Method for detecting trace benzene series in atmosphere

Abstract

The invention relates to a mass spectrometry detection technology, in particular to a method for detecting trace benzene series in atmosphere, and the specific structure of the method comprises a sampling pipeline, a bundled capillary column, a mass spectrometer, an air pump and a control computer. The method is simple to operate and high in detection sensitivity, and can realize real-time online analysis of trace benzene series in the atmospheric environment.

Description

Technical Field

[0001] The present invention relates to mass spectrometry detection technology, specifically a method for detecting trace benzene series in the atmosphere, wherein the specific structure of the method comprises a sampling pipeline, a cluster capillary column, a mass spectrometer, a vacuum pump and a control computer. The method is simple to operate, has high detection sensitivity, and can realize real-time online analysis of trace benzene series in the atmosphere. Background Art

[0002] The detection of trace benzene derivatives in the atmosphere is the measurement and analysis of trace concentrations of benzene and its derivatives (benzene derivatives) in the atmosphere in environmental science. Benzene and its derivatives are an important class of volatile organic compounds that are widely present in the atmosphere. The main sources include automobile exhaust, industrial emissions, combustion processes, and the release of volatile organic compounds.

[0003] The trace concentrations of benzene and its derivatives in the atmosphere have a significant impact on air quality and public health. Benzene is a carcinogen, and long-term exposure to high concentrations of benzene gas may cause harm to human health, especially to the respiratory and immune systems. In addition, benzene and its derivatives will also participate in atmospheric chemical reactions to form secondary pollutants such as ozone and fine particulate matter, which have a negative impact on the atmospheric environment.

[0004] Therefore, monitoring and measuring the concentration of trace BTEX in the atmosphere is crucial for assessing air quality, understanding the sources of air pollution, and formulating effective environmental protection policies. Common BTEX detection methods include gas chromatography-mass spectrometry (GC-MS), gas chromatography-mass spectrometry (GC-MS / MS), gas chromatography-flame ionization detection (GC-FID), etc.

[0005] With the continuous development of environmental monitoring technology, the sensitivity and accuracy of trace benzene detection have been continuously improved. At the same time, the construction of monitoring networks has become increasingly perfect, enabling researchers to better understand the distribution and changes of benzene in the atmosphere, so as to take effective measures to protect the environment and human health. Summary of the invention

[0006] The purpose of the present invention is to utilize the powerful detection capability of mass spectrometry to quantitatively analyze the concentration of benzene series in the atmospheric environment and provide data support for environmental assessment and improvement.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] A method for detecting trace benzene series in the atmosphere, the device used includes a sampling pipeline, a cluster capillary column, an air pump, and a mass spectrometer, one end of the cluster capillary column is connected to a purge gas source via a first three-way solenoid valve, the third interface of the first three-way solenoid valve is connected to an open end of a sampling pipeline with two openings; the other end of the cluster capillary column is connected to an injection port of the mass spectrometer via a second three-way solenoid valve, the third interface of the second three-way solenoid valve is connected to an air inlet of the air pump;

[0009] The whole testing process is divided into two stages:

[0010] The first stage is sample enrichment: the sampling pipeline is switched to be connected to the cluster capillary column through the first three-way solenoid valve; at the same time, the vacuum pump is switched through the second three-way solenoid valve and connected to the other end of the cluster capillary column, and the vacuum pump is turned on to allow the gas to pass through the cluster capillary column and be enriched therein;

[0011] The second stage is desorption detection, at which time the first three-way solenoid valve is switched to connect the purge gas source and the clustered capillary column, and the second three-way solenoid valve is switched to connect the mass spectrometer and the other end of the clustered capillary column; finally, the desorbed components in the clustered capillary column enter the mass spectrometer for detection under the carrier of the purge gas.

[0012] The suction flow rate of the sampling pump is 0.1-2L / min, and the sample enrichment time is 2-5min.

[0013] The desorption temperature of the cluster capillary column is 150-200°C, the purge gas flow rate during desorption is 1-10mL / min, the purge gas type is high-purity nitrogen, and the high-purity nitrogen in the nitrogen cylinder is used as the purge gas source. A mass flow controller is provided on the connecting pipeline between the first three-way solenoid valve and the purge gas source, and the purge gas flow rate is controlled by the mass flow controller.

[0014] Different pipelines connected to the two solenoid valves are switched by controlling the two solenoid valves with one button at the control end of the control computer; the flow control of the mass flow controller and the sampling pump and the data collection of the mass spectrometer are all carried out on the control computer.

[0015] The mass spectrometer may be one or more of a time-of-flight mass spectrometer, an ion trap mass spectrometer, a quadrupole mass spectrometer, and the like.

[0016] The clustered capillary column is composed of 5-7 Agilent HP-PLOT Q quartz capillary columns with a length of 0.1-0.2m and an inner diameter of 0.05mm-0.53mm, which are filled in parallel in a hollow stainless steel tube with an inner diameter of 2-2.6cm and an outer diameter of 2.4-3cm; the capillary column is fixed in the stainless steel tube by filling the space between the outer wall of the capillary and the inner wall of the stainless steel tube with filling glue.

[0017] The method is simple to operate and has high detection sensitivity, and can realize real-time online analysis of trace benzene derivatives in the atmospheric environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic structural diagram of a method for detecting trace amounts of benzene series in the atmosphere;

[0019] Figure 2 It is the quantitative curve of 3 benzene series;

[0020] Figure 3 Mass spectra for atmospheric environment detection. DETAILED DESCRIPTION

[0021] See also Figure 1 , which is a schematic diagram of the structure of the present invention.

[0022] The device used includes a sampling pipeline 4, a clustered capillary column 5, an air pump 7, and a mass spectrometer 8. One end of the clustered capillary column 5 is connected to a purge gas source via a first three-way solenoid valve 3 (a two-position three-way solenoid valve), and the third interface of the first three-way solenoid valve 3 is connected to an open end of the sampling pipeline 4 with two openings; the other end of the clustered capillary column 5 is connected to an injection port of the mass spectrometer 8 via a second three-way solenoid valve 6 (a two-position three-way solenoid valve), and the third interface of the second three-way solenoid valve 6 is connected to an air inlet of the air pump 7;

[0023] The whole testing process is divided into two stages:

[0024] The first stage is sample enrichment: the sampling line 4 is switched to be connected to the cluster capillary column 5 through the first three-way solenoid valve 3; at the same time, the vacuum pump 7 is switched to be connected to the other end of the cluster capillary column 5 through the second three-way solenoid valve 6, and the vacuum pump 7 is turned on to allow the gas to pass through the cluster capillary column 5 and be enriched therein;

[0025] The second stage is desorption detection, at this time, the first three-way solenoid valve 3 is switched to connect the purge gas source and the clustered capillary column 5, and the second three-way solenoid valve 6 is switched to connect the mass spectrometer 8 with the other end of the clustered capillary column 5; finally, the desorbed components in the clustered capillary column 5 enter the mass spectrometer 8 for detection under the carrier of the purge gas.

[0026] The suction flow rate of the sampling pump 7 is 0.5 L / min, and the sample enrichment time is 3 min.

[0027] The desorption temperature of the cluster capillary column 5 is 160°C, the purge gas flow rate during desorption is 5 mL / min, the purge gas type is high-purity nitrogen, and the high-purity nitrogen in the nitrogen cylinder 1 is used as the purge gas source. A mass flow controller 2 is provided on the connecting pipeline between the first three-way solenoid valve 3 and the purge gas source, and the purge gas flow rate is controlled by the mass flow controller 2.

[0028] The different pipelines connected to the two solenoid valves are switched by controlling the two solenoid valves with one button at the control end of the control computer 9; the flow control of the mass flow controller 2 and the sampling pump 7 and the data collection of the mass spectrometer are all performed on the control computer 9.

[0029] The mass spectrometer 8 is a time-of-flight mass spectrometer;

[0030] The clustered capillary column 5 is composed of 6 Agilent HP-PLOT Q quartz capillary columns with a length of 0.1 m and an inner diameter of 0.32 mm, which are filled in parallel in a hollow stainless steel tube with an inner diameter of 2.2 cm and an outer diameter of 2.4 cm. Kraft 705 silica gel filling glue is used to fill the space between the outer wall of the capillary and the inner wall of the stainless steel tube to fix the capillary column in the stainless steel tube.

[0031] Example:

[0032] The quantitative curves of benzene, toluene and xylene were drawn using the above detection method. The horizontal axis is the concentration of the three compounds, and the vertical axis is the signal intensity measured at the corresponding concentration. Figure 2 As shown, the benzene series in the air near No. 911 Huangpu Road, Dalian High-tech Zone was tested, and the results are as follows Figure 3 As shown in the test results, the concentrations of benzene, toluene and xylene near the address are 0, 0.5 and 16.4 μg / m 3 .

Claims

1. A method for detecting trace amounts of benzene series in the atmosphere, the device used comprising a sampling pipeline (4), a clustered capillary column (5), an air pump (7), and a mass spectrometer (8), wherein one end of the clustered capillary column (5) is connected to a purge gas source via a first three-way solenoid valve (3), and the third interface of the first three-way solenoid valve (3) is connected to an open end of a sampling pipeline (4) with two open ends; the other end of the clustered capillary column (5) is connected to an injection port of the mass spectrometer (8) via a second three-way solenoid valve (6), and the third interface of the second three-way solenoid valve (6) is connected to an air inlet of the air pump (7); Features: The whole testing process is divided into two stages: The first stage is sample enrichment: the sampling pipeline (4) is switched to be connected to the cluster capillary column (5) through the first three-way solenoid valve (3); at the same time, the vacuum pump (7) is switched to be connected to the other end of the cluster capillary column (5) through the second three-way solenoid valve (6), and the vacuum pump (7) is turned on to allow the gas to pass through the cluster capillary column (5) and be enriched therein; The second stage is desorption detection, at which the first three-way solenoid valve (3) is switched to connect the purge gas source and the clustered capillary column (5), while the second three-way solenoid valve (6) is switched to connect the mass spectrometer (8) and the other end of the clustered capillary column (5); finally, the desorbed components in the clustered capillary column (5) enter the mass spectrometer (8) for detection under the carrier of the purge gas.

2. The detection method according to claim 1, characterized in that: The suction flow rate of the sampling pump (7) is 0.1-2 L / min, and the sample enrichment time is 2-5 min.

3. The detection method according to claim 1, characterized in that: The desorption temperature of the cluster capillary column (5) is 150-200° C., the purge gas flow rate during desorption is 1-10 mL / min, the purge gas type is high-purity nitrogen, and the high-purity nitrogen in the nitrogen cylinder (1) is used as the purge gas source. A mass flow controller (2) is provided on the connecting pipeline between the first three-way solenoid valve (3) and the purge gas source, and the purge gas flow rate is controlled by the mass flow controller (2).

4. The detection method according to claim 1, 2 or 3, characterized in that: Different pipelines connected to the two solenoid valves are switched by controlling the two solenoid valves with one key at the control end of the control computer (9); the flow control of the mass flow controller (2) and the sampling pump (7) and the data collection of the mass spectrometer are all performed on the control computer (9).

5. The detection method according to claim 1 or 4, characterized in that: The mass spectrometer (8) can be one or more of a time-of-flight mass spectrometer, an ion trap mass spectrometer, a quadrupole mass spectrometer, etc.

6. The detection method according to claim 1 or 4, characterized in that: The clustered capillary column (5) is composed of 5-7 Agilent HP-PLOT Q quartz capillary chromatographic columns with a length of 0.1-0.2 m and an inner diameter of 0.05 mm-0.53 mm, which are filled in parallel in a hollow stainless steel tube with an inner diameter of 2-2.6 cm and an outer diameter of 2.4-3 cm; the capillary chromatographic column is fixed in the stainless steel tube by filling the space between the outer wall of the capillary and the inner wall of the stainless steel tube with filling glue.

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