CN111650272B - Device and method for measuring ketone compounds in gas - Google Patents
Device and method for measuring ketone compounds in gas Download PDFInfo
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- CN111650272B CN111650272B CN202010585810.3A CN202010585810A CN111650272B CN 111650272 B CN111650272 B CN 111650272B CN 202010585810 A CN202010585810 A CN 202010585810A CN 111650272 B CN111650272 B CN 111650272B
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- -1 ketone compounds Chemical class 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 41
- 239000007789 gas Substances 0.000 claims abstract description 96
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 66
- 239000012159 carrier gas Substances 0.000 claims abstract description 30
- 150000005839 radical cations Chemical class 0.000 claims abstract description 30
- 230000003993 interaction Effects 0.000 claims abstract description 5
- 150000001875 compounds Chemical class 0.000 claims abstract description 3
- 150000002500 ions Chemical class 0.000 claims description 22
- 150000002576 ketones Chemical class 0.000 claims description 17
- 238000001819 mass spectrum Methods 0.000 claims description 14
- 239000007864 aqueous solution Substances 0.000 claims description 10
- 150000003254 radicals Chemical class 0.000 claims description 10
- 238000002372 labelling Methods 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 6
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 claims description 3
- 229910052805 deuterium Inorganic materials 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 238000007405 data analysis Methods 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 238000001514 detection method Methods 0.000 abstract description 19
- 230000008569 process Effects 0.000 abstract description 5
- 239000003960 organic solvent Substances 0.000 abstract description 3
- 238000004451 qualitative analysis Methods 0.000 abstract 1
- 238000004445 quantitative analysis Methods 0.000 abstract 1
- 230000035945 sensitivity Effects 0.000 abstract 1
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 55
- 238000004458 analytical method Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 6
- 201000010099 disease Diseases 0.000 description 6
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 6
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- 230000000155 isotopic effect Effects 0.000 description 3
- 238000004949 mass spectrometry Methods 0.000 description 3
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- 238000012986 modification Methods 0.000 description 3
- 238000001184 proton transfer reaction mass spectrometry Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000013467 fragmentation Methods 0.000 description 2
- 238000006062 fragmentation reaction Methods 0.000 description 2
- 238000010249 in-situ analysis Methods 0.000 description 2
- 239000003550 marker Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000000824 selected ion flow tube mass spectrometry Methods 0.000 description 2
- 238000004885 tandem mass spectrometry Methods 0.000 description 2
- WHBMMWSBFZVSSR-UHFFFAOYSA-N 3-hydroxybutyric acid Chemical class CC(O)CC(O)=O WHBMMWSBFZVSSR-UHFFFAOYSA-N 0.000 description 1
- 206010006895 Cachexia Diseases 0.000 description 1
- 241000282412 Homo Species 0.000 description 1
- 208000007976 Ketosis Diseases 0.000 description 1
- 206010058467 Lung neoplasm malignant Diseases 0.000 description 1
- 150000004729 acetoacetic acid derivatives Chemical class 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
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- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- CSCPPACGZOOCGX-WFGJKAKNSA-N deuterated acetone Substances [2H]C([2H])([2H])C(=O)C([2H])([2H])[2H] CSCPPACGZOOCGX-WFGJKAKNSA-N 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
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- 229930195729 fatty acid Natural products 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 150000004665 fatty acids Chemical group 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 238000002290 gas chromatography-mass spectrometry Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000004140 ketosis Effects 0.000 description 1
- 210000004185 liver Anatomy 0.000 description 1
- 201000005202 lung cancer Diseases 0.000 description 1
- 208000020816 lung neoplasm Diseases 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- XNLICIUVMPYHGG-UHFFFAOYSA-N pentan-2-one Chemical compound CCCC(C)=O XNLICIUVMPYHGG-UHFFFAOYSA-N 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000029058 respiratory gaseous exchange Effects 0.000 description 1
- 238000010206 sensitivity analysis Methods 0.000 description 1
- 238000002470 solid-phase micro-extraction Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/68—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
The invention discloses a device and a method for measuring ketone compounds in gas, wherein the device comprises an ionization channel, a gas channel and a mass spectrometer; the ionization channel comprises a discharge needle, a first carrier gas channel, a first pipeline, a high-voltage source, a first capillary, a sample placing device and a first flowmeter; the gas channel includes a gas source, a second carrier gas channel, a second flow meter, a second conduit, and a second capillary. The method for forming the base peak [ M+H 2O]+· ] compound by utilizing the interaction of the water radical cations and the ketone compounds can improve the detection sensitivity of the ketone compounds and reduce the corresponding detection limit so as to realize the rapid qualitative and quantitative analysis of the ketone compounds in the gas, and can solve the problems that pretreatment is needed, an organic solvent is needed, on-line detection cannot be realized, the device is complex and the like in the process of analyzing the gas in the prior art.
Description
Technical Field
The invention relates to the technical field of gas detection, in particular to a device and a method for measuring ketone compounds in gas.
Background
The ketone compounds are ubiquitous in nature and have wide application in various fields. For example, acetone is the major ketone contained in exhaled breath of humans and is often a marker for ketosis. The liver can produce a large number of ketone bodies, including acetoacetates, beta-hydroxybutyrates and acetone, through oxidation and decomposition of fatty acids. Wherein the acetone is produced in a smaller amount than the other two ketone bodies and is exhaled by respiration due to its higher vapor pressure. In addition, in cachexia, the ketone body content, especially acetone, is increased by the metabolism of proteins, which occurs mainly in the late stages of the disease. Furthermore, acetone, butanone, pentanone are a marker component in the exhalation of lung cancer patients and gradually increase with the severe content of the disease. Thus, detection and analysis of ketone compounds in exhaled breath may provide key information for early detection of disease.
So far, the analysis of ketone compounds in exhaled breath has been relatively popular and many methods have been developed. For example, solid phase microextraction is combined with gas chromatography mass spectrometry (SPME-GC-MS), which is a gold standard for off-line exhaled gas analysis. However, SPME-GC-MS requires sample collection and pretreatment, and cannot be performed in situ, which is relatively complex and time consuming. It is therefore important that the detection of acetone in exhaled breath can be performed directly without or with minimal sample pretreatment. Currently, the more popular methods include selective ion flow mass spectrometry (SIFT-MS), proton transfer reaction mass spectrometry (PTR-MS), electrospray extraction ionization mass spectrometry (EESI-MS), which can analyze exhaled gas online. However, these methods have the disadvantages of using organic solvents, easily causing environmental pollution, complex flow and the like. For example, SIFT-MS requires a specialized microwave ionization source while coupling a quadrupole mass analyzer; PTR-MS requires the use of specialized hollow cathode plasma ionization source devices. These undoubtedly increase the cost of detection and analysis and are not very versatile. Therefore, there is a need to develop simpler, more versatile methods and devices for detecting ketones in exhaled breath.
Disclosure of Invention
The invention aims to provide a device and a method for measuring ketone compounds in gas, which are used for solving the problems that pretreatment is needed, an organic solvent is needed, on-line detection cannot be realized and the like in the process of analyzing the gas in the prior art.
The invention provides a device for measuring ketone compounds in gas, which is characterized by comprising an ionization channel, a gas channel and a mass spectrometer;
The ionization channel comprises a discharge needle, a first carrier gas channel, a first pipeline, a high-voltage source, a first capillary, a sample placing device and a first flowmeter;
the first carrier gas channel is inserted into the sample placing device and is used for providing inert gas for the sample placing device;
One end of the first pipeline is inserted into the sample placing device, the other end of the first pipeline is connected with the first capillary through a first two-way valve, the discharge needle is arranged in the first capillary, and the high-pressure source is used for providing high pressure for the discharge needle;
The gas channel comprises a gas source, a second carrier gas channel, a second flowmeter, a second pipeline and a second capillary;
the gas source is connected with the second carrier gas channel, the second carrier gas channel is connected with the second flowmeter, the second flowmeter is connected with the second pipeline, and the second pipeline is connected with the second capillary;
The first capillary and the second capillary are both located at the front end of the mass spectrometer inlet.
In another aspect, the present invention provides a method for determining ketone compounds in a gas, using the above device, the method comprising:
Closing the gas channel, and introducing moist water vapor into the ionization channel to the needle point of the discharge needle; meanwhile, high voltage of 1.5-2.5 kV is applied to a discharge needle to prepare a high-abundance water radical cation cluster (H 2O)2 +· ion M/z 36), under the condition that a gas channel is closed, a ketone compound aqueous solution sample with a certain concentration is added into a sample discharging device of an ionization channel, ketone and water vapor both flow into a first capillary under the drive of carrier gas flow to form abundant (H 2O)2 +· when reaching the vicinity of the discharge needle, meanwhile, surrounding ketone vapor rapidly interacts with the formed water radical cation (H 2O)2 +· in a three-dimensional space to generate a radical peak ion [ M+H 2O]+· compound with the mass number increased by 18 Da; the solvent water in the ketone compound solution is replaced by D 2 O and H 2 18 O respectively by adopting deuterium labeling and isotope 18 O labeling, other conditions are kept unchanged, and the complex formed by interaction of the ion with the ketone compound with the H 2O+· with the mass number increased by 18Da can be determined through corresponding primary mass spectrum data and secondary mass spectrum data analysis;
Firstly closing the gas channel, and sequentially adding ketone compound aqueous solutions with different concentrations into a sample placing device of the ionization channel to obtain a better linear relation between the ketone compound aqueous solutions with different concentrations and a water-added free radical cation signal m/z 76;
And (3) changing the sample in the ionization channel into pure water, opening the gas channel, detecting the gas component in the gas source, and measuring the concentration of the ketone compound in the gas source.
According to the device and the method for measuring the ketone compounds in the gas, provided by the invention, the device and the method have the following beneficial effects:
by adopting the device and the method for measuring the ketone compounds in the gas, when the air humidity is low, the carrier gas can be used for bringing water vapor in; when the air humidity is higher, the carrier gas is not needed to be introduced, and the water vapor in the air is directly ionized, so that the use is convenient. Through regulating and controlling the electric field intensity, ionized water vapor generates a large number of water radical cation clusters, the formed water radical cation clusters interact with ketone compounds in exhaled air to generate high-abundance adduct water radical cation product peaks, the whole device is simple, the modification cost is low, on-line in-situ analysis can be realized, no sample pretreatment is needed, the whole analysis process is less than 1 minute, the method can be carried out at normal temperature and normal pressure, water is used as a carrier, the method is green and pollution-free, the reaction time of the water radical cation clusters and the ketone compounds is quick, high-flux analysis can be realized, and the method has important significance for rapid detection and analysis of the ketone compounds in a gas source. When the gas source is provided with the expiration device, the on-line expiration detection of the human body can be realized, and a rapid, simple and low-cost method and device are provided for the early detection of human diseases.
In addition, the device for measuring the ketone compounds in the gas provided by the invention can also have the following additional technical characteristics:
further, the discharge needle is a stainless steel conical discharge needle.
Further, the ionization channel further comprises a first flowmeter, and the first flowmeter is arranged on the first carrier gas channel.
Further, the gas source comprises an exhalation device for direct exhalation use by the human body.
Further, the gas source includes a gas collection bag for collecting gas for detection.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic structural diagram of an apparatus for measuring ketone compounds in a gas according to an embodiment of the present invention;
FIG. 2 is a mass spectrum of water radical cations prepared by regulating energy charge transfer rule in example 1 (gas channel closed);
FIG. 3 is a primary and secondary mass spectrum of water radical cations formed in the ionization channel interacting with acetone to form an additive water radical cation product (m/z 76), and a corresponding isotopic label plot;
FIG. 4 is a total ion flow diagram and a selective ion flow diagram of the action of water radical cations with acetone;
FIG. 5 is a schematic illustration of the reaction mechanism of a water radical cation interacting with acetone to form a water radical cation addition product and the corresponding product after tandem mass spectrometry fragmentation;
FIG. 6 is a total ion flow and primary mass spectrum of the addition product (m/z 76) formed by the action of water radical cations formed by the ionization channel and acetone in the gas of the gas channel;
FIG. 7 is a block diagram of different types of ketones.
FIG. 8 is a mass spectrum of the effect of different types of ketone compounds on water radical cations.
Detailed Description
In order that the objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Several embodiments of the invention are presented in the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "mounted" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and the like are used herein for descriptive purposes only and not to indicate or imply that the apparatus or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an apparatus for determining ketone compounds in a gas according to an embodiment of the present invention includes an ionization channel, a gas channel, and a mass spectrometer 30;
The ionization channel comprises a discharge needle 11, a first pipeline 12, a first carrier gas channel 13, a high-voltage source 14, a first capillary 15 and a sample placing device 16.
The sample placing device 16 may be used to store a sample, pure water, or the like, the first carrier gas channel 13 is inserted into the sample placing device 16, and the first carrier gas channel 13 is used to provide inert gas, such as argon, to the sample placing device 16. The purpose of the inert gas provided in the ionization channel is to bring out the water while avoiding interference with other impurities when the tip of the discharge needle 11 ionizes the water.
One end of the first pipe 12 is inserted into the sample setting device 16, the other end of the first pipe 12 is connected to the first capillary 15 through a first flow meter such as a two-way valve (not shown), the discharge needle 11 is provided in the first capillary 15, and the high voltage source 14 is used for applying a high voltage of 2kV to the discharge needle 11, for example, to ionize water vapor, and generate water radical cation clusters by corona discharge ionization. Specifically, the discharge needle 11 is a stainless steel conical discharge needle.
The loft device 16 has two functions, among others: (1) The water storage device is used for storing water, providing water vapor and generating water radical cations through corona discharge; (2) The water vapor brings the ketone out to the power supply discharge needle, and water molecules are ionized to form water radical cations and fully react with surrounding ketone compounds to react.
Wherein the provision of the first capillary 15 has two functions: (1) Wrapping the discharge needle 11 to avoid exposing the whole discharge needle 11 outside; (2) A neutral water/sample gas flow is introduced to bring the water gas flow into sufficient operative contact with the discharge needle 11.
The gas channel includes a gas source 23, a second carrier gas channel 22, a second flowmeter 25, a second conduit 21, and a second capillary 24;
The gas source 23 is connected with the second carrier gas channel 22, the second carrier gas channel 22 is connected with the second flowmeter 25, and the second flowmeter 25 is used for controlling the size of the gas source;
one end of the second pipe 21 is connected to the second flowmeter 25, and the other end of the second pipe 21 is connected to the second capillary 24.
The gas source 23 may be a direct on-site exhalation of a human body, where the gas source includes an exhalation device, such as an oxygen mask, for use in exhaling, the second flow meter 25 is used to control the flow of exhaled gas to maintain a steady flow, and the second carrier gas channel 22 is used to deliver a flow of gas to introduce chemical components in the exhaled gas to the front end of the inlet of the mass spectrometer 30.
The gas source 23 may also be expired ex vivo and collected using a gas collection bag, in which case the gas source comprises a gas collection bag.
The gas source 23 may also be other types of gas, such as ambient gas, etc., and may be collected using a collection bag, where the gas source comprises a collection bag.
The outlet end of the first capillary 15 is located at the front end of the inlet of the mass spectrometer 30, and is located at a distance a=15 mm from the front end of the inlet of the mass spectrometer 30, the outlet end of the second capillary 24 is also located at the front end of the inlet of the mass spectrometer 30, and is located at a distance a=15 mm from the front end of the inlet of the mass spectrometer 30, the outlet end of the first capillary 15 is located at a distance b=5 mm from the outlet end of the second capillary 24, the included angle α between the outlet end of the first capillary 15 and the front end of the inlet of the mass spectrometer 30 is 150 o, the included angle α between the outlet end of the second capillary 24 and the front end of the inlet of the mass spectrometer 30 is also 150 o, the included angle β between the outlet end of the first capillary 15 and the outlet end of the second capillary 24 is 60 o, and the outlet end of the second capillary 24 and the front end of the mass spectrometer 30 are all located in a closed device, which enables water radical cation radicals formed in an ionization channel and ketone compounds to be mixed with the front end of the mass spectrometer 30, and the mass spectrometer can sufficiently cause mass spectrometer loss of the sample.
Preferably, the ionization channel further comprises a first flowmeter 17, and the first flowmeter 17 is arranged on the first carrier gas channel 13 and is used for controlling the flow rate of the gas in the ionization channel.
Based on the device, a method for measuring ketone compounds in gas comprises the following steps:
Introducing an inert gas into the sample placing device 16 through the first carrier gas channel 13 to form an inert gas with water vapor, and simultaneously introducing a sample in the gas into the front end of the inlet of the mass spectrometer 30 in a gas form through the second carrier gas channel 22 by a gas source;
Applying a high voltage of 1.5-2.5 kV to the needle tip of the discharge needle 11 through the high voltage source 14 to enable water radical cations to be taken as a base peak, and introducing moist water vapor to the needle tip of the discharge needle 11 through the first pipeline 12 to generate water radical cation clusters through corona discharge ionization;
The formed water free radical cation clusters react with ketone sample molecules in the gas source in a three-dimensional space to generate ketone-containing adducted water free radical cation peaks;
the formed ketone-containing adduct water free radical cation product is detected by the mass spectrometer 30, and is analyzed by the mass spectrometer 30 to obtain characteristic ion fragments with definite structures, so that the high-sensitivity analysis of ketone components in a gas source is realized.
The invention is further illustrated by the examples below.
Example 1
With the apparatus shown in fig. 1, with the gas passage closed, moist water vapor was introduced into the ionization passage to the tip of the discharge needle, while applying a high voltage of 2kV to the discharge needle, a water radical cation cluster (H 2O)2 +· ion m/z 36, particularly as shown in fig. 2, where m/z 54 is (H 2O)3 +· ion and m/z 55 is (H 2O)3H+ ion) was prepared in high abundance.
Example 2
With the apparatus shown in fig. 1, with the gas channel closed, a sample of acetone aqueous solution (Mw 58) of a certain concentration was added to the sample-setting apparatus of the ionization channel to interact with the formed water radical cations (H 2O)2 +· in three dimensions, further generating the base peak ions m/z 76 of 18Da mass number increase, initially inferred to be addition H 2O+· (shown in fig. 3 a). The aqueous acetone solution was further replaced by (D 2 O and acetone) solution and (H 2 18 O and acetone) solution by isotopic deuterium labeling and isotopic 18 O labeling experiments, Other conditions remained unchanged, and the ion with the mass increased by 18Da was determined to be the product of interaction of H 2O+· with acetone (shown in FIG. 3b and FIG. 3 c) by analysis of corresponding primary mass spectrometry data, i.e. the ion of the product with the mass increased by 18Da was derived from H 2 O. Further comparing and analyzing the secondary mass spectrum of [ M+H 2O]+· (shown in figure 3D), [ M+D 2O]+· (shown in figure 3 e) with the secondary mass spectrum of [ M+H 2 18O]+· (shown in figure 3 f) formed by the isotope 18 O labeling experiment, It was found that [ M+H 2O]+· ] was subjected to collision to mainly undergo OH loss and H 2 O loss to form protonated acetone M/z 59 and acetone radical cation M/z 58, respectively (shown in FIG. 3 e); [ M+D 2O]+· ] mainly loses OD after collision, H/D exchange occurs after OD loss and D 2 O loss respectively form deuterated acetone M/z 60, protonated acetone M/z 59 and acetone radical cation M/z 58 (shown in FIG. 3 f); [ M+H 2 18O]+· ] is mainly lost H 2 O after collision, The loss 18 OH and the loss H 2 18 O form acetone- 18 O radical cation m/z 60 respectively, protonated acetone m/z 59 and acetone radical cation m/z 58 (shown in FIG. 3 f). Thus, it was determined that the 18Da mass increased ion was the product of H 2O+· interacting with acetone, i.e., the 18Da increased product ion was from the device-induced H 2 O.
Referring to FIG. 5, FIG. 5 shows the process of forming [ M+H 2O]+· ] by interaction of water radical cations with acetone (FIG. 5 a) and the specific mechanism of forming protonated acetone M/z 59 and acetone radical cations M/z 58 by further fragmentation of [ M+H 2O]+· to loss of OH and H 2 O in tandem mass spectrometry (FIG. 5 b).
Referring to fig. 4, fig. 4 shows a total ion flow diagram (TIC) and a selective ion flow diagram (EIC) obtained by introducing a certain amount of water vapor into the ionization channel and then introducing a certain amount of acetone aqueous solution under the condition that the gas channel is closed, it can be found that m/z 36 is rapidly decreased and m/z 76 is rapidly increased after introducing acetone. This indicates that m/z 36 is reacted away to form a new m/z 76.
Example 3
The method performance of the device was evaluated using the device shown in fig. 1. Meanwhile, by adopting the same method and the same experimental parameter conditions as those of the example 2 and the same mass spectrum experimental conditions, firstly closing the gas channel, and sequentially adding acetone aqueous solutions (0.01 mu M,0.1 mu M,0.25 mu M,0.5 mu M and 1 mu M) with different concentrations into a sample device of the ionization channel, a better linear relation between the different concentrations of the acetone aqueous solution and the water-adding free radical cation signal M/z 76 can be obtained (figure 6 b), and obvious M/z 76 ions can still be detected when the acetone concentration is 0.01 mu M (figure 6 a). Changing the sample in the ionization channel into water, opening the gas channel, and detecting the gas component in the gas source, wherein the signal of m/z 76 is obviously enhanced; FIG. 6c is an EIC graph of m/z 76 for detection, where a significant increase in m/z 76 is found and stable; FIG. 6d is a corresponding mass spectrum showing that the concentration of acetone in the gas source was measured to be about 0.25. Mu.M.
Example 4
The universality of the method was evaluated using the apparatus shown in fig. 1. The same experiment was performed with a series of ketones, the structure of which is shown in FIG. 7. The same method as in example 2 and the same experimental parameter conditions and the same mass spectrum experimental conditions are adopted, the gas channel is closed firstly, and different types of ketone aqueous solutions are sequentially added into a sample placing device of the ionization channel, so that signals (figure 8) of the actions of various types of ketone compounds and water-added free radical cations can be obtained, which shows that the ketone compounds very form water-added free radical cation peaks with high abundance with water-added free radical cations, and the device can be suitable for rapid detection and analysis of the ketone compounds, is particularly suitable for direct mass spectrum analysis and research of the ketone compounds in a gas source, and is hopeful to be applied to early detection of diseases and the like.
In summary, by adopting the device and the method for measuring the ketone compounds in the gas, when the air humidity is low, the carrier gas can be used for bringing water vapor in; when the air humidity is higher, the carrier gas is not needed to be introduced, and the water vapor in the air is directly ionized, so that the use is convenient. Through regulating and controlling the electric field intensity, ionized water vapor generates a large number of water radical cation clusters, the formed water radical cation clusters interact with ketone compounds in exhaled air to generate high-abundance adduct water radical cation product peaks, the whole device is simple, the modification cost is low, on-line in-situ analysis can be realized, no sample pretreatment is needed, the whole analysis process is less than 1 minute, the method can be carried out at normal temperature and normal pressure, water is used as a carrier, the method is green and pollution-free, the reaction time of the water radical cation clusters and the ketone compounds is quick, high-flux analysis can be realized, and the method has important significance for rapid detection and analysis of the ketone compounds in a gas source. When the gas source is provided with the expiration device, the on-line expiration detection of the human body can be realized, and a rapid, simple and low-cost method and device are provided for the early detection of human diseases.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (5)
1. A method for measuring ketone compounds in a gas, wherein the method is applied to a device for measuring ketone compounds in the gas, and the device comprises an ionization channel, a gas channel and a mass spectrometer; the ionization channel comprises a discharge needle, a first carrier gas channel, a first pipeline, a high-voltage source, a first capillary, a sample placing device and a first flowmeter; the first carrier gas channel is inserted into the sample placing device and is used for providing inert gas for the sample placing device; one end of the first pipeline is inserted into the sample placing device, the other end of the first pipeline is connected with the first capillary through a first two-way valve, the discharge needle is arranged in the first capillary, and the high-pressure source is used for providing high pressure for the discharge needle; The first flowmeter is arranged on the first carrier gas channel; the gas channel comprises a gas source, a second carrier gas channel, a second flowmeter, a second pipeline and a second capillary; the gas source is connected with the second carrier gas channel, the second carrier gas channel is connected with the second flowmeter, the second flowmeter is connected with the second pipeline, and the second pipeline is connected with the second capillary; the first capillary and the second capillary are both positioned at the front end of the inlet of the mass spectrometer; the method comprises the following steps: closing the gas channel, and introducing moist water vapor into the ionization channel to the needle point of the discharge needle; meanwhile, high voltage of 1.5-2.5 kV is applied to the discharge needle to prepare high-abundance water radical cation clusters (H 2O)2 +· ions m/z 36; under the condition that the gas channel is closed, a ketone compound water solution sample with a certain concentration is added into a sample placing device of the ionization channel, ketone and water vapor both flow into the first capillary under the drive of carrier gas flow, and are enriched when reaching the vicinity of the discharge needle (H 2O)2 +·, meanwhile, the surrounding ketone vapor rapidly interacts with the formed water radical cations (H 2O)2 +· in three-dimensional space, Generating a base peak ion [ M+H 2O]+· complex with mass number increased by 18 Da; The isotope deuterium labeling and the isotope 18 O labeling are adopted to replace the solvent water in the ketone compound solution with D 2 O and H 2 18 O respectively, Other conditions are kept unchanged, and the ion with the mass number increased by 18Da can be determined to be a compound formed by interaction of H 2O+· and ketone compounds through corresponding primary mass spectrum data and secondary mass spectrum data analysis; Firstly closing the gas channel, and sequentially adding ketone compound aqueous solutions with different concentrations into a sample placing device of the ionization channel to obtain a better linear relation between the ketone compound aqueous solutions with different concentrations and a water-added free radical cation signal m/z 76; and (3) changing the sample in the ionization channel into pure water, opening the gas channel, detecting the gas component in the gas source, and measuring the concentration of the ketone compound in the gas source.
2. The method for measuring ketone compounds in a gas according to claim 1, wherein the discharge needle is a stainless steel conical discharge needle.
3. The method of claim 1, wherein the first flow meter is a two-way valve.
4. The method of claim 1, wherein the gas source comprises an exhalation device.
5. The method of claim 1, wherein the gas source comprises a gas collection bag.
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