CN115547806A - Online mass spectrum atmospheric pressure chemical ionization source and application thereof - Google Patents
Online mass spectrum atmospheric pressure chemical ionization source and application thereof Download PDFInfo
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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
- H01J49/14—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers
- H01J49/145—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers using chemical ionisation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
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- 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
- H01J49/049—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 with means for applying heat to desorb the sample; Evaporation
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Abstract
The invention discloses an online mass spectrum atmospheric pressure chemical ionization source and application thereof, belonging to the field of analytical instruments and comprising a halogen lamp, a mass spectrometer, a sample injection capillary tube, a four-way tube, a plasma flow, a radio frequency high-voltage electrode and a central ground electrode; the whole device realizes integrated integration through a four-way pipe. The main pipeline and the branch pipeline I and the branch pipeline II in the four-way pipe are vertical to each other in pairs and are crossed with each other to form a crossed area which is communicated with the plasma flow, the thermal desorption light path, the auxiliary reagent inlet and the sample sampling cotton swab, and the halogen lamp is focused on the crossed area. The whole device integrates photothermal analysis, chemical ionization and sample introduction, reduces the loss of samples in the transmission process, improves the sensitivity of online mass spectrometry by assisting the analysis and ionization of the samples with double auxiliary reagents, utilizes a sampling cotton swab to collect samples at any positions, can quickly analyze solid and liquid, is convenient and quick, has small volume, and is convenient for on-site and online quick analysis.
Description
Technical Field
The invention belongs to the field of analytical instruments, and particularly relates to an online mass spectrum atmospheric pressure chemical ionization source and application thereof.
Background
Dielectric barrier discharge is an important technical branch in the technology of atmospheric pressure ionization sources. The dielectric barrier discharge isAn unbalanced gas discharge with an insulating medium inserted into the discharge space. The dielectric barrier discharge can work in a high pressure and wide frequency range, and the working pressure is 10 4 Pa—10 5 Pa or higher, and a power supply frequency of 50 Hz-1 MHz. The discharge gas may be helium, nitrogen, air, or the like. The plasma generated by the discharge gas has electron energy exceeding 15eV, can generate positive and negative ions, and when an analyte contacts with the plasma, a series of chemical reactions can occur to be ionized.
In 2007, zhanneling et al utilize a dielectric barrier discharge device to ionize a reaction gas which can be used for chemical ionization (CN 200610011548.1), so that the reaction gas is ionized to generate reaction ions, and the reaction ions and an organic matter to be detected generate ion-molecule reactions, thereby realizing effective ionization of the organic matter to be detected. In 2011, a novel dielectric barrier discharge mass spectrum ionization source device (CN 201110232457.1) is designed by the Houbrand and the like, and the invention discloses a dielectric barrier discharge ionization source which uses a 30kHz radio frequency power supply as a discharge electrode, and the other electrode is grounded. The discharge electrode takes quartz glass as a medium, the inner diameter of the quartz glass tube where the radio-frequency high-voltage electrode is located is 10mm, and the diameter of the quartz glass tube where the ground electrode is located is 50mm. By using this ionization source in conjunction with online mass spectrometry, samples of explosives in the 50mm diameter range were detected for 3 seconds. A T-shaped dielectric barrier discharge mass spectrometry ionization source (CN 201210536370.8) is designed in 2012, and the device mainly comprises a T-shaped glass tube, a central ground electrode, a radio-frequency high-voltage electrode and a front-end ground electrode. When the ionization device works, two discharge areas are formed between the radio-frequency high-voltage electrode and the center ground electrode and between the radio-frequency high-voltage electrode and the front end ground electrode, and more heat can be generated for sample thermal analysis. Reagent gas is introduced through the T-tube and mixed with the plasma to form a plasma beam that is desorbed and selectively ionized when it is ejected onto the surface of the solid analyte. The device utilizes the plasma beam to directly contact with a sample to finish analysis and ionization, the flow rate of the used helium gas is about 0.2L/min, interference can be generated on the plasma beam after auxiliary gas is added into a discharge area by utilizing purge gas, the discharge efficiency is reduced, the introduced large-flow gas can dilute the analyte, and the sensitivity is reduced.
A mass spectrum ion source device (CN 201610491641.0) developed in Jiangjie et al in 2016 mainly comprises a needle point electrode, an insulating medium, a power supply, an instrument interface and a gas conduit, wherein the needle point electrode is connected with an alternating current power supply and a direct current power supply, the instrument interface is grounded, a strong electric field can be formed between the needle point electrode and the instrument interface, the insulating medium adhered with a sample is contacted with the tip part of the needle point electrode, discharge gas is filled between the insulating medium and the instrument interface through the gas conduit, and plasma can be formed under the action of the strong electric field. An open atmospheric pressure ionization device and method (cn201691572. X) developed in 2016 naughty road red, etc. comprises a dielectric barrier discharge ion source, a container, a conveying unit, a spray head, a power supply, and a sample injector. The device ionizes the auxiliary liquid emitted by the spray head by using the plasma source, the sample to be detected emitted by the sample injector is ionized by the ionized auxiliary liquid, and the ionization efficiency of the nonpolar compound can be enhanced by combining electrospray and dielectric barrier discharge, so that the device is suitable for ionization of the liquid sample.
Therefore, there is a need to develop an ionization source suitable for analysis of nonvolatile compounds, and to improve the analysis sensitivity and shorten the analysis time.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide an online mass spectrum atmospheric pressure chemical ionization source and application thereof. The ionization source provided by the invention integrates photothermal analysis, chemical ionization and sample introduction into one region, so that the loss of a sample in the transmission process is reduced, the analysis efficiency and the ionization efficiency of the sample are enhanced by respectively utilizing two auxiliary reagents, the analysis sensitivity is improved, liquid and solid samples at any positions are quickly collected by using a cotton swab, the operation is convenient, the applicability is wide, and the analysis speed is high.
In order to realize the purpose, the technical scheme of the invention is as follows:
in one aspect, an online mass spectrometry atmospheric pressure chemical ionization source, comprising: photothermal desorption-chemical ionization-sample introduction region, plasma generation region;
the photothermal analysis-chemical ionization-sample introduction region comprises a mass spectrometer, a sample introduction capillary tube, a four-way pipe, a heating device and a plasma flow;
the plasma generation area is used for generating a plasma flow;
the photothermal analysis, the chemical ionization, the sample injection region and the plasma generation region are integrated through a four-way pipe;
the four-way pipe consists of a main pipeline and three branch pipelines, wherein a first four-way branch pipeline and a second four-way branch pipeline are arranged in the photothermal analysis-chemical ionization-sample injection region, and a third four-way branch pipeline is arranged in the plasma generation region; the four-way pipe main pipeline, the four-way pipe branch pipeline I and the four-way pipe branch pipeline II are vertical to each other in pairs and are mutually crossed to form a crossed area;
the heating device is focused on the cross region;
the mass spectrometer is connected with a four-way pipe main pipeline through a sample injection capillary.
On the other hand, the online mass spectrometry atmospheric pressure chemical ionization source is applied to the field mass spectrometry of the volatile organic compounds.
The invention designs an online mass spectrum atmospheric pressure chemical ionization source based on dielectric barrier discharge, integrates photothermal analysis, chemical ionization and sample introduction into one region, reduces the loss of a sample in the transmission process, enhances the analysis and ionization efficiency of the sample by respectively utilizing two auxiliary reagents, improves the analysis sensitivity, can rapidly collect liquid and solid samples at any position by using a cotton swab, and has convenient operation, high analysis speed and high sensitivity.
The invention has the beneficial effects that:
the invention designs an online mass spectrum atmospheric pressure chemical ionization source based on dielectric barrier discharge, integrates photothermal analysis, chemical ionization and sample introduction into one region, reduces the loss of a sample in the transmission process, enhances the analysis and ionization efficiency of the sample by respectively utilizing two auxiliary reagents, improves the analysis sensitivity, can rapidly collect liquid and solid samples at any position by using a cotton swab, and has the advantages of convenient operation, high analysis speed, high sensitivity and wide applicability.
The ionization source of the invention designs double reagents of an ionization auxiliary reagent and a volatilization auxiliary reagent to assist the dielectric barrier discharge chemical ionization, soft ionization is realized by adding the ionization auxiliary reagent, the ionization efficiency of a sample is improved, the sample analysis efficiency is improved by volatilizing the auxiliary reagent, and the double reagents assist the improvement of the chemical ionization sensitivity. The invention adopts an optical radiation heating method, and integrates an optical radiation thermal analysis region and a chemical ionization region, thereby reducing the volume of the device and the transmission loss of samples.
In the detection and analysis process of the ionization source, the cotton swab can be directly used for sampling and sample introduction analysis of a non-volatile sample, both a solid sample and a liquid sample can be detected, samples at any positions can be collected, the operation is convenient, the analysis speed is high, and the analysis time of the whole analysis process is less than 1min.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are included to illustrate an exemplary embodiment of the invention and not to limit the invention.
FIG. 1 is a two-dimensional structure diagram of an online mass spectrometry atmospheric pressure chemical ionization source according to embodiment 1 of the present invention;
fig. 2 is a three-dimensional structure diagram of an online mass spectrometry atmospheric pressure chemical ionization source according to embodiment 1 of the present invention.
FIG. 3 is a mixture spectrum obtained by using an online mass spectrometry atmospheric pressure chemical ionization source in example 2 of the present invention;
FIG. 4 is a comparative spectrum of a 0.5ng ketamine sample with and without the aid of two reagents, obtained by using an online mass spectrometry atmospheric pressure chemical ionization source in example 3 of the present invention;
FIG. 5 is a 100ng/ml ketamine saliva sample spectrum obtained by using an online mass spectrometry atmospheric pressure chemical ionization source in example 3 of the present invention;
FIG. 6 is a comparison spectrum of the signal obtained by on-line mass spectrometry of atmospheric pressure chemical ionization source and nano-ESI analysis of MDMA with the same concentration in the comparative example of the present invention.
Wherein, 1: photothermal desorption-chemical ionization-sample introduction region, 2: plasma generation region, 3: halogen lamp, 4: mass spectrometer, 5: four-way pipe main line, 6: four-way branch pipe line one, 7: a four-way branch pipeline II, 8: plasma flow, 9: radio frequency high voltage electrode, 10: four-way branch pipeline three, 11: center ground electrode, 12: and (4) injecting a sample capillary.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The invention provides an online mass spectrum atmospheric pressure chemical ionization source and application thereof, aiming at improving the analysis sensitivity of a nonvolatile compound and shortening the analysis time of the nonvolatile compound.
In an exemplary embodiment of the present invention, there is provided an online mass spectrometry atmospheric pressure chemical ionization source, including: photothermal desorption-chemical ionization-sample introduction region, plasma generation region;
the photothermal analysis-chemical ionization-sample introduction region comprises a mass spectrometer, a sample introduction capillary tube, a four-way pipe, a heating device and a plasma flow;
the plasma generation area is used for generating a plasma flow;
the photothermal analysis, the chemical ionization, the sample injection region and the plasma generation region are integrated through a four-way pipe;
the four-way pipe consists of a main pipeline and three branch pipelines, wherein a first four-way branch pipeline and a second four-way branch pipeline are arranged in the photothermal analysis-chemical ionization-sample injection region, and a third four-way branch pipeline is arranged in the plasma generation region; the four-way pipe main pipeline, the four-way pipe branch pipeline I and the four-way pipe branch pipeline II are vertical to each other in pairs and are mutually crossed to form a cross area;
the heating device is focused on the cross region;
the mass spectrometer is connected with a four-way pipe main pipeline through a sample injection capillary.
In some embodiments of the present invention, the first four-way branch pipe is an inlet for the sample to be tested and the auxiliary reagent to be volatilized; the volatile auxiliary reagent comprises one or more of methanol, ethanol and butanol.
In some examples of this exemplary embodiment, the second bypass branch line is an ionization auxiliary reagent inlet; the ionization auxiliary reagent comprises one or more of acetone, butanone, toluene, anisole, ethanol or chlorobenzene.
In some embodiments of this exemplary embodiment, the four-way branch pipe three is a discharge gas inlet; the discharge gas comprises one or more of helium, nitrogen and air.
In some embodiments of the exemplary embodiment, the specific operations of the sample to be tested and the volatile auxiliary reagent entering the first four-way branch pipe are as follows: and sampling a sample to be detected by using a cotton swab, dropwise adding a volatile auxiliary reagent at the top of the cotton swab to perform auxiliary analysis, inserting the cotton swab into the main four-way pipe from the first four-way pipe branch pipe, and placing the sample in the cross area of the three pipelines. The cotton swab is used for sampling, so that liquid and solid samples at any positions can be rapidly collected, the operation is convenient, and the universality is wide. And a certain volume of volatile auxiliary reagent is dripped on the sampling cotton swab, so that the gasification efficiency of the sample can be improved, and the sensitivity of online mass spectrometry is improved.
In some embodiments of the exemplary embodiment, the specific operations of the ionization auxiliary reagent entering the second four-way branch pipe are as follows: and dropping an ionization auxiliary reagent on the top of the cotton swab, inserting the cotton swab into the four-way branch pipe II, and allowing gas formed by volatilization of the ionization auxiliary reagent to enter the cross region to be mixed with the plasma and be ionized to form reagent ions. The four-way branch pipe is used for inserting the cotton swabs dropwise added with the ionization auxiliary reagent, so that the ionization efficiency can be improved. And ionization auxiliary reagent has high volatility, utilizes the cotton swab to dip in the ionization auxiliary reagent who gets needs, fills in four-way pipe branch line two, need not extra sweeping gas, and ionization auxiliary reagent room temperature volatilizees the gas that forms by oneself and gets into four-way pipe main line, can reduce the dilution and the interference of sample.
In some examples of this exemplary embodiment, the discharge gas has a flow rate of 90 to 110ml/min.
In some examples of this exemplary embodiment, the heating device includes a halogen lamp, an infrared heating lamp, or an ultraviolet heating lamp.
In some examples of this exemplary embodiment, the heating device is a halogen lamp; the halogen lamp has a focusing heating function, light emitted by the halogen lamp is focused on a cross area through the four-way pipe, and a sample is gasified through focusing light heat.
In some examples of the exemplary embodiment, the cross-piece is made of quartz or glass.
In some embodiments of this exemplary embodiment, the crossover region is 1-10mm from the main cross-pipe to mass spectrometer connection.
In some embodiments of the exemplary embodiment, the bypass three is perpendicular to the bypass main conduit and parallel to the bypass one.
The distance between the four-way pipe branch and the four-way pipe main pipeline is 1-10mm far away from the mass spectrometer end.
In some examples of this exemplary embodiment, the plasma generation region includes a radio frequency high voltage electrode, a center ground electrode.
The radio frequency high voltage electrode is a metal ring with the inner diameter matched with the main four-way pipe, and is sleeved between the first four-way pipe branch pipeline and the third four-way pipe branch pipeline. The radio frequency high voltage electrode is as close to the first four-way pipe branch pipe as possible, so that the plasma density of the cross region is maximum.
The central ground electrode is a metal rod, is inserted into the four-way pipe at the end of the four-way pipe main pipeline far away from the mass spectrometer and is partially overlapped with the radio frequency high-voltage electrode.
The radio frequency high voltage electrode is connected with a high voltage output end of a radio frequency power supply, and the central ground electrode is connected with a radio frequency voltage grounding end.
The radio frequency high voltage electrode can ionize the introduced discharge gas to generate excited ions, electrons and the like to form plasma flow. Gas generated by volatilization of the ionization auxiliary reagent enters the four-way pipe main pipeline through the two four-way pipe branch pipelines and is mixed with the plasma flow in the cross area so as to be ionized to form reagent ions. The cotton swab with the sample to be detected is inserted into the first four-way branch pipeline, the sample to be detected and the halogen lamp focus are placed in the cross area of the three pipelines, the sample is rapidly heated by the halogen lamp and volatilized to form gas, formed gaseous sample molecules directly collide with plasma and reagent ions to be ionized in processes of proton transfer, charge transfer or molecular fragmentation, and then enter a mass spectrometer through an outlet to be analyzed.
The invention designs an online mass spectrum atmospheric pressure chemical ionization source based on dielectric barrier discharge, integrates photothermal analysis, chemical ionization and sample introduction into one region, reduces the loss of a sample in the transmission process, enhances the analysis and ionization efficiency of the sample by respectively utilizing two auxiliary reagents, improves the analysis sensitivity, can rapidly collect liquid and solid samples at any position by using a cotton swab, and has convenient operation, high analysis speed and high sensitivity.
According to another exemplary embodiment of the invention, the application of the online mass spectrometry atmospheric pressure chemical ionization source in the field mass spectrometry of the nonvolatile organic compounds is provided.
In some embodiments of this embodiment, the application is specifically operative to:
introducing discharge gas;
adjusting the halogen lamp, and adjusting the focus of the halogen lamp to just fall in the intersection area of the three pipelines;
turning on a radio frequency power supply, adjusting voltage frequency, and ionizing the introduced discharge gas by a radio frequency high-voltage electrode to generate excited ions, electrons and the like to form plasma flow;
dropping an ionization auxiliary reagent on the top of the cotton swab, inserting the cotton swab into the second four-way branch pipe, and allowing gas formed by volatilization of the ionization auxiliary reagent to enter the cross region to be mixed with the plasma and be ionized to form reagent ions;
sampling a sample to be detected by using a cotton swab, dripping a volatile auxiliary reagent at the top of the cotton swab to perform auxiliary analysis, inserting the cotton swab into a main four-way pipe from a first four-way pipe branch pipe, and placing the sample in a cross area of three pipes;
and starting a mass spectrometer analysis system, starting a halogen lamp, volatilizing a sample stained on the cotton swab to form a gas state, mixing the gas state with plasma flow and reagent ions, carrying out proton transfer, charge transfer or molecular fragmentation to ionize, and then sucking the gas state into a mass spectrometer by a mass spectrometer sample inlet pipe for analysis.
In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.
Example 1
Online mass spectrum atmospheric pressure chemical ionization source
As shown in FIG. 1, an atmospheric pressure chemical ionization source for online mass spectrometry comprises a photothermal desorption-ionization-sample introduction zone 1 and a plasma generation zone 2.
The photothermal desorption-ionization-sample introduction region 1 comprises a mass spectrometer 4, a sample introduction capillary tube 12, a four-way pipe, a halogen lamp 3 and a plasma flow 8. The plasma generation zone 2 comprises a radio frequency high voltage electrode 9, a central ground electrode 11. The photothermal desorption-chemical ionization-sample introduction region 1 and the plasma generation region 2 are integrated through a four-way pipe. The sample injection capillary tube 12 connects the mass spectrometer 4 with the four-way pipe, and one end of the sample injection capillary tube 12 is inserted into the position 3mm inside the four-way pipe main pipe 5 through a small hole with the diameter of 2mm at the left side of the four-way pipe main pipe 5.
The four-way pipe consists of one main pipeline and three branch pipelines, and specifically comprises a four-way pipe main pipeline 5, a four-way pipe branch pipeline I6, a four-way pipe branch pipeline II 7 and a four-way pipe branch pipeline III 10. The first four-way branch pipe 6 and the second four-way branch pipe 7 are arranged in the photothermal desorption-chemical ionization-sample introduction region 1, and the third four-way branch pipe 10 is arranged in the plasma generation region 2. The four-way pipe main pipeline 5, the four-way pipe branch pipeline I6 and the four-way pipe branch pipeline II 7 are vertical to each other in pairs and are mutually crossed to form a crossed area. The four-way branch pipeline three 10 is perpendicular to the four-way main pipeline 5 and parallel to the four-way branch pipeline one 6.
The used four-way pipe main pipeline 5 is a quartz cylinder with the length of 36mm, the outer diameter of 6mm and the inner diameter of 4mm, and the four-way pipe branch pipeline I6, the four-way pipe branch pipeline II 7 and the four-way pipe branch pipeline III 10 are all quartz cylinders with the outer diameter of 6mm, the inner diameter of 4mm and the length of 27 mm.
The radio frequency high voltage electrode 8 is a metal ring with the inner diameter of 6.1mm, the wall thickness of 0.1mm and the length of 16mm, is sleeved on the four-way pipe main pipeline 5 and is positioned between the four-way pipe branch pipeline one 6 and the four-way pipe branch pipeline three 7, and the radio frequency high voltage electrode 9 is connected with the output end of the adjustable alternating current high voltage power supply. The central ground electrode 11 is a metal round tube with the outer diameter of 1.58mm and the length of 100mm, is inserted into the tube at the right side of the four-way tube main pipeline 5, is partially overlapped with the radio frequency high-voltage electrode and is connected with the ground electrode of the adjustable alternating current high-voltage power supply.
The halogen lamp 3 has the power of 100W, and can form a focus with the diameter of 2mm at the position of 35mm, the temperature at the focus can rise to 250 ℃ within 2s, and the focus is adjusted to just fall on the crossed area of the three pipelines.
And turning on a radio frequency power supply, adjusting the voltage frequency, and providing an alternating current high voltage with a peak value of 1.6kVp-p and a frequency of 25kH for the radio frequency high voltage electrode 9 to generate dielectric barrier discharge and generate plasma.
In the application of the online mass spectrum atmospheric pressure chemical ionization source in the field analysis of the volatile organic compounds, the specific steps are as follows:
discharge gas is introduced, and the flow rate of the helium gas in the discharge gas is 100ml/min.
The halogen lamp is adjusted to have a focus just in the intersection area of the three pipelines.
The radio frequency power supply is turned on, the voltage frequency is adjusted, the radio frequency high-voltage electrode can ionize the introduced discharge gas to generate excited ions, electrons and the like, and plasma flow is formed.
And dropping an ionization auxiliary reagent on the top of the cotton swab, inserting the cotton swab into the four-way branch pipe II, and allowing gas formed by volatilization of the ionization auxiliary reagent to enter the cross region to be mixed with the plasma and be ionized to form reagent ions.
And sampling a sample to be detected by using a cotton swab, dropwise adding a volatile auxiliary reagent at the top of the cotton swab to perform auxiliary analysis, inserting the cotton swab into the main four-way pipe from the first four-way pipe branch pipe, and placing the sample in the cross area of the three pipelines.
And starting a mass spectrometer analysis system, starting a halogen lamp, volatilizing a sample stained on the cotton swab to form a gas state, mixing the gas state with plasma flow and reagent ions, carrying out proton transfer, charge transfer or molecular fragmentation to ionize, and then sucking the gas state into an analyzer by a mass spectrometer sample inlet pipe for analysis.
Example 2
The application of the online mass spectrum atmospheric pressure chemical ionization source in the field analysis of the volatile organic compounds in the embodiment 1. The online mass spectrum atmospheric pressure chemical ionization source of example 1 is adopted, the continuous sample injection type ion trap mass spectrum is used as an analytical instrument, the mixture of amphetamine, methamphetamine and MDMA is measured in a positive ion mode, and the concentration of three drugs is 10ppm.
Wherein, a liquid-transfering gun is used for sucking a mixture solution with the concentration of 10ppm and dripping the mixture solution on the top of a cotton swab, then the liquid-transfering gun is used for sucking 5 mul of butanol solvent and dripping the butanol solvent on the same position, and then the cotton swab is inserted into a cross area from a first four-way pipe branch; using a pipette gun, 20. Mu.l of acetone solvent was pipetted and dropped onto the top of another cotton swab, and the swab was inserted into the second branch of the four-way tube, and the procedure was otherwise the same as in example 1.
The analysis result is shown in fig. 3, and fig. 3 is a mixture spectrogram obtained in a full spectrum mode, wherein ions with mass-to-charge ratio 117 are dimer ion peaks formed by the auxiliary reagent acetone gas, ions with mass-to-charge ratio 136 are protonated molecular ion peaks of amphetamine, ions with mass-to-charge ratio 150 are protonated molecular ion peaks of amphetamine, and ions with mass-to-charge ratio 194 are protonated molecular ion peaks of MDMA.
Example 3
The application of the online mass spectrum atmospheric pressure chemical ionization source in the field analysis of the volatile organic compounds in the embodiment 1.
The online mass spectrum atmospheric pressure chemical ionization source is used together with an analysis instrument in the embodiment 1, the continuous injection type ion trap mass spectrum is used as the analysis instrument, and the analyte is qualitatively analyzed more accurately in a multi-reaction monitoring mode of a mass spectrometer of the continuous injection type ion trap.
Sucking 1 mu l of ketamine standard solution with the concentration of 500ng/ml by using a pipette gun, dripping the ketamine standard solution on the top of a cotton swab, sucking 5 mu l of butanol solvent by using the pipette gun, dripping the butanol solvent at the same position, inserting the cotton swab into a cross area from a four-way pipe branch I, and simultaneously ensuring that the focus of a halogen lamp is concentrated on the surface of the cotton swab, wherein the absolute amount of a sample on the cotton swab is 0.5ng; and (3) sucking 20 mu l of acetone solvent by using a pipette gun, dripping the acetone solvent on the top of another cotton swab, inserting the cotton swab into a second branch of the four-way pipe, wherein the formed acetone gas enters a cross region to be mixed with plasma and ionized to form reagent ions because the acetone is volatile at room temperature, and the rest steps are consistent with the steps in the example 1.
Fig. 4 is a comparative mass spectrum of the 500pg signal of a standard sample of ketamine with and without the addition of the dual auxiliary reagent, 219 is the characteristic fragment ion of ketamine, a) is the characteristic fragment ion intensity of ketamine with the addition of the dual auxiliary reagent, b) is the characteristic fragment ion intensity of ketamine with the addition of no auxiliary reagent, and it can be seen that the signal intensity of the characteristic fragment ion peak of ketamine is increased by one order of magnitude.
FIG. 5 is a graph of the spectra obtained from the analysis of a 100ng/ml sputum sample of ketamine dipped with a cotton swab, which has successfully detected ketamine. As 100ng/ml ketamine in saliva is the primary confirmation threshold value for toxic driving roadside rapid detection, the sensitivity of the online mass spectrum atmospheric pressure chemical ionization source in the field analysis application of the volatile organic compounds can be used for roadside rapid toxic driving screening.
Table 1 shows the lowest detection limits of six common drugs obtained by this embodiment, wherein the detection limits of methamphetamine hydrochloride, MDMA, MDA, ketamine are as low as 50pg, and the detection limits of cocaine and benzoylekinin are as low as 100pg, and table 1 shows that the online mass spectrometry atmospheric pressure chemical ionization source of the present invention has high sensitivity and great potential in the rapid roadside poison screening aspect.
TABLE 1
Comparative example 1
The difference from example 3 is that the MDMA standard solution was analyzed using commercial nano-ESI, using the same analytical equipment and parameters, 10. Mu.l of MDMA amine standard solution with a concentration of 1. Mu.g/ml was taken using a pipette, and filled into a quartz glass capillary, inserted into a metal electrode and applied with 1200V DC voltage, and as the liquid is under DC high voltage, a spray was formed and the analyte therein was ionized and analyzed by the instrument.
FIG. 6 is a signal-versus-mass spectrum of an MDMA standard solution for online mass spectrometry of atmospheric pressure chemical ionization source and nano-ESI analysis, a) a signal mass spectrum of an MDMA standard solution for online mass spectrometry of atmospheric pressure chemical ionization source, and b) a signal mass spectrum of an MDMA standard solution for nano-ESI analysis. From figure 6 it can be seen that the signal intensity of the characteristic fragment ion peak of MDMA is improved by an order of magnitude when analyzed by the online mass spectrometry atmospheric pressure chemical ionization source of the present invention using the same concentration and volume of standard solution and the same instruments and parameters.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An online mass spectrometry atmospheric pressure chemical ionization source, comprising: photothermal desorption-chemical ionization-sample introduction region, plasma generation region;
the photothermal analysis-chemical ionization-sample introduction region comprises a mass spectrometer, a sample introduction capillary tube, a four-way pipe, a heating device and a plasma flow;
the plasma generation area is used for generating a plasma flow;
the photothermal analysis, the chemical ionization, the sample injection region and the plasma generation region are integrated through a four-way pipe;
the four-way pipe consists of a main pipeline and three branch pipelines, wherein a first four-way branch pipeline and a second four-way branch pipeline are arranged in the photothermal analysis-chemical ionization-sample injection region, and a third four-way branch pipeline is arranged in the plasma generation region; the four-way pipe main pipeline, the four-way pipe branch pipeline I and the four-way pipe branch pipeline II are vertical to each other in pairs and are mutually crossed to form a cross area;
the heating device is focused on the cross region;
the mass spectrometer is connected with the main pipeline of the four-way pipe through the sample injection capillary.
2. The online mass spectrometry atmospheric pressure chemical ionization source of claim 1, characterized by: the first four-way branch pipeline is an inlet for a sample to be tested and a volatilization auxiliary reagent, preferably, the volatilization auxiliary reagent comprises one or more of methanol, ethanol and butanol;
or the four-way branch pipe line II is an ionization auxiliary reagent inlet, preferably, the ionization auxiliary reagent comprises one or more of acetone, butanone, toluene, anisole, ethanol or chlorobenzene;
or, the four-way pipe branch pipe three is a discharge gas inlet, preferably, the discharge gas comprises one or more of helium, nitrogen and air.
3. The online mass spectrometry atmospheric pressure chemical ionization source of claim 2, wherein: the specific operation that the sample to be tested and the volatile auxiliary reagent enter the first four-way branch pipeline is as follows: sampling a sample to be detected by using a cotton swab, dropwise adding a volatile auxiliary reagent at the top of the cotton swab for auxiliary analysis, inserting the cotton swab into a main four-way pipe from a first four-way pipe branch pipe, and placing the sample in a cross area of three pipelines;
or the specific operation of the auxiliary ionization reagent entering the second four-way branch pipe is as follows: dropping an ionization auxiliary reagent on the top of the cotton swab, inserting the cotton swab into the second four-way branch pipe, and allowing gas formed by volatilization of the ionization auxiliary reagent to enter the cross region to be mixed with the plasma and be ionized to form reagent ions;
or the flow rate of the discharge gas is 90-110ml/min.
4. The online mass spectrometry atmospheric pressure chemical ionization source of claim 1, characterized by: the heating device comprises a halogen lamp, an infrared heating lamp or an ultraviolet heating lamp, and is preferably a halogen lamp; further preferably, the halogen lamp has a focusing heating function, light emitted from the halogen lamp is focused on the cross region through the four-way pipe, and the sample is gasified by focusing light and heat.
5. The online mass spectrometry atmospheric pressure chemical ionization source of claim 1, characterized by: the four-way pipe is made of quartz or glass.
6. The online mass spectrometry atmospheric pressure chemical ionization source of claim 1, characterized by: the distance between the cross region and the connection end of the four-way pipe main pipeline and the mass spectrometer is 1-10mm.
7. The online mass spectrometry atmospheric pressure chemical ionization source of claim 1, characterized by: the four-way pipe branch line three is perpendicular to the four-way pipe main pipeline and parallel to the four-way pipe branch line one;
preferably, the three distances between the four-way pipe branch and the four-way pipe main pipeline are 1-10mm far away from the mass spectrometer end.
8. The on-line mass spectrometry atmospheric pressure chemical ionization source of claim 1, wherein: the plasma generating region comprises a radio frequency high-voltage electrode and a central ground electrode;
the radio frequency high-voltage electrode is a metal ring with the inner diameter matched with the four-way pipe main pipeline, the metal ring is sleeved between the four-way pipe branch pipeline I and the four-way pipe branch pipeline III, the central ground electrode is a metal rod, the end, far away from the mass spectrometer, of the four-way pipe main pipeline is inserted into the four-way pipe, and the metal rod is partially overlapped with the radio frequency high-voltage electrode;
the radio frequency high voltage electrode is connected with a high voltage output end of a radio frequency power supply, and the central ground electrode is connected with a radio frequency voltage grounding end.
9. Use of the online mass spectrometry atmospheric pressure chemical ionization source of any one of claims 1-8 for in situ analysis of refractory organics.
10. The use of the online mass spectrometry atmospheric pressure chemical ionization source of claim 9 in the field analysis of refractory organics, characterized in that: the specific operation is as follows:
introducing discharge gas;
adjusting the halogen lamp, and adjusting the focus of the halogen lamp to just fall in the intersection area of the three pipelines;
turning on a radio frequency power supply, adjusting voltage frequency, and ionizing introduced discharge gas by a radio frequency high-voltage electrode to generate excited ions, electrons and the like to form plasma flow;
dropping an ionization auxiliary reagent on the top of the cotton swab, inserting the cotton swab into the second four-way branch pipe, and allowing gas formed by volatilization of the ionization auxiliary reagent to enter the cross region to be mixed with the plasma and be ionized to form reagent ions;
sampling a sample to be detected by using a cotton swab, dropwise adding a volatile auxiliary reagent at the top of the cotton swab for auxiliary analysis, inserting the cotton swab into a main four-way pipe from a first four-way pipe branch pipe, and placing the sample in a cross area of three pipelines;
starting a mass spectrometer analysis system, starting a halogen lamp, volatilizing a sample stained on the cotton swab to form a gas state, mixing the gas state with plasma flow and reagent ions, carrying out proton transfer, charge transfer or molecular fragmentation to be ionized, and then sucking the ionized gas into a mass spectrometer by a mass spectrometer sample inlet pipe for analysis.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211115743.4A CN115547806A (en) | 2022-09-14 | 2022-09-14 | Online mass spectrum atmospheric pressure chemical ionization source and application thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211115743.4A CN115547806A (en) | 2022-09-14 | 2022-09-14 | Online mass spectrum atmospheric pressure chemical ionization source and application thereof |
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| CN202211115743.4A Pending CN115547806A (en) | 2022-09-14 | 2022-09-14 | Online mass spectrum atmospheric pressure chemical ionization source and application thereof |
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