Gas chromatographic analysis device for volatile and medium volatile organic compounds

Abstract

The utility model discloses a gas chromatographic analysis device for volatile and medium volatile organic compounds, which relates to the technical field of gas sampling detection, and comprises a two-position six-way valve, a collector and a gas chromatographic column, the two-position six-way valve comprises a port A, a port B, a port C, a port D, a port E and a port F, the port A is connected with a sample introduction pipe, the port B is connected with a vacuum pump, the port C is connected with a first end of a backflushing pipe, and the port D is connected with a second end of the backflushing pipe. The port D is connected with a helium gas source, the port E is connected with the gas chromatographic column, the port F is connected with the first end of the collector, and the second end of the collector is connected with the second end of the backwashing pipe; a first adsorption layer and a second adsorption layer with gradually enhanced adsorbability are sequentially arranged in the collector from the first end to the second end of the collector, and a heater is arranged outside the collector and is used for heating the collector to perform thermal desorption. The device disclosed by the utility model can be used for enriching volatile and medium-volatile organic compounds and carrying out on-line synchronous measurement on the volatile and medium-volatile organic compounds.

Description

Technical Field

[0001] The utility model relates to the technical field of gas sampling and detection, in particular to a gas chromatographic analysis device for volatile and intermediate-volatility organic compounds. Background Technique

[0002] Organic compounds are very important measurement components in the atmospheric troposphere and play an extremely important role in the atmospheric chemical reaction process. They have important impacts on some regional environmental problems, such as cross-pollution of photochemical smog, secondary organic pollution, and oxidation ability of background atmosphere. Volatile organic compounds (VOCs, C * ≥10 6 μg / m 3 ) and intermediate-volatility organic compounds (IVOCs, C * being 10 3 -10 6 μg / m 3 ) are important precursors of atmospheric ozone and secondary organic aerosols. Achieving online and accurate monitoring of atmospheric gaseous volatile and intermediate-volatility organic compounds is the basis for studying the pollution characteristics and chemical mechanisms of atmospheric organic compounds. However, in existing measurement technologies, there is a lack of instrument equipment that can achieve online synchronous measurement and quantitative analysis of gaseous volatile and intermediate-volatility organic compounds. Content of the Utility Model

[0003] The purpose of the utility model is to provide a gas chromatographic analysis device for volatile and intermediate-volatility organic compounds to solve the problems existing in the above-mentioned prior art, and to be able to achieve the enrichment of volatile and intermediate-volatility organic compounds and conduct online synchronous measurement.

[0004] To achieve the above purpose, the utility model provides the following scheme:

[0005] The utility model provides a gas chromatographic analysis device for volatile and intermediate-volatility organic compounds, which includes a two-position six-way valve, a collector, and a gas chromatographic column. The two-position six-way valve includes ports A, B, C, D, E, and F. Port A is connected to a sampling tube, port B is connected to a vacuum pump, port C is connected to the first end of a backflush tube, port D is connected to a helium gas source, port E is connected to the gas chromatographic column, port F is connected to the first end of the collector, and the second end of the collector is connected to the second end of the backflush tube;

[0006] Inside the collector, a first adsorption layer and a second adsorption layer with gradually increasing adsorption properties are sequentially arranged from its first end to its second end. A heater is arranged outside the collector for heating the collector for thermal desorption.

[0007] Preferably, the first adsorption layer is filled with Tenax TA adsorbent.

[0008] Preferably, the second adsorption layer includes a Carbopack B adsorption layer and a Carbopack X adsorption layer arranged in sequence, and the Carbopack B adsorption layer is arranged close to the first adsorption layer.

[0009] Preferably, a metal filter is further provided in the collector, and the metal filter is located on the side of the first adsorption layer facing away from the second adsorption layer.

[0010] Preferably, gaps are provided between the metal filter and the first adsorption layer, between the first adsorption layer and the Carbopack B adsorption layer, and between the Carbopack B adsorption layer and the Carbopack X adsorption layer, and the gaps are filled with glass beads.

[0011] Preferably, the collector on the side of the Carbopack X adsorption layer facing away from the Carbopack B adsorption layer is filled with glass wool.

[0012] The utility model has achieved the following technical effects compared with the prior art:

[0013] For the gas chromatography analysis device for volatile and semi-volatile organic compounds provided by the utility model, during sampling, the air flow flows from the first end to the second end of the collector, and during desorption, the air flow flows in the reverse direction, so that the semi-volatile organic compounds do not interact with the second adsorption layer with stronger erosion, ensuring that both volatile and semi-volatile organic compounds can produce clear chromatographic peaks, thereby achieving the purpose of enriching volatile and semi-volatile organic compounds and performing on-line synchronous measurement. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 It is a schematic structural diagram of the gas chromatography analysis device for volatile and semi-volatile organic compounds in the embodiment of the present utility model;

[0016] Figure 2 It is a schematic internal structural diagram of the collector in the embodiment of the present utility model.

[0017] In the figure: 1 - two-position six-way valve, 2 - collector, 3 - gas chromatography column, 4 - injection tube, 5 - vacuum pump, 6 - backflush tube, 7 - helium gas source, 8 - first adsorption layer, 9 - second adsorption layer, 91 - Carbopack B adsorption layer, 92 - Carbopack X adsorption layer, 10 - metal filter, 11 - glass beads, 12 - glass wool. Specific embodiments

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0019] The purpose of the present invention is to provide a gas chromatography analysis device for volatile and semi-volatile organic compounds to solve the problems existing in the prior art and to achieve the enrichment and on-line synchronous measurement of volatile and semi-volatile organic compounds.

[0020] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] As Figure 1 - Figure 2 shown, this embodiment provides a gas chromatography analysis device for volatile and semi-volatile organic compounds, including a two-position six-way valve 1, a collector 2, and a gas chromatography column 3. The two-position six-way valve 1 includes ports A, B, C, D, E, and F. Port A is connected to the injection tube 4, port B is connected to the vacuum pump 5, port C is connected to the first end of the backflush tube 6, port D is connected to the helium gas source 7, port E is connected to the gas chromatography column 3, port F is connected to the first end of the collector 2, and the second end of the collector 2 is connected to the second end of the backflush tube 6;

[0022] Inside the collector 2, a first adsorption layer 8 and a second adsorption layer 9 with gradually increasing adsorption properties are sequentially provided from its first end to its second end. A heater is provided outside the collector 2 for heating the collector 2 for thermal desorption.

[0023] When sampling, the A port of the two-position six-way valve 1 is connected to the F port, and the C port is connected to the B port. The sampling tube 4 is connected to the first end of the collector 2 through the two-position six-way valve 1. The second end of the collector 2 is connected to the vacuum pump 5 through the backflush tube 6 and the two-position six-way valve 1. Under the action of the vacuum pump 5, the sampling gas is pumped into the collector 2, and the medium-volatile organic compounds in it are adsorbed by the first adsorption layer 8 in the collector 2, and the volatile organic compounds are adsorbed by the second adsorption layer 9. During sampling, the temperature of the collector 2 should be at least several degrees higher than the dew point to avoid condensation of water in the system. The temperature of the collector 2 is usually about 30°C. After sampling is completed, the two-position six-way valve 1 is switched, its F port is connected to the E port, and the C port is connected to the D port. The second end of the collector 2 is connected to the helium gas source 7 through the backflush tube 6 and the two-position six-way valve 1. The first end of the collector 2 is connected to the gas chromatography column 3 through the two-position six-way valve 1. Under the backflush action of helium and the heating action of the heater, the collector 2 is heated from the ambient temperature to 260°C, and the adsorbed volatile and medium-volatile organic compounds in the collector 2 are desorbed onto the gas chromatography column 3 for analysis. During sampling, the gas flow flows from the first end to the second end of the collector 2. During desorption, the gas flow reverses, so that the medium-volatile organic compounds do not interact with the more corrosive second adsorption layer 9, ensuring that both volatile and medium-volatile organic compounds can produce clear chromatographic peaks, thereby achieving the purpose of enriching volatile and medium-volatile organic compounds and performing on-line synchronous measurement.

[0024] In this embodiment, the first adsorption layer 8 is filled with Tenax TA adsorbent. The second adsorption layer 9 includes a Carbopack B adsorption layer 91 and a Carbopack X adsorption layer 92 arranged in sequence, and the Carbopack B adsorption layer 91 is arranged close to the first adsorption layer 8.

[0025] In this embodiment, a metal filter 10 is further provided in the collector 2, and the metal filter 10 is located on the side of the first adsorption layer 8 facing away from the second adsorption layer 9. Through the metal filter 10, substances such as low-volatile, semi-volatile, and particulate matter in the gas can be captured, and then during backflushing, simultaneous desorption of low-volatile, semi-volatile, and particulate matter in the gas can be achieved.

[0026] In this embodiment, gaps are provided between the metal filter 10 and the first adsorption layer 8, between the first adsorption layer 8 and the Carbopack B adsorption layer 91, and between the Carbopack B adsorption layer 91 and the Carbopack X adsorption layer 92, and glass beads 11 are filled. The glass beads 11 separate the layers and ensure the gas flow through.

[0027] In this embodiment, the collector 2 on the side of the Carbopack X adsorption layer 92 facing away from the Carbopack B adsorption layer 91 is filled with glass wool 12, which forms an isolation protection for Carbopack X and ensures the air flow throughability.

[0028] In the present utility model, specific examples are used to elaborate on the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. A gas chromatography analysis device for volatile and semi-volatile organic compounds, characterized in that: It includes a two-position six-way valve, a collector, and a gas chromatography column. The two-position six-way valve includes ports A, B, C, D, E, and F. Port A is connected to an injection tube, port B is connected to a vacuum pump, port C is connected to the first end of a backflush tube, port D is connected to a helium gas source, port E is connected to the gas chromatography column, port F is connected to the first end of the collector, and the second end of the collector is connected to the second end of the backflush tube; Inside the collector, a first adsorption layer and a second adsorption layer with gradually increasing adsorption properties are successively arranged from its first end to its second end. A heater is provided outside the collector for heating the collector for thermal desorption.

2. The gas chromatography analysis device for volatile and moderately volatile organic compounds according to claim 1, wherein: The first adsorption layer is filled with Tenax TA adsorbent.

3. The gas chromatographic analysis device for volatile and medium-volatile organic compounds according to claim 2, characterized in that: The second adsorption layer includes a Carbopack B adsorption layer and a Carbopack X adsorption layer arranged in sequence. The Carbopack B adsorption layer is arranged close to the first adsorption layer.

4. The gas chromatographic analysis device for volatile and semi-volatile organic compounds according to claim 3, characterized in that: A metal filter is further provided inside the collector, and the metal filter is located on the side of the first adsorption layer facing away from the second adsorption layer.

5. The gas chromatographic analysis device for volatile and semi-volatile organic compounds according to claim 4, characterized in that: Gaps are provided between the metal filter and the first adsorption layer, between the first adsorption layer and the Carbopack B adsorption layer, and between the Carbopack B adsorption layer and the Carbopack X adsorption layer, and the gaps are filled with glass beads.

6. The gas chromatographic analysis device for volatile and semi-volatile organic compounds according to claim 3, characterized in that: Glass wool is filled inside the collector on the side of the Carbopack X adsorption layer facing away from the Carbopack B adsorption layer.

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