavity and the extension line of the weak polar solvent spray droplet inlet to the inner cavity of the extraction ionization cavity respectively;
The sample spray droplet inlet of the extraction ionization cavity is connected with the outlet of the sample spray device, the polar solvent spray droplet inlet is connected with the outlet of the polar solvent electrospray device, the weak polar solvent spray droplet inlet is connected with the outlet of the weak polar solvent electrospray device, and the outlet is connected with the inlet of the dielectric barrier discharge device.
Preferably, the sample spraying device comprises:
the sample spray liquid drop inlet is arranged in the extraction ionization cavity, and is used for injecting or dripping a sample.
Preferably, the electrospray extraction ionization source device further comprises a direct-current high-voltage power supply and a high-frequency change-over switch;
the polar solvent electrospray device comprises a polar solvent spray body;
The weak polar solvent electrospray device comprises a weak polar solvent spray body;
The direct-current high-voltage power supply is in communication connection with the high-frequency change-over switch, and the high-frequency change-over switch is respectively and electrically connected with the capillary of the polar solvent spraying main body and the capillary of the weak polar solvent spraying main body.
The polar solvent spray body comprises a polar solvent injection pump and a polar electrospray capillary, wherein the inlet end of the polar electrospray capillary is connected with the outlet end of the polar solvent injection pump, and the outlet end of the polar electrospray capillary is connected with the polar solvent spray droplet inlet and is electrically connected with the high-frequency change-over switch;
the weak polar solvent spray main body comprises a weak polar solvent injection pump and a weak polar electrospray capillary, wherein the inlet end of the weak polar electrospray capillary is connected with the outlet end of the weak polar solvent injection pump, and the outlet end of the weak polar solvent spray capillary is connected with the weak polar solvent spray droplet inlet and is electrically connected with the high-frequency change-over switch.
Preferably, the sample spray droplet inlet is arranged at the top end of the extraction ionization cavity, the polar solvent spray droplet inlet and the weak polar solvent spray droplet inlet are arranged on the same side wall of the extraction ionization cavity, and the outlet is arranged on the other side wall of the extraction ionization cavity and is respectively opposite to the polar solvent spray droplet inlet and the weak polar solvent spray droplet inlet;
The outlet end of the polar electrospray capillary is connected with the polar solvent spray droplet inlet in a downward inclined mode along the horizontal direction, and the outlet end of the weak polar electrospray capillary is connected with the weak polar solvent spray droplet inlet in an upward inclined mode along the horizontal direction.
According to the technical scheme, the composite ionization source device for simultaneous mass spectrometry of substances with different polarities is designed in series by the two ionization source devices, namely the electrospray extraction ionization device and the dielectric barrier discharge device, so that high-efficiency ionization of polar substances and weak-polarity and nonpolar substances of a sample spray drop is conveniently finished, and coverage of mass spectrometry is improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a composite ionization source apparatus for simultaneous mass spectrometry of different polarity substances according to an embodiment of the present invention;
fig. 2 is a flow chart of a composite ionization source device for simultaneous mass spectrometry of substances of different polarities according to an embodiment of the present invention.
The device comprises a high-frequency micropore oscillation sheet 1, an extraction ionization cavity 2, a sample solution capillary 3, a polar electrospray capillary 4, a weak polar electrospray capillary 5, an insulating tube 6, an electrode tube 7, carbon fibers 8, a medium tube 9, a ring electrode 10, a gas conveying pipe to be ionized 11, a T-shaped conveying pipe 12, an air pump 13 and a mass spectrometer 14.
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.
The embodiment of the invention provides a composite ionization source device for simultaneous mass spectrometry of substances with different polarities, which is shown in figure 1 and comprises an electrospray extraction ionization source device and a dielectric barrier discharge device;
The inlet of the dielectric barrier discharge device is connected to the outlet of the electrospray extraction ionization source device for connection to the inlet of the mass spectrometer 14, wherein the solvent electrospray portion of the electrospray extraction ionization source device comprises a polar solvent electrospray and a weak polar solvent electrospray.
It should be noted that the electrospray extraction ionization source device further includes a sample spraying portion. More specifically, the sample spray droplets formed by the sample spray part and the solvent spray droplets formed by electrospraying the two solvents with different polarities are subjected to collision extraction and charge transfer reaction, wherein the electrospraying of the polar solvent is used for extracting and ionizing the polar substances to be tested in the sample spray droplets, and the electrospraying of the weak polar solvent is used for extracting the weak polar or nonpolar substances to be tested in the sample spray droplets, but the electric charge of the electrospraying of the weak polar solvent is limited, so that the weak polar or nonpolar substances to be tested are not ionized at the moment. In this way, the serial design of the two ionization source devices, namely the electrospray extraction ionization device and the dielectric barrier discharge device, further enables the liquid drops extracted with the weak-polarity or nonpolar substances to enter the dielectric barrier discharge device for continuous ionization, and the weak-polarity or nonpolar substances to be detected are ionized by triggering molecular ion reaction of water molecules and the substances to be detected in the air through plasma, so that the simultaneous ionization of the polar, weak-polarity and nonpolar substances in the sample is facilitated.
That is, the electrospray extraction ionization device and the dielectric barrier discharge device of the scheme are designed in series, the electrospray extraction ionization device can be used for extracting and ionizing substances with relatively high polarity to be detected in sample electrospray droplets, then the dielectric barrier discharge device is used for relatively small amounts of substances to be detected in sample electrospray droplets, and further ionization is realized by only extracting the weak-polarity and nonpolar substances which are not ionized in the electrospray extraction ionization stage, so that simultaneous ionization of single-sample-injection polarity, weak-polarity and nonpolar substances is facilitated.
According to the technical scheme, the composite ionization source device for simultaneous mass spectrometry of substances with different polarities is designed in series through the two ionization source devices, namely the electrospray extraction ionization device and the dielectric barrier discharge device, so that high-efficiency ionization of the polar substances and the low-polarity and nonpolar substances of a sample spray drop is conveniently finished, and the coverage of mass spectrometry is improved.
Specifically, as shown in fig. 1, the dielectric barrier discharge device includes a dielectric tube 9, an electrode tube 7, and a ring electrode 10;
The medium pipe 9 is provided with an inlet for connecting a gas conveying pipe 11 to be ionized, wherein the gas to be ionized can be helium;
The first end of the electrode tube 7 is inserted into the first end of the medium tube 9, and the second end is positioned outside the medium tube 9 and connected with the outlet of the electrospray extraction ionization source device;
The ring electrode 10 is sleeved on the outer wall of the medium pipe 9 and is electrically connected with the electrode pipe 7 through alternating current high-voltage power supply. The dielectric barrier discharge device is designed so as to form the effect of flowing type dielectric barrier discharge, so that weak polar and nonpolar substances in sample electrospray droplets can obtain better ionization effect, and the dielectric barrier discharge device has the characteristics of simple structure, easiness in design and the like. Preferably, the medium tube 9 is a quartz tube, the electrode tube 7 is a stainless steel electrode tube, and the ring electrode 10 is a copper ring electrode.
Further, as shown in fig. 1, the dielectric barrier discharge device further includes:
Carbon fiber 8 is disposed in the medium tube 9 and disposed on the outer wall of the first end of the electrode tube 7. That is, the outer wall of the first end of the electrode tube 7 is modified with carbon fiber 8 in this embodiment, so as to improve the discharge efficiency, generate more plasma, and thus help to improve the ionization efficiency of the dielectric barrier discharge device.
Further, in order to realize the electrical isolation between the electrospray extraction ionization device and the electrode tube 7 and ensure the safe cooperation between the electrospray extraction ionization device and the dielectric barrier discharge device, correspondingly, as shown in fig. 1, the composite ionization source device for simultaneous mass spectrometry of substances with different polarities provided by the embodiment of the invention further comprises an insulating tube 6;
one end of the insulating tube 6 is connected with the outlet of the electrospray extraction ionization source device, and the other end is connected with the second end of the electrode tube 7.
In order to further optimize the above technical solution, as shown in fig. 1, the composite ionization source device for simultaneous mass spectrometry of substances with different polarities provided in the embodiment of the present invention further includes a T-shaped transmission tube 12 and an air pump 13;
The T-shaped transfer tube 12 has a first end connected to the second end of the media tube 9, which is adapted to be connected to the inlet of the mass spectrometer 14, and a third end connected to the inlet of the pump 13. The air pump 13 pumps out redundant air in the ions, so that ion loss caused by air diffusion is avoided, and meanwhile, the ion transmission efficiency is improved.
In this embodiment, as shown in fig. 1, the electrospray extraction ionization source device includes a sample spraying device, a polar solvent electrospray device, a weak polar solvent electrospray device, and an extraction ionization cavity 2;
the extraction ionization cavity 2 is provided with a sample spray droplet inlet, a polar solvent spray droplet inlet, a weak polar solvent spray droplet inlet and an outlet respectively, wherein the extension line of the sample spray droplet inlet to the inner cavity of the extraction ionization cavity 2 is intersected with the extension line of the polar solvent spray droplet inlet to the inner cavity of the extraction ionization cavity 2 and the extension line of the weak polar solvent spray droplet inlet to the inner cavity of the extraction ionization cavity 2 respectively;
The sample spray droplet inlet of the extraction ionization cavity 2 is connected with the outlet of the sample spray device, the polar solvent spray droplet inlet is connected with the outlet of the polar solvent electrospray device, the weak polar solvent spray droplet inlet is connected with the outlet of the weak polar solvent electrospray device, and the outlet is connected with the inlet of the dielectric barrier discharge device.
It should be noted that, the inner extension line of the sample spray droplet inlet intersects with the inner extension line of the polar solvent spray droplet inlet and the inner extension line of the weak polar solvent spray droplet inlet respectively, so that the sample spray droplet and the two paths of solvent spray droplets with different polarities can form an intersection point in the extraction ionization cavity 2, and then the three spray droplets collide in the extraction ionization cavity 2 for extraction and charge transfer, and the corresponding substances to be detected in the sample are extracted and ionized. The method comprises the steps of performing electrospray extraction by using a polar solvent, ionizing a polar substance to be detected in sample spray droplets, performing electrospray extraction by using a weak polar solvent, and ionizing a weak polar substance to be detected in sample spray droplets. That is, the electrospray extraction ionization in the solution occurs in the extraction ionization cavity 2, which can avoid being influenced by external factors such as ambient air flow, and the angles of the two paths of solvent spray droplets with different polarities and the space position between the two paths of solvent spray droplets and the outlet of the electrospray extraction ionization source device are fixed, thereby being beneficial to improving the stability and repeatability of the electrospray extraction ionization.
Specifically, as shown in fig. 1, the sample spraying device includes:
The high-frequency micropore oscillation piece 1 is arranged at a sample spray drop inlet of the extraction ionization cavity 2 and is used for injecting or dripping samples. The sample is applied to the high-frequency micropore oscillation sheet 1, and rapidly passes through the micropore sheet of the high-frequency micropore oscillation sheet 1 under the action of high-frequency oscillation, is crushed into micron-sized fine liquid drop spray, and then enters the extraction ionization cavity 2. In addition, the high-frequency micropore oscillation piece 1 is used as a sample spraying device so as to atomize a sample into micron-sized liquid drop plumes, the sample spraying device is suitable for continuously flowing solution samples, liquid drop samples, cell samples and the like, and the micropore oscillation cutting atomization can crush the cell samples and release intracellular substances into sample liquid drops, so that the composite ionization source device can finish the broad spectrum mass spectrum analysis of polar, weak polar and nonpolar substances in single cells.
Furthermore, as shown in fig. 1, the sample spraying device further includes a sample solution injection pump and a sample solution capillary 3;
The inlet end of the sample solution capillary tube 3 is connected with the outlet end of the sample solution injection pump, and the outlet end is used for aligning the high-frequency microporous oscillation piece 1, namely, the outlet end of the sample solution capillary tube 3 and the microporous piece of the high-frequency microporous oscillation piece 1 form alignment fit. This scheme so designed to the sample solution to the automatic injection of high frequency micropore vibration piece 1 is realized to the realization, still adopts no atomizing gas auxiliary sample solution syringe pump to provide power for sample solution transmission moreover, even make this sample atomizer be no atomizing gas auxiliary sample atomizer, thereby help getting rid of the restriction that uses the steel bottle gas, reduced use cost, and made this device portable integration and removal easily.
Further, the electrospray extraction ionization source device also comprises a direct-current high-voltage power supply and a high-frequency change-over switch;
the polar solvent electrospray device comprises a polar solvent spray body;
the weak polar solvent electrospray device comprises a weak polar solvent spray body;
The direct-current high-voltage power supply is in communication connection with the high-frequency change-over switch, and the high-frequency change-over switch is respectively and electrically connected with the capillary of the polar solvent spraying main body and the capillary of the weak polar solvent spraying main body. The scheme is designed so that high-voltage electricity and high-frequency switching provided by a direct-current high-voltage power supply is conveniently output to capillaries of a polar solvent spraying main body and a weak polar solvent spraying main body through a high-frequency switching switch, so that alternating occurrence of polar and weak polar solvent electrospray is realized, and further, polar and weak polar substances in ionized sample liquid drops are conveniently extracted respectively. That is, the double-solvent electrospray device with different polarities is adopted in the scheme, so that alternating electrospray of polar and weak polar solvents is conveniently carried out, and polar and weak polar substances in ionized sample liquid drops are conveniently extracted respectively, so that simultaneous ionization analysis of multiple substances is realized to the greatest extent. In addition, it is clear that the polar solvent electrospray device and the weak polar solvent electrospray device of the present embodiment share the same dc high voltage power supply.
Still further, as shown in FIG. 1, the polar solvent spray body comprises a polar solvent injection pump and a polar electrospray capillary 4, wherein the inlet end of the polar electrospray capillary 4 is connected with the outlet end of the polar solvent injection pump, and the outlet end is connected with the polar solvent spray droplet inlet and is electrically connected with the high-frequency change-over switch;
The weak polar solvent spraying main body comprises a weak polar solvent injection pump and a weak polar electrospray capillary 5, wherein the inlet end of the weak polar electrospray capillary 5 is connected with the outlet end of the weak polar solvent injection pump, and the outlet end is connected with the weak polar solvent spraying droplet inlet and is electrically connected with the high-frequency change-over switch. The solvent spraying main body with the two different polarities is powered by the solvent injection pump without the assistance of atomizing gas for the transmission of the electrospray solvent, namely, the two solvent electrospray devices are all solvent electrospray devices without the assistance of atomizing gas, so that the limitation of using steel cylinder gas is eliminated, the use cost is reduced, and the device is easy to portable integrate and move.
Specifically, as shown in fig. 1, a sample spray droplet inlet is formed at the top end of an extraction ionization cavity 2 so as to enable sample spray droplets to fall into the extraction ionization cavity 2 vertically and naturally, wherein the bottom end of a high-frequency micropore oscillation piece 1 is connected with the top end of the extraction ionization cavity 2;
as shown in fig. 1, the outlet end of the polar electrospray capillary 4 is connected to the inlet of the polar solvent spray droplet in a downward inclination in the horizontal direction, and the outlet end of the weak polar electrospray capillary 5 is connected to the inlet of the weak polar solvent spray droplet in an upward inclination in the horizontal direction. That is, the polar and weak polar solvent electrospray of the solution are sequentially introduced from one side wall of the extraction ionization cavity 2 at a certain angle along the horizontal direction, and are alternately collided with sample spray droplets vertically falling in the extraction ionization cavity 2, so as to extract the substances to be detected with ionized polarity and weak polarity respectively, and then enter the dielectric barrier discharge device for further ionization. The design of this scheme is so as to make the high-speed air current direction of two-beam solvent electrospray keep unanimous with extraction ionization cavity 2 export direction, avoid influencing the transmission efficiency of ion.
The present solution is further described below in connection with specific embodiments:
the invention relates to a composite ionization source device for simultaneously analyzing polar, weak polar and nonpolar substances in a complex matrix sample by mass spectrometry, which is formed by connecting two ionization modules of micropore oscillation-electrospray extraction ionization and flow-through dielectric barrier discharge in series. Samples (including continuous flow solutions, droplets, cells, etc.) are cut into micron-sized spray droplets through a high frequency microporous vibrating plate, with the direction facing vertically downward. The polar solvent electrospray in the horizontal direction (containing a certain angle) extracts polar substances in the sample liquid drops, and the other path of weak polar solvent electrospray only extracts weak polar and nonpolar substances in the sample, and the weak polar and nonpolar substances are transmitted to the dielectric barrier discharge module to be ionized. Thus, extraction ionization of polar, weak polar and nonpolar substances in the sample is completed, and the sample enters a mass spectrometer for analysis.
The invention relates to a composite ionization source for simultaneous mass spectrometry of polar, weak-polar and nonpolar substances, which is formed by connecting two ionization modules in series, namely micropore oscillation-electrospray extraction ionization and flow-through dielectric barrier discharge. The overall flow chart of the invention is shown in figure 2. The continuous flow solution, liquid drop or cell sample is contacted with the high-frequency micropore oscillation sheet, sheared and atomized into micron-sized liquid drops, and vertically enters the extraction ionization cavity. Two paths of electrospray of solvents with different polarities are introduced from the side wall of the extraction ionization cavity along the horizontal direction (with a certain inclination angle), and micron-sized electrospray liquid drops and sample liquid drops are subjected to collision extraction and charge transfer reaction. The method comprises the steps of performing electrospray extraction on a polar solvent, ionizing a polar substance to be detected in sample liquid drops, and performing electrospray extraction on a weak polar or nonpolar substance in the sample liquid drops by using a weak polar solvent. The small liquid drops extracted with the weak polar or nonpolar substances enter a dielectric barrier discharge module, and the plasma triggers molecular ion reaction of water molecules and substances to be detected in the air so as to ionize the weak polar or nonpolar substances. Therefore, the simultaneous ionization of polar, weak polar and nonpolar substances in the sample is realized, and the substances enter a mass spectrometer for analysis.
The working principle of the device is as follows:
The micropore vibration sheet can realize high-frequency up-and-down vibration under the drive of 24V direct current voltage, and the middle vibration sheet is covered with micropores with the size of micrometers. The continuous flow solution, liquid drops, cells and other samples are contacted with the vibration piece, are instantaneously cut and atomized into micron-sized liquid drops (the cells are broken), and vertically enter the cylindrical extraction ionization cavity downwards. According to the principle of similar compatibility, polar electrospray droplets can extract polar substances in a sample, the charged quantity of the polar electrospray droplets is high, ionization of the polar substances can be realized through charge transfer reaction, and weak polar electrospray droplets extract weak polar and nonpolar substances, but the charged quantity of the weak polar electrospray droplets is small, complete ionization of the weak polar and nonpolar substances to be detected cannot be realized, and the weak polar and nonpolar substances enter a dielectric barrier discharge module and react with molecular ions in air under the action of plasma to finish ionization. The composite ionization source thus completes complete extraction ionization of polar, weak polar and nonpolar substances, and enters the mass spectrometer.
The device structure, components and functions thereof:
the schematic structure of the device is shown in fig. 1, wherein:
the high-frequency micropore oscillating sheet 1 has optional diameter (10-30 mm) and micropore number (1000-3000 meshes) and is driven by direct current 24V voltage. In the working state, the sample solution penetrates through the microporous sheet under the action of high-frequency oscillation and is cut into micron-sized droplet spray, and in the cell sample analysis, cell membranes are broken, and intracellular substances are released. A continuous flow of sample solution is introduced by a sample solution capillary 3 and atomized droplets enter the extraction ionization chamber 2.
The extraction ionization cavity 2 is manufactured by 3D printing. The top end of the upper opening and the lower opening are connected with the micropore oscillation piece, the side wall of the upper opening is provided with an opening, and the upper opening and the lower opening are respectively connected with the polarity electrospray capillary 4, the weak polarity electrospray capillary 5 and the polyether-ether-ketone insulating tube, so that the upper opening and the lower opening are places where spray intersection and extraction ionization occur.
A sample solution capillary 3.
The polar electrospray capillary 4 has an outer diameter of 360 micrometers, an inner diameter of 20 micrometers and an inner diameter of 10 micrometers at the tip end, generates polar electrospray under the action of direct-current high voltage (3-5 kV), and spray plumes are in interactive collision with sample liquid drops in the extraction ionization cavity 2 to extract and ionize polar substances to be detected in the sample liquid drops.
The weak-polarity electrospray capillary 5 has an outer diameter of 360 micrometers, an inner diameter of 20 micrometers and an inner diameter of 10 micrometers at the tip end, generates weak-polarity electrospray under the action of direct-current high voltage (4-6 kV), and the spray plume is in interactive collision with sample liquid drops in the extraction ionization cavity 2 to extract (not ionize) substances to be detected in the sample liquid drops.
The polyether-ether-ketone insulating tube (namely an insulating tube 6) is connected with the extraction ionization cavity 2 and a stainless steel electrode tube (namely an electrode tube 7) modified by carbon fiber in the dielectric barrier discharge module and is used for connection and ion transmission.
The carbon fiber modified stainless steel electrode tube, one of the electrodes in the dielectric barrier discharge module is connected with the copper ring electrode (namely the ring electrode 10) through alternating current high voltage (2-4 kV,5-50 kHz).
The carbon fiber 8 modified on the surface of the stainless steel electrode improves the discharge efficiency and generates more plasmas, thereby improving the ionization efficiency.
The quartz tube (namely the medium tube 9) charges the medium of the dielectric barrier discharge module.
One of the electrodes in the dielectric barrier discharge module is connected with a carbon fiber modified stainless steel electrode tube through alternating current high voltage electricity (2-4 kV,5-50 kHz).
The helium gas transmission pipe (namely the gas transmission pipe 11 to be ionized) provides helium gas for the dielectric barrier discharge module, the helium gas is ionized into plasma when discharged by the electrode, molecular ion reaction of water molecules and substances to be detected in the air is triggered, and the ionization process is completed.
The T-shaped polyether-ether-ketone transmission tube (namely the T-shaped transmission tube 12) is respectively connected with the dielectric barrier discharge cavity, the mass spectrometer inlet and the air extracting pump by three ports for ion transmission and air evacuation.
And the air pump 13 is connected with one port of the T-shaped polyether-ether-ketone transmission pipe and pumps out redundant air.
The working flow is as follows:
1. starting a high-frequency micropore vibration sheet 1;
2. The polarity electrospray and the weak polarity electrospray are started, and the two paths of electrospray are alternately triggered and started and controlled by a direct-current high-voltage power supply and a high-frequency change-over switch;
3. Starting alternating-current high-voltage power of the dielectric barrier discharge module;
4. starting the air extracting pump 13;
5. introducing helium from a helium delivery line at a flow rate of 1-3 liters/minute;
6. sample is introduced from a sample solution capillary 3, or liquid drops are directly dripped into the high-frequency microporous oscillation piece 1.
7. Mass spectrometry data is collected.
And processing, namely processing the extraction ionization cavity 2 by a 3D printing mode. The carbon fiber-modified stainless steel electrode tube is formed by modifying carbon fibers to the stainless steel electrode tube in an electrochemical mode. Other high-frequency micropore oscillating sheets, direct-current high-voltage power supplies, transmission capillaries, electrospray capillaries and the like are commodity parts.
The invention has the advantages that:
1. The series connection of the two ionization modules of micropore oscillation-electrospray extraction ionization and flow-through dielectric barrier discharge can respectively finish the high-efficiency ionization of polar substances and weak-polarity and nonpolar substances, thereby improving the coverage range of mass spectrometry.
2. The method of micropore oscillation-electrospray extraction ionization can effectively reduce the influence of matrix interference in a sample on ionization, and improves ionization efficiency;
3. the micropore vibration, cutting and atomizing can crush a cell sample, release intracellular substances into sample liquid drops, and the composite ionization source can complete the broad-spectrum mass spectrometry analysis of polar, weak-polar and nonpolar substances in single cells.
The key point and the point to be protected of the invention are as follows:
1. Micro-pore oscillation-electrospray extraction ionization and flow-through dielectric barrier discharge form a composite ionization source, so that single sample introduction of simultaneous ionization of polar, weak-polar and nonpolar substances is realized;
2. the stainless steel tube modified by carbon fiber is used as an inner electrode of the flow-through dielectric barrier discharge, so that the discharge and plasma generation efficiency is improved, and the ionization efficiency is improved;
3. And redundant gas is discharged by adopting the air pump, so that ion loss caused by gas diffusion is avoided, and meanwhile, the ion transmission efficiency is improved.
Explanation of the related terms of the scheme:
Mass spectrometer is an instrument for separating and detecting charged ions according to the difference of the 'mass/charge' ratio under the action of electromagnetic field. Mass spectrometers mainly comprise an ionization source, a mass analyzer, a detector, etc.
Ionization source-a device that ionizes a sample solution (neutral, uncharged) into charged ions.
And the micropore oscillating piece is formed by embedding a metal piece with a micron-sized aperture with an oscillator, and can directly cut and atomize liquid contacted with the metal piece into micron-sized droplets through high-frequency oscillation.
Electrospray, in which, solvent flows through a capillary, a direct-current high voltage is applied at the outlet of the capillary, and solvent molecules are sprayed at the outlet of the capillary under the action of electric field force and coulomb force to be atomized into micron-sized charged droplets.
Polar electrospray-electrospray by polar solvent.
Weak polarity electrospray-electrospray generated by weak polarity solvent.
Electrospray extraction ionization, namely, sample electrospray and pure solvent electrospray cross collide at a certain angle to generate droplet collision extraction and charge transfer, so as to extract and ionize substances to be detected in the sample.
Dielectric barrier discharge, which is to insert an insulating medium into a discharge space to discharge a non-equilibrium gas, and to generate stable low-temperature plasma at atmospheric pressure.
Continuous flow solution-solution flowing continuously at a rate of from 1 to 10 microliters per minute.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
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| CN102522312A (en) * | 2011-12-21 | 2012-06-27 | 复旦大学 | Electrochemistry electrospray ionization source |
| CN108776168A (en) * | 2018-08-16 | 2018-11-09 | 中国科学技术大学 | A photoionization mass spectrometry imaging device combined with desorption electrospray ionization |
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| US9691598B2 (en) * | 2013-08-02 | 2017-06-27 | Shimadzu Corporation | Ionizer and mass spectrometer including first section for ionizing sample under atmospheric pressure while vaporizing or desorbing the sample component and second section for generating corona discharge |
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| CN102522312A (en) * | 2011-12-21 | 2012-06-27 | 复旦大学 | Electrochemistry electrospray ionization source |
| CN108776168A (en) * | 2018-08-16 | 2018-11-09 | 中国科学技术大学 | A photoionization mass spectrometry imaging device combined with desorption electrospray ionization |
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