CN111579315B - VOCs and IVOCs simultaneous online collection and detection method - Google Patents

VOCs and IVOCs simultaneous online collection and detection method Download PDF

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CN111579315B
CN111579315B CN202010465082.2A CN202010465082A CN111579315B CN 111579315 B CN111579315 B CN 111579315B CN 202010465082 A CN202010465082 A CN 202010465082A CN 111579315 B CN111579315 B CN 111579315B
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ivocs
vocs
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sample
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CN111579315A (en
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李英杰
黄成�
景盛翱
王红丽
楼晟荣
高雅琴
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Shanghai Academy of Environmental Sciences
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    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling
    • G01N1/2214—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling by sorption
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2247—Sampling from a flowing stream of gas
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2273—Atmospheric sampling
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/06—Preparation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/16—Injection
    • G01N30/20—Injection using a sampling valve
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/60—Construction of the column
    • G01N30/6034—Construction of the column joining multiple columns
    • G01N30/6043—Construction of the column joining multiple columns in parallel
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/16—Injection
    • G01N30/20—Injection using a sampling valve
    • G01N2030/201—Injection using a sampling valve multiport valves, i.e. having more than two ports
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
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Abstract

The invention belongs to the technical field of environmental monitoring, and particularly relates to a method for simultaneously collecting and detecting volatile organic compounds and medium volatile organic compounds on line. The method for simultaneously collecting and detecting VOCs and IVOCs on line comprises the following steps of: a standard sample or ambient air enters a TD system through a temperature-control sampling channel, and a group of sampling tube groups in the TD system simultaneously adsorb and sample target substances; meanwhile, the other group of sampling tube groups adopts inert gas to desorb target substances, and the desorbed target substances are loaded into a GC/MS analysis system through a sample transmission pipeline by high-purity helium gas; and in the GC/MS analysis system, the target object VOCs separated firstly are separated secondarily by means of a Dean-Switch switching system, and the target object VOCs separated secondarily and the target object IVOCs are detected and analyzed simultaneously by a mass spectrum detector. The method for simultaneously collecting and detecting VOCs and IVOCs on line realizes the purpose of simultaneously collecting and analyzing VOCs and IVOCs on line by one-time sampling.

Description

VOCs and IVOCs simultaneous online collection and detection method
Technical Field
The invention belongs to the technical field of environmental monitoring, and particularly relates to a method for simultaneously collecting and detecting volatile organic compounds and medium volatile organic compounds on line.
Background
The organic matter in the atmosphere can be classified into medium volatile organic compounds (IVOCs) according to the saturation concentration (C), and the saturation concentration range is 10 3 μg/m 3 ＜C*＜10 6 μg/m 3 ) And volatile organic compounds (VOCs, saturation concentration range C >)10 6 μg/m 3 ). Since VOCs are considered to be O 3 And important precursors of Secondary Organic Aerosols (SOAs), have been the focus of research by researchers and related regulatory authorities. Recent studies have shown that IVOCs are also atmospheric O 3 And important precursors of SOA, and have attracted considerable interest to researchers. In addition, VOCs and IVOCs are also important hazards to human health.
The saturation concentration range of VOCs corresponds to C 3 ～C 12 Between normal paraffins of (C), the IVOCs saturation concentration range corresponds to C 12 ～C 22 N-alkanes. At present, detection technology for organic components and concentration levels of VOCs is relatively mature, and monitoring technical guidelines or standards, such as US EPA 5030C, are established; monitoring technical guidelines Technical Guidance Note (TGN) M8 and M16 formulated by the european union environmental protection agency; and the determination of environmental air volatile organic compounds (HJ 759-2015) issued by China, and a monitoring technology for offline collection and analysis of VOCs based on gas chromatography/mass spectrometry (GC/MS) standards is specified. In addition, because the boiling point of VOCs is low, the VOCs are generally volatile at 50-250 ℃, and the like, the online collection and analysis of the VOCs based on thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) are realized at present. However, IVOCs are relatively low in ambient concentration levels relative to VOCs, relatively high in viscosity, and prone to system carryover. Therefore, the analysis of IVOCs is mainly based on TD-GC/MS for offline collection and analysis, with lower time resolution. At present, an effective means is lacked to continuously track and observe the pollution level of IVOCs, so that the exact response relation between different IVOCs monomers and SOA cannot be accurately obtained, and the contribution of IVOCs to SOA generation is difficult to scientifically evaluate.
Chinese patent CN201910212822.9 discloses a near-online detecting device for medium volatile organic compounds, which modifies the original TD-GC/MS system for online collecting and analyzing VOCs, and adds the capability of online collecting and analyzing IVOCs based on the original device. In addition to the difference in saturation vapor pressure and viscosity, the concentrations of VOCs and IVOCs in the ambient atmosphere are orders of magnitude different and therefore it is more difficult to achieve simultaneous on-line collection and real-time analysis on one sampling tube. Thus, after improvementThe device of (2) can only be used for collecting and analyzing one target object of VOCs or IVOCs on line. However, either VOCs or IVOCs are considered to be specific to O 3 And the generation of SOAs. Therefore, if the capability of the original device for analyzing the organic matters can be widened, VOCs and IVOCs can be simultaneously collected and analyzed on line, precious data can be provided for analysis and detection in the field of the organic matters, and data support can be provided for environmental pollution, human health risk exposure evaluation and the like.
Disclosure of Invention
Aiming at the technical problem that the existing online detection device is difficult to collect and analyze VOCs and IVOCs simultaneously, the invention aims to provide a method for collecting and detecting VOCs and IVOCs simultaneously online.
The method for simultaneously collecting and detecting VOCs and IVOCs on line comprises the following steps of:
and the standard sample or the ambient air enters a TD (thermal desorption) system through a temperature control sampling channel, a group of sampling tube groups in the TD system simultaneously adsorb and sample target substances, and the same group of sampling tube groups comprise sampling tubes filled with VOCs (volatile organic compounds) adsorbents and sampling tubes filled with IVOCs adsorbents.
And the sampling tube group after adsorbing and sampling the target substance adopts inert gas to desorb the target substance, and the desorbed target substance is loaded into a GC/MS analysis system by the inert gas through a sample transmission pipeline connected with the GC/MS analysis system.
In the GC/MS analysis system, a Dean-Switch switching system is adopted to firstly Switch the VOCs target substances separated by the IVOCs gas chromatographic column to the VOCs gas chromatographic column for secondary separation to obtain target VOCs, after a certain time, the IVOCs target substances separated by the IVOCs gas chromatographic column are switched to a deactivated quartz capillary column to obtain target IVOCs, and after the secondary separation, the VOCs target substances and the IVOCs target substances are converged through a three-way valve, and then detection and analysis are carried out simultaneously by a mass spectrum detector.
The sampling duration time when the sampling tube group is used for carrying out adsorption sampling on the target substances is set to be between 0 and 999min, the temperature of the sampling tube is controlled to be between-40 and 20 ℃ when the sampling tube is used for adsorbing and sampling standard samples or ambient air, and the temperature of the temperature-control sampling channel is set to be between 220 and 350 ℃.
The inert gas desorbs the target substance at 150-350 ℃;
the inert gas adopts 99.999% of high-purity helium. And (3) when the target substance is desorbed, the target substance is desorbed after the target substance is heated to 300 ℃ for 5min at the speed of 1-40 ℃/s under the high-purity helium flow and then heated to 350 ℃ at the speed of 1-40 ℃/s for 5-15 min.
The TD system comprises two groups of sampling tube groups, wherein one group of sampling tube groups simultaneously adsorbs and samples a target substance, the other group of sampling tube groups desorbs the target substance by adopting inert gas, and the two groups of sampling tube groups alternately perform sampling and desorption steps.
Two sampling tubes in each group of sampling tube groups are connected through a tee joint, and ambient air or standard samples are shunted through the tee joint to realize the simultaneous acquisition of VOCs and IVOCs.
The temperature control sampling channel, the two groups of tee joints and the sample transmission pipeline connected with the GC/MS analysis system are connected through a four-way valve, and the two groups of sampling tube groups are alternately subjected to sampling, desorption and analysis detection steps through switching the four-way valve.
When the two sampling pipes in the same group are used for sampling and adsorbing the target substances, the two sampling pipes are respectively controlled by the same mass flowmeter to sample at the same time and different sampling flow rates.
When the mass flowmeter is adopted to respectively control two sampling pipes to sample at the same time and different sampling flow rates through one flow rate control valve, the sampling pipe filled with the VOCs adsorbent is controlled to sample at the low sampling flow rate of 0-100ml/min, and the sampling pipe filled with the IVOCs adsorbent is controlled to sample at the high sampling flow rate of 100-500 ml/min.
The on-line collecting and detecting device comprises a temperature control sampling channel, a TD system connected with the temperature control sampling channel and a GC/MS analysis system connected with the TD system, wherein the TD system comprises at least one group of sampling tube groups, each sampling tube group comprises a sampling tube containing VOCs adsorbent and a sampling tube containing IVOCs adsorbent, and the temperature control sampling channel is connected with the two sampling tubes through a tee joint after passing through a four-way valve.
The GC/MS analysis system comprises a sample transmission pipeline connected with the TD system, a sample inlet, an IVOCs gas chromatographic column communicated with the sample inlet, wherein the outlet end of the IVOCs gas chromatographic column is respectively connected with the inlet end of the VOCs chromatographic column and the inlet end of the deactivated quartz capillary column through a Dean-Switch switching system, and the outlet end of the VOCs chromatographic column and the outlet end of the deactivated quartz capillary column are connected with the mass spectrum detector through a three-way valve.
The TD system comprises two groups of sampling tube groups, the temperature control sampling channel and the two groups of sampling tube groups are respectively connected with two inlet ends of a four-way valve through an interface I end of a tee joint, and an outlet end of the four-way valve is connected with a sample inlet of the GC/MS analysis system through a sample transmission pipeline.
The three-way valve and the four-way valve adopt temperature-controllable electromagnetic valves, and the temperature controllable ranges of the three-way valve and the four-way valve are all room temperature-350 ℃.
The sample transmission pipeline adopts a transmission pipeline with controllable temperature, and the controllable temperature range of the transmission pipeline is between room temperature and 300 ℃.
And a shunt pipeline is further arranged at the downstream of the outlet end of the four-way valve.
The inlet end of each sampling tube is connected with the interface II end of the tee joint, and the outlet end of each sampling tube is communicated with the outside or inert gas pipeline after being connected with the mass flowmeter through a flow rate control valve.
And two flow rate control valves in the same group are connected with the same mass flowmeter.
The invention has the positive progress effects that: the method for simultaneously collecting and detecting VOCs and IVOCs on line realizes the purpose of simultaneously collecting and analyzing VOCs and IVOCs on line by one-time sampling.
Drawings
FIG. 1 is a schematic view of the overall structure of the device of the present invention;
FIG. 2 is a schematic flow chart of the present invention;
FIG. 3 is a schematic view of an air path in which two groups of sampling tube groups alternately sample and desorb;
FIG. 4 is a schematic diagram of another gas circuit in which two groups of sampling tube groups alternately sample and desorb;
FIG. 5 is a schematic diagram illustrating the operation of the Dean-Switch switching system of the present invention;
fig. 6 is another operation diagram of the Dean-Switch switching system of the present invention.
Detailed Description
In order that the manner in which the invention is practiced, as well as the features and objects and functions thereof, will be readily understood and appreciated, the invention will be further described in connection with the accompanying drawings.
Referring to fig. 1, the on-line collecting and detecting device comprises a temperature-controlled sampling channel 1, a TD (thermal desorption) system 2 and a GC/MS (gas chromatography/mass spectrometry) analysis system 3, wherein the TD system 2 comprises at least one group of sampling tube groups, each of which comprises a sampling tube 21 filled with VOCs adsorbent and a sampling tube 22 filled with IVOCs adsorbent, and the two sampling tubes are respectively connected with two parallel interfaces (II ends) of a tee joint 23. Preferably, the TD system 2 includes two sets of sampling tube sets, sampling tube set A and sampling tube set B, respectively. The interface (I end) of the tee joint 23 and the temperature control sampling channel 1 in each group of sampling tube groups are respectively connected with two inlet ends of the four-way valve 24. The three-way valve 23 and the four-way valve 24 adopt electromagnetic valves with controllable temperature, and the controllable temperature ranges of the three-way valve 23 and the four-way valve 24 are all between room temperature and 350 ℃.
The sampling inlet end of each sampling tube is connected with the II end of the tee joint 23, and the sampling outlet end of each sampling tube is communicated with the outside or inert gas pipeline through the flow rate control valve 25. Preferably, an air flow switching valve can be arranged between the flow rate control valve 25 and the external or inert gas pipeline, and the sampling pipe is communicated with the external or inert gas pipeline through the air flow switching valve. Both flow control valves in the same group are connected to the same mass flow meter 26. As shown in fig. 1, there are two mass flowmeters 26, mass flowmeter 1 and mass flowmeter 2, respectively. The two mass flowmeters 26 each independently control a set of sampling tube sets.
The outlet end of the four-way valve 24 is connected with a sample inlet 31 of the GC/MS analysis system 3 through a sample transmission pipeline 4, the sample transmission pipeline 4 adopts a transmission pipeline with controllable temperature, and the temperature of the transmission pipeline 4 is controlled within the range of room temperature to 300 ℃. A shunt line 5 is also provided downstream of the outlet end of the four-way valve 24.
The GC/MS analysis system 3 includes a sample transmission line 4 connected to the TD system 2, a sample inlet 31, an IVOCs gas chromatography column 32 (DB-5 MS column) in communication with the sample inlet 31, an outlet end of the IVOCs gas chromatography column 32 being connected to an inlet end of the VOCs chromatography column 34 (DB 624 column) and an inlet end of the deactivated quartz capillary column 35, respectively, through a Dean-Switch switching system 33, and an outlet end of the VOCs chromatography column 34 and an outlet end of the deactivated quartz capillary column 35 being connected to a mass spectrum detector 37 through a three-way valve 36.
Referring to fig. 2, the method for simultaneously collecting and detecting vocs and IVOCs online comprises the following steps performed by using an online collecting and detecting device:
step S1, sampling: and a standard sample or ambient air enters the TD system through the temperature-control sampling channel, and a group of sampling tube groups in the TD system simultaneously adsorb and sample target substances, wherein the same group of sampling tube groups comprise sampling tubes filled with VOCs (volatile organic compounds) adsorbents and sampling tubes filled with IVOCs adsorbents.
When sampling is carried out, a TD system is adopted, and TD on-line sampling and sampling are completed by a temperature control sampling channel and a sampling tube group. When the sampling tube adsorbs a sampling target substance, the sampling duration is set to be between 0 and 999 minutes, and the temperature of the sampling tube is controlled to be between-40 and 20 ℃.
The sample tube set in the TD system consists of VOCs and IVOCs sample tubes, i.e., two sample tubes containing VOCs and IVOCs adsorbents. Two sampling tubes in each group of sampling tube groups are connected through a tee joint, and VOCs and IVOCs are collected simultaneously through three-way flow distribution.
When two sampling pipes in the same group adsorb target substances, the two sampling pipes are respectively controlled by the same mass flowmeter and sampled at different sampling flow rates. Specifically, a flow rate control valve can be installed at the tail end of each sampling tube, when a mass flowmeter is adopted to respectively control two sampling tubes to sample at the same time and at different sampling flow rates, the sampling tube filled with the VOCs adsorbent is controlled to sample at the low sampling flow rate of 0-100ml/min, and the sampling tube filled with the IVOCs adsorbent is controlled to sample at the high sampling flow rate of 100-500ml/min, so that the total amount of target substances meeting the detection requirements of an analysis system, VOCs and IVOCs, can be collected in the same sampling time.
Step S2, desorption: and the sampling tube group after adsorbing and sampling the target substance adopts inert gas to desorb the target substance, and the desorbed target substance is loaded into the GC/MS analysis system by the inert gas through a sample transmission pipeline connected with the GC/MS analysis system.
The inert gas is used for desorbing target substances at 150-350 ℃, and 99.999% of high-purity helium is adopted as the inert gas. In the desorption of the target substance in this step, it is preferable to keep the target substance at a temperature of 300℃for 5 minutes at a rate of 1 to 40℃per second under a high-purity helium stream, and then to keep the target substance at a temperature of 350℃at a rate of 1 to 40℃per second for 5 to 15 minutes.
The TD system comprises two groups of sampling tube groups, namely a sampling tube group A and a sampling tube group B, wherein when one group of sampling tube groups simultaneously adsorbs and samples a target substance, the other group of sampling tube groups is subjected to the following step S2, the target substance is desorbed by adopting inert gas, and the two groups of sampling tube groups alternately perform sampling and desorption steps. Namely: when sampling of the sampling tube group A and the sampling tube group B is completed, the sampling tube group A collects VOCs and IVOCs in ambient air under set sampling conditions, and meanwhile the sampling tube group B starts to heat and desorb target substances under set thermal desorption conditions.
The temperature control sampling channel, the two groups of tee joints and a sample transmission pipeline connected with the GC/MS analysis system are connected through a four-way valve, and the two groups of sampling tube groups are alternately subjected to sampling and desorption steps through switching the four-way valve.
Referring to fig. 3, after the ambient air passes through the temperature-controlled sampling channel, the ambient air passes through the four-way valve and the tee joint and enters two sampling tubes of the sampling tube group A for adsorption sampling, and target substances are respectively enriched in the two sampling tubes of the sampling tube group A (during the sampling period, the temperature of the sampling tubes is set to be between-40 ℃ and 20 ℃); meanwhile, the sampling tube group B carries out thermal desorption, target substances after desorption are transported by carrier gas (helium gas, 99.999%), and after the target substances sequentially pass through the three-way valve and the four-way valve, under the set split flow condition, one part of target substances are sent to the GC/MS analysis system through the sample transmission pipeline, and the other part of target substances are discharged into the ambient air through the split flow pipeline.
Referring to fig. 4, the sampling tube set a completes the adsorption sampling, and after the sampling tube set B completes the thermal desorption, the sampling tube set a performs the thermal desorption, and the sampling tube set B performs the adsorption sampling, so as to realize the alternate sampling and thermal desorption of the two sets of sampling tube sets.
Step S3, separation detection: in a GC/MS analysis system, switching the VOCs target substances separated by the IVOCs gas chromatographic column into the VOCs gas chromatographic column by adopting a Dean-Switch switching system for secondary separation to obtain target VOCs; after the separation of the VOCs target substances is completed within a set time, switching the IVOCs target substances separated subsequently to a deactivated quartz capillary column by adopting a Dean-Switch switching system to obtain target IVOCs, merging the target VOCs separated secondarily and the target IVOCs passing through the quartz capillary column through a three-way valve, and then entering a mass spectrum detector for detection and analysis.
The step adopts the precise control of a Dean-Switch switching system (commercial system), VOCs target substances enter a DB624 chromatographic column for secondary separation, and IVOCs target substances enter a deactivated quartz capillary column. Finally, the tail ends of the DB624 chromatographic column and the deactivated quartz capillary column are connected by a three-way valve, enter a mass spectrum detector, realize that the mass spectrum detector detects VOCs and IVOCs simultaneously, and identify and quantitatively analyze organic matters according to the peak-out time (i.e. residence time) of target substances and the difference of the characteristics of ion fragments.
Referring to fig. 5, a target substance in the td system is sent to a GC sample inlet from high purity helium through a sample transmission line, enters a DB-5MS gas chromatographic column first, and is switched to a DB624 chromatographic column for secondary separation through a Dean-Switch switching system, at this time, an electromagnetic valve in the Dean-Switch switching system is in an "ON" state, and VOCs split by the DB624 chromatographic column enter a mass spectrum for detection after passing through a three-way valve;
referring to fig. 6, after a certain set time, the IVOCs target substance separated from the DB-5MS gas chromatographic column is switched to the deactivated quartz capillary column by the Dean-Switch switching system, and at this time, the solenoid valve in the Dean-Switch switching system is in an "OFF" closed state, and is transported by high purity helium gas, and enters mass spectrometry detection after passing through the deactivated quartz capillary column and the three-way valve.
According to the method, through continuous alternate sampling and thermal desorption of the two groups of sampling tube groups A and B of the TD system, target substances subjected to thermal desorption are sent to the GC/MS system for analysis, and the functions of online simultaneous collection and analysis of VOCs and IVOCs are realized.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (12)

  1. The method for simultaneously collecting and detecting VOCs and IVOCs on line is characterized by comprising the following steps of:
    a standard sample or ambient air enters a TD system through a temperature-controlled sampling channel;
    a group of sampling tube groups in the TD system simultaneously carry out adsorption sampling on target substances, and the same group of sampling tube groups comprise sampling tubes filled with VOCs (volatile organic compounds) adsorbents and sampling tubes filled with IVOCs adsorbents;
    the sampling tube group after absorbing and sampling the target substances adopts inert gas to desorb the target substances, and the desorbed target substances are loaded into a GC/MS analysis system by the inert gas through a sample transmission pipeline connected with the GC/MS analysis system;
    in the GC/MS analysis system, a Dean-Switch switching system is adopted to Switch the VOCs target substances separated by the IVOCs gas chromatographic column into the VOCs chromatographic column for secondary separation to obtain target object VOCs, after a certain time, the IVOCs target substances separated by the IVOCs gas chromatographic column are switched into a deactivated quartz capillary column to obtain target object IVOCs, and the target object VOCs and the target object IVOCs after secondary separation are detected and analyzed by a mass spectrum detector.
  2. 2. The method for simultaneous on-line collection and detection of VOCs and IVOCs according to claim 1, wherein said TD system comprises two sets of said sampling tube sets, one set of said sampling tube sets is used to desorb a target substance while the other set of said sampling tube sets is used to simultaneously adsorb and sample said target substance, and said two sets of said sampling tube sets are used to alternately perform the steps of sampling and desorbing.
  3. 3. The method for simultaneously collecting and detecting VOCs and IVOCs on line according to claim 2, wherein the temperature of the temperature-controlled sampling channel is set between 220 ℃ and 350 ℃;
    the sampling duration time of the sampling tube group when the target substance is adsorbed and sampled is set to be between 0 and 999min, and the temperature of the sampling tube is set to be between-40 and 20 ℃ during the adsorption of the target substance;
    the inert gas desorbs the target substance at 150-350 ℃.
  4. 4. The simultaneous on-line collection and detection method of VOCs and IVOCs according to claim 3, wherein the inert gas is high purity helium gas, and the target substance is desorbed by heating the target substance to 300 ℃ at a speed of 1 to 40 ℃/s under high purity helium gas flow for 5min, and then heating the target substance to 350 ℃ at a speed of 1 to 40 ℃/s for 5 to 15 min.
  5. 5. The method for simultaneously collecting and detecting VOCs and IVOCs on line according to claim 2, wherein two sampling tubes in each group of the sampling tube groups are connected through a tee joint, and the simultaneous collection of VOCs and IVOCs is realized through the split flow of the tee joint;
    the temperature control sampling channel, the two groups of tee joints and the sample transmission pipeline connected with the GC/MS analysis system are connected through a four-way valve, and the two groups of sampling tube groups are alternately subjected to sampling and desorption steps through switching the four-way valve.
  6. 6. The method for simultaneous on-line collection and detection of VOCs and IVOCs according to claim 1, wherein two of said sampling tubes in the same group are simultaneously sampled at different sampling flow rates by controlling the two sampling tubes respectively using the same mass flowmeter when sampling and adsorbing said target substance.
  7. 7. The simultaneous on-line collection and detection method of VOCs and IVOCs of claim 6 wherein said mass flowmeter is used to control said two sampling tubes to simultaneously sample at different sampling flow rates, respectively, and to control said sampling tube containing VOCs adsorbent to simultaneously sample at a low sampling flow rate of 0-100ml/min and said sampling tube containing IVOCs adsorbent to simultaneously sample at a high sampling flow rate of 100-500 ml/min.
  8. 8. The simultaneous on-line collection and detection method of VOCs and IVOCs according to any one of claims 1 to 7, wherein said on-line collection and detection device comprises a temperature-controlled sampling channel, a TD system connected to said temperature-controlled sampling channel, a GC/MS analysis system connected to said TD system, said TD system comprising at least one set of sampling tube sets each comprising a sampling tube containing VOCs adsorbent and a sampling tube containing IVOCs adsorbent, said temperature-controlled sampling channel being connected to two of said sampling tubes respectively by a tee;
    the GC/MS analysis system comprises a sample transmission pipeline connected with the TD system, a sample inlet, an IVOCs gas chromatographic column communicated with the sample inlet, wherein the outlet end of the IVOCs gas chromatographic column is respectively connected with the inlet end of the VOCs chromatographic column and the inlet end of the deactivated quartz capillary column through a Dean-Switch switching system, and the outlet end of the VOCs chromatographic column and the outlet end of the deactivated quartz capillary column are connected with the mass spectrum detector through a three-way valve.
  9. 9. The method for simultaneously collecting and detecting VOCs and IVOCs on line according to claim 8, wherein the TD system comprises two groups of the sampling tube sets, the temperature-controlled sampling channel and the two groups of the sampling tube sets are respectively connected to three inlet ends of a four-way valve through an interface I end of a tee joint, and an outlet end of the four-way valve is connected to a sample inlet of the GC/MS analysis system through the sample transmission line.
  10. 10. The method for simultaneously collecting and detecting VOCs and IVOCs on line according to claim 9, wherein the three-way valve and the four-way valve adopt temperature-controllable electromagnetic valves, and the temperature controllable ranges of the three-way valve and the four-way valve are all between room temperature and 350 ℃; the sample transmission pipeline adopts a transmission pipeline with controllable temperature, and the controllable temperature range of the transmission pipeline is between room temperature and 300 ℃.
  11. 11. The method for simultaneous on-line collection and detection of VOCs and IVOCs of claim 9 wherein a diverter line is further provided downstream of the outlet end of the four-way valve.
  12. 12. The method for simultaneous on-line collection and detection of VOCs and IVOCs of claim 8 wherein the sampling inlet end of each of said sampling tubes is connected to the interface II end of said tee and the sampling outlet end of each of said sampling tubes is in communication with the outside or inert gas line through a flow rate control valve;
    and two flow rate control valves in the same group are connected with the same mass flowmeter.
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