Apparatus and method for linear dynamic range of ionization region variable pressure lift mass spectrometer

Abstract

This invention provides a device for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region. The device comprises, from top to bottom, a stacked, sealed ionization source cavity, a sealed ion transport region cavity, and a sealed mass analyzer cavity, separated by partitions. A gas outlet is provided on the side wall of the ionization source cavity, and the gas outlet is connected to a multi-channel selective control solenoid valve via a vacuum pipeline. An ionization source is disposed inside the ionization source cavity. Vacuum pump interfaces are respectively provided on the side walls of the ion transport region cavity and the mass analyzer cavity. The method for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region automatically adjusts the ionization source gas pressure by computer-controlled vacuum solenoid valve, selecting an appropriate ionization source gas pressure to ensure that the mass spectrometry signal intensity and the concentration of the target compound in the sample gas are within a linear response range, thereby improving the linear dynamic range of the mass spectrometry.

Description

Technical Field

[0001] This invention belongs to the field of mass spectrometry analysis instruments and methods, specifically relating to a device and method for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region. Background Technology

[0002] Mass spectrometry (MS) is a detection technique that analyzes the chemical composition of substances by measuring the mass-to-charge ratio (MTR) of ions. It features high resolution and sensitivity, fast analysis speed, and strong qualitative capabilities, making it one of the most widely used analytical techniques in the field of analytical testing. The ionization source, as the core component of mass spectrometry, is used to ionize molecules or atoms. It not only determines the characteristics of the obtained mass spectrum but also significantly affects the accuracy and sensitivity of the mass spectrometer. Traditional organic matter detection mass spectrometry typically uses a 70 eV electron impact ionization (EI) source, which has high ionization efficiency but produces a large number of fragment ions. Especially when analyzing complex mixtures, this can easily cause severe peak overlap, making spectral interpretation difficult and hindering rapid, online analysis.

[0003] "Soft" ionization techniques, primarily based on photoionization (PI) and chemical ionization (CI), generate molecular or quasi-molecular ions by causing sample molecules to absorb photon energy or undergo ion-molecule reactions with reagent ions. This results in simple mass spectra that are easy to interpret, making them suitable for rapid, online detection of complex organic samples. In photoionization or chemical ionization sources, the ionization process consumes some photons or reagent ions. Typically, the concentration of sample molecules within the ionization source is much lower than the photon density or reagent ion concentration. The consumption of a relatively small amount of photons or reagent ions has little impact on the ionization process, resulting in a relatively stable sample ion yield. The intensity of the generated sample ions is directly proportional to the concentration of sample molecules. However, as the concentration of sample molecules within the ionization source increases, excessive photon or reagent ion consumption significantly affects the ionization process. The sample ion yield decreases, and the intensity of the generated sample ions exhibits a "saturation" phenomenon with increasing sample molecular weight, causing the instrument's response to deviate from linearity with changes in sample concentration. In addition, issues such as charge repulsion and detector response “saturation” during the ionization, transport, and detection of high-intensity ions can further affect the linear response of mass spectrometers, resulting in the linear dynamic range of photoionization mass spectrometry and chemical ionization mass spectrometry typically being only 2 to 3 orders of magnitude under certain ionization source or sample introduction conditions.

[0004] In photoionization and chemical ionization sources, the sample ion yield is positively correlated with the number density of sample molecules within the ionization source, while the number density of sample molecules is directly proportional to the ionization source pressure. Taking photoionization as an example, the sample ion yield R... PI It can be represented as:

[0005]

[0006] Where, σ PI (Mb, 1Mb = 10) -18 cm 2 I0 (photons / s) is the photoionization cross section of the analyte, I0 (photons / s) is the luminous intensity of the lamp, L (cm) is the photoionization length, and N (cm) is the photoionization length. -3 Where is the molecular number density of the analyte, P (Pa) is the ionization pressure, c is the volume concentration of the analyte, and T is the temperature of the ionization source. Therefore, by adjusting the ionization source pressure to regulate the sample ion yield within the ionization source, it is expected to improve the linear dynamic range of mass spectrometry. Chinese invention patent [201010567193.0] discloses a composite ionization source for mass spectrometry that combines vacuum ultraviolet photoionization and chemical ionization. It utilizes a single vacuum ultraviolet light source to switch between vacuum ultraviolet photoionization and chemical ionization modes under certain ionization source pressure conditions. The injection volume can be controlled by adjusting the flow rate of the side extraction valve and by changing the inner diameter and length of the reagent gas inlet tube and sample gas inlet tube, thereby adjusting the vacuum level within the ionization source chamber and broadening the range of samples that the instrument can detect. However, this ionization source technology does not address improving the linear dynamic range of mass spectrometry. Summary of the Invention

[0007] The purpose of this invention is to provide an apparatus and method for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region. By automatically adjusting the ionization source gas pressure through a computer-controlled vacuum solenoid valve, and selecting a suitable ionization source gas pressure, the mass spectrometry signal intensity and the concentration of the target compound in the sample gas are within the linear response range, thereby improving the linear dynamic range of the mass spectrometry.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A device for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region includes, from top to bottom, a sealed ionization source cavity, a sealed ion transport region cavity, and a sealed mass analyzer cavity, arranged in a stacked configuration separated by partitions. Ion through-holes are provided in the partitions between the ionization source cavity and the ion transport region cavity, as well as between the ion transport region cavity and the mass analyzer cavity. A gas outlet is provided on the side wall of the ionization source cavity, and the gas outlet is connected to a multi-channel selective control solenoid valve via a vacuum pipeline. An ionization source is located inside the ionization source cavity. Vacuum pump interfaces are respectively provided on the side walls of the ion transport region cavity and the mass analyzer cavity.

[0010] The multi-channel selective control solenoid valve includes two or more parallel vacuum lines with different inner diameters ranging from 1 to 100 mm. The inlets of all vacuum lines are interconnected, forming the inlet end of the multi-channel selective control solenoid valve. The inlet end is connected to the gas outlet provided on the side wall of the ionization source cavity through the vacuum line. The outlets of all vacuum lines are interconnected, forming the outlet end of the multi-channel selective control solenoid valve. The outlet end is connected to the vacuum pump through the vacuum line. Each vacuum line is controlled by an independently controlled vacuum solenoid switch valve.

[0011] A gas injection capillary passes through the outer wall of the ionization source cavity and extends into the ionization source cavity to introduce the sample gas into the ionization source;

[0012] An ion transmission lens is installed inside the ion transmission region cavity; a mass analyzer is installed inside the mass analyzer cavity, and the ion signal output terminal of the mass analyzer is connected to the data acquisition card.

[0013] The control terminals of the data acquisition card and the multi-channel selective control solenoid valve are connected to the computer via signal lines. The computer controls the data acquisition card to acquire the mass spectrometry data of the mass analyzer and the on / off state of each vacuum solenoid switch valve of the multi-channel selective control solenoid valve.

[0014] The ionization source mentioned is a photoionization source or a chemical ionization source;

[0015] The mass analyzer mentioned is a time-of-flight mass analyzer, a quadrupole mass analyzer, an ion trap mass analyzer, or a magnetic mass analyzer.

[0016] The diluent used in the standard gas is one or more of nitrogen, oxygen, argon, and air.

[0017] The method for achieving increased linear dynamic range of mass spectrometry by varying gas pressure in the ionization region using the above-mentioned device includes the following steps:

[0018] 1) Selectively control the on / off state of different solenoid valves in a multi-channel selective control solenoid valve, in 10 -4 ~10 3 Within the mbar pressure range, set a group of ionization source pressures p containing two or more different values. i The ratio of the absolute values ​​of the gas pressures of any two ionization sources (the one with the higher absolute value / the one with the lower absolute value) is ≥2;

[0019] 2) Within the volume concentration range of the target compound to be tested (10) -12 ~10 -1 Within each concentration range, select two or more concentration points to prepare standard gases for the target compound to be tested, wherein the ratio of the concentration of the target compound to be tested in any two standard gases is ≥2.

[0020] 3) Standard gases containing different known concentrations of the target compound are introduced into the ionization source via a gas injection capillary for ionization and mass spectrometry detection. The gas pressure p of each ionization source is set as described above. i Mass spectrometry analysis was performed, and the current ionization source gas pressure p was recorded using a data acquisition card. i The mass spectrometry signal intensity Y of the target compound to be tested i Baseline noise N near the target compound's mass spectrum peak i Establish the gas pressure p of each ionization source i The signal-to-noise ratio Y of the mass spectrometry signal of the target compound i / N i (signal strength Y) i With noise N i The concentration response curve Y between the ratio of and its concentration c i / N i =a i *c+b i ;

[0021] 4) Based on the gas pressure p of each ionization source established above i The concentration response curve of the target compound is used, and the minimum signal-to-noise ratio Y within the linear range is selected. i / N i The air pressure increase threshold T Li Maximum signal-to-noise ratio Y i / N i For the air pressure reduction threshold T Hi T Li Size in 10 0 ~10 2 T Hi Size in 10 3 ~10 5 ;

[0022] 5) Introduce sample gas into the gas inlet capillary, and control the multi-channel selective solenoid valve to make the ionization source operate at any of the ionization source gas pressures p set above. i Below, the current ionization source gas pressure p is continuously monitored in real time using a data acquisition card. i The mass spectrometry signal intensity S of the target compound to be tested i Baseline noise N near the target compound's mass spectrum peak i ;

[0023] 6) Calculate the signal-to-noise ratio S of the mass spectrometry signal of the target compound. i / N i When S i / N i ≤T Li At that time, the multi-channel selective control solenoid valve is controlled by a computer to adjust the ionization source gas pressure p. iIncrease; when S i / N i ≥T Hi At that time, the multi-channel selective control solenoid valve is controlled by a computer to adjust the ionization source gas pressure p. i Decrease, when T Li <S i / N i <T Hi At that time, based on the above, the current ionization source gas pressure p is established. i The linear response curves were used to quantitatively analyze the target compound.

[0024] This invention provides an apparatus and method for improving the linear dynamic range of mass spectrometry by varying the ionization source pressure. The method involves pre-establishing linear response curves of target compounds under different ionization source pressures and continuously monitoring the mass spectral intensity of the target compounds in the sample gas in real time. Based on the comparison between the mass spectral intensity of the target compounds in the sample gas and the linear response curves under the same ionization source pressure, a computer-controlled multi-channel selective solenoid valve is used to automatically adjust the ionization source pressure. This selects a suitable ionization source pressure, ensuring that the mass spectral signal intensity and the concentration of the target compounds in the sample gas fall within the linear response range, thereby improving the linear dynamic range of the mass spectrometry. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a device for improving the linear dynamic range of mass spectrometry by varying the pressure in the ionization region, according to the present invention.

[0026] Figure 2 This invention provides a method for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region using the aforementioned device.

[0027] Figure 3 The concentration response curve of the toluene mass spectrum signal between the signal-to-noise ratio and the concentration when the ionization source gas pressure is 0.01 mbar, as presented in this invention.

[0028] Figure 4 The concentration response curve of the toluene mass spectrum signal between the signal-to-noise ratio and the concentration when the ionization source pressure is 0.5 mbar, as presented in this invention.

[0029] Figure 5 The concentration response curve of toluene mass spectrometry signal between its signal-to-noise ratio and concentration is shown when the ionization source pressure is 4 mbar, according to the present invention. Detailed Implementation

[0030] Please see Figure 1The present invention discloses a device for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region. The device comprises, from top to bottom, a stacked, sealed ion source cavity 101, a sealed ion transport region cavity 102, and a sealed mass analyzer cavity 103, separated by partitions. Ion through-holes are provided in the partitions between the ion source cavity 101 and the ion transport region cavity 102, and between the ion transport region cavity 102 and the mass analyzer cavity 103. A gas outlet is provided on the side wall of the ion source cavity 101, and the gas outlet is connected to a multi-channel selective control solenoid valve 107 via a vacuum pipeline. An ion source 106 is disposed inside the ion source cavity 101. Vacuum pump interfaces are respectively provided on the side walls of the ion transport region cavity 102 and the mass analyzer cavity 103.

[0031] The multi-channel selective control solenoid valve 107 includes three parallel vacuum lines with inner diameters of 6, 12, and 20 mm respectively. The inlets of all vacuum lines are interconnected, forming the inlet end 108 of the multi-channel selective control solenoid valve 107. The inlet end 108 is connected to the gas outlet provided on the side wall of the ionization source chamber 101 through the vacuum line. The outlets of all vacuum lines are interconnected, forming the outlet end 109 of the multi-channel selective control solenoid valve 107. The outlet end 109 is connected to the vacuum pump 110 through the vacuum line. Each vacuum line is controlled by an independently controlled vacuum solenoid switch valve (SMC, VX264).

[0032] A gas injection capillary 104 passes through the outer wall of the ionization source cavity 101 and extends into the interior of the ionization source cavity 101 to introduce sample gas 105 into the ionization source 106.

[0033] An ion transmission lens 113 is provided inside the ion transmission region cavity 102; a mass analyzer 114 is provided inside the mass analyzer cavity 103, and the ion signal output terminal of the mass analyzer 114 is connected to the data acquisition card 112.

[0034] The control terminals of the data acquisition card 112 and the multi-channel selective control solenoid valve 107 are connected to the computer 111 via signal lines. The computer 111 controls the data acquisition card 112 (FAST ComTec GmbH, P7888) to acquire the mass spectrometry data of the mass analyzer 114 and the on / off state of each vacuum solenoid switch valve of the multi-channel selective control solenoid valve 107.

[0035] The method for achieving increased linear dynamic range of mass spectrometry by varying gas pressure in the ionization region using the above-mentioned device includes the following steps:

[0036] 1) Selectively control the on / off state of different solenoid valves in the multi-channel selective control solenoid valve 107, in 10 -4 ~10 3 Set a set of ionization source pressures p with 3 different values ​​within the mbar pressure range.i The values ​​are 0.01, 0.5 and 4 mbar, respectively, where the ratio of any two ionization source pressure values ​​(the one with the higher absolute pressure value / the one with the lower absolute pressure value) is ≥2.

[0037] 2) Within the concentration range of the target compound toluene to be detected (10... -10 ~10 -3 Within ), 24 solutions containing different concentrations (1×10⁻⁶) were prepared. -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 for the target compound toluene is used, and the dilution gas is clean air. The ratio of the concentrations of the target compound in any two standard gases is ≥2.

[0038] 3) Standard gases containing different known concentrations of the target compound toluene are introduced into the ionization source 108 via the gas injection capillary 104 for ionization and mass spectrometry detection. The gas pressure p of each ionization source is set as described above. i Mass spectrometry analysis was performed, and the current ionization source gas pressure p was recorded using data acquisition card 112. i The mass spectrometry signal intensity Y of the target compound to be tested i Baseline noise N near the target compound's mass spectrum peak i Establish the gas pressure p of each ionization source i The signal-to-noise ratio Y of the mass spectrometry signal of the target compound i / N i (signal strength Y) i With noise N i Concentration response curves between the ratio of Y to its concentration c (expressed in terms of Y, Y, and C respectively). i / Ni (with concentration c as the x and y axes);

[0039] 4) Based on the gas pressure p of each ionization source established above i The concentration response curve of the target compound was obtained, and the linear range Y was taken. i / N i =a i *c+b i Minimum signal-to-noise ratio Y i / N i The air pressure increase threshold T Li Maximum signal-to-noise ratio Y i / N i For the air pressure reduction threshold T Hi ;

[0040] 5) Sample gas 105 is introduced into the gas inlet capillary 104, and the ionization source is operated at any of the ionization source gas pressure p set above by controlling the multi-channel selective control solenoid valve 107. i The current ionization source gas pressure p is continuously monitored in real time using data acquisition card 112. i Mass spectral signal intensity S of the target compound at (0.001, 0.1, 1 and 10 mbar) i Baseline noise N near the target compound's mass spectrum peak i ;

[0041] 6) The mass spectrometry signal intensity S of the target compound to be tested i Divide by the baseline noise N near the target compound's mass spectrum peak i The signal-to-noise ratio S of the mass spectrometry signal of the target compound was obtained. i / N i When S i / N i ≤T Li At that time, the multi-channel selective control solenoid valve 107 is controlled by computer 111 to adjust the ionization source gas pressure p i Repeat step 5) indefinitely; when S i / N i ≥T Hi At that time, the multi-channel selective control solenoid valve 109 is controlled by computer 111 to adjust the ionization source gas pressure p i Reduce the repetition of step 5); when T Li <S i / N i <T Hi At that time, based on the above, the current ionization source gas pressure p is established. i The linear response curves were used to quantitatively analyze the target compound.

[0042] Example 1

[0043] For the examination of the ionization region variable pressure mass spectrometry linear dynamic range device and method described in this invention, the ionization source 108 is a photoionization source, and the mass analyzer 114 is a time-of-flight mass analyzer. In the experiment, air was used as the dilution gas in the standard gas, and 24 solutions containing different concentrations (1×10⁻⁶) were prepared. -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 Toluene standard gas was introduced into the ionization source 108 via the gas injection capillary 104 for ionization and mass spectrometry detection. Mass spectrometry analysis was performed at each of the aforementioned ionization source pressures of 0.01, 0.5, and 4 mbar. The signal-to-noise ratio (Y) of the target compound's mass spectrometry signal at each ionization source pressure was established. i / N i The concentration response curve between its concentration c and the concentration c. Figure 3 As shown, at an ionization source pressure of 0.01 mbar, the linear response range of toluene is within 2 × 10⁻⁶ mbar. -6 ~5×10 -4 The corresponding linear response curve is Y1 / N1 = 16.2 * c + 20.6 (where c is in units of 10⁻⁶). 6 ), air pressure increase threshold T L1 Set to 53, air pressure reduction threshold T H1 The value is set to 8100. (By...) Figure 4 As shown, under an ionization source pressure of 0.5 mbar, the linear response range of toluene is 2 × 10⁻⁶. -8 ~5×10 -6 The corresponding linear response curve is Y² / N² = 6.5 * c + 6.9 (c is on the order of 10). -8 (volume concentration), pressure increase threshold TL2 Set to 20, air pressure reduction threshold T H2 The value is set to 3200. (By...) Figure 5 As shown, under an ionization source pressure of 4 mbar, the linear response range of toluene is within 1 × 10⁻⁶ mbar. -10 ~5×10 -8 The corresponding linear response curve is Y3 / N3 = 32.5*c + 37.6 (where c is in units of 10). -10 ), air pressure increase threshold T L3 Set to 70, air pressure reduction threshold T H3 The value is set to 16000. Therefore, although toluene has only a linear dynamic range of 2 to 3 orders of magnitude under a single ionization source pressure, its linear dynamic range can be extended to 6 to 7 orders of magnitude by dynamically adjusting the signal-to-noise ratio of the real-time detected toluene mass spectrum signal by comparing it with the pressure adjustment threshold during mass spectrometry detection.

[0044] 1) The sample gas 105 is introduced into the gas injection capillary 104. By controlling the multi-channel selective control solenoid valve 107, the ionization source is made to work at the 0.5 mbar ionization source gas pressure set above. The data acquisition card 112 continuously monitors the mass spectrum signal intensity S2 of the target compound and the baseline noise N2 near the mass spectrum peak of the target compound under the current ionization source gas pressure.

[0045] 2) The signal-to-noise ratio (S² / N²) of the mass spectrometry signal of the target compound toluene was calculated to be 358, which falls within the range of 12 < S² / N² < 3200. Based on the linear response curve established above at the current ionization source pressure of 0.5 mbar, the target compound was quantitatively analyzed, and the volume concentration of toluene was found to be 5.4 × 10⁻⁶. -7 .

Claims

1. A method for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region, characterized in that: The device for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region includes, from top to bottom, a sealed ionization source cavity (101), a sealed ion transport region cavity (102), and a sealed mass analyzer cavity (103) arranged in a stacked manner separated by partitions; ion through holes are provided in the partitions between the ionization source cavity (101) and the ion transport region cavity (102) and between the ion transport region cavity (102) and the mass analyzer cavity (103); a gas outlet is provided on the side wall of the ionization source cavity (101), and the gas outlet is connected to a multi-channel selective control solenoid valve (107) through a vacuum pipeline; an ionization source (106) is provided inside the ionization source cavity (101); vacuum pump interfaces are respectively provided on the side walls of the ion transport region cavity (102) and the mass analyzer cavity (103); The multi-channel selective control solenoid valve (107) includes two or more parallel vacuum pipelines with different inner diameters ranging from 1 to 100 mm. The inlets of all vacuum pipelines are interconnected, forming the inlet end (108) of the multi-channel selective control solenoid valve (107). The inlet end (108) is connected to the gas outlet provided on the side wall of the ionization source cavity (101) through the vacuum pipeline. The outlets of all vacuum pipelines are interconnected, forming the outlet end (109) of the multi-channel selective control solenoid valve (107). The outlet end (109) is connected to the vacuum pump (110) through the vacuum pipeline. Each vacuum pipeline is controlled by an independently controlled vacuum solenoid switch valve. A gas injection capillary (104) passes through the outer wall of the ionization source cavity (101) and extends into the interior of the ionization source cavity (101) to introduce sample gas (105) into the ionization source (106); An ion transmission lens (113) is provided inside the ion transmission region cavity (102); a mass analyzer (114) is provided inside the mass analyzer cavity (103), and the ion signal output terminal of the mass analyzer (114) is connected to the data acquisition card (112). The control terminals of the data acquisition card (112) and the multi-channel selective control solenoid valve (107) are connected to the computer (111) via signal lines. The computer (111) controls the data acquisition card (112) to acquire the mass spectrometry data of the mass analyzer (114) and the on / off state of each vacuum solenoid valve of the multi-channel selective control solenoid valve (107). The method for improving the linear dynamic range of mass spectrometry by varying the gas pressure in the ionization region using the above-mentioned device includes the following steps: 1) Selectively control the on / off state of different solenoid switching valves in the multi-channel selective control solenoid valve (107), in 10 -4 ~10 3 Within the mbar pressure range, set a group of ionization source pressures p containing two or more different values. i The ratio of the absolute values ​​of the gas pressures of any two ionization sources (the one with the higher absolute value / the one with the lower absolute value) is ≥2; 2) Within the volume concentration range of the target compound to be tested (10) -12 ~10 -1 Within each concentration range, select two or more concentration points to prepare standard gases for the target compound to be tested, wherein the ratio of the concentration of the target compound to be tested in any two standard gases is ≥2. 3) Standard gases containing different known concentrations of the target compound to be tested are introduced into the ionization source (108) through the gas injection capillary (104) for ionization and mass spectrometry detection, respectively, at the gas pressure p of each ionization source set above. i Mass spectrometry analysis was performed, and the current ionization source pressure p was recorded using a data acquisition card (112). i The mass spectrometry signal intensity Y of the target compound to be tested i Baseline noise N near the target compound's mass spectrum peak i Establish the gas pressure p of each ionization source i The signal-to-noise ratio Y of the mass spectrometry signal of the target compound i / N i (signal strength Y) i With noise N i The concentration response curve (in terms of the ratio of Y) to its concentration c i / N i (where c and concentration are the x and y axes, respectively); 4) Based on the gas pressure p of each ionization source established above i The concentration response curves of the target compounds were obtained, with linear ranges Y and Y respectively. i / N i =a i *c+b i Minimum signal-to-noise ratio Y i / N i The air pressure increase threshold T Li Maximum signal-to-noise ratio Y i / N i For the air pressure reduction threshold T Hi T Li Size in 10 0 ~10 2 T Hi Size in 10 3 ~10 5 ; 5) Introduce the sample gas (105) into the gas inlet capillary (104), and control the multi-channel selective control solenoid valve (107) to make the ionization source operate at any of the ionization source gas pressure p set above. i The current ionization source gas pressure p is continuously and in real time monitored using a data acquisition card (112). i The mass spectrometry signal intensity S of the target compound to be tested i Baseline noise N near the target compound's mass spectrum peak i ; 6) Calculate the signal-to-noise ratio S of the mass spectrometry signal of the target compound. i / N i If S i / N i ≤T Li At that time, the multi-channel selective control solenoid valve (107) is controlled by computer (111) to adjust the ionization source gas pressure p i Increase the repetition of step 5); if S i / N i ≥T Hi At that time, the multi-channel selective control solenoid valve (109) is controlled by computer (111) to adjust the ionization source gas pressure p i Reduce the repetition of step 5); if T Li <S i / N i <T Hi At that time, based on the above, the current ionization source gas pressure p is established. i The linear response curves were used to quantitatively analyze the target compound.

2. The method according to claim 1, characterized in that: The ionization source (108) is a photoionization source or 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 used in the standard gas is one or more of nitrogen, oxygen, argon, and air.

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