CN212301412U - Calibration system based on nitric acid chemical ionization time-of-flight mass spectrometer - Google Patents
Calibration system based on nitric acid chemical ionization time-of-flight mass spectrometer Download PDFInfo
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- CN212301412U CN212301412U CN202021948366.9U CN202021948366U CN212301412U CN 212301412 U CN212301412 U CN 212301412U CN 202021948366 U CN202021948366 U CN 202021948366U CN 212301412 U CN212301412 U CN 212301412U
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- 238000000451 chemical ionisation Methods 0.000 title claims abstract description 33
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 title claims abstract description 22
- 229910017604 nitric acid Inorganic materials 0.000 title claims abstract description 22
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 178
- 239000007789 gas Substances 0.000 claims abstract description 152
- 238000006243 chemical reaction Methods 0.000 claims abstract description 71
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 52
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims abstract description 46
- 229910001868 water Inorganic materials 0.000 claims abstract description 36
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 16
- 238000005187 foaming Methods 0.000 claims abstract description 9
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 30
- 229910052753 mercury Inorganic materials 0.000 claims description 30
- 239000010453 quartz Substances 0.000 claims description 18
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 18
- 229910001220 stainless steel Inorganic materials 0.000 claims description 10
- 239000010935 stainless steel Substances 0.000 claims description 10
- 230000003287 optical effect Effects 0.000 claims description 9
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- 238000001514 detection method Methods 0.000 claims description 3
- 150000003254 radicals Chemical class 0.000 description 23
- 239000000443 aerosol Substances 0.000 description 19
- 238000000034 method Methods 0.000 description 12
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 description 12
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- 230000003647 oxidation Effects 0.000 description 5
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- 235000011149 sulphuric acid Nutrition 0.000 description 5
- 239000001117 sulphuric acid Substances 0.000 description 5
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000005587 bubbling Effects 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
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- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 241000282414 Homo sapiens Species 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
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Abstract
The utility model discloses a calibration system based on a nitric acid chemical ionization time-of-flight mass spectrometer, which comprises a first gas mass flow controller, a second gas mass flow controller, a third gas mass flow controller, a fourth gas mass flow controller and a fifth gas mass flow controller, the device comprises a water bath foaming device and a sulfuric acid generation reaction chamber, one end of a first gas mass flow controller is connected with sulfur dioxide gas with standard concentration, the other end of the first gas mass flow controller is connected with a main path inlet of the sulfuric acid reaction generation chamber, one end of a second gas mass flow controller, one end of a third gas mass flow controller, one end of a fourth gas mass flow controller and the other end of the fourth gas mass flow controller are respectively connected with high-purity nitrogen, the other end of the second gas mass flow controller is connected with a branch path inlet of the sulfuric acid generation reaction chamber, the other end of the third gas mass flow controller and the other end of the fourth gas mass flow controller are respectively connected with a main path inlet of the sulfuric acid generation reaction chamber, one end of a fifth gas mass flow controller is connected. The utility model can better control the generation concentration of the sulfuric acid standard sample.
Description
Technical Field
The utility model belongs to mass spectrograph application, more specifically say, relate to a calibration system based on nitric acid chemical ionization time of flight mass spectrograph.
Background
The aerosol refers to a relatively stable suspension system formed by liquid or solid particles uniformly distributed in the atmosphere, and the aerosol can be divided into organic aerosol and inorganic aerosol according to the components of the aerosol, and the organic aerosol can be divided into Primary Organic Aerosol (POA) and Secondary Organic Aerosol (SOA) according to the different generation ways of the organic aerosol. POA broadly refers to organic aerosols that are discharged directly into the atmosphere and semi-volatile organic compounds that can condense directly under atmospheric conditions; SOA refers to organic aerosols generated from volatile organic compounds in the atmosphere through various chemical reactions and gas-solid conversion processes.
The aerosol can not only affect the radiation balance and further affect the global climate, but also the heterogeneous chemical reaction on the surface of the aerosol can affect the gas phase chemical process, and the long-term exposure to the high-concentration aerosol environment can increase the probability of the cardiopulmonary disease of human beings. Analysis results of aerosol components observed by aerosol mass spectrometry all over the world show that oxygen-containing organic matters are ubiquitous in organic aerosol and have high concentration ratio, and the high O/C value in the aerosol cannot be explained only by the route of POA oxidation, so that the SOA is also shown as the main component of the atmospheric organic aerosol.
One of the main generation mechanisms of SOA is the phenomenon of New Particle Formation (NPF), in which low-volatility gaseous substances generated by the oxidation of volatile organic compounds condense and nucleate in the atmosphere and then the particle size of the nuclei is continuously increased. Volatile organic compounds and O in the atmosphere3The process of reacting to form high oxidation state organic compounds (HOMs) contributes to the occurrence of NPF.
A nitrating Chemical Ionization Time Of Flight Mass spectrometer (Nitrate CIMS for short) is a precise analyzer capable Of precisely measuring high oxidation state organic matters in the atmosphere, and in order to ensure the measurement precision, it is necessary to calibrate the instrument, and the standard gas used for calibrating the instrument is gaseous sulfuric acid which is mainly measured by the nitrating Chemical Ionization Time Of Flight Mass spectrometer and has higher content in the atmosphere.
The gaseous sulfuric acid plays an important role in the formation and conversion processes of atmospheric particulates and has important significance in the research of the atmospheric dust-haze process. At present, the measurement method of the gaseous sulfuric acid mainly uses a chemical ionization mass spectrometer technology (CIMS), and the accuracy of the measurement method is mainly a calibration method of the chemical ionization mass spectrometer. The established calibration technique is the quantitative generation of OH radicals (R1) by photolysis of water using a mercury lamp (184.9nm) and the use of excess SO2The OH is quantitatively converted to sulfuric acid, and the specific equation is as follows:
H20+ hv (UV) - - ->OH+H (1)
SO2+OH--->HSO3 (2)
HSO3+O2--->SO3+HO2 (3)
SO3+H2O--->H2SO4 (4)
The radiation intensity of the mercury lamp directly determines the amount of OH radicals produced, i.e. the final sulfuric acid concentration. The existing calibration technology is to use a photoelectric tube sensitive to ultraviolet rays to directly measure the radiation intensity of a mercury lamp, the measurement accuracy is determined by the measurement environment (temperature, humidity and the like) and the conversion efficiency of the photoelectric tube, and the system error is not less than 30% of the measured value. This has a great negative impact on the study of the nucleation process of sulfuric acid in the atmosphere.
The Chinese patent with the patent publication number of CN106093176A and the publication number of 2016, 11 and 9 discloses a technical scheme of a calibration method and a calibration device for measuring gaseous sulfuric acid, wherein the calibration method generates excessive OH free radicals and uses SO with known concentration2Converting into sulfuric acid standard sample, the concentration of the sulfuric acid standard sample is passed through SO2Determining the concentration of (c); and (4) passing the sulfuric acid standard sample through a chemical ionization mass spectrometer, and carrying out system calibration on the chemical ionization mass spectrometer.
The technical scheme has the following problems: the concentration of OH radicals formed cannot be controlled, and only excess OH radicals are formed. Since the photochemical reactions involved in this principle are all reversible incomplete reactions, SO is used to control the concentration of sulfuric acid in the gas phase2At lower concentrations, OH radicals cannot be inhibited and can also react with other gas molecules such as CO and hydrocarbons.
Disclosure of Invention
1. Problems to be solved
Carry out the problem of the concentration of the OH free radical that the system calibration can't control the formation to chemical ionization mass spectrograph among the prior art, the utility model provides a calibration system based on nitric acid chemical ionization type time mass spectrograph.
2. Technical scheme
In order to solve the above problem, the utility model discloses the technical scheme who adopts as follows: a calibration system based on a nitric acid chemical ionization time-of-flight mass spectrometer comprises a first gas mass flow controller, a second gas mass flow controller, a third gas mass flow controller, a fourth gas mass flow controller, a fifth gas mass flow controller, a water bath foaming device and a sulfuric acid generation reaction chamber, wherein one end of the first gas mass flow controller is connected with sulfur dioxide with standard concentration, the other end of the first gas mass flow controller is connected with a main path inlet of the sulfuric acid reaction generation chamber, one ends of the second gas mass flow controller, the third gas mass flow controller and the fourth gas mass flow controller are respectively connected with high-purity nitrogen, the other end of the second gas mass flow controller is connected with a branch path inlet of the sulfuric acid generation reaction chamber, the other ends of the third gas mass flow controller and the fourth gas mass flow controller are respectively connected with a main path inlet of the sulfuric acid generation reaction chamber, and a water bath foaming device is arranged between the fourth gas mass flow controller and, one end of the fifth gas mass flow controller is connected with the high-cleanliness air, the other end of the fifth gas mass flow controller is connected with the main path inlet of the sulfuric acid generation reaction chamber, and the output end of the sulfuric acid generation reaction chamber is connected with the calibrated instrument. Dioxygen of standard concentrationSulfur sulfide refers to sulfur dioxide with a volume concentration of 100ppmv, high purity nitrogen N2Refers to a gas with a nitrogen concentration of 99.999%; the high-cleanliness air is air which only contains 21% of oxygen and 79% of nitrogen, and components such as inert gases, particles, bacteria and the like in the atmosphere are removed. The technical scheme can generate OH free radicals with expected concentration, and the concentration of the OH free radicals can be calculated by autonomously generating airflow with saturated water vapor, so that the concentration of a sulfuric acid standard sample can be calculated more directly; and each gas circuit can adjust the concentration of the reaction gas, so that the generation concentration of the sulfuric acid standard sample can be better controlled.
Further, the sulfuric acid generation reaction chamber comprises a mercury lamp, an optical filter, a quartz tube and a photosensitive diode, an opaque lampshade covers the mercury lamp, the quartz tube is sleeved on a main pipeline of the sulfuric acid generation reaction chamber, the mercury lamp and the photosensitive diode are respectively arranged on two sides of the quartz tube, and light emitted by the mercury lamp penetrates through the quartz tube through the optical filter and irradiates the photosensitive diode.
Further, the output end of the sulfuric acid generation reaction chamber is provided with a pressure relief exhaust port.
Further, the water bath bubbling device comprises a water bath kettle and a bubbler, deionized water is arranged in the bubbler, the water bath kettle heats the deionized water in the bubbler to generate saturated water vapor, and nitrogen enters the sulfuric acid generation reaction chamber from the upper part of the saturated water vapor.
Further, the temperature range of the water bath in the water bath kettle is 50-75 ℃.
Furthermore, the range of the first gas mass flow controller is 0-5ml, the range of the second gas mass flow controller is 0-500ml, the range of the third gas mass flow controller is 0-20ml, the range of the fourth gas mass flow controller is 0-2L, and the range of the fifth gas mass flow controller is 0-100 ml.
Furthermore, a connecting pipe between the sulfuric acid generation reaction chamber and the gas mass flow controller is a PFA cutting sleeve hose, and a connecting pipe between the sulfuric acid generation reaction chamber and the calibrated instrument is a stainless steel pipe.
Furthermore, the output end of the sulfuric acid generation reaction chamber is also provided with a temperature and humidity detection device.
A calibration method based on nitric acid chemical ionization time-of-flight mass spectrometer, which utilizes a sulfuric acid standard sample with known concentration to carry out system calibration on the chemical ionization mass spectrometer by measuring the concentration of the sulfuric acid standard sample, and is characterized in that: the calibration method comprises the steps of firstly photolyzing water vapor by ultraviolet light to generate OH free radicals with set concentration, and then carrying out photolysis on SO with known concentration2Converting the standard sample into a sulfuric acid standard sample, and carrying out system calibration on a nitric acid chemical ionization time-of-flight mass spectrometer by passing the sulfuric acid standard sample through the nitric acid chemical ionization time-of-flight mass spectrometer of a calibrated instrument; the concentration of the sulfuric acid standard sample is as follows:
wherein the content of the first and second substances,
[H2SO4]、[H2O]、[SO2]、[O2]respectively represent sulfuric acid, water and SO2、O2The concentration of (a) in (b),
which is indicative of the flow rate of the water vapor,
represents SO2The flow rate of (a) to (b),represents N2The flow rate of (a) to (b),
indicating the flow rate of air, Psat(T) is the saturated vapor pressure of water, NAIs an Avogastron constant, R is an ideal gas constant, T is a reaction temperature, and I is ultraviolet light intensity;
k1＝7.22×10-20cm2
3. advantageous effects
Compared with the prior art, the beneficial effects of the utility model are that:
(1) the utility model can generate OH free radicals with expected concentration, and the concentration of the OH free radicals can be calculated by automatically generating airflow with saturated vapor, so that the concentration of the sulfuric acid standard sample can be calculated more directly;
(2) each gas circuit in the utility model can adjust the gas flow, and uses the SO with high concentration2Standard gas, relatively increases SO in gas path2To reduce the concentration of other gases, thereby ensuring that OH radicals are only mixed with SO as much as possible2The reaction occurs, so that the generated concentration of the sulfuric acid standard sample can be better controlled.
Drawings
Fig. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic structural view of a sulfuric acid production reaction chamber according to the present invention;
in the figure: 1: a first gas cylinder; 2: a second gas cylinder; 3: a third gas cylinder; 4: a first gas mass flow controller; 5: a second gas mass flow controller; 6: a third gas mass flow controller; 7: a fourth gas mass flow controller; 8: a fifth gas mass flow controller; 9: a water bath foaming device; 10: a sulfuric acid generation reaction chamber; 11: a pressure relief vent; 12: a nitric acid chemical ionization time-of-flight mass spectrometer of a calibrated instrument; 13: mercury lamps; 14: an optical filter; 15: a quartz tube; 16: a photodiode.
Detailed Description
The present invention will be further described with reference to the following specific embodiments.
The utility model discloses an effect can produce the sulphuric acid standard sample of known concentration according to the demand, can adjust the concentration that this system produced sulphuric acid standard sample moreover for it can carry out multiple concentration gradient's demarcation to being carried out by calibration instrument nitric acid chemical ionization time of flight mass spectrograph.
The utility model discloses produce sulphuric acid standard sample and mainly rely on ultraviolet lamp light to shine saturated vapor, sulfur dioxide gas, dry air and nitrogen gas that the premixing is good, and its rationale is that water gas can photodissociation generate OH free radical under the illumination that receives the ultraviolet lamp, and OH free radical can become sulfur trioxide with sulfur dioxide oxidation under the circumstances of oxygen, meets water gas and generates sulphuric acid standard sample at last. The chemical equation of the above series of reactions is as follows:
H20+ hv (UV) - - ->OH+H (1)
SO2+OH--->HSO3 (2)
HSO3+O2--->SO3+HO2 (3)
SO3+H2O--->H2SO4 (4)
As shown in fig. 1, the present invention includes a first gas cylinder 1, a second gas cylinder 2, a third gas cylinder 3, a first gas mass flow controller 4, a second gas mass flow controller 5, a third gas mass flow controller 6, a fourth gas mass flow controller 7, a fifth gas mass flow controller 8, a water bath bubbling device 9, a sulfuric acid generation reaction chamber 10, a pressure relief exhaust 11, a mercury lamp 13, a filter/14, a quartz tube 15 and a photodiode 16; wherein, the first gas steel cylinder 1 is connected with one end of a first gas mass flow controller 4, the third gas steel cylinder 3 is connected with one end of a fifth gas mass flow controller 8, the second gas steel cylinder 2 is respectively connected with one end of a second gas mass flow controller 5, one end of a third gas mass flow controller 6 and one end of a fourth gas mass flow controller 7, the other end of the second gas mass flow controller 5 is connected with a branch of a sulfuric acid reaction generating chamber 10, the other end of the fourth gas mass flow controller 7 is connected with one end of a water bath foaming device 9, the other end of the water bath foaming device 9 and the other end of the first gas mass flow controller 4, the other end of the third gas mass flow controller 6 and the other end of the fifth gas mass flow controller 8 are both connected with one end of a main path of a sulfuric acid generation reaction chamber 10, and the other end of the main path of the sulfuric acid reaction generation chamber 10 is connected with a nitric chemical ionization time-of-flight mass spectrometer 12 of a calibrated instrument. As shown in fig. 2, the sulfuric acid reaction generation chamber 10 includes a mercury lamp 13, a filter 14, a quartz tube 15 and a photodiode 16, wherein the mercury lamp 13 is disposed in the mercury lamp chamber, the mercury lamp chamber is disposed in the sulfuric acid reaction generation chamber 10, light emitted by the mercury lamp chamber passes through the filter 14 and the quartz tube 15 sleeved on the pipeline of the gas path to irradiate the photodiode 16, and the photodiode 16 and the mercury lamp 13 are respectively disposed at two sides of the gas path.
The utility model provides a gas pipeline is the Teflon (PFA, Polyfluoroalkoxy, soluble polytetrafluoroethylene) cutting ferrule hose of external diameter 1/4 inch all at sulphuric acid formation reaction chamber 10 front end, then is the stainless steel pipe of external diameter 1/2 inch at its rear end. The water bath bubbling device 9 comprises a water bath kettle and a bubbler (bubbler).
The utility model discloses a work flow as follows: the required gas in the utility model is sulfur dioxide SO with standard concentration2High purity nitrogen N2And high cleanliness air, wherein the standard concentration of sulfur dioxide refers to a volume concentration of 100ppmv sulfur dioxide, and the high purity nitrogen N2Of fingersIs gas with nitrogen concentration of 99.999 percent; the high-cleanliness air is air only containing 21% of oxygen and 79% of nitrogen, and components such as inert gases, particles, bacteria and the like in the atmosphere are removed; wherein the sulfur dioxide SO has standard concentration2High purity nitrogen N stored in a first gas cylinder 12The high-purity air is stored in a second gas steel cylinder 2, the high-purity air is stored in a third gas steel cylinder 3, the sulfur dioxide gas with standard concentration flows out of the first gas steel cylinder 1 and passes through a first gas mass flow controller 4, the high-purity nitrogen gas flows out of the second gas steel cylinder 2 and is divided into three paths which respectively pass through a second gas mass flow controller 5, a third gas mass flow controller 6 and a fourth gas mass flow controller 7, the high-purity air flows out of the third gas steel cylinder 3 and passes through a fifth gas mass flow controller 8, and the five gas mass flow controllers are used for controlling the flow of the whole system so as to achieve the purposes of balancing pressure and controlling the concentration of generated sulfuric acid.
Wherein, the sulfur dioxide gas with standard concentration passes through the first gas mass flow controller 1, and the air with high cleanliness directly enters the sulfuric acid generation reaction chamber 10 after passing through the fifth mass flow controller 8; the nitrogen gas is divided into three gas paths, the first path enters a branch of the sulfuric acid generation reaction chamber 10 after passing through the second mass flow controller 5, does not enter a main gas path, and then enters a mercury lamp chamber in the sulfuric acid generation reaction chamber 10 to protect a mercury lamp 13; the second path directly enters a sulfuric acid generation reaction chamber 10 after passing through a third mass flow controller 6 and is used as a background gas protection and dilution main gas path; the third path passes through a fourth mass flow controller 7 and then enters a bubbler, a proper amount of deionized water is added into the bubbler, saturated water vapor can be generated under the heating of a water bath kettle, nitrogen is introduced from a pipe positioned above the liquid level, the saturated water vapor flows out from another pipe positioned below the liquid level, finally enters a sulfuric acid generation reaction chamber 10 together with the nitrogen to react with sulfur dioxide, air and the like, finally a sulfuric acid standard sample with fixed concentration is generated, a calibrated instrument nitric acid chemical ionization time-of-flight mass spectrometer 12 connected with the rear end of the sulfuric acid generation reaction chamber 10 extracts gas with required flow from the sulfuric acid generation reaction chamber 10, and redundant gas is discharged through a pressure relief exhaust port 11; the outer part of the bubbler in the embodiment is a conical bottle, the top of the bubbler is sealed by a rubber plug inserted with two glass tubes, and the whole bubbler has a very good sealing effect.
The utility model provides a main gas circuit or main route refer to nitrogen gas, sulfur dioxide, aqueous vapor and air mixing and produce chemical reaction's gas circuit, and branch gas circuit or branch road refer not to produce chemical reaction, only supply the gas circuit that the gas got into or unnecessary gas escapes.
In specific implementation, as the gaseous sulfuric acid is easy to be lost, a pipeline from the sulfuric acid generation reaction chamber 10 to the calibrated instrument nitric chemical ionization time-of-flight mass spectrometer 12 needs to be as short as possible, and the gaseous sulfuric acid is easy to be lost in a teflon (PFA) pipe, so that the stainless steel pipe is used for replacing the PFA hose in the section of the pipeline, the outer diameter of the stainless steel pipe is 1/2 inch, and the pipeline is convenient to be connected with the calibrated instrument nitric chemical ionization time-of-flight mass spectrometer 12.
In the sulfuric acid generation reaction chamber 10, the gas path has only two inlets and one outlet, the gas inlet and the gas outlet for the reaction gas to enter are communicated with each other and kept horizontal, the other gas inlet is arranged on the side surface of the sulfuric acid generation reaction chamber 10 and connected to the mercury lamp chamber where the mercury lamp 13 is arranged, and the shell of the sulfuric acid generation reaction chamber 10 is hermetically wrapped by stainless steel to avoid the interference of other light and gas. The mercury lamp 13 can emit ultraviolet light of a predetermined wavelength band after being energized, and after passing through the optical filter 14, it can be ensured that only 184.9nm of ultraviolet light can be irradiated onto the transparent quartz tube 15 for photochemical reaction, and the ultraviolet light of an unnecessary wavelength is filtered and removed. After passing through the quartz tube 15, the ultraviolet light is irradiated onto the photodiode 16, so as to detect the wavelength and intensity of the generated ultraviolet light.
In this example, SO2High concentration SO needs to be stored in standard concentration gas cylinders2The larger the concentration, the better, but considering SO2Toxic, and in particular embodiments, a concentration in the range of 50 to 500ppmv is suitable. To facilitate the calculation of the concentration of the sulfuric acid standards, a 100ppmv concentration of SO was used in this example2The rest is nitrogen N2To fill.
In order to accurately control the required flow, the range of each gas mass flow controller is different, specifically, the range of the first gas mass flow controller 4 is 0-5ml, the range of the second gas mass flow controller 5 is 0-500ml, the range of the third gas mass flow controller 6 is 0-20ml, the range of the fourth gas mass flow controller 7 is 0-2L, and the range of the fifth gas mass flow controller 8 is 0-100 ml.
In addition, the temperature of the water bath set in the water bath bubbling device 9 needs to be moderate and cannot be too high, the temperature range set in the embodiment is 50-75 ℃, and the temperature setting adopted in the embodiment is 60 ℃.
In order to guarantee that sulfuric acid generates reaction chamber 10 and does not receive the interference of other external light, must adopt totally enclosed design, only two air inlets and a gas outlet, the size of the cutting ferrule hose that two air inlets used can have several kinds of selections, the external diameter specification of cutting ferrule hose generally has 1/8 inch, 1/4 inch, 3/8 inch, 1/2 inch etc. above four kinds of models all are applicable to the utility model discloses, but keep unanimous for whole set of equipment, avoid because the internal pressure sudden change that size change leads to, the PFA cutting ferrule hose of 1/4 inch has all been selected to two air inlets in this embodiment. The stainless steel tube at the outlet is selected to have the same size as the inlet, and stainless steel tubes with an outer diameter of 3/8 inch, 1/2 inch, or 5/8 inch can be used, in this embodiment, the inlet of the nitric acid chemical ionization time-of-flight mass spectrometer 12 is a stainless steel tube with an outer diameter of 1/2 inch, and the quartz tube inside which the photochemical reaction is performed must have an outer diameter of 1/2 inch, and in order to facilitate connection of the outlet with the subsequent nitric acid chemical ionization time-of-flight mass spectrometer 12, a stainless steel tube with an outer diameter of 1/2 inch is preferably used in this embodiment. The inlet port into which the reaction gas enters and the outlet port are internally communicated and kept horizontal, and the other inlet port is provided on the side of the sulfuric acid production reaction chamber 10 and connected to a mercury lamp chamber in which a mercury lamp 13 is located.
The pressure-discharging air-release port 11 is mainly used for discharging redundant gas, is very close to an air outlet of the sulfuric acid generation reaction chamber 10, and is also provided with a temperature and humidity detection device for detecting the temperature and humidity of the air flow discharged by the pressure-discharging air-release port 11 so as to adjust the temperature and humidity in time and prevent the temperature and humidity from influencing the photochemical reaction in the system.
The mercury lamp 13 is provided with a mercury lamp chamber outside, the mercury lamp chamber is a lighttight casing, ultraviolet light emitted by the mercury lamp 13 can be irradiated to the outside only through the optical filter 14, the optical filter 14 is arranged on one side of the quartz tube 15 sleeved on the pipeline of the air path, and the ultraviolet light penetrating through the optical filter 14 is completely penetrated through the quartz tube 15 and finally is completely absorbed by the photosensitive diode 16 arranged on the other side of the quartz tube 15.
The concentration of the sulfuric acid standard sample generated by the calibration system can be calculated by several methods, and the concentration can be calculated by the following formulas in the embodiment:
based on the four chemical reaction formulas (1), (2), (3) and (4) and the chemical reaction constants thereof, the theoretical concentration [ H ] of the sulfuric acid standard sample can be obtained2SO4]：
Wherein [ H ]2SO4]、[H2O]、[SO2]、[O2]Respectively represent sulfuric acid, water and SO2、O2The concentration in the pipeline is negligible to the consumption of reactants due to the weak series of reactions.
QairRespectively represent water and SO2、N2The flow rates of the four paths of air are obtained by mass flow controllers which respectively control the four air paths, NAThe temperature and humidity of the pressure relief and exhaust port are measured by a temperature and humidity detector, and the intensity of I is ultraviolet light intensity measured by a photosensitive diode; psat(T) is the saturated vapor pressure of water; k is a radical of1、k2、k3、k4Then the chemical reaction constants of equations (1), (2), (3) and (4) are:
k1＝7.22×10-20cm2
the concentration of the OH free radicals generated in the utility model is influenced by the intensity of the ultraviolet light and the concentration of the water vapor in the reaction chamber, the OH free radicals with the expected concentration are generated by adjusting the concentration of the water vapor, and the intensity of the ultraviolet light keeps the OH free radicals stable; the concentration of OH free radicals can be calculated by autonomously generating airflow with saturated water vapor, and the concentration of a sulfuric acid standard sample can be more directly calculated; each gas circuit in the utility model can be adjusted, and the SO with high concentration is used2Standard gas, relatively increases SO in gas path2To reduce the concentration of other gases, thereby ensuring that OH radicals are only mixed with SO as much as possible2Carrying out reaction; the utility model discloses in every gas circuit all can adjust flow, consequently can be nimbleAdjusting the concentration of each reaction gas, i.e. by adjusting SO2The concentration of the other reaction gases in the system, such as the concentration of OH free radicals, the concentration of water vapor and the like, so that the generation concentration of the sulfuric acid standard sample can be better controlled.
Claims (8)
1. A calibration system based on nitric acid chemical ionization time-of-flight mass spectrometer is characterized in that: comprises a first gas mass flow controller, a second gas mass flow controller, a third gas mass flow controller, a fourth gas mass flow controller, a fifth gas mass flow controller, a water bath foaming device and a sulfuric acid generation reaction chamber, one end of the first gas mass flow controller is connected with sulfur dioxide with standard concentration, the other end is connected with the main path inlet of the sulfuric acid reaction generation chamber, one end of each of the second, third and fourth gas mass flow controllers is respectively connected with high-purity nitrogen, the other end of the second gas mass flow controller is connected with a branch inlet of the sulfuric acid generation reaction chamber, the other end of each of the third and fourth gas mass flow controllers is respectively connected with a main path inlet of the sulfuric acid generation reaction chamber, a water bath foaming device is arranged between the fourth gas mass flow controller and the sulfuric acid generation reaction chamber, one end of the fifth gas mass flow controller is connected with high-cleanliness air, the other end of the fifth gas mass flow controller is connected with a main path inlet of the sulfuric acid generation reaction chamber, and the output end of the sulfuric acid generation reaction chamber is connected with a calibrated instrument.
2. The calibration system for a nitric acid chemical ionization time-of-flight mass spectrometer according to claim 1, wherein: the sulfuric acid generation reaction chamber comprises a mercury lamp, an optical filter, a quartz tube and a photosensitive diode, wherein an opaque lampshade covers the mercury lamp, the quartz tube is sleeved on a main pipeline of the sulfuric acid generation reaction chamber, the mercury lamp and the photosensitive diode are respectively arranged on two sides of the quartz tube, and light emitted by the mercury lamp penetrates through the quartz tube through the optical filter and irradiates the photosensitive diode.
3. The calibration system for a nitric acid chemical ionization time-of-flight mass spectrometer according to claim 1, wherein: and the output end of the sulfuric acid generation reaction chamber is provided with a pressure relief exhaust port.
4. The calibration system for a nitric acid chemical ionization time-of-flight mass spectrometer according to claim 1, wherein: the water bath foaming device comprises a water bath kettle and a bubbler, deionized water is arranged in the bubbler, the water bath kettle heats the deionized water in the bubbler to generate saturated water vapor, and nitrogen enters a sulfuric acid generation reaction chamber from the upper part of the saturated water vapor.
5. The calibration system for a nitric acid chemical ionization time-of-flight mass spectrometer according to claim 4, wherein: the water bath temperature range in the water bath kettle is 50-75 ℃.
6. Calibration system for a nitric acid chemical ionization time-of-flight mass spectrometer according to any one of claims 1 to 5, characterized in that: the range of the first gas mass flow controller is 0-5ml, the range of the second gas mass flow controller is 0-500ml, the range of the third gas mass flow controller is 0-20ml, the range of the fourth gas mass flow controller is 0-2L, and the range of the fifth gas mass flow controller is 0-100 ml.
7. Calibration system for a nitric acid chemical ionization time-of-flight mass spectrometer according to any one of claims 1 to 5, characterized in that: the connecting pipe between the sulfuric acid generation reaction chamber and the gas mass flow controller is a PFA cutting sleeve hose, and the connecting pipe between the sulfuric acid generation reaction chamber and the calibrated instrument is a stainless steel pipe.
8. Calibration system for a nitric acid chemical ionization time-of-flight mass spectrometer according to any one of claims 1 to 5, characterized in that: and the output end of the sulfuric acid generation reaction chamber is also provided with a temperature and humidity detection device.
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| CN113964015A (en) * | 2021-10-27 | 2022-01-21 | 广西电网有限责任公司电力科学研究院 | Device for external standard quantification of time-of-flight mass spectrum |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113964015A (en) * | 2021-10-27 | 2022-01-21 | 广西电网有限责任公司电力科学研究院 | Device for external standard quantification of time-of-flight mass spectrum |
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