Method for simultaneously analyzing polychlorinated biphenyl, polycyclic aromatic hydrocarbon and organochlorine pesticide in water

Abstract

The invention discloses a method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water, which comprises the following steps: simultaneously extracting polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in a water sample by using a mixed solvent of n-hexane and dichloromethane, merging while extracting, purifying, concentrating and fixing volume, and testing on a machine in two groups, the polychlorinated biphenyl and the organochlorine pesticide are independently used as a group, the polycyclic aromatic hydrocarbon is used as a group, when an extraction solvent adopts a mixed solvent of dichloromethane and n-hexane, the extraction efficiency is gradually increased along with the increase of the proportion of the n-hexane, and when the volume ratio of the n-hexane to the dichloromethane is 9: 1, the extraction recovery rate can reach 78.9%-111%. When 1% of polyethylene glycol 4000 is added in the mixed extraction process with the volume ratio of n-hexane to dichloromethane being 9: 1, the extraction efficiency is remarkably improved, the extraction efficiency recovery rate reaches 84.6%-112%, and it is indicated that the addition of polyethylene glycol 4000 has the remarkable improvement effect. Compared with the prior art, the extraction efficiency is remarkably improved, and the accuracy and precision of the method completely meet the determination and analysis requirements for measuring complex water samples.

Description

Technical Field

[0001] The invention belongs to the field of analysis and detection, and particularly relates to a method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water. Background Art

[0002] Residues of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons (PAHs) in aquatic environments are of growing global concern. These substances are highly toxic, have long half-lives, are difficult to degrade, and are bioaccumulative. They readily enter the food chain and persist in sediments, water, and organisms for long periods of time. Accumulating through the food chain, they can adversely impact human health and the environment. In today's large-scale environmental surveys and monitoring missions, large numbers of samples are collected. Organic pollutants are unstable due to their volatility and biodegradability. Therefore, their analysis requires particular attention to timeliness: water sample pretreatment should be completed within 7-14 days of collection, and analysis should be completed within 40 days. Currently, the main methods for detecting organochlorine pesticides, PCBs, and PAHs in the environment include gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and gas chromatography-tandem mass spectrometry (GC-MS / MS). However, standard analytical methods for PCBs, OCPs, and PAHs, both domestically and internationally, primarily involve extraction, cleanup, and determination of each separately. These methods not only have long analysis cycles, affecting the timeliness of sample testing, but also have high experimental consumption, increasing testing costs, and are unable to meet the current growing demand for analysis and testing of environmental monitoring samples. Therefore, there is an urgent need for simultaneous extraction and analysis methods for the determination of persistent organic pollutants such as PCBs, OCPs, and PAHs in environmental samples. Developing rapid, simultaneous, and efficient sample pretreatment methods to improve the extraction efficiency of pretreatment and the accuracy of analytical data is of great practical significance. Summary of the Invention

[0003] In view of the existing problems in the prior art of separate extraction, purification and determination, which leads to a long analysis cycle, affects the timeliness of sample testing, and has high experimental consumption, increasing testing costs and analysis time. The present invention provides an analytical method for the simultaneous detection of organochlorine pesticides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons. The analytical method adopts a mixed extraction solvent to simultaneously extract persistent organic matter in water samples, and analyzes them separately on a machine, which has excellent analytical results.

[0004] The method of the present invention simultaneously analyzes polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides in water. The method adopts a mixed solvent of n-hexane and dichloromethane to simultaneously extract the PCBs, PAHs and organochlorine pesticides in the water sample. The extraction, purification, concentration and volume determination are completed together. The method is divided into two groups for testing on a machine: the PCBs and organochlorine pesticides are in a separate group, and the PAHs are in a separate group.

[0005] The method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water comprises the following specific pretreatment steps: taking 1000 mL of a water sample into a 2000 mL separating funnel, adding 10 ng of a substitute, then adding 20 g of sodium chloride, shaking until completely dissolved, extracting the water sample with 30 mL of a mixed solvent of n-hexane and dichloromethane, standing the sample for separation, adding 30 mL of a mixed solvent of n-hexane and dichloromethane, and repeating the extraction twice; combining the two extracts, dehydrating the extracts with anhydrous sodium sulfate, and concentrating the extracts to 1 mL with a multi-sample parallel quantitative concentrator; adding 20 ng of an internal standard; fully mixing the concentrate; and finally transferring the concentrate into a sample bottle for storage to be tested.

[0006] The method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water is characterized in that the analytical conditions of the polychlorinated biphenyls and organochlorine pesticides are as follows: chromatographic conditions: injection port: 300° C., splitless injection, injection volume 1 μL; column flow rate 1.0 mL / min, constant flow, column temperature 100° C. maintained for 6 minutes, increased to 260° C. at 20° C. / min, maintained for 0 minute, then increased to 300° C. at 5° C. / min and maintained for 13 minutes, for a total operation of 35 minutes; SIM scanning; EI ion source at 300° C.; quadrupole at 200° C.; solvent delay 15 minutes, interface temperature 300° C.; carrier gas is helium.

[0007] The present invention provides a method for simultaneously analyzing polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides in water. The PAH analysis conditions are as follows: Chromatographic conditions: Inlet: 300°C, splitless injection, injection volume: 1 μL; column flow rate: 1.0 mL / min, constant flow; column temperature: 60°C, maintained for 2 minutes, then increased at 20°C / min to 180°C, maintained for 5 minutes, then increased at 10°C / min to 290°C and maintained for 21 minutes, for a total run time of 45 minutes; SIM scanning; EI ion source: 300°C; quadrupole: 200°C; solvent delay: 9.5 minutes; interface temperature: 300°C; carrier gas: helium.

[0008] The method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water of the present invention is preferably such that the volume ratio of the mixed solvent of n-hexane and dichloromethane is 9:1.

[0009] In the method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water, the mixed extraction solvent preferably further comprises polyethylene glycol, wherein the polyethylene glycol is selected from polyethylene glycol 4000.

[0010] In the method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water, the amount of polyethylene glycol 4000 added is preferably 0.5% to 10% of the mass of the extraction solvent.

[0011] In the method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water, the amount of polyethylene glycol 4000 added is preferably 1% of the mass of the extraction solvent.

[0012] Compared with the prior art, the present invention has achieved beneficial effects in that it can simultaneously extract, purify and determine organochlorine pesticides and polychlorinated biphenyls. The extraction efficiency is significantly improved compared with the prior art by using a mixed extraction solvent. The precision and accuracy of the method fully meet the requirements of existing environmental monitoring. The specific beneficial effects are shown in the experimental results:

[0013] (1) When the extraction solvent is n-hexane, the extraction recovery rate is 56.6%-103%, and the extraction recovery rate of dichloromethane is 45.6%-89.6%. The extraction effect of n-hexane on organochlorine pesticides and polychlorinated biphenyls is better than that of dichloromethane, and the effect of dichloromethane on polycyclic aromatic hydrocarbons is better than that of n-hexane. When the extraction solvent is a mixed solvent of dichloromethane and n-hexane, the extraction efficiency gradually increases with the increase of the proportion of n-hexane. When the volume ratio of n-hexane to dichloromethane is 9:1, the extraction recovery rate can reach 78.9%-111%. When 1% polyethylene glycol 4000 is added to the mixed extraction with a volume ratio of n-hexane to dichloromethane of 9:1, the extraction efficiency is significantly improved, and the extraction efficiency recovery rate reaches 84.6%-112%, indicating that the addition of polyethylene glycol 4000 has a significant improvement effect.

[0014] (2) The experimental results show that when 0.5% by mass of polyethylene glycol 4000 is added to the mixed extraction solvent, the extraction effect has no obvious change. When 1% by mass of polyethylene glycol 4000 is added, the extraction efficiency is significantly improved. As the mass increases, the extraction efficiency decreases slightly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : Chromatograms of 26 organochlorine pesticides and polychlorinated biphenyls.

[0016] Figure 2 : Chromatograms of 16 PAHs. DETAILED DESCRIPTION

[0017] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods in the examples are conventional methods. Unless otherwise specified, the reagents used are conventional commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered a limitation of the present invention, but rather should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0018] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0019] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0020] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0021] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0022] Example 1

[0023] 1. Preparation of samples

[0024] Take 1000mL of water sample and place it in a 2000mL separating funnel. Add 10ng of substitute: concentration: 1000μg / L, amount added: 10μL, then add 20g of sodium chloride, shake until completely dissolved, extract the water sample with 30mL of n-hexane, let it stand and separate the liquid, then add 30mL of n-hexane and repeat the extraction twice. Combine the two extracts, dehydrate with anhydrous sodium sulfate, and concentrate to about 1mL using a multi-sample parallel quantitative concentrator. Add 20ng of internal standard: concentration: 1000μg / L, amount added: 20μL, mix the concentrate thoroughly, and finally transfer it to a sample bottle for storage.

[0025] 2. Instrument conditions

[0026] 2.1. The analytical conditions for polychlorinated biphenyls and organochlorines were as follows: Chromatographic conditions: Inlet: 300°C, splitless injection, injection volume 1 μL; column flow rate 1.0 mL / min, constant flow; column temperature 100°C, held for 6 min, increased at 20°C / min to 260°C, held for 0 min, then increased at 5°C / min to 300°C and held for 13 min, for a total run time of 35 min; SIM scanning; EI ion source 300°C; quadrupole 200°C; solvent delay 15 min; interface temperature 300°C; carrier gas: helium.

[0027] 2.2 PAH analysis conditions were as follows: Chromatographic conditions: Injection: 300°C, splitless injection, 1 μL injection volume; column flow rate, 1.0 mL / min, constant flow. Column temperature: 60°C, held for 2 min, then increased at 20°C / min to 180°C, held for 5 min, then increased at 10°C / min to 290°C and held for 21 min, for a total run time of 45 min; SIM scanning; EI ion source, 300°C; quadrupole, 200°C; solvent delay, 9.5 min; interface temperature, 300°C; carrier gas: helium.

[0028] 3. Drawing of calibration curve

[0029] 3.1 Organochlorine pesticides and polychlorinated biphenyls curves

[0030] A series of standard solutions containing 13 organochlorine pesticides, 9 polychlorinated biphenyls, and 2 surrogate compounds were prepared using 5mL volumetric flasks. The concentrations of the standard series were 2.00μg / L, 5.00μg / L, 10.0μg / L, 20.0μg / L, 50.0μg / L, and 100μg / L, respectively. 20μL of 1000μg / L internal standard solution was added to each solution to bring the concentration to 20.0μg / L. Analysis was performed under instrument reference conditions to obtain mass spectra of each target compound at different concentrations. A calibration curve was plotted with the ratio of the target compound to the internal standard compound concentration as the horizontal axis and the ratio of the target compound quantification ion response to the internal standard compound quantification ion response as the vertical axis.

[0031] Table 1 Calibration curves of 13 organochlorine pesticides, 9 polychlorinated biphenyls, and 2 surrogates

[0032]

[0033] 3.2 Pipette different volumes of 16 PAH mixed standard solutions and 2 surrogates respectively, and use 5mL volumetric flasks to prepare 2.00μg / L, 5.00μg / L, 10.0μg / L, 20.0μg / L, 50.0μg / L and 100μg / L. Add 20μL of 1000μg / L internal standard solution to make the concentration of each solution 20.0μg / L, dilute to the scale with n-hexane, and analyze according to the instrument reference conditions. Draw a calibration curve with the ratio of the target compound concentration to the internal standard compound concentration as the horizontal axis and the response value of the target compound quantitative ion to the response value of the internal standard compound quantitative ion as the vertical axis. The calibration curves of 16 PCB compounds and 2 PCB surrogates are shown in Table 2:

[0034] Table 2 Calibration curves of 16 PAH targets and 2 surrogates

[0035]

[0036] 4. Sample determination

[0037] The treated water samples were measured under the same instrument analysis conditions as those used to draw the calibration curve.

[0038] 5. Result calculation and presentation

[0039] 5.1 Qualitative analysis

[0040] Data was collected in full scan mode, and qualitative analysis was performed based on the relative retention time (RRT) of the target compound in the sample and the abundance ratio of the auxiliary qualifier ion to the target ion (Q) compared to that in the standard solution. The difference between the relative retention time of the target compound in the sample and the average relative retention time of the compound in the calibration curve should be within ±0.06. The relative deviation of the peak area ratio of the auxiliary qualifier ion and quantifier ion of the target compound in the sample (Q sample) and the peak area ratio of the auxiliary qualifier ion and quantifier ion of the target compound in the standard curve (Q standard) was controlled within ±30%.

[0041] 5.2 Quantitative analysis

[0042] Data were collected using the selected ion scanning (SIM) method and quantified using the internal standard method. The mass concentration of the target compound in the sample, ρi (ng / L), was calculated according to formula (1).

[0043]

[0044] Where: ρi—concentration of PAH compounds or surrogates in the sample, ng / L;

[0045] ρis—the concentration of PAHs or their surrogates according to the standard curve, μg / L;

[0046] V—sample volume, mL;

[0047] Vs—water sample volume, mL.

[0048] Example 2

[0049] 1. Sample preparation: blank sample spiked and extracted

[0050] Take 1000mL of blank sample and place it in a 2000mL separating funnel. Add 10ng of mixed standard solution and substitute each: concentration 1000μg / L, addition volume 10μL, then add 20g of sodium chloride, shake until completely dissolved, extract the water sample with 30mL of different mixed extraction solvents, let it stand and separate the liquid, then add 30mL of extraction solvent and repeat the extraction twice. After combining the extracts, dehydrate with anhydrous sodium sulfate, concentrate to about 1mL using a multi-sample parallel quantitative concentrator, add 20ng of internal standard with concentration: 1000μg / L, addition volume: 20μL, mix the concentrate thoroughly, and finally transfer it to a sample bottle for storage and test, and test the blank sample simultaneously.

[0051] 2. Instrument conditions

[0052] 2.1 Analysis conditions for organochlorine pesticides and polychlorinated biphenyls were as follows: Chromatographic conditions: Column: HP-5ms: 60m x 0.25mm x 0.25μm; Injection port: 300°C, splitless injection, injection volume 1µL; Column flow rate: 1.0mL / min, constant flow. Column temperature: 100°C, held for 6 minutes, then increased at 20°C / min to 260°C, held for 0 minutes, then increased at 5°C / min to 300°C and held for 13 minutes, for a total run time of 35 minutes. Mass spectrometry conditions: SIM scan; EI ion source: 300°C; quadrupole: 200°C; solvent delay: 15 minutes; interface temperature: 300°C; carrier gas: helium.

[0053] 2.2 PAH analysis conditions were as follows: Chromatographic conditions: Injection: 300°C, splitless injection, 1 μL injection volume; column flow rate, 1.0 mL / min, constant flow. Column temperature: 60°C, held for 2 min, then increased at 20°C / min to 180°C, held for 5 min, then increased at 10°C / min to 290°C and held for 21 min, for a total run time of 45 min; SIM scanning; EI ion source, 300°C; quadrupole, 200°C; solvent delay, 9.5 min; interface temperature, 300°C; carrier gas: helium.

[0054] 3. Selection of extraction reagents:

[0055] The experimental results are shown in Table 3 below: n-hexane, dichloromethane, n-hexane / dichloromethane volume ratios of 3:1, 5:1, and 9:1, and n-hexane + dichloromethane volume ratios of 9:1 + polyethylene glycol 4000 (the added amount is 1% of the mass of n-hexane and dichloromethane).

[0056] Table 3 Recovery rates of extractions with different extraction solvents

[0057]

[0058]

[0059] The results show that when the extraction solvent is n-hexane, the extraction recovery rate is 56.6%-103%, and the extraction recovery rate of dichloromethane is 45.6%-89.6%. n-hexane has a better extraction effect on organochlorine pesticides and polychlorinated biphenyls than dichloromethane, and dichloromethane is better than n-hexane for polycyclic aromatic hydrocarbons. When the extraction solvent is a mixed solvent of dichloromethane and n-hexane, the extraction efficiency gradually increases with the increase of the proportion of n-hexane. When the volume ratio of n-hexane to dichloromethane is 9:1, the extraction recovery rate can reach 78.9%-111%. When 1% polyethylene glycol 4000 is added to the mixed extraction with a volume ratio of n-hexane to dichloromethane of 9:1, the extraction efficiency is significantly improved, and the extraction efficiency recovery rate reaches 84.6%-112%, indicating that the addition of polyethylene glycol 4000 has a significant improvement effect.

[0060] Example 3

[0061] 1. Preparation of samples

[0062] Take 1000mL of blank sample in a 2000mL separatory funnel, add 10ng of mixed standard solution and surrogate each (1000μg / L×10μL), then add 20g of sodium chloride, shake until completely dissolved, and extract the water sample with 30mL of mixed extraction solvent (n-hexane + dichloromethane 9:1) and 1-10% mass of polyethylene glycol 4000. After standing, separate the liquid, add 30mL of the same mixed extraction solvent as the first time and repeat the extraction twice. After combining the extracts, dehydrate with anhydrous sodium sulfate and concentrate to about 1mL using a multi-sample parallel quantitative concentrator. Add 20ng of internal standard, concentration: 1000μg / L, addition volume: 20μL, mix the concentrate thoroughly, and finally transfer it to a sample bottle for testing. Test the blank sample simultaneously.

[0063] 2. Instrument conditions

[0064] 2.1 Analysis conditions for organochlorine pesticides and polychlorinated biphenyls were as follows: Chromatographic conditions: Column: HP-5ms: 60m x 0.25mm x 0.25μm; Injection port: 300°C, splitless injection, injection volume 1µL; Column flow rate: 1.0mL / min, constant flow. Column temperature: 100°C, held for 6 minutes, then increased at 20°C / min to 260°C, held for 0 minutes, then increased at 5°C / min to 300°C and held for 13 minutes, for a total run time of 35 minutes. Mass spectrometry conditions: SIM scan; EI ion source: 300°C; quadrupole: 200°C; solvent delay: 15 minutes; interface temperature: 300°C; carrier gas: helium.

[0065] 2.2 PAH analysis conditions were as follows: Chromatographic conditions: Injection: 300°C, splitless injection, 1 μL injection volume; column flow rate, 1.0 mL / min, constant flow. Column temperature: 60°C, held for 2 min, then increased at 20°C / min to 180°C, held for 5 min, then increased at 10°C / min to 290°C and held for 21 min, for a total run time of 45 min; SIM scanning; EI ion source, 300°C; quadrupole, 200°C; solvent delay, 9.5 min; interface temperature, 300°C; carrier gas: helium.

[0066] 3. Selection of mixed extractant:

[0067] The volume ratio of n-hexane to dichloromethane was 9:1, and 0.5-10% of the weight of polyethylene glycol 4000 was added to the extraction mixed solvent. The experimental results are shown in Table 4 below:

[0068] Table 4 Extraction results with different amounts of polyethylene glycol 4000

[0069]

[0070]

[0071] The experimental results show that when 0.5% by mass of polyethylene glycol 4000 is added to the mixed extraction solvent, the extraction effect has no obvious change. When 1% by mass of polyethylene glycol 4000 is added, the extraction efficiency is significantly improved. As the mass increases, the extraction efficiency decreases slightly.

Claims

1. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and organochlorine pesticides in water, characterized by: A mixed solvent of n-hexane and dichloromethane was used to simultaneously extract polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water samples. The extraction, purification, concentration and volume adjustment were completed together. When the machine was put into operation, the test was divided into two groups, with polychlorinated biphenyls and organochlorine pesticides in a separate group and polycyclic aromatic hydrocarbons in a separate group.

2. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and organochlorine pesticides in water according to claim 1, characterized in that: The specific pretreatment steps are as follows: take 1000mL of water sample into a 2000mL separatory funnel, add 10ng of the substitute, then add 20g of sodium chloride, shake until completely dissolved, extract the water sample with 30mL of a mixed solvent of n-hexane and dichloromethane, let it stand and separate the liquid, then add 30mL of a mixed solvent of n-hexane and dichloromethane and repeat the extraction twice, combine the two extracts, dehydrate with anhydrous sodium sulfate, and concentrate to 1mL using a multi-sample parallel quantitative concentrator, add 20ng of the internal standard, mix the concentrate thoroughly, and finally transfer it to a sample bottle for storage.

3. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and organochlorine pesticides in water according to claim 1, characterized in that: The analytical conditions for polychlorinated biphenyls and organochlorine are as follows: chromatographic conditions: injection port: 300°C, splitless injection, injection volume 1uL; column flow rate 1.0mL / min, constant flow, column temperature 100°C maintained for 6 minutes, increased to 260°C at 20°C / min, maintained for 0 minutes, then increased to 300°C at 5°C / min and maintained for 13 minutes, a total run time of 35 minutes; SIM scanning; EI ion source is 300°C; quadrupole rod is 200°C; solvent delay is 15 minutes, interface temperature is 300°C; carrier gas is helium.

4. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and organochlorine pesticides in water according to claim 1, characterized in that: The analysis conditions of polycyclic aromatic hydrocarbons are as follows: Chromatographic conditions: Inlet: 300°C, splitless injection, injection volume 1uL; column flow rate 1.0mL / min, constant flow; column temperature 60°C maintained for 2min, increased to 180°C at 20°C / min, maintained for 5min, then increased to 290°C at 10°C / min and maintained for 21min, for a total run time of 45min; SIM scanning; EI ion source 300°C; quadrupole 200°C; solvent delay 9.5min, interface temperature 300°C; carrier gas is helium.

5. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water according to claim 1 or 2, characterized in that: The volume ratio of the mixed solvent of n-hexane and dichloromethane is 9:

1.

6. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and organochlorine pesticides in water as claimed in claim 1 or 2, characterized in that: The mixed extraction solvent also includes polyethylene glycol 4000.

7. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water according to claim 6, characterized in that: The amount of polyethylene glycol 4000 added is 0.5% to 10% of the mass of the extraction solvent.

8. A method for simultaneously analyzing polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in water according to claim 7, characterized in that: The amount of polyethylene glycol 4000 added is 1% of the mass of the extraction solvent.

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