Dioxin purification analysis device for flue gas online detection and purification detection method

Abstract

The invention discloses a dioxin purification analysis device for flue gas online detection and a purification detection method, and belongs to the technical field of pollutant treatment. The dioxin purification analysis device comprises a solvent bottle, a high-pressure pump, a six-way valve, an LC liquid phase column, a switching valve, a concentration device, a PTV large-volume sample injection instrument and a GC-ECD or GC / MS instrument, a pyrenyl ethyl (PYE) column is selected as a liquid chromatography stationary phase, and the dioxin purification analysis device is obtained by utilizing the planarity difference of an annular closed conjugated system formed by pi electrons in aromatic and alicyclic structures. According to the method, dioxin and polychlorinated aromatic hydrocarbon (polychlorinated biphenyl, hexachlorobenzene and tetrachloronaphthalene) are separated, and meanwhile, liquid phase effluent is transferred to a GC-ECD or GC / MS instrument by utilizing a concentration device and large-volume sample introduction for final analysis. The device integrates sample purification and detection technologies, and realizes the whole process of automatic purification and analysis of the flue gas sample.

Description

Technical Field

[0001] The invention belongs to the technical field of pollutant treatment, and in particular relates to a dioxin purification and analysis device for online flue gas detection and a purification detection method. Technical Background

[0002] Dioxins are a class of persistent organic pollutants, including 75 polychlorinated dibenzodioxins and 135 polychlorinated dibenzofurans, which are carcinogenic, teratogenic, and mutagenic. In addition, dioxins are lipophilic and chemically stable, and can eventually enter the human body through environmental migration and bioaccumulation. Therefore, dioxins are included in the list of the Stockholm Convention on Persistent Organic Pollutants, and 17 of the dioxin compounds are considered to be extremely harmful to human health.

[0003] At present, due to the complex matrix of the environment in which trace dioxins in flue gas are located and the interference of other organic chlorinated aromatic hydrocarbons with similar chemical structures, it is often difficult to completely purify dioxins even with conventional multiple purification column composite separation methods. This results in complex structural design of dioxin online detection equipment, low detection sensitivity and high development difficulty.

[0004] CN102235949A discloses a dioxin pretreatment device based on gas-liquid phase coupling, but the stationary phase used in the liquid phase of the device is one or more of fillers such as silica gel (acidic silica gel, alkaline silica gel, silver nitrate silica gel, etc.), alumina, anhydrous sodium sulfate, copper powder, Florisil, activated carbon, etc., which often makes it difficult to separate dioxins from other chlorinated aromatic hydrocarbons. Summary of the invention

[0005] In order to solve the technical problems existing in the background technology, the purpose of the present invention is to provide a dioxin purification and analysis device and purification detection method for flue gas online detection. The device adopts loop injection technology and realizes liquid-gas phase online coupling through flow path switching, which can separate dioxin substances in samples and complete the automatic purification and analysis process of dioxin samples. Compared with traditional methods, this method consumes less organic solvents, has simple purification steps, and improves analysis efficiency.

[0006] The above object of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a dioxin purification and detection device for online flue gas detection, comprising a solvent bottle 1, a high-pressure pump 2, a six-way valve 3, an LC liquid phase column 4, a switching valve 5, a concentration device 6, a PTV large-volume injection system 7, and a GC-ECD or GC / MS instrument 8, which are connected in sequence;

[0008] Among them, the sample is injected from position ② of the six-way valve 3, a quantitative tube is connected between positions ① and ④ of the six-way valve, position ③ of the six-way valve is connected to a waste liquid bottle, position ⑤ of the six-way valve is connected to the outlet end of the solvent pumped out by the high-pressure pump 2, and position ⑥ is connected to the inlet of the LC liquid column 4; the outlet of the LC liquid column 4 is connected to the center of the switching valve 5, position ① of the switching valve is connected to the waste liquid bottle, position ③ is connected to the concentrator 6, the outlet of the concentrator 6 is connected to the inlet of the PTV large-volume injection system 7, and the PTV large-volume injection system 7 is connected to the GC-ECD or GC / MS instrument 8.

[0009] Based on the above technical solution, further, the LC liquid phase column 4 is a pyrenylethyl (PYE) fixed column; the gas phase analysis column includes DB-5, HP-Ultra 2, RTX-5MS, DB-DIOX column.

[0010] Based on the above technical solution, further, the PTV large volume injection system 7 includes a total flow control valve, a diverter valve, a diverter outlet control valve, a septum nut and a septum, a septum purge control valve, a liner, a column nut and a sealing gasket.

[0011] The present invention also provides a purification and analysis method for the above-mentioned dioxin purification and detection device for online flue gas detection. The purification and analysis method separates impurities through liquid phase, enriches dioxin samples in a concentration device through fraction cutting, and after concentration, injects the sample into a gas phase or gas phase / mass spectrometry instrument with an electron capture detector for analysis.

[0012] Based on the above technical solution, further, the purification analysis method comprises the following steps:

[0013] (1) Preparation stage: Positions ⑤ and ⑥ of the six-way valve 3 are connected, positions ① and ② are connected, positions ③ and ④ are connected, and the switching valve 5 is in position ①;

[0014] (2) Injection stage: The extract of the flue gas sample is excessively injected from position ② of the six-way valve 3, and then the six-way valve 3 is twisted so that position ⑥ is connected to position ①, position ② is connected to position ③, and position ④ is connected to position ⑤, and the sample is introduced into the LC liquid phase column 4;

[0015] (3) Separation stage: The solvent in the solvent bottle 1 flows into the LC liquid phase column 4 for elution under the action of the high-pressure pump 2. The eluate flowing out of the LC liquid phase column 4 enters the switching valve 5. The switching valve 5 switches between positions ① and ③ according to the peak time of dioxins, and the dioxin fraction is introduced into the concentration device, and the impurity fraction is discharged into the waste liquid bottle;

[0016] (4) Detection stage: The dioxin-containing eluate concentrated in the concentration device is injected into a GC-ECD or GC / MS instrument via a PTV large volume injection system 7 for detection.

[0017] Based on the above technical solution, further, the liquid phase elution conditions in the separation stage in step (3) are:

[0018] a) Elution flow rate: 0.5-1 mL / min;

[0019] b) the elution solvent is a mixed solvent consisting of solvent A and solvent B, wherein solvent A is selected from one or a combination of two or more of n-hexane, cyclohexane, isooctane, cyclopentane and heptane; and solvent B is selected from one or a combination of two or more of methanol, acetonitrile, ethyl acetate, dichloromethane and chloroform;

[0020] c) within 3 to 5 minutes after the start of the program, the elution is non-gradient, wherein the volume fraction of solvent A is between 90% and 100%; then within 50 to 70 minutes, the volume fraction of solvent A is gradually reduced to between 30% and 10% and maintained for 0-10 minutes; finally, the volume fraction of solvent A is gradually reduced to 0 and maintained until the end of elution;

[0021] d) According to the chlorine substitution position, the elution range of dioxins is: 2,3,7,8-TCDD: 7.0-9.0min; 2,3,7,8-TCDF: 12.0-15.0min; 1,2,3,7,8-PCDD: 16.0-19.0min; 1,2,3,7,8-PCDF, 2,3,4,7,8-PCDF: 21.0-24.0min; 1,2,3,4,7,8-H6CDD / F, 1,2,3,6,7,8-H6C DD / F, 1,2,3,7,8,9-H6CDD / F, 2,3,4,6,7,8-H6CDF: 24.0-35.0min; 1,2,3,4,6,7,8-H7CDD / F: 36.0-41.0min; 1,2,3,4,7,8,9-H7CDF: 42.0-45.0min; OCDD: 53.0-58.0min; OCDF: 58.0-63.0min to obtain the receiving solution, and then the concentrated solution was obtained after concentration.

[0022] Based on the above technical solution, further, in step (4), when high-resolution gas chromatography / triple quadrupole tandem mass spectrometer is used for detection, the detection conditions of dioxins are: injection port temperature is 280-310°C; injection volume is 50-150μL; carrier gas: He, flow rate is 0.5-1.5mL / min; chromatographic column: RTX-5MS column, 60m×0.25mm×0.25μm; column program temperature rise: initial temperature 100-130°C, initial time 1-2min, 40°C / min to 180-220°C, 3°C / min to 310-315°C and maintained for 8-12min; transmission line temperature is 250-300°C; ion source temperature is 220-260°C; electron emission energy: 60-80ev; ion source: EI+.

[0023] Based on the above technical solution, further, in step (4), when high-resolution gas chromatography / triple quadrupole tandem mass spectrometer is used for detection, the detection conditions of dioxins are: injection port temperature is 290°C; injection volume is 100 μL; carrier gas: He, flow rate is 1.0 mL / min; chromatographic column: RTX-5MS column, 60m×0.25mm×0.25μm; column program temperature rise: initial temperature 120°C, initial time 1min, 40°C / min to 200°C, 3°C / min to 312°C and maintained for 10min; transmission line temperature is 280°C; ion source temperature is 240°C; electron emission energy: 70ev; ion source: EI+.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention adopts a pyrene ethyl (PYE) column as a liquid stationary phase, and utilizes its ability to distinguish the planarity differences of the cyclic closed conjugated system composed of π electrons in aromatic and alicyclic structures to achieve the separation of dioxins and polychlorinated aromatic hydrocarbons (such as polychlorinated biphenyls, hexachlorobenzene, and tetrachloronaphthalene), which effectively solves the problem of cumbersome operation and poor separation effect when separating dioxins and other chlorinated aromatic hydrocarbons using conventional composite purification columns and gas chromatography columns.

[0026] (2) The dioxin purification and detection device for online flue gas detection of the present invention uses a small amount of solvent, and the amount of waste solvent generated is also reduced accordingly, thereby reducing the use and treatment costs of organic solvents. The solvent required for one experiment of the present invention is only 60-100 mL, and the liquid column used for purification can be reused, thereby complying with the principles of green chemistry and sustainable development and reducing the exposure risk of organic solvents to experimenters.

[0027] (3) The purification and detection method of the dioxin purification and detection device for online flue gas detection of the present invention can, in principle, also achieve purification and detection of other pollutants by optimizing appropriate conditions, and can be widely used in the analysis of trace pollutants in complex matrices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.

[0029] Figure 1 The present invention is a schematic diagram of the process of purifying and detecting dioxins by the dioxin purification and detection device for online flue gas detection.

[0030] Figure 2 This is a schematic diagram of a dioxin purification and detection device for online flue gas detection according to the present invention.

[0031] Among them, 1-solvent bottle, 2-high pressure pump, 3-six-way valve, 4-LC liquid column, 5-switching valve, 6-concentration device, 7-PTV large volume injection system, 8: GC-ECD or GC / MS instrument.

[0032] Figure 3 The mass spectra of polychlorinated dibenzo-p-dioxins in Example 2 (left) and Standard Method Comparative Example 1 (right) are compared.

[0033] Figure 4 The mass spectra of polychlorinated dibenzofurans in Example 2 (left) and Standard Method Comparative Example 1 (right) are compared. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific implementation modes, but the scope of protection claimed by the present invention is not limited to the following implementation modes.

[0035] Example 1

[0036] The present invention provides a dioxin purification and detection device for online flue gas detection, comprising a solvent bottle 1, a high-pressure pump 2, a six-way valve 3, an LC liquid phase column 4, a switching valve 5, a concentration device 6, a PTV large-volume injection system 7, and a GC-ECD or GC / MS instrument 8, which are connected in sequence;

[0037] Wherein, the sample is injected from position ② of the six-way valve 3, a quantitative tube is connected between positions ① and ④ of the six-way valve, position ③ of the six-way valve is connected to a waste liquid bottle, position ⑤ of the six-way valve is connected to the outlet end of the solvent pumped out by the high-pressure pump 2, and position ⑥ is connected to the inlet of the LC liquid phase column 4; the outlet of the LC liquid phase column 4 is connected to the center of the switching valve 5, position ① of the switching valve is connected to the waste liquid bottle, position ③ is connected to the concentrator 6, the outlet of the concentrator 6 is connected to the inlet of the PTV large volume injection system 7, and the PTV large volume injection system 7 is connected to the GC-ECD or GC / MS instrument 8;

[0038] LC liquid phase column 4 is a commercially available pyrenylethyl (PYE) fixed column; gas phase analysis columns are non-polar, weakly polar and polar columns such as DB-5, HP-Ultra 2, RTX-5MS and DB-DIOX;

[0039] The above-mentioned PTV large volume injection system 7 includes a total flow control valve, a diverter valve, a diverter outlet control valve, a septum nut and a septum, a septum purge control valve, a liner, a column nut and a sealing gasket; the injection volume of the quantitative tube is 10-100 μL;

[0040] The device has the functions of online flue gas sample introduction, fraction cutting and collection, solvent evaporation, solution transfer and analysis and detection.

[0041] Example 2

[0042] This embodiment provides a method for using the above-mentioned dioxin purification and detection device for online flue gas detection, comprising the following steps:

[0043] (1) obtaining a dioxin sample extract;

[0044] (2) The extract obtained in step (1) is injected into the liquid phase column 4 through the position ② of the six-way valve, and the elution condition is: 1 mL / min, and the elution gradient is: 0 min n-hexane 100% dichloromethane 0%; 5 min n-hexane 100% dichloromethane 0%; 65 min n-hexane 10% dichloromethane 90%; 70 min n-hexane 10% dichloromethane 90%; 80 min n-hexane 0% dichloromethane 100%. According to Table 1, the dioxin-containing eluate is accurately received by switching the valve 5 to the position ③ to obtain the receiving liquid, and the remaining time period is switched to the position ① and discarded. The final receiving liquid is concentrated by the concentrator.

[0045] Table 1 The starting and ending time of dioxins in the liquid column

[0046]

[0047] (3) The concentrated solution in step (2) is injected into a high-resolution gas chromatography / triple quadrupole tandem mass spectrometer through a large-volume injection device to detect dioxins in the purified sample; the injection port temperature is 290°C; the large-volume injection is 100 μL; the carrier gas is He, and the flow rate is 1.0 mL / min; the chromatographic column is an RTX-5MS column, 60 m×0.25 mm×0.25 μm; the column temperature program is: initial temperature 120°C, initial time 1 min, 40°C / min to 200°C, 3°C / min to 312°C and maintained for 10 min; the transmission line temperature is 280°C; the ion source temperature is 240°C; the electron emission energy is 70 eV; the ion source is EI+; the scanning mode is Full Scan; and the mass spectrometry mode is Q1MS.

[0048] Comparative Example 1

[0049] (1) The same dioxin extract as in Example 1.

[0050] (2) The sample in step (1) was placed in a non-gel filter cartridge and the filter cartridge opening was sealed with absorbent cotton, then placed in a Soxhlet extractor, and extracted with 260 mL of a mixed solvent of n-hexane / dichloromethane (1:1, v / v) for 16 h to obtain an extract;

[0051] (3) Use a rotary evaporator to concentrate the extract obtained in step (2) to about 1 mL, prepare a sieve plate chromatography column (inner diameter: 32 mm), and add 4 g of purified anhydrous sodium sulfate, 0.9 g of activated silica gel, 3 g of 2% potassium hydroxide silica gel, 0.9 g of activated silica gel, 4.5 g of 44% acidified silica gel, 6 g of 22% acidified silica gel, 0.9 g of activated silica gel, 3 g of 10% silver nitrate silica gel, and 6 g of anhydrous sodium sulfate in sequence. 100 mL of n-hexane is used to elute the silica gel column; the silica gel mixed with the extract is poured into the chromatography column and 200 mL of n-hexane is added as the eluent, and the elution flow rate is controlled at 1 drop / s to obtain eluent A.

[0052] (4) The eluent A obtained in step (3) was concentrated and purified by passing it through an alumina column to obtain eluent B, which was then blown dry and fixed to 10 μL for later use.

[0053] The above-mentioned medium alumina column is loaded with 10 g of alumina and 3 g of anhydrous sodium sulfate from bottom to top, and the alumina column is rinsed with 50 mL of n-hexane and set aside.

[0054] The above purification method is: the eluent A is transferred to the alumina column, eluted with a n-hexane / dichloromethane mixed solvent (volume ratio of 98:2), and then eluted with 150 mL of a n-hexane / dichloromethane mixed solvent (volume ratio of 50:50).

[0055] (5) A high-resolution gas chromatography / triple quadrupole tandem mass spectrometer was used to detect dioxins in the purified sample. The injection port temperature was 290°C; the large volume injection was 100 μL; the carrier gas was He, and the flow rate was 1.0 mL / min; the chromatographic column was RTX-5MS column, 60 m×0.25 mm×0.25 μm; the column temperature program was: initial temperature 120°C, initial time 1 min, 40°C / min to 200°C, 3°C / min to 312°C and maintained for 10 min; the transmission line temperature was 280°C; the ion source temperature was 240°C; the electron emission energy was 70 ev; the ion source was EI+; the scanning mode was Full Scan; and the mass spectrometry mode was Q1MS.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dioxin purification and detection device for online flue gas detection, characterized in that: It comprises a solvent bottle (1), a high-pressure pump (2), a six-way valve (3), an LC liquid phase column (4), a switching valve (5), a concentration device (6), a PTV large volume injection system (7), and a GC-ECD or GC / MS instrument (8) which are connected in sequence; The sample is injected from position ② of the six-way valve (3), a quantitative tube is connected between positions ① and ④ of the six-way valve, position ③ of the six-way valve is connected to a waste liquid bottle, position ⑤ of the six-way valve is connected to the outlet end of the solvent pumped out by the high-pressure pump (2), and position ⑥ is connected to the inlet of an LC liquid column (4); the outlet of the LC liquid column (4) is connected to the center of a switching valve (5), position ① of the switching valve is connected to the waste liquid bottle, position ③ is connected to a concentrator (6), the outlet of the concentrator (6) is connected to the inlet of a PTV large-volume injection system (7), and the PTV large-volume injection system (7) is connected to a GC-ECD or GC / MS instrument (8).

2. The dioxin purification and detection device according to claim 1, characterized in that: The LC liquid phase column (4) is a pyrenylethyl (PYE) fixed column; the gas phase analysis columns include DB-5, HP-Ultra 2, RTX-5MS, and DB-DIOX columns.

3. The dioxin purification and detection device according to claim 1, characterized in that: The PTV large volume injection system (7) comprises a total flow control valve, a diverter valve, a diverter outlet control valve, a septum nut and a septum, a septum purge control valve, a liner, a column nut and a sealing gasket.

4. The purification and analysis method of the dioxin purification and detection device for online flue gas detection according to any one of claims 1 to 3, characterized in that: The purification analysis method separates impurities through liquid phase, enriches dioxin samples in a concentration device through fraction cutting, and injects them into a gas phase or gas phase / mass spectrometer with an electron capture detector for analysis after concentration.

5. The purification analysis method according to claim 4, characterized in that: The purification analysis method comprises the following steps: (1) Preparation stage: Positions ⑤ and ⑥ of the six-way valve (3) are connected, positions ① and ② are connected, positions ③ and ④ are connected, and the switching valve (5) is in position ①; (2) Injection stage: The extract of the flue gas sample is excessively injected from position ② of the six-way valve (3), and then the six-way valve (3) is twisted so that position ⑥ is connected to position ①, position ② is connected to position ③, and position ④ is connected to position ⑤, and the sample is introduced into the LC liquid phase column 4; (3) Separation stage: The solvent in the solvent bottle (1) flows into the LC liquid phase column (4) for elution under the action of the high-pressure pump (2). The eluate flowing out of the LC liquid phase column (4) enters the switching valve (5). The switching valve (5) switches between positions ① and ③ according to the peak time of dioxins, and the dioxin fraction is introduced into the concentration device, and the impurity fraction is discharged into the waste liquid bottle; (4) Detection stage: The dioxin-containing eluate concentrated in the concentration device is injected into a GC-ECD or GC / MS instrument via a PTV large volume injection system (7) for detection.

6. The purification analysis method according to claim 5, characterized in that: The liquid phase elution conditions in the separation stage in step (3) are: a) Elution flow rate: 0.5-1 mL / min; b) the elution solvent is a mixed solvent consisting of solvent A and solvent B, wherein solvent A is selected from one or a combination of two or more of n-hexane, cyclohexane, isooctane, cyclopentane and heptane; and solvent B is selected from one or a combination of two or more of methanol, acetonitrile, ethyl acetate, dichloromethane and chloroform; c) within 3 to 5 minutes after the start of the program, the elution is non-gradient, wherein the volume fraction of solvent A is between 90% and 100%; then within 50 to 70 minutes, the volume fraction of solvent A is gradually reduced to between 30% and 10% and maintained for 0-10 minutes; finally, the volume fraction of solvent A is gradually reduced to 0 and maintained until the end of elution; d) According to the chlorine substitution position, the elution range of dioxins is: 2,3,7,8-TCDD: 7.0-9.0min; 2,3,7,8-TCDF: 12.0-15.0min; 1,2,3,7,8-PCDD: 16.0-19.0min; 1,2,3,7,8-PCDF, 2,3,4,7,8-PCDF: 21.0-24.0min; 1,2,3,4,7,8-H6CDD / F, 1,2,3,6,7,8-H6C DD / F, 1,2,3,7,8,9-H6CDD / F, 2,3,4,6,7,8-H6CDF: 24.0-35.0min; 1,2,3,4,6,7,8-H7CDD / F: 36.0-41.0min; 1,2,3,4,7,8,9-H7CDF: 42.0-45.0min; OCDD: 53.0-58.0min; OCDF: 58.0-63.0min to obtain the receiving solution, and then the concentrated solution was obtained after concentration.

7. The purification analysis method according to claim 5, characterized in that: In step (4), when high-resolution gas chromatography / triple quadrupole tandem mass spectrometry is used for detection, the detection conditions of dioxins are: injection port temperature is 280-310°C; injection volume is 50-150 μL; carrier gas: He, flow rate is 0.5-1.5 mL / min; Chromatographic column: RTX-5MS column, 60m×0.25mm×0.25μm; column temperature program: initial temperature 100-130℃, initial time 1-2min, 40℃ / min to 180-220℃, 3℃ / min to 310-315℃ and keep for 8-12min; transmission line temperature 250-300℃; ion source temperature 220-260℃; electron emission energy: 60-80ev; ion source: EI+.

8. The purification analysis method according to claim 7, characterized in that: In step (4), when high-resolution gas chromatography / triple quadrupole tandem mass spectrometer is used for detection, the detection conditions of dioxins are: injection port temperature is 290° C.; injection volume is 100 μL; carrier gas: He, flow rate is 1.0 mL / min; Chromatographic column: RTX-5MS column, 60m×0.25mm×0.25μm; column temperature program: initial temperature 120℃, initial time 1min, 40℃ / min to 200℃, 3℃ / min to 312℃ and keep for 10min; transfer line temperature 280℃; ion source temperature 240℃; electron emission energy: 70ev; Ion source: EI+.

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