CN116264151A - Device and method for improving linear dynamic range of mass spectrum by changing air pressure in ionization region - Google Patents
Device and method for improving linear dynamic range of mass spectrum by changing air pressure in ionization region Download PDFInfo
- Publication number
- CN116264151A CN116264151A CN202111528185.XA CN202111528185A CN116264151A CN 116264151 A CN116264151 A CN 116264151A CN 202111528185 A CN202111528185 A CN 202111528185A CN 116264151 A CN116264151 A CN 116264151A
- Authority
- CN
- China
- Prior art keywords
- ionization source
- cavity
- ionization
- mass spectrum
- air pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/0027—Methods for using particle spectrometers
- H01J49/0031—Step by step routines describing the use of the apparatus
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/0027—Methods for using particle spectrometers
- H01J49/0036—Step by step routines describing the handling of the data generated during a measurement
Abstract
The invention provides a device for improving the linear dynamic range of mass spectrum by changing air pressure in an ionization region, which comprises a sealed ionization source cavity, a sealed ion transmission region cavity and a sealed mass analyzer cavity, wherein the sealed ionization source cavity, the sealed ion transmission region cavity and the sealed mass analyzer cavity are sequentially separated from top to bottom by partition plates; a gas outlet is arranged on the side wall of the ionization source cavity and is connected with a multichannel selection control electromagnetic valve through a vacuum pipeline; an ionization source is arranged in the ionization source cavity; and vacuum pump interfaces are respectively arranged on the side walls of the ion transmission area cavity and the mass analyzer cavity. The method for improving the linear dynamic range of the mass spectrum by changing the air pressure in the ionization region is characterized in that the air pressure of the ionization source is automatically regulated by a vacuum electromagnetic valve of the ionization source controlled by a computer, and the proper air pressure of the ionization source is selected, so that the signal intensity of the mass spectrum and the concentration of a target compound in sample gas are in a linear response range, and the linear dynamic range of the mass spectrum is further improved.
Description
Technical Field
The invention belongs to the field of mass spectrometry instruments and methods, and particularly relates to a device and a method for improving linear dynamic range of mass spectrum by changing air pressure in an ionization region.
Background
The mass spectrometry technology is a detection technology for realizing analysis of chemical components of substances by measuring mass-to-charge ratios (mass-to-charge ratios) of ions, has the characteristics of high resolution and sensitivity, high analysis speed and strong fixing capability, and has become one of the most widely used analysis technologies in the analysis and test fields. The ionization source, which is used as a core component of mass spectrometry, is used to ionize molecules or atoms of a substance, which not only determines the characteristics of the mass spectrum that can be obtained, but also affects the accuracy and sensitivity of the analysis of the mass spectrometer to a great extent. The traditional organic matter detection mass spectrum generally adopts a 70eV electron bombardment ionization (EI) source, has high ionization efficiency, but can generate a large amount of fragment ions, and particularly when a complex mixture is analyzed, the serious overlapping of spectrum peaks is easy to cause, the spectrum identification is difficult, and the rapid and online analysis is not facilitated.
The soft ionization technology mainly comprises Photoionization (PI) and Chemical Ionization (CI), and the molecular ion or quasi-molecular ion is mainly generated by making the sample molecule to be detected absorb photon energy or generate ion-molecule reaction with reagent ion, and few fragment ions are generated, so that the obtained mass spectrogram is simple, easy to analyze, and suitable for rapid and on-line detection of complex organic matter samples. In photoionization sources or chemical ionization sources, the ionization process of sample molecules consumes a portion of the photons or reagent ions. In general, the concentration of the sample molecules to be measured in the ionization source is far lower than the photon density or the concentration of the reagent ions, a relatively small amount of photons or reagent ions are consumed, the influence on the ionization process of the sample molecules is small, the yield of the sample ions is relatively stable, and the strength of the generated sample ions is proportional to the concentration of the sample molecules. When the concentration of the sample molecules to be detected in the ionization source is continuously increased and excessive photons or reagent ions are consumed, the ionization process of the sample molecules can be greatly influenced, the yield of the sample ions is reduced, the generated sample ions have the 'saturation' phenomenon along with the increase of the sample molecules, and the response of the instrument deviates from the linearity along with the change of the sample concentration. In addition, the problems of charge rejection, detector response saturation and the like of high-intensity ions in ionization, transmission and detection processes can further influence the linear response of a mass spectrometer, so that the linear dynamic range of the photoionization mass spectrum and the chemical ionization mass spectrum is usually only 2-3 orders of magnitude under certain ionization source or sample injection conditions.
In both photoionization and chemical ionization sources, the yield of sample ions is positively correlated with the number density of sample molecules within the ionization source, which is proportional to the ionization source gas pressure. Taking photoionization as an example, the yield of sample ions, R PI Can be expressed as:
wherein sigma PI (Mb,1Mb＝10 -18 cm 2 ) Is the photoionization section of the analyte, I 0 (photons/s) is the intensity of the lamp, L (cm) is the photoionization length, N (cm) -3 ) Is the molecular number density of the analyte, P (Pa) is the ionization region gas pressure, c is the volumetric concentration of the analyte, and T is the temperature of the ionization source. Therefore, the sample ion yield in the ionization source is regulated and controlled by regulating the air pressure of the ionization source, and the linear dynamic range of the mass spectrum is hopeful to be improved. Chinese invention patent [201010567193.0 ]]The invention discloses a composite ionization source for vacuum ultraviolet ionization and chemical ionization for mass spectrometry, which utilizes a single vacuum ultraviolet light source to realize the switching of two ionization modes of vacuum ultraviolet ionization and chemical ionization under the condition of certain ionization source air pressure, can control the sample injection amount according to the adjustment of the flow of a side pumping valve and the change of the inner diameters and the lengths of a reagent gas sample injection tube and a sample gas sample injection tube, adjusts the vacuum degree in a cavity of the ionization source, and widens the range of a detectable sample of an instrument. However, the ionization source technique does not involve an improvement in the dynamic range of mass spectral lines.
Disclosure of Invention
The invention aims to provide a device and a method for improving the linear dynamic range of a mass spectrum by changing air pressure in an ionization region, wherein the air pressure of an ionization source is automatically regulated by a vacuum electromagnetic valve of an ionization source controlled by a computer, and the proper air pressure of the ionization source is selected, so that the signal intensity of the mass spectrum and the concentration of a target compound in sample gas are in a linear response range, and the linear dynamic range of the mass spectrum is further improved.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the device for improving the linear dynamic range of the mass spectrum by changing the air pressure in the ionization region comprises a sealed ionization source cavity, a sealed ion transmission region cavity and a sealed mass analyzer cavity which are arranged in a stacked manner and are sequentially separated from top to bottom by a partition plate; ion through holes are formed in the partition plates between the ionization source cavity and the ion transmission area cavity and between the ion transmission area cavity and the mass analyzer cavity; a gas outlet is arranged on the side wall of the ionization source cavity and is connected with a multichannel selection control electromagnetic valve through a vacuum pipeline; an ionization source is arranged in the ionization source cavity; vacuum pump interfaces are respectively arranged on the side walls of the ion transmission area cavity and the mass analyzer cavity;
the multi-channel selection control electromagnetic valve comprises 2 or more than 3 vacuum pipelines which are connected in parallel and have different inner diameters within the range of 1-100 mm, air inlets of all the vacuum pipelines are mutually communicated to form an inlet end of the multi-channel selection control electromagnetic valve, and the inlet end is connected with a gas outlet arranged on the side wall of the ionization source cavity through the vacuum pipelines; the air outlets of all the vacuum pipelines are mutually communicated to form an outlet end of the multi-channel selection control electromagnetic valve, and the outlet end is connected with the vacuum pump through the vacuum pipeline; each vacuum pipeline is controlled to be switched on and off by an independently controlled vacuum electromagnetic switch valve;
a gas sample injection capillary tube penetrates through the outer wall of the ionization source cavity and stretches into the ionization source cavity to introduce sample gas into the ionization source;
an ion transmission lens is arranged in the cavity of the ion transmission area; a mass analyzer is arranged in the cavity of the mass analyzer, and an ion signal output end of the mass analyzer is connected with a data acquisition card;
the control ends of the data acquisition card and the multichannel selective control electromagnetic valve are respectively connected with a computer through signal lines, and the computer controls the data acquisition card to acquire mass spectrum data of the mass analyzer and the on-off of each vacuum electromagnetic switch valve of the multichannel selective control electromagnetic valve;
the ionization source is a photoelectric ionization source and a chemical ionization source;
the mass analyzer is a time-of-flight mass analyzer, a quadrupole mass analyzer, an ion trap mass analyzer and a magnetic mass analyzer.
The diluent gas used in the standard gas is one or more of nitrogen, oxygen, argon and air.
The method for improving the linear dynamic range of the mass spectrum by adopting the device for realizing the variable air pressure in the ionization region comprises the following steps:
1) Selectively controlling the on-off of different electromagnetic switch valves in the multi-channel selective control electromagnetic valve at 10 -4 ～10 3 A group of ionization source pressures p with different values of 2 or more are arranged in the mbar pressure range i Wherein the ratio of the absolute values of the air pressure of any two ionization sources (the higher air pressure absolute value/the lower air pressure absolute value) is more than or equal to 2;
2) In the volume concentration range (10) -12 ～10 -1 ) In the method, 2 or more than 3 concentration points are selected in each concentration level interval to prepare standard gas of the target compound to be detected, wherein the ratio of the concentration of the target compound to be detected in any two standard gases is more than or equal to 2;
3) Introducing standard gas containing target compounds to be detected with different known concentrations into ionization sources through gas sample injection capillaries for ionization and mass spectrum detection, wherein the pressure p of each ionization source is set as above i Mass spectrum analysis is carried out, and the current ionization source air pressure p is recorded by utilizing a data acquisition card i Mass spectrum signal intensity Y of target compound to be measured i And baseline noise N near the mass spectrum peak of the target compound i Build up of each ionization source pressure p i Signal to noise ratio Y of mass spectrum signal of lower target compound i /N i (Signal Strength Y) i And noise N i Ratio of) to its concentration c) and a concentration response curve Y i /N i ＝a i *c+b i ；
4) Each ionization source pressure p established according to the above i Concentration response curve of lower target compound, lineMinimum signal-to-noise ratio Y within the sexual range i /N i For adjusting and increasing the threshold T of the air pressure Li Maximum signal to noise ratio Y i /N i For adjusting the pressure to reduce the threshold T Hi Wherein T is Li Is of a size of 10 0 ～10 2 ，T Hi Is of a size of 10 3 ～10 5 ；
5) Sample gas is introduced into the gas sampling capillary tube, and the ionization source works at any ionization source pressure p set as above by controlling the multi-channel selection control electromagnetic valve i Under the condition, the current ionization source air pressure p is continuously monitored in real time by utilizing a data acquisition card i Mass spectrum signal intensity S of the target compound to be measured i And baseline noise N near the mass spectrum peak of the target compound i ；
6) Calculating the signal-to-noise ratio S of the spectrum signal of the target compound i /N i When S i /N i ≤T Li During the process, the ionization source air pressure p is caused by controlling the multi-channel selection control electromagnetic valve through a computer i Increasing; when S is i /N i ≥T Hi During the process, the ionization source air pressure p is caused by controlling the multi-channel selection control electromagnetic valve through a computer i Reduced, when T Li ＜S i /N i ＜T Hi When the current ionization source pressure p is established according to the above i The linear response curve below quantitatively analyzes the target compound.
According to the device and the method for improving the linear dynamic range of the mass spectrum by changing the air pressure in the ionization region, provided by the invention, the linear response curves of target compounds under different air pressures of the ionization source are established in advance, the mass spectrum intensity of the target compounds in sample gas is continuously monitored in real time, the air pressure of the ionization source is automatically adjusted by utilizing a computer to control a multi-channel selection control electromagnetic valve according to the comparison result of the mass spectrum intensity of the target compounds in the sample gas under the same air pressure of the ionization source and the linear response curves, and the proper air pressure of the ionization source is selected, so that the mass spectrum signal intensity and the concentration of the target compounds in the sample gas are in the linear response range, and the linear dynamic range of the mass spectrum is further improved.
Drawings
FIG. 1 is a schematic diagram of an apparatus for increasing linear dynamic range of a mass spectrum by changing air pressure in an ionization region according to the present invention.
FIG. 2 shows a method for improving linear dynamic range of mass spectrum by using the device to change air pressure in ionization region.
FIG. 3 is a concentration response curve of the signal to noise ratio of a toluene mass spectrum signal versus its concentration for an ionization source of the present invention at 0.01 mbar.
FIG. 4 is a concentration response curve of the signal to noise ratio of a toluene mass spectrum signal versus its concentration for an ionization source of the present invention at 0.5 mbar.
FIG. 5 is a concentration response curve of the signal to noise ratio of a toluene mass spectrum signal versus its concentration for an ionization source of the present invention at a gas pressure of 4 mbar.
Detailed Description
Referring to fig. 1, the device for improving linear dynamic range of mass spectrum by changing air pressure in ionization region according to the present invention includes a sealed ionization source cavity 101, a sealed ion transmission region cavity 102 and a sealed mass analyzer cavity 103, which are arranged in a stacked manner and are separated by a partition plate in sequence from top to bottom; ion through holes are formed in the separation plates between the ionization source cavity 101 and the ion transmission area cavity 102 and between the ion transmission area cavity 102 and the mass analyzer cavity 103; a gas outlet is arranged on the side wall of the ionization source cavity 101 and is connected with a multichannel selective control electromagnetic valve 107 through a vacuum pipeline; an ionization source 106 is disposed inside the ionization source chamber 101; vacuum pump interfaces are respectively arranged on the side walls of the ion transmission area cavity 102 and the mass analyzer cavity 103;
the multi-channel selection control electromagnetic valve 107 comprises 3 parallel vacuum pipelines with inner diameters of 6, 12 and 20mm respectively, and air inlets of all the vacuum pipelines are mutually communicated to form an inlet end 108 of the multi-channel selection control electromagnetic valve 107, and the inlet end 108 is connected with a gas outlet arranged on the side wall of the ionization source cavity 101 through the vacuum pipelines; the air outlets of all the vacuum pipelines are mutually communicated to form an outlet end 109 of the multi-channel selection control electromagnetic valve 107, and the outlet end 109 is connected with a vacuum pump 110 through the vacuum pipelines; each vacuum pipeline is controlled to be switched on and off by an independently controlled vacuum electromagnetic switch valve (SMC, VX 264);
a gas injection capillary 104 extends into the ionization source cavity 101 through the outer wall of the ionization source cavity 101, and introduces the sample gas 105 into the ionization source 106;
an ion transmission lens 113 is arranged inside the ion transmission area cavity 102; a mass analyzer 114 is arranged in the mass analyzer cavity 103, and an ion signal output end of the mass analyzer 114 is connected with the data acquisition card 112;
the control ends of the data acquisition card 112 and the multi-channel selection control electromagnetic valve 107 are respectively connected with a computer 111 through signal lines, and the computer 111 controls the data acquisition card 112 (FAST ComTec GmbH, P7888) to acquire mass spectrum data of the mass analyzer 114 and the on-off of each vacuum electromagnetic switch valve of the multi-channel selection control electromagnetic valve 107;
the method for improving the linear dynamic range of the mass spectrum by adopting the device for realizing the variable air pressure in the ionization region comprises the following steps:
1) The on-off of different electromagnetic switch valves is selectively controlled in the multi-channel selective control electromagnetic valve 107, at 10 -4 ～10 3 A group of ionization source pressures p containing 3 different values are arranged in the mbar pressure range i The ratio of the air pressure values of any two ionization sources (the air pressure value with higher absolute value/the air pressure value with lower absolute value) is more than or equal to 2, which are respectively 0.01, 0.5 and 4 mbar;
2) In the concentration range of toluene which is the target compound to be detected (10 -10 ～10 -3 ) In the interior, 24 compositions containing different concentrations (1X 10) -10 、2×10 -10 、5×10 -10 、1×10 -9 、2×10 -9 、5×10 -9 、1×10 -8 、2×10 -8 、5×10 -8 、1×10 -7 、2×10 -7 、5×10 -7 、1×10 -6 、2×10 -6 、5×10 -6 、1×10 -5 、2×10 -5 、5×10 -5 、1×10 -4 、2×10 -4 、5×10 -4 、1×10 -3 、2×10 -3 、5×10 -3 ) Standard gas of toluene of a target compound to be detected, wherein the dilution gas is clean air, and the numerical ratio of the concentration of the target compound in any two standard gases is more than or equal to 2;
3) Will beStandard gas containing toluene with different known concentrations of target compounds to be detected is introduced into ionization source 108 through gas sample introduction capillary 104 for ionization and mass spectrum detection, and the pressure p of each ionization source is set as above i Mass spectrometry is carried out, and the current ionization source air pressure p is recorded by utilizing a data acquisition card 112 i Mass spectrum signal intensity Y of target compound to be measured i And baseline noise N near the mass spectrum peak of the target compound i Build up of each ionization source pressure p i Signal to noise ratio Y of mass spectrum signal of lower target compound i /N i (Signal Strength Y) i And noise N i Ratio of (c) and its concentration c (respectively in Y) i /N i And concentration c is the aspect coordinate);
4) Each ionization source pressure p established according to the above i The concentration response curve of the lower target compound is in a linear range Y i /N i ＝a i *c+b i Minimum signal to noise ratio Y within i /N i For adjusting and increasing the threshold T of the air pressure Li Maximum signal to noise ratio Y i /N i For adjusting the pressure to reduce the threshold T Hi ；
5) Sample gas 105 is introduced into the gas sampling capillary 104, and the ionization source works at any ionization source pressure p set as described above by controlling the multi-channel selection control electromagnetic valve 107 i Under the condition, the current ionization source air pressure p is continuously monitored in real time by utilizing the data acquisition card 112 i Mass spectrum signal intensity S of test target compound at (0.001, 0.1, 1 and 10 mbar) i And baseline noise N near the mass spectrum peak of the target compound i ；
6) Mass spectrum signal intensity S of target compound to be detected i Divided by baseline noise N near the mass spectrum peak of the target compound i Obtaining the signal to noise ratio S of the spectrum signal of the target compound i /N i When S i /N i ≤T Li At the time, the computer 111 controls the multi-channel selection control electromagnetic valve 107 to ensure the pressure p of the ionization source i Increasing the repetition of the process of step 5); when S is i /N i ≥T Hi At the time, the computer 111 controls the multi-channel selection control electromagnetic valve 109 to ensure the pressure p of the ionization source i Reducing the repetition of the process of step 5); when T is Li ＜S i /N i ＜T Hi When the current ionization source pressure p is established according to the above i The linear response curve below quantitatively analyzes the target compound.
Example 1
For the examination of an ionization region variable air pressure boost mass spectrometry linear dynamic range device and method of the present invention, ionization source 108 employs a photo ionization source and mass analyzer 114 employs a time-of-flight mass analyzer. In the experiment, 24 samples containing different concentrations (1X 10) were prepared using air as the diluent in the standard gas -10 、2×10 -10 、5×10 -10 、1×10 -9 、2×10 -9 、5×10 -9 、1×10 -8 、2×10 -8 、5×10 -8 、1×10 -7 、2×10 -7 、5×10 -7 、1×10 -6 、2×10 -6 、5×10 -6 、1×10 -5 、2×10 -5 、5×10 -5 、1×10 -4 、2×10 -4 、5×10 -4 、1×10 -3 、2×10 -3 、5×10 -3 ) The standard gas of toluene is introduced into the ionization source 108 through the gas sample injection capillary 104 for ionization and mass spectrum detection, mass spectrum analysis is carried out under the conditions of 0.01, 0.5 and 4mbar of each ionization source pressure set as above, and the signal to noise ratio Y of the mass spectrum signal of the target compound under each ionization source pressure is established i /N i And its concentration c. As shown in FIG. 3, the toluene linear response range is 2X 10 at 0.01mbar ionization source pressure -6 ～5×10 -4 The corresponding linear response curve is Y 1 /N 1 =16.2×c+20.6 (unit 10 'of c' 6 ) Pressure regulating threshold T L1 Set to 53, air pressure regulating threshold T H1 Is set to 8100. As shown in FIG. 4, the toluene linear response range is 2X 10 at 0.5mbar ionization source pressure -8 ～5×10 -6 The corresponding linear response curve is Y 2 /N 2 =6.5×c+6.9 (order of magnitude 10 of c -8 Volume concentration), air pressure regulating threshold T L2 Set to 20, the air pressure is regulated to reduce the threshold value T H2 Is set to 3200. As shown in FIG. 5, the toluene linear response range is 1X 10 at a pressure of 4mbar ionization source -10 ～5×10 -8 The corresponding linear response curve is Y 3 /N 3 =32.5×c+37.6 (unit 10 of c -10 ) Pressure regulating threshold T L3 Set to 70, the air pressure is regulated to reduce the threshold value T H3 Is set at 16000. Therefore, although toluene has a linear dynamic range of only 2-3 orders of magnitude under the air pressure of a single ionization source, the linear dynamic range can be improved to 6-7 orders of magnitude by comparing the signal-to-noise ratio of a toluene mass spectrum signal detected in real time with an air pressure adjusting threshold value for dynamic adjustment in the mass spectrum detection process.
1) Sample gas 105 to be detected is introduced into the gas sample injection capillary 104, the ionization source works under the set ionization source pressure of 0.5mbar by controlling the multi-channel selection control electromagnetic valve 107, and the mass spectrum signal intensity S of the target compound to be detected under the current ionization source pressure is continuously monitored in real time by utilizing the data acquisition card 112 2 And baseline noise N near the mass spectrum peak of the target compound 2 ；
2) Calculating signal to noise ratio S of toluene mass spectrum signal of target compound 2 /N 2 358, at 12 < S 2 /N 2 < 3200, quantitatively analyzing the target compound according to the linear response curve under the current ionization source air pressure of 0.5mbar, and obtaining toluene with volume concentration of 5.4X10 -7 。
Claims (3)
1. A method for improving linear dynamic range of mass spectrum by changing air pressure in ionization region is characterized by comprising the following steps: the device for improving the linear dynamic range of the mass spectrum by changing the air pressure in the ionization region comprises a sealed ionization source cavity (101), a sealed ion transmission region cavity (102) and a sealed mass analyzer cavity (103) which are arranged in a stacked manner and are sequentially separated from top to bottom by a partition plate; ion through holes are formed in the separation plates between the ionization source cavity (101) and the ion transmission area cavity (102) and between the ion transmission area cavity (102) and the mass analyzer cavity (103); a gas outlet is arranged on the side wall of the ionization source cavity (101), and the gas outlet is connected with a multichannel selection control electromagnetic valve (107) through a vacuum pipeline; an ionization source (106) is arranged in the ionization source cavity (101); vacuum pump interfaces are respectively arranged on the side walls of the ion transmission area cavity (102) and the mass analyzer cavity (103);
the multi-channel selection control electromagnetic valve (107) comprises 2 or more than 3 vacuum pipelines which are in parallel connection and have different inner diameters within the range of 1-100 mm, air inlets of all the vacuum pipelines are mutually communicated to form an inlet end (108) of the multi-channel selection control electromagnetic valve (107), and the inlet end (108) is connected with a gas outlet arranged on the side wall of the ionization source cavity (101) through the vacuum pipelines; the air outlets of all the vacuum pipelines are mutually communicated to form an outlet end (109) of the multi-channel selection control electromagnetic valve (107), and the outlet end (109) is connected with a vacuum pump (110) through the vacuum pipelines; each vacuum pipeline is controlled to be switched on and off by an independently controlled vacuum electromagnetic switch valve;
a gas injection capillary (104) penetrates through the outer wall of the ionization source cavity (101) and stretches into the ionization source cavity (101), and sample gas (105) is introduced into the ionization source (106);
an ion transmission lens (113) is arranged in the ion transmission area cavity (102); a mass analyzer (114) is arranged in the mass analyzer cavity (103), and an ion signal output end of the mass analyzer (114) is connected with a data acquisition card (112);
the control ends of the data acquisition card (112) and the multi-channel selection control electromagnetic valve (107) are respectively connected with the computer (111) through signal lines, and the computer (111) controls the data acquisition card (112) to acquire mass spectrum data of the mass analyzer (114) and the on-off of each vacuum electromagnetic switch valve of the multi-channel selection control electromagnetic valve (107);
the method for improving the linear dynamic range of the mass spectrum by adopting the device for realizing the variable air pressure in the ionization region comprises the following steps:
1) Selectively controlling the on-off of different electromagnetic switch valves in a multi-channel selective control electromagnetic valve (107), at 10 -4 ～10 3 A group of ionization source pressures p with different values of 2 or more are arranged in the mbar pressure range i Wherein the ratio of the absolute values of the air pressure of any two ionization sources (the higher air pressure absolute value/the lower air pressure absolute value) is more than or equal to 2;
2) In the volume concentration range of the target compound to be detected(10 -12 ～10 -1 ) In the method, 2 or more than 3 concentration points are selected in each concentration level interval to prepare standard gas of the target compound to be detected, wherein the ratio of the concentration of the target compound to be detected in any two standard gases is more than or equal to 2;
3) Introducing standard gas containing target compounds to be detected with different known concentrations into ionization sources (108) through gas sampling capillaries (104) for ionization and mass spectrum detection, wherein the pressure p of each ionization source is respectively set as above i Mass spectrometry is carried out, and the current ionization source air pressure p is recorded by a data acquisition card (112) i Mass spectrum signal intensity Y of target compound to be measured i And baseline noise N near the mass spectrum peak of the target compound i Build up of each ionization source pressure p i Signal to noise ratio Y of mass spectrum signal of lower target compound i /N i (Signal Strength Y) i And noise N i Ratio of (c) and its concentration c (in Y) i /N i And the concentration c is the longitudinal and transverse coordinates, respectively);
4) Each ionization source pressure p established according to the above i The concentration response curves of the lower target compounds respectively take linear ranges Y i /N i ＝a i *c+b i Minimum signal to noise ratio Y within i /N i For adjusting and increasing the threshold T of the air pressure Li Maximum signal to noise ratio Y i /N i For adjusting the pressure to reduce the threshold T Hi Wherein T is Li Is of a size of 10 0 ～10 2 ，T Hi Is of a size of 10 3 ～10 5 ；
5) Sample gas (105) to be detected is introduced into the gas sampling capillary (104), and the ionization source works at any ionization source pressure p in the arrangement by controlling the multi-channel selection control electromagnetic valve (107) i Continuously and real-time monitoring the current ionization source air pressure p by utilizing a data acquisition card (112) i Mass spectrum signal intensity S of the target compound to be measured i And baseline noise N near the mass spectrum peak of the target compound i ；
6) Calculating the signal-to-noise ratio S of the spectrum signal of the target compound i /N i If when S i /N i ≤T Li When in use, lead toControlling the multi-channel selection control electromagnetic valve (107) by a computer (111) to ensure the pressure p of the ionization source i Increasing the repetition of the process of step 5); if when S i /N i ≥T Hi When the ionization source pressure p is controlled by a computer (111) to control a multi-channel selection control electromagnetic valve (109) i Reducing the repetition of the process of step 5); if when T Li ＜S i /N i ＜T Hi When the current ionization source pressure p is established according to the above i The linear response curve below quantitatively analyzes the target compound.
2. The method according to claim 1, characterized in that:
the ionization source (108) is a photoionization source and a chemical ionization source;
the mass analyzer (114) is a time-of-flight mass analyzer, a quadrupole mass analyzer, an ion trap mass analyzer, or a magnetic mass analyzer.
3. The method according to claim 1, characterized in that:
the diluent gas used in the standard gas is one or more of nitrogen, oxygen, argon and air.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111528185.XA CN116264151A (en) | 2021-12-14 | 2021-12-14 | Device and method for improving linear dynamic range of mass spectrum by changing air pressure in ionization region |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111528185.XA CN116264151A (en) | 2021-12-14 | 2021-12-14 | Device and method for improving linear dynamic range of mass spectrum by changing air pressure in ionization region |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116264151A true CN116264151A (en) | 2023-06-16 |
Family
ID=86723510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111528185.XA Pending CN116264151A (en) | 2021-12-14 | 2021-12-14 | Device and method for improving linear dynamic range of mass spectrum by changing air pressure in ionization region |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116264151A (en) |
-
2021
- 2021-12-14 CN CN202111528185.XA patent/CN116264151A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8373117B2 (en) | Gas delivery system for mass spectrometer reaction and collision cells | |
| CN201993338U (en) | Sweeping type film inlet-cushion chamber device with fast online enrichment of mass spectra | |
| US20090095901A1 (en) | Chemical ionization reaction or proton transfer reaction mass spectrometry with a quadrupole mass spectrometer | |
| CN112816436B (en) | Spectrum-mass spectrum combined device and detection method | |
| US20090095902A1 (en) | Chemical ionization reaction or proton transfer reaction mass spectrometry with a time-of-flight mass spectrometer | |
| JP2011043495A (en) | Gc-ms analysis device | |
| CN111239062A (en) | Gas quantitative detection equipment and method | |
| Shi et al. | Development of membrane inlet photoionization ion trap mass spectrometer for trace VOCs analysis | |
| CN103776818A (en) | Glow discharge-based plasma generator and spectrum detection system formed by same | |
| Zhu et al. | Development and application of a miniature mass spectrometer with continuous sub-atmospheric pressure interface and integrated ionization source | |
| CN112611798B (en) | Online mass spectrum detection method for isomers | |
| US11581177B2 (en) | System for introducing particle-containing samples to an analytical instrument and methods of use | |
| CN211122658U (en) | Organic and inorganic mixed gas fast quantitative analysis mass spectrometer | |
| CN116264151A (en) | Device and method for improving linear dynamic range of mass spectrum by changing air pressure in ionization region | |
| CN108493091B (en) | High-electron-utilization-rate low-energy ionization device, mass spectrum system and method | |
| CN110085504B (en) | Ion source system based on small-hole in-situ sampling interface and miniaturized mass spectrometer | |
| Zhang et al. | Exploiting the native inspiratory ability of a mass spectrometer to improve analysis efficiency | |
| O'Hanlon et al. | Residual Gas Analyzers | |
| CN112946058A (en) | Signal correction method for photoionization mass spectrum | |
| CN203674162U (en) | Novel mass spectrometer tuning device | |
| US6518581B1 (en) | Apparatus for control of gas flow into a mass spectrometer using a series of small orifices | |
| CN110854009A (en) | Mass spectrum device of wide-range mass measurement ion source and mass spectrum method thereof | |
| CN212514440U (en) | Organic matter detection device of bipolar proton transfer reaction mass spectrum | |
| US6956206B2 (en) | Negative ion atmospheric pressure ionization and selected ion mass spectrometry using a 63NI electron source | |
| CN116879381A (en) | Online accurate quantitative photo-induced chemical ionization mass spectrum system and method for organic acid in atmosphere under different humidity |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |