CN111487358A - Full-component automatic analysis system and method for atmospheric volatile organic compounds - Google Patents
Full-component automatic analysis system and method for atmospheric volatile organic compounds Download PDFInfo
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Abstract
The invention belongs to the field of analysis of atmospheric volatile organic compounds, and discloses a full-component automatic analysis system and method for atmospheric volatile organic compounds. The system comprises a full-automatic sample introduction device and an analysis device; the full-automatic sample introduction device comprises a plurality of gas sample introduction channels which are switched and controlled to be opened and closed through a multi-channel switcher; the analysis device comprises a preconcentrator, a low-temperature T-shaped cold trap and a parallel double-column double detector which are sequentially communicated; the low-temperature T-shaped cold trap comprises a filler column and a sleeve sleeved on the filler column, a gap is formed between the filler column and the sleeve, an inlet is formed in the middle section of the sleeve, and outlets are formed in the two ends of the sleeve; the parallel double-column double detector consists of two parallel detection branches, one branch consists of a chromatographic column I and an MSD detector which are sequentially communicated, and the other branch consists of a chromatographic column II and an FID detector which are sequentially communicated. The full-component automatic analysis system for the atmospheric volatile organic compounds can realize automatic sample introduction and can realize full-component detection of C2-C12.
Description
Technical Field
The invention belongs to the field of analysis of atmospheric volatile organic compounds, and particularly relates to a full-component automatic analysis system and method for atmospheric volatile organic compounds.
Background
Volatile Organic Compounds (VOCs) are the second most widely distributed and varied emissions in addition to particulate matter, specifically including non-methane hydrocarbons, oxygen-containing organics, chlorine-containing organics, nitrogen-containing organics, sulfur-containing organics, etc., and are secondary air pollutants of photochemical processes, where PAMS is also an important precursor for secondary organic aerosols. Since 2013 implementation of an "air pollution prevention action plan", the national environmental air quality is continuously improved, but some local environmental pollution is still extraordinarily prominent, the detection and monitoring of environmental pollutants are unreleasable, and especially many substances in the VOCs have stimulation effects on human bodies and various senses, have certain toxicity, even can generate great harm to environmental safety and human health, and are one of the objects of continuous attention of people.
National environmental standards HJ 759-2015 and United states standard EPA TO-15 for detecting VOCs require Suyda can for sampling, and VOCs in ambient air are analyzed by combining preconcentration-gas chromatography-mass spectrometry, substances commonly analyzed by existing gas chromatography-mass spectrometry comprise TO-15 and PAMS, wherein TO-15 comprises alkanes, alkenes, aromatics, halogenated hydrocarbons, oxygen-containing organic matters and the like, PAMS refers TO non-methane hydrocarbons from C2 TO C12, compound interference is easy TO occur only by adopting gas chromatography analysis due TO the fact that the types of VOCs are various, and a preconcentrator (8910, Nutech) -gas chromatography-mass spectrometer (GC2010QP P L US) is adopted for combination, although 101 components such as C4-C12 and the like can be detected, sensitivity of alkanes, alkenes and alkynes with low carbon chain (C2-C3) components is low, so that the alkanes, alkenes and alkynes with low carbon chain (C2-C3) components cannot be detected, and the alkanes and alkynes are widely used in industry, and the alkenes are easy TO burn, and have toxicity TO atmospheric health hazards, and certain technologies of olefin and low carbon chain quality monitoring technologies are provided for human bodies.
Disclosure of Invention
The invention aims to overcome the defect that the existing preconcentrator-gas chromatography-mass spectrometer combination can only measure the components C4-C12 and cannot realize the separation and detection of the components C2-C3, and provides an analysis system and an analysis method which can realize the detection of all the components C2-C12 and can realize automatic sample injection.
The system comprises a full-automatic sampling device, an analysis device, a data acquisition device, a data processing device and a data processing device, wherein the full-automatic analysis device comprises a data processing module, a data processing module and a data processing module; the full-automatic sample introduction device comprises a plurality of gas sample introduction channels, and switches of different gas sample introduction channels are switched and controlled through a multi-channel switcher; the analysis device comprises a preconcentrator, a low-temperature T-shaped cold trap and a parallel double-column double detector which are sequentially communicated; the low-temperature T-shaped cold trap comprises a packing column and a sleeve sleeved on the packing column, a gap is formed between the packing column and the sleeve, and liquid CO is arranged in the middle section of the sleeve2An inlet and two ends of the inlet are provided with liquid CO2Outlet and liquid CO2The opening and closing of the inlet are controlled by a switch; the parallel double-column double detector consists of two parallel detection branches, one branch consists of a chromatographic column I and an MSD detector which are sequentially communicated, and the other branch consists of a chromatographic column II and an FID detector which are sequentially communicated; full autoinjection device's gaseous sampling passageway export communicates with the entry of preconcentrator, the export of preconcentrator communicates with the entry of filler column in the low temperature T type cold trap, the export of filler column communicates with chromatographic column I and MSD detector all the way in proper order in the low temperature T type cold trap, another way communicates with chromatographic column II and FID detector in proper order.
Furthermore, the number of the gas sample introduction channels of the full-automatic sample introduction device is 8-12.
Furthermore, the diameter of a gas sample injection channel of the full-automatic sample injection device is 1-2mm, the maximum air tightness is 0.8-1MPa, and the maximum water pressure resistance is 1-1.2 MPa.
Furthermore, the material of the gas contacted in the multi-channel switcher of the full-automatic sampling device is polytetrafluoroethylene.
Furthermore, the switching of the multi-channel switcher of the full-automatic sampling device is controlled by software.
Further, full autoinjection device includes a plurality of air inlets, a gas outlet, multichannel switch and power converter, power converter is used for converting the voltage into and supplies the required voltage of multichannel switch use, and the air inlet forms gaseous introduction passageway with the gas outlet intercommunication, and the switch of different gaseous introduction passageways passes through multichannel switch switching control.
Further, the preconcentrator is a three-stage cold trap preconcentrator.
Further, the preconcentrator is 8910-Nutech.
Furthermore, the length of a filler column in the low-temperature T-shaped cold trap is greater than that of the sleeve, and the filler column extends out from two ends of the sleeve.
Further, the length of the filler column is 10-30cm, and the length of the sleeve is 4-20 cm.
Further, the filler filled in the filler column is 6% of cyanopropylphenyl-94% of methyl polysiloxane.
Further, the chromatographic column I is a DB-624 capillary column, and the chromatographic column II is an HP-P L OT Q capillary column.
The invention also provides a full-component automatic analysis method of the atmospheric volatile organic compounds, wherein the method is carried out by adopting the full-component automatic analysis system of the atmospheric volatile organic compounds, specifically, the full-component automatic analysis system of the atmospheric volatile organic compounds is started, system parameters are set, and liquid CO is mixed with the liquid CO2From liquid CO2And introducing the atmospheric volatile organic compounds into a full-automatic sample introduction device for sample introduction after the system stably operates, and closing a sleeve switch after sample introduction is carried out for 3.5-10 min.
Further, the parameters of the pre-concentration instrument are set as follows: the collecting temperature of the cold trap I is-150 ℃, the preheating temperature is-30 ℃, the resolving temperature is 30 ℃, the resolving time is 2min, the baking temperature is 180 ℃, and the baking time is 10 min; the trapping temperature of the cold trap II is-20 ℃, the preheating temperature is 30 ℃, the resolving temperature is 230 ℃, the resolving time is 2.5min, the baking temperature is 235 ℃, the baking time is 4min, the trapping temperature of the cold trap III is-180 ℃, the sample injection time is 1.5min, the baking temperature is 230 ℃, and the baking time is 3 min.
Further, the temperature of the low-temperature T-shaped cold trap is-40 ℃, and the sleeve switch is closed after sample injection is carried out for 5 min.
Furthermore, the flow ratio of the chromatographic column I to the chromatographic column II is 1 to (2-4).
Furthermore, the injection port temperature of the chromatographic column I and the chromatographic column II is 200 ℃, the carrier gas is high-purity helium, and a constant pressure mode is adopted and the pressure is 100 psi.
Further, the temperature rise program of the chromatographic column I and the chromatographic column II is that the temperature is kept for 5min at 35 ℃, the temperature is raised to 160 ℃ at the speed of 3 ℃/min, and then is raised to 240 ℃ at the speed of 40 ℃/min, and the temperature is kept for 2 min.
The method takes a gas chromatograph as a research object, and adopts the modes of automatic sample introduction, preconcentration, low-temperature T-shaped cold trap treatment and parallel connection of double-column double detectors around a gas chromatographic analysis technology and a gas enrichment and pretreatment means, wherein the automatic sample introduction not only can solve the time-consuming problem for scientific research personnel, greatly saves the working time of the scientific research personnel and reduces the labor cost, but also can utilize night work, improve the working efficiency of the instrument and accelerate the progress of sample analysis; the pre-concentration can realize the preliminary removal of impurities and water and the concentration and enrichment of gas; the low-temperature T-shaped cold trap treatment utilizes the characteristic that the temperature of liquid carbon dioxide is-40 ℃, the filler column penetrating through the cold trap is kept at-40 ℃, at the cold trap, some components in the atmospheric volatile organic compounds are frozen, while other components which can not be frozen flow out first and respectively flow into two chromatographic columns connected in parallel, then the cold trap is closed, the components frozen at the cold trap are gradually released along with the slow rise of the temperature and flow into two chromatographic columns connected in parallel, the purpose of separating the sample is achieved, and the double-column double-detector parallel analysis is matched, so that the detection of all the components of volatile organic compounds C2-C12 in the atmosphere can be realized, and the components (such as tetrafluorodichloroethane and isobutane) with superposed peaks can be separated from the peaks, so that the detection capability of the instrument is upgraded from 101 components for traditional detection of C4-C12 and the like to 105 components for detection of C2-C12 and the like. In conclusion, the automatic analysis system for the total components of the atmospheric volatile organic compounds can measure more acetylene, ethylene, ethane, propane and other components in C2-C3 on the basis of the prior preconcentrator-gas chromatography-mass spectrometer, has high sensitivity and accurate quantification, makes up the defects of the prior equipment, enables the components (such as tetrafluorodichloroethane and isobutane) with superposed peaks to separate peaks, is convenient to analyze, can analyze and obtain the total components of the atmospheric volatile organic compounds by only one-time sample injection, more comprehensively monitors the quality of the VOCs in the environment, provides technical support, improves the working efficiency, improves the detection strength and reduces the labor cost.
Drawings
FIG. 1 is a schematic diagram of a full-automatic sample introduction device connected with a preconcentrator;
FIG. 2 is a diagram of a multi-channel switch control software interface;
FIG. 3 is a technical circuit diagram of an atmospheric volatile organic compound full-component automatic analysis system provided by the invention;
FIG. 4 is a schematic structural diagram of an atmospheric volatile organic compound full-component automated analysis system provided by the present invention;
FIG. 5 is a graph showing the results of comparison before and after the use of the low-temperature T-type cold trap.
Detailed Description
In the invention, the full-automatic sampling device comprises a plurality of gas sampling channels, and switches of different gas sampling channels are switched and controlled by a multi-channel switcher. Specifically, as shown in fig. 1, the full-automatic sampling device includes a plurality of air inlets, an air outlet, a multi-channel switch and a power converter, the power converter is used for converting voltage (usually 220V) into voltage (for example, 28V) required for the multi-channel switch to use, the air inlets and the air outlet are communicated to form a gas sampling channel, and switches of different gas sampling channels are switched and controlled by the multi-channel switch. The switching of the multi-channel switcher is controlled by computer software, the software is developed by Nanjing Runzi fluid control equipment Limited and is named as a special debugging tool v0.2, an operation interface of the multi-channel switcher is shown in figure 2, the editable instruction quantity in the software is not limited, the instruction action comprises two types of reset and rotation, the position is 1-10 (can be expanded according to the actual situation), and the delay time can be as short as 1 ms. Generally, the 1 st instruction is set to be reset, namely, the instruction is stopped at the No. 1 position, then, the channel can be set to stop at the specified position for a certain time according to the instruction, and the channel automatically rotates to the position specified by the next instruction after the set time is reached. And inputting the time delay (unit: ms) according to the time length of sample analysis, and automatically switching to the next sample after the sample is analyzed, so as to realize automatic and continuous sample collection.
The gas sampling channels are expandable, namely the number of the gas sampling channels can be adjusted according to actual conditions, and the gas sampling device can meet the requirements by using 8-12 channels. Fig. 1 shows a ten-channel full-automatic sample introduction device, which includes ten gas inlets (1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, respectively), one gas outlet, a multi-channel switch and a power converter, wherein the gas inlets are connected to a suma tank or a Tadla sampling bag, the middle channel "0" is the gas outlet, and is connected to a preconcentrator, the ten gas inlets are respectively communicated with the gas outlet to form ten gas sample introduction channels, the opening and closing of the different gas sample introduction channels are controlled by switching the multi-channel switch, and the power converter is used for converting voltage (usually 220V) into voltage (for example, 28V) required by the multi-channel switch. Wherein the switching of the multi-channel switch is controlled by computer software. The power for sample collection comes from the preconcentrator.
The technical route of the full-automatic analysis system for the atmospheric volatile organic compounds is shown in fig. 3, the full-automatic sampling device is driven by a software command, a channel is switched to a sample to be detected, the sample is pre-concentrated, collected, processed by a low-temperature system and then enters a double chromatographic column and a double detector for parallel detection, and the full-automatic continuous analysis of VOCs in the sample is realized.
The material of the gas contacted in the multi-channel switcher is polytetrafluoroethylene, the material is inert with most chemicals at room temperature, the heat resistance and the corrosion resistance are realized, the volume from the port to the port is 27.5 mu L, the adsorption to the sample is negligible, and the full-automatic sample injection device has two advantages that (1) the multi-channel is expandable, the number of the channels can be expanded according to the requirement, and the requirement of detecting more samples is met, and (2) the application range is expandable, the material of the multi-channel switching device is inert, the diameter of the channels is 1-2mm, the maximum air tightness is 0.8-1MPa, and the maximum water pressure resistance is 1-1.2MPa, so the full-automatic sample injection device can be applied to gas samples and.
In the present invention, it is preferable to use a PEEK tube with 1/16 outside diameter and 0.75mm inside diameter as the main gas flow path, and to use a PEEK tube with 1/8 outside diameter, 1.6mm inside diameter and a PEEK tube connector with corresponding dimensions at the interface transition, so as to effectively prevent the sample from being adsorbed during the collection process, and to minimize the length of the tube line as much as possible to minimize the dead volume of the tube line during the manufacturing process.
The pre-concentration instrument is used for primarily removing impurities and water and realizing concentration and enrichment of gas. The preconcentrator can be selected conventionally in the field, is preferably a three-stage cold trap preconcentrator, and can be 8910-Nutech in particular.
As shown in fig. 4, the low-temperature T-shaped cold trap includes a packing column and a sleeve pipe sleeved on the packing column, and a gap is formed between the packing column and the sleeve pipe for supplying liquid CO2Circulating, wherein the middle section of the sleeve is provided with liquid CO2An inlet and two ends of the inlet are provided with liquid CO2Outlet and liquid CO2The opening and closing of the inlet is controlled by a switch. The low-temperature T-shaped cold trap extends into the column incubator, and when the low-temperature T-shaped cold trap works, the atmospheric volatile organic compounds are introduced into the full-automatic sample introduction device for sample introduction, and meanwhile, the switch is turned on to introduce liquid CO2Liquid CO2Liquid CO from the middle of the casing2The liquid CO flows in from the inlet and is fine at two ends2Spraying out from the outlet, frosting at the sleeve, maintaining the temperature at-40 deg.C, not affected by the temperature of column oven, achieving low temperature refrigeration, freezing some components in atmospheric volatile organic compounds, allowing other components incapable of being frozen to flow out, respectively flowing into two chromatographic columns in parallel, injecting sample for 3.5-10min, closing the sleeve switch to stop introducing liquid CO2The component frozen at the cold trap gradually increases with the temperatureGradually releases and flows into two chromatographic columns connected in parallel to achieve the purpose of separating a sample, and is matched with a double-column double-detector for parallel analysis, so that the detection of all components of volatile organic compounds C2-C12 in the atmosphere can be realized. In order to facilitate the connection and fixation between the low-temperature T-shaped cold trap and the pre-concentration instrument and between the parallel double-column double detectors, preferably, the length of the packing column in the low-temperature T-shaped cold trap is greater than that of the sleeve, and the packing column extends out from two ends of the sleeve. Specifically, the length of the packed column is 10-30cm, and the length of the sleeve is 4-20 cm. At the moment, one end of the packed column is connected with a pre-concentration pipe in the pre-concentration instrument through a metal bi-pass, the pre-concentration pipe and the packed column are respectively fixed in the bi-pass through a single-hole graphite pad in a sealing mode, the other end of the packed column is connected with an inlet of a metal tee joint, the other two outlets of the tee joint are respectively connected with a chromatographic column I and a chromatographic column II, the chromatographic column I is connected with an MSD detector, and the chromatographic column II is connected with an FID detector. At the moment, the sample enriched by the preconcentrator firstly enters the filler column through the carrier gas, and then respectively enters two parallel double-column double detectors for full component analysis. In addition, the filler packed in the packed column may be 6% cyanopropylphenyl-94% methylpolysiloxane.
The invention uses double-column double detectors in parallel, can simultaneously analyze a sample to obtain all the components of VOCs, and can be applied to component separation of successive peaks by matching with a low-temperature T-shaped cold trap, wherein one path of the double-column double detector consists of a chromatographic column I and an MSD detector which are sequentially communicated, and the other path of the double-column double detector consists of a chromatographic column II and an FID detector which are sequentially communicated, wherein the chromatographic column I connected with the MSD detector is a DB-624(Agilent) capillary column with 60m × 0.25.25 mm × 1.4 mu m, the chromatographic column II connected with the FID detector is an HP-P L OT Q (Agilent) capillary column with 30m × 0.32mm × 20 mu m, the flow ratio of the chromatographic column I to the chromatographic column II is 1: 2-4 (flow speed: flow speed), and the most preferably is 1: 3.
The full-component automatic analysis method of the atmospheric volatile organic compounds provided by the invention is carried out by adopting the full-component automatic analysis system of the atmospheric volatile organic compounds, specifically, the full-component automatic analysis system of the atmospheric volatile organic compounds is started, system parameters are set, and liquid CO is subjected to full-component automatic analysis2From liquid CO2Low temperature is introduced into the inletAnd (3) in a sleeve of the T-shaped cold trap, introducing the atmospheric volatile organic compounds into a full-automatic sample introduction device for sample introduction after the system stably operates, and closing a sleeve switch after sample introduction is carried out for 3.5-10 min.
1. The test conditions were as follows:
(1) standard gas
Standard gases 57 PAMS ozone precursor standard gases (1. mu. mol/mol, 1L), 65 TO15 standard gases (1. mu. mol/mol, 1L) and 4 internal standard gases (1. mu. mol/mol, 0.8L) were purchased from L INDE company, and a part of compounds in PAMS standard gases and TO15 standard gases were overlapped.
The mixing standard used gas was a gas dynamic diluter (NT4600, ENTECH), and the flow rate of the standard gas was 4950m L/min, and the flow rate of nitrogen (purity > 99.999%) was 50m L/min, i.e., 100-fold dilution was 10nmol/mol, which was preserved for 30 days.
(2) Preconcentrator (8910, Nutech) tertiary cold trap temperature
And (3) cold trap I: the collecting temperature is-150 deg.C, the preheating temperature is-30 deg.C, the resolving temperature is 30 deg.C, the resolving time is 2min, the baking temperature is 180 deg.C, and the baking time is 10 min.
And (3) cold trap II: the collecting temperature is-20 deg.C, the preheating temperature is 30 deg.C, the resolving temperature is 230 deg.C, the resolving time is 2.5min, the baking temperature is 235 deg.C, and the baking time is 4 min.
And (3) cold trap III: the collecting temperature is-180 ℃, the sample feeding time is 1.5min, the baking temperature is 230 ℃, and the baking time is 3 min.
(3) Chromatographic conditions
Column I DB-624(Agilent) capillary column, 60m × 0.25mm × 1.4.4 μm.
Chromatographic column II HP-P L OT Q (Agilent) capillary column, 30m × 0.32mm × 20 μm.
The sample inlets of the chromatographic column I and the chromatographic column II are at 200 ℃, the carrier gas is high-purity helium, and a constant pressure mode is adopted and the pressure is 100 psi.
The flow ratio of the chromatographic column I to the chromatographic column II is 1 to (2-4) (flow rate: flow rate), and the most preferable ratio is 1 to 3.
Temperature rise programs of the chromatographic column I and the chromatographic column II are as follows: maintaining at 35 deg.C for 5min, increasing to 160 deg.C at 3 deg.C/min, increasing to 240 deg.C at 40 deg.C/min, and maintaining for 2 min. Wherein, the temperature-raising program is started when the sample injection is started.
(4) Detector
An MSD detector: the ion source is an EI source, the energy of the EI source is 70eV, the solvent delay is 4.2min, the transmission line temperature is 230 ℃, and the full scanning range is 35-300.
FID detector: the temperature of the detector is 250 ℃ and H2The flow rate is 45m L/min, the air flow rate is 300m L/min, and the tail-blown nitrogen is 10m L/min.
(5) Low-temperature T-shaped cold trap
Opening the switch before the low-temperature T-shaped cold trap is analyzed, enabling liquid carbon dioxide to flow into the low-temperature T-shaped cold trap, freezing a packed column located in the sleeve, keeping the temperature for 3.5-10min (preferably 5min) after GC (gas chromatography) operation (namely sample injection), and then closing the switch.
2. The test results were as follows:
(1) and (3) configuring to obtain 10nmol/mol of VOCs standard gas by using a dynamic dilution instrument.
The original preconcentration-GCMS can analyze 101 components, the analysis of acetylene, ethylene, ethane and propane is increased, and the components with superposed peaks can be separated to obtain 105 VOC components. Both FID and MSD detectors can measure propylene, and the following propylene data were obtained using FID analysis. Because a double-column double-detection parallel analysis system is used, the flow ratio of the chromatographic column I to the chromatographic column II is 1: 3 (flow velocity: flow velocity), namely the MSD detection sensitivity is reduced to 1/4, but the MSD detection component quantity is unchanged, the retention time deviation is within 0.05min, and the peak intensity can be improved by increasing the sample injection volume.
(2) Precision, detection limit and reproducibility of retention time of detection results of C2-C3 components
Configuring 10nmol/mol PAMS standard gas 7 tanks, respectively connecting to No. 1-7 positions of an automatic sample injection device, collecting and analyzing each Suma tank for 1 time, comparing 7 analysis results, analyzing that the relative standard deviation range of C2-C3 components is 0.37-0.93%, and the method detection limit (MD L) is 0.22-0.47 mu g/m3(ii) a The retention time RSD is 0.004-0.044%. Through analysis, the relative standard deviation range of the C4-C12 components is 0.019-0.101%; method of producing a composite materialThe detection limit (MD L) is 0.003-0.017 mu g/m3(ii) a The retention time RSD is 0.001-0.099%. The results of the analysis of the VOCs components are shown in tables 1 and 2.
According to the analysis result, the automatic analysis system for the atmospheric volatile organic compounds has the advantages that the automatic sampling device is accurately switched, the air tightness is good, the analysis system is stable, the detection capability of the instrument can be upgraded from the traditional detection of 101 components such as C4-C12 to the detection of 105 components such as C2-C12, and the analysis method is suitable for analysis of VOC samples in the atmospheric environment.
(3) Functional effect of using low-temperature T-shaped cold trap
The results of the comparison before and after the use of the low temperature T-type cold trap function are shown in fig. 5. Wherein, a low-temperature T-shaped cold trap is not used, the peak appearance is shown as a peak a, and the peak a is a peak formed by connecting tetrafluorodichloroethane and isobutane; after the low-temperature T-shaped cold trap is used, the peak is shown as the peak b, and the two components can separate the peaks. It can be seen that the components with superimposed peaks can be separated into peaks by using a low-temperature T-shaped cold trap.
In summary, the technical index pair of the functions of the instrument and the equipment before and after the completion of the invention is shown in table 3.
TABLE 3
Therefore, the automatic analysis system for the full components of the atmospheric volatile organic compounds can realize single sample injection to analyze the full components of the volatile organic compounds C2-C12 in the gas, can separate the peaks of the components which successively appear, such as tetrafluorodichloroethane and isobutane, and can also realize automatic continuous analysis of samples, thereby improving the detection efficiency, improving the detection capability of the instrument, reducing the labor cost and being more beneficial to the management of the instrument. In addition, the automatic sampling device is also suitable for liquid phase samples, so that the device is more popularized.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.
Claims (10)
1. The full-component automatic analysis system for the atmospheric volatile organic compounds is characterized by comprising a full-automatic sample introduction device and an analysis device; the full-automatic sample introduction device comprises a plurality of gas sample introduction channels, and switches of different gas sample introduction channels are switched and controlled through a multi-channel switcher; the analysis device comprises a preconcentrator, a low-temperature T-shaped cold trap and a parallel double-column double detector which are sequentially communicated; the low-temperature T-shaped cold trap comprises a packing column and a sleeve sleeved on the packing column, wherein the packing column and the sleeve areThe middle section of the sleeve is provided with liquid CO2An inlet and two ends of the inlet are provided with liquid CO2Outlet and liquid CO2The opening and closing of the inlet are controlled by a switch; the parallel double-column double detector consists of two parallel detection branches, one branch consists of a chromatographic column I and an MSD detector which are sequentially communicated, and the other branch consists of a chromatographic column II and an FID detector which are sequentially communicated; full autoinjection device's gaseous sampling passageway export communicates with the entry of preconcentrator, the export of preconcentrator communicates with the entry of filler column in the low temperature T type cold trap, the export of filler column communicates with chromatographic column I and MSD detector all the way in proper order in the low temperature T type cold trap, another way communicates with chromatographic column II and FID detector in proper order.
2. The full-automatic analysis system for atmospheric Volatile Organic Compounds (VOCs) according to claim 1,
the number of the gas sample introduction channels of the full-automatic sample introduction device is 8-12;
the diameter of a gas sample introduction channel of the full-automatic sample introduction device is 1-2mm, the maximum air tightness is 0.8-1MPa, and the maximum water pressure resistance is 1-1.2 MPa;
the material of gas contacted in the multi-channel switcher of the full-automatic sampling device is polytetrafluoroethylene;
the switching of the multi-channel switcher of the full-automatic sampling device is controlled by software;
full autoinjection device includes a plurality of air inlets, a gas outlet, multichannel switch and power converter, power converter is used for converting the voltage into and supplies the multichannel switch to use required voltage, and the air inlet forms gaseous introduction passageway with the gas outlet intercommunication, and the switch of different gaseous introduction passageways passes through multichannel switch switching control.
3. The atmospheric volatile organic full-ingredient automatic analysis system according to claim 1, wherein the preconcentrator is a three-stage cold trap preconcentrator; the preconcentrator is 8910-Nutech.
4. The full-automatic analysis system for atmospheric volatile organic compounds according to claim 1, wherein the length of the filler column in the low-temperature T-shaped cold trap is greater than that of the sleeve, and the filler column extends out from two ends of the sleeve; the length of the filler column is 10-30cm, and the length of the sleeve is 4-20 cm; the filler filled in the filler column is 6% of cyanopropylphenyl-94% of methyl polysiloxane.
5. The full-automatic analysis system for atmospheric Volatile Organic Compounds (VOCs) according to claim 1, wherein the chromatographic column I is a DB-624 capillary column, and the chromatographic column II is an HP-P L OT Q capillary column.
6. A method for automatically analyzing all components of atmospheric volatile organic compounds, which is characterized by adopting the system for automatically analyzing all components of atmospheric volatile organic compounds as claimed in any one of claims 1 to 5, specifically, starting the system for automatically analyzing all components of atmospheric volatile organic compounds, setting system parameters, and adding liquid CO2From liquid CO2And introducing the atmospheric volatile organic compounds into a full-automatic sample introduction device for sample introduction after the system stably operates, and closing a sleeve switch after sample introduction is carried out for 3.5-10 min.
7. The method for automatically analyzing the full components of the atmospheric volatile organic compounds according to claim 6, wherein the parameters of the pre-concentrator are set as follows:
the cold trap I has trapping temperature of-150 deg.C, preheating temperature of-30 deg.C, resolving temperature of 30 deg.C, resolving time of 2min, baking temperature of 180 deg.C, and baking time of 10min
The trapping temperature of the cold trap II is-20 deg.C, the preheating temperature is 30 deg.C, the resolving temperature is 230 deg.C, the resolving time is 2.5min, the baking temperature is 235 deg.C, and the baking time is 4min
The trapping temperature of the cold trap III is-180 ℃, the sample injection time is 1.5min, the baking temperature is 230 ℃, and the baking time is 3 min.
8. The method for automatically analyzing the full components of the atmospheric volatile organic compounds according to claim 6, wherein the temperature of the low-temperature T-shaped cold trap is-40 ℃, and the sleeve switch is closed after the sample is injected for 5 min.
9. The method for automatically analyzing the full components of the atmospheric volatile organic compounds according to claim 6, wherein the flow ratio of the chromatographic column I to the chromatographic column II is 1 to (2-4); the sample inlets of the chromatographic column I and the chromatographic column II are at 200 ℃, the carrier gas is high-purity helium, and a constant pressure mode is adopted and the pressure is 100 psi.
10. The method for automatically analyzing the full components of the atmospheric volatile organic compounds according to claim 6, wherein the temperature rise programs of the chromatographic column I and the chromatographic column II are that the temperature is kept for 5min at 35 ℃, is increased to 160 ℃ at the rate of 3 ℃/min, is increased to 240 ℃ at the rate of 40 ℃/min, and is kept for 2 min.
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