CN111579315A - VOCs and IVOCs simultaneous on-line collecting and detecting method - Google Patents

VOCs and IVOCs simultaneous on-line collecting and detecting method Download PDF

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CN111579315A
CN111579315A CN202010465082.2A CN202010465082A CN111579315A CN 111579315 A CN111579315 A CN 111579315A CN 202010465082 A CN202010465082 A CN 202010465082A CN 111579315 A CN111579315 A CN 111579315A
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sampling
ivocs
vocs
temperature
sample
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CN111579315B (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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    • 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
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    • 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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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 the TD system through a temperature control sampling channel, and a group of sampling tube groups in the TD system simultaneously adsorb and sample a target substance; simultaneously, the other group of sampling tube groups desorb target substances by inert gas, and the desorbed target substances are loaded into a GC/MS analysis system by high-purity helium through a sample transmission pipeline; in a GC/MS analysis system, by means of a Dean-Switch switching system, performing secondary separation on the target object VOCs separated firstly, and simultaneously detecting and analyzing the target object VOCs and the target object IVOCs separated secondarily by a mass spectrum detector. The method for simultaneously collecting and detecting VOCs and IVOCs on line realizes the purposes of sampling once and simultaneously collecting and analyzing VOCs and IVOCs on line.

Description

VOCs and IVOCs simultaneous on-line collecting and detecting 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 compounds in the atmosphere can be classified into medium volatile organic compounds (IVOCs) according to the saturation concentration (C), wherein the saturation concentration is 103μg/m3＜C*＜106μg/m3) And volatile organic compounds (VOCs, saturated concentration range C > 10)6μg/m3). Since VOCs are considered to be O3And Secondary Organic Aerosol (SOA), and has been the focus of research by researchers and related management departments. Recent studies have shown that IVOCs are also atmospheric O3And important precursors of SOAs, and has attracted extensive interest to researchers. In addition, VOCs and IVOCs also pose significant health risks to humans.
The range of saturated concentrations of VOCs corresponds to C3～C12In the range of saturated concentration of IVOCs corresponding to C12～C22And (3) n-alkanes. At present, the detection technology for the organic matter components and concentration levels of the VOCs is relatively mature, and a monitoring technical guide or standard is established, such as the US EPA 5030C; technical Guide Note (TGN) M8 and M16, the monitoring Technical guide Note established by the European Union environmental protection agency; and the measurement of volatile organic compounds in the environmental air (HJ 759-. In addition, due to the characteristics that the boiling point of the VOCs is low, the VOCs are generally at 50-250 ℃, are easy to volatilize and the like, the VOCs are collected and analyzed on line based on thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). However, IVOCs are relatively low in ambient concentration levels relative to VOCs and relatively viscous and prone to remain in the system. Therefore, the analysis of IVOCs is mainly based onThe off-line collection and analysis was performed in TD-GC/MS with lower time resolution. At present, effective means for continuously tracking and observing the pollution level of IVOCs is lacked, so that the exact response relation between different IVOCs monomers and SOA cannot be accurately obtained, and the contribution of the IVOCs to SOA generation is difficult to scientifically evaluate.
Chinese patent CN201910212822.9 discloses a near online detection device for moderate volatile organic compounds, which modifies the original TD-GC/MS system for online collection and analysis of VOCs and adds the online collection and analysis capability of IVOCs on the basis of the original device. In addition to the differences in saturation vapor pressure and viscosity, the concentrations of VOCs and IVOCs in ambient atmosphere differ by orders of magnitude, and thus, simultaneous on-line collection and real-time analysis on a single sample tube is difficult to achieve. Thus, the improved device can only be used for on-line collection and analysis of VOCs or IVOCs as a target alone. However, VOCs or IVOCs are considered to be both on O3And SOA generation have important contributions. Therefore, if the capability of analyzing organic matters of the original device can be widened, the simultaneous online collection and analysis of VOCs and IVOCs can be realized, valuable data information can be provided for the analysis and detection in the field of organic matters, and data support can be provided for the exposure evaluation of environmental pollution, human health risks and the like.
Disclosure of Invention
The invention aims to solve the technical problem that the existing online detection device is difficult to simultaneously collect and analyze VOCs and IVOCs, and provides a method for simultaneously collecting and detecting VOCs and IVOCs online.
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 (thermal desorption) system through a temperature-controlled sampling channel, a group of sampling tube groups in the TD system simultaneously carry out adsorption sampling on a target substance, 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 the target substance is adsorbed and sampled adopts inert gas to desorb the target substance, and the desorbed target substance is loaded into a GC/MS (gas chromatography/mass spectrometry) analysis system through a sample transmission pipeline connected with the GC/MS analysis system by the inert gas.
In the GC/MS analysis system, a Dean-Switch switching system is adopted to Switch VOCs target substances separated from an IVOCs gas chromatographic column to the VOCs gas chromatographic column for secondary separation to obtain target substances VOCs, after a certain period of time, the IVOCs target substances separated from the IVOCs gas chromatographic column are switched to a deactivated quartz capillary column to obtain target substances IVOCs, and the VOCs target substances and the IVOCs target substances after secondary separation are converged by a three-way valve and then are simultaneously detected and analyzed by a mass spectrometer.
The sampling duration time of the sampling pipe set for carrying out adsorption sampling on the target substance is set to be 0-999min, the temperature of the sampling pipe is controlled to be-40-20 ℃ when the sampling pipe adsorbs a sampling standard sample or ambient air, and the temperature of the temperature control sampling channel is set to be 220-350 ℃.
Desorbing the target substance by the inert gas at 150-350 ℃;
the inert gas adopts high-purity helium gas with the purity of 99.999 percent. And when the target substance is desorbed, the temperature is increased to 300 ℃ at the speed of 1-40 ℃/s for 5min under the high-purity helium flow, then the temperature is increased to 350 ℃ at the speed of 1-40 ℃/s, and the target substance is desorbed by keeping the temperature for 5-15 min.
The TD system comprises two groups of sampling pipe groups, one group of sampling pipe groups is used for simultaneously adsorbing and sampling a target substance, the other group of sampling pipe groups is used for desorbing the target substance by adopting inert gas, and the two groups of sampling pipe groups are used for alternately carrying out sampling and desorption steps.
Two sampling pipes in each group of sampling pipe group are connected through a tee joint, and the VOCs and the IVOCs are simultaneously collected by the environmental air or the standard sample through the shunting of the tee joint.
The temperature control sampling channel, the two tee joints and the sample transmission pipeline connected with the GC/MS analysis system are connected through a four-way valve, and the two sampling pipe groups are alternately subjected to sampling, desorption and analysis detection through switching of the four-way valve.
When the two sampling pipes in the same group are used for sampling and adsorbing the target substance, the same mass flow meter is adopted to respectively control the two sampling pipes to sample at different sampling flow rates simultaneously.
And when the mass flow meter is adopted to respectively control the two sampling pipes to sample at the same time through a flow rate control valve and at different sampling flow rates, the sampling pipes filled with the VOCs adsorbent are controlled to sample at the low sampling flow rate of 0-100ml/min and the sampling pipes filled with the IVOCs adsorbent are controlled to sample at the high sampling flow rate of 100-500ml/min at the same time.
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 pipe groups, each sampling pipe group comprises a sampling pipe filled with a VOCs adsorbent and a sampling pipe filled with an IVOCs adsorbent, and the temperature control sampling channel is connected with the two sampling pipes through a tee joint respectively after passing through a four-way valve.
The GC/MS analysis system comprises a sample transmission pipeline connected with the TD system, a sample injection port and an IVOCs gas chromatographic column communicated with the sample injection port, 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 a mass spectrum detector through a three-way valve.
The TD system comprises two groups of sampling pipe groups, the temperature control sampling channel and the two groups of sampling pipe 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 the sample transmission pipeline.
The tee joint and the four-way valve adopt temperature-controllable electromagnetic valves, and the temperature controllable ranges of the tee joint and the four-way valve are both room temperature-350 ℃.
The sample transmission pipeline adopts a transmission pipeline with controllable temperature, and the temperature of the transmission pipeline is controllable within the range of room temperature to 300 ℃.
And a flow distribution pipeline is also arranged at the downstream of the outlet end of the four-way valve.
The inlet end of each sampling pipe is connected with the interface II end of the tee joint, and the outlet end of each sampling pipe is communicated with the outside or an inert gas pipeline after being connected with a mass flow meter through a flow rate control valve.
And the two flow rate control valves in the same group are connected with the same mass flow meter.
The positive progress effects of the invention are as follows: the method for simultaneously collecting and detecting VOCs and IVOCs on line realizes the purposes of sampling once and simultaneously collecting and analyzing VOCs and IVOCs on line.
Drawings
FIG. 1 is a schematic view of the overall structure of the apparatus of the present invention;
FIG. 2 is a schematic flow chart of the present invention;
FIG. 3 is a schematic view of a gas path for alternately sampling and desorbing two sets of sampling tube sets according to the present invention;
FIG. 4 is a schematic view of another gas path for alternately sampling and desorbing two groups of sampling tube sets according to the present invention;
FIG. 5 is a schematic diagram of the Dean-Switch switching system according to the present invention;
fig. 6 is another schematic diagram of the Dean-Switch switching system according to the present invention.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific 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 pipes, each group of sampling pipes comprises a sampling pipe 21 containing a VOCs adsorbent and a sampling pipe 22 containing an IVOCs adsorbent, and the two sampling pipes are respectively connected with two parallel interfaces (II ends) of a tee 23. Preferably, the TD system 2 includes two sets of sampling tube sets, a sampling tube set a and a sampling tube set B. The interface (I end) of the tee 23 in each group of sampling tube sets and the temperature control sampling channel 1 are respectively connected with two inlet ends of a four-way valve 24. The three-way 23 and the four-way valve 24 adopt temperature-controllable electromagnetic valves, and the temperature controllable ranges of the three-way 23 and the four-way valve 24 are both room temperature-350 ℃.
The sampling inlet end of each sampling pipe is connected with the II end of the tee 23, and the sampling outlet end of each sampling pipe is communicated with the outside or an inert gas pipeline through a flow rate control valve 25. Preferably, a gas flow switching valve can be arranged between the flow rate control valve 25 and the outside or inert gas pipeline, and the gas flow switching valve is used for switching to realize the communication between the sampling pipe and the outside or inert gas pipeline. Both flow rate 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 the 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 controllable 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 comprises a sample transmission pipeline 4 connected with the TD system 2, a sample injection port 31, and an IVOCs gas chromatographic column 32(DB-5MS chromatographic column) communicated with the sample injection port 31, wherein the outlet end of the IVOCs gas chromatographic column 32 is respectively connected with the inlet end of a VOCs chromatographic column 34(DB624 chromatographic column) and the inlet end of a deactivated quartz capillary column 35 through a Dean-Switch switching system 33, and the outlet end of the VOCs chromatographic column 34 and the outlet end of the deactivated quartz capillary column 35 are connected with 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 on line includes the following steps by using an on-line collecting and detecting device:
step S1, sampling: a standard sample or ambient air enters a TD 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 adsorbents and sampling tubes filled with IVOCs adsorbents.
When sampling is carried out, a TD system is adopted, and TD on-line sampling and sample introduction 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 0-999min, and the temperature of the sampling tube is controlled to be-40-20 ℃.
The sampling pipe group in the TD system consists of VOCs and IVOCs sampling pipes, namely two sampling pipes filled with VOCs and IVOCs adsorbents. Two sampling pipes in every group sampling nest of tubes pass through three-way connection, realize gathering VOCs and IVOCs simultaneously through the reposition of redundant personnel of tee bend.
When the two sampling pipes in the same group adsorb a target substance, the same mass flow meter is adopted to respectively control the two sampling pipes to sample at different sampling flow rates. Specifically, a flow rate control valve can be installed at the tail end of each sampling tube, and when two sampling tubes are respectively controlled by a mass flow meter to sample at different sampling flow rates at the same time, 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 at the same time, so that the total amount of target substances meeting the detection requirements of an analysis system on VOCs and IVOCs can be collected within the same sampling time.
Step S2, desorption: and the sampling tube group after adsorbing the sampling 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 target substance is desorbed by inert gas at 150-350 ℃, and the inert gas adopts 99.999% of high-purity helium. When the target substance is desorbed in the step, the temperature is preferably raised to 300 ℃ at the speed of 1-40 ℃/s for 5min under the high-purity helium flow, and then the temperature is raised to 350 ℃ at the speed of 1-40 ℃/s and is kept for 5-15 min to desorb the target substance.
The TD system comprises two groups of sampling pipe groups, namely a sampling pipe group A and a sampling pipe group B, when one group of sampling pipe groups is used for simultaneously adsorbing and sampling the target substance, the other group of sampling pipe groups is subjected to the following step S2, the inert gas is adopted for desorbing the target substance, and the two groups of sampling pipe groups are used for alternately carrying out sampling and desorbing steps. Namely: sampling and thermal desorption work are carried out alternately to sampling pipe group A and sampling pipe group B, and when sampling pipe group B sampling is completed, sampling pipe group A collects VOCs and IVOCs in the ambient air under the set sampling condition, and sampling pipe group B begins to heat and desorb the target substance under the set thermal desorption condition.
The temperature control sampling channel, the two groups of three-way pipes 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 pipe groups are switched to alternately perform sampling and desorption steps through the switching of the four-way valve.
Referring to fig. 3, after passing through a temperature-controlled sampling channel, the ambient air enters two sampling tubes of a sampling tube group a through a four-way valve and a three-way valve for adsorption sampling, and target substances are respectively enriched in the two sampling tubes of the sampling tube group a (during sampling, the temperature of the sampling tubes is set to be-40-20 ℃); meanwhile, the sampling tube group B is used for carrying out thermal desorption, the desorbed target substance is transported by carrier gas (helium gas, 99.999 percent), and after passing through the three-way valve and the four-way valve in sequence, under the set flow dividing condition, a part of the target substance is sent to the GC/MS analysis system through the sample transmission pipeline, and the other part of the target substance is discharged into the ambient air through the flow dividing pipeline.
Referring to fig. 4, after the sampling pipe group a completes adsorption sampling, and the sampling pipe group B completes thermal desorption, the sampling pipe group a performs thermal desorption, and the sampling pipe group B performs adsorption sampling, so that two groups of sampling pipe groups alternately perform sampling and thermal desorption.
Step S3, separation detection: in a GC/MS analysis system, a Dean-Switch switching system is adopted to Switch VOCs target substances separated out firstly by an IVOCs gas chromatographic column into the VOCs gas chromatographic column for secondary separation to obtain target substances VOCs; after the separation of VOCs target substances is completed within a set time, a Dean-Switch switching system is adopted to Switch subsequently separated IVOCs target substances to a deactivated quartz capillary column to obtain target substances IVOCs, and the secondarily separated target substances VOCs and the target substances IVOCs passing through the quartz capillary column are converged by a three-way valve and then enter a mass spectrum detector for simultaneous detection and analysis.
In the step, a Dean-Switch switching system (commercial system) is adopted for accurate control, VOCs target substances enter a DB624 chromatographic column for secondary separation, and IVOCs target substances enter a deactivated quartz capillary column. And finally, connecting the ends of the DB624 chromatographic column and the deactivated quartz capillary column by a three-way valve, allowing the chromatographic column to enter a mass spectrum detector, realizing simultaneous detection of VOCs and IVOCs by the mass spectrum detector, and identifying and quantitatively analyzing organic matters according to the difference of the peak-out time (namely, the retention time) and the ion fragment characteristics of the target substance.
Referring to fig. 5, a target substance in the TD system is sent to a GC sample inlet through a sample transmission pipeline from high-purity helium, enters a DB-5MS gas chromatographic column first, and a target substance of VOCs separated from the DB-5MS gas chromatographic column first passes through a Dean-Switch switching system and is switched to a DB624 chromatographic column for secondary separation, at this time, an electromagnetic valve in the Dean-Switch switching system is in an "ON" open state, and the VOCs split by the DB624 chromatographic column pass through a three-way valve and then enter mass spectrometry detection;
referring to fig. 6, after a certain set time, the target substances of the IVOCs subsequently separated from the DB-5MS gas chromatographic column are switched to the deactivated quartz capillary column by the Dean-Switch system, at this time, the electromagnetic valve in the Dean-Switch system is in an "OFF" closed state, and the high-purity helium gas is transported through the deactivated quartz capillary column and the three-way valve and enters mass spectrometry detection.
According to the method, two groups of sampling tube groups A and B of the TD system are used for sampling and thermal desorption continuously and alternately, and the target substances subjected to thermal desorption are sent to the GC/MS system for analysis, so that the functions of online simultaneous collection and analysis of VOCs and IVOCs are realized.
The foregoing shows and describes the general principles, essential 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, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (10)

  1. The method for simultaneously collecting and detecting VOCs and IVOCs on line is characterized by comprising the following steps of:
    the standard sample or the ambient air enters the TD system through the temperature-controlled sampling channel;
    a group of sampling tube groups in the TD system simultaneously carry out adsorption sampling on a target substance, wherein the same group of sampling tube groups comprises sampling tubes filled with VOCs adsorbent and sampling tubes filled with IVOCs adsorbent;
    the sampling tube group after the target substance is adsorbed and sampled 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 Switch VOCs target substances separated from an IVOCs gas chromatographic column firstly to the VOCs chromatographic column for secondary separation to obtain target substances VOCs, after a certain time, the IVOCs target substances separated from the IVOCs gas chromatographic column are switched to enter a deactivated quartz capillary column to obtain target substances IVOCs, and the target substances VOCs and the target substances IVOCs after secondary separation are detected and analyzed by a mass spectrum detector.
  2. 2. The method of claim 1, wherein the TD system comprises two sets of said sampling tube sets, one set of said sampling tube sets simultaneously performing adsorption sampling on a target substance, the other set of said sampling tube sets performing desorption of said target substance using an inert gas, and the two sets of said sampling tube sets alternately performing sampling and desorption steps.
  3. 3. The method for the simultaneous on-line collection and detection of VOCs and IVOCs of claim 2, wherein the temperature of the temperature-controlled sampling channel is set between 220-350 ℃;
    the sampling duration time of the sampling pipe group during adsorption sampling of the target substance is set to be 0-999min, and the temperature of the sampling pipe during adsorption of the target substance is set to be-40-20 ℃;
    desorbing the target substance by the inert gas at 150-350 ℃;
    preferably, the inert gas is high-purity helium, when the target substance is desorbed, the temperature is raised to 300 ℃ at the speed of 1-40 ℃/s for 5min under the flow of the high-purity helium, and then the temperature is raised to 350 ℃ at the speed of 1-40 ℃/s and is kept for 5-15 min to desorb the target substance.
  4. 4. The method for simultaneously collecting and detecting VOCs and IVOCs according to claim 2, wherein two sampling tubes in each group of sampling tubes are connected by a tee, and the VOCs and IVOCs are simultaneously collected by shunting of the tee;
    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 pipe groups are alternately subjected to sampling and desorption steps through switching of the four-way valve.
  5. 5. The method for simultaneously collecting and detecting VOCs and IVOCs according to claim 1, wherein when two sampling tubes in the same group are used for sampling and adsorbing the target substances, the same mass flow meter is used for respectively controlling the two sampling tubes to sample at the same time and at different sampling flow rates;
    preferably, when the mass flow meter is adopted to respectively control the two sampling pipes to sample at the same time and at different sampling flow rates, 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 100-500ml/min at the same time.
  6. 6. The method for simultaneously collecting and detecting VOCs and IVOCs in an on-line manner as claimed in any one of claims 1 to 5, wherein the on-line collecting and detecting device comprises a temperature-controlled sampling channel, a TD system connected with the temperature-controlled sampling channel, and a GC/MS analysis system connected with the TD system, the TD system comprises at least one group of sampling tube groups, each group of sampling tube groups comprises a sampling tube containing VOCs adsorbent and a sampling tube containing IVOCs adsorbent, and the temperature-controlled sampling channel is respectively connected with two sampling tubes through a tee;
    the GC/MS analysis system comprises a sample transmission pipeline connected with the TD system, a sample injection port and an IVOCs gas chromatographic column communicated with the sample injection port, 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 a mass spectrum detector through a three-way valve.
  7. 7. The method for simultaneously collecting and detecting VOCs and IVOCs according to claim 6, wherein the TD system comprises two sets of the sampling tube sets, the temperature-controlled sampling channel and the two sets of the sampling tube sets are respectively connected to two inlet ends of a four-way valve through an I end of a three-way interface, 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.
  8. 8. The method for simultaneously collecting and detecting VOCs and IVOCs in an online manner according to claim 7, wherein the three-way valve and the four-way valve are temperature-controllable solenoid valves, and the temperature of the three-way valve and the temperature of the four-way valve are both in a range of room temperature to 350 ℃; the sample transmission pipeline adopts a transmission pipeline with controllable temperature, and the temperature of the transmission pipeline is controllable within the range of room temperature to 300 ℃.
  9. 9. The method for the simultaneous on-line collection and detection of VOCs and IVOCs of claim 6, wherein a shunt line is further provided downstream of the outlet end of the four-way valve.
  10. 10. The method for simultaneously collecting and detecting VOCs and IVOCs according to claim 6, wherein the sampling inlet end of each sampling tube is connected to the interface II end of the tee, and the sampling outlet end of each sampling tube is connected to an external or inert gas pipeline through a flow rate control valve;
    and the two flow rate control valves in the same group are connected with the same mass flow meter.
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