A method for detecting 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water using gas chromatography

Abstract

The present invention discloses a method for detecting 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water by gas chromatography, which comprises the following steps: taking a standard stock solution of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine, performing gradient dilution with acetonitrile to obtain a series of standard working solutions, conducting gas chromatography detection, recording chromatographic data, and plotting a calibration curve and a linear regression equation; subjecting the soil sample and water sample to be tested to pretreatment and then conducting gas chromatography detection, recording the chromatographic data, substituting the peak area of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the sample into the linear regression equation, and calculating to obtain the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the sample to be tested. In the present invention, the linear relationship of the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine is good in the range of 0.50-10.0 μg / L, the linear equation is y = 22.51x + 10.76, and the correlation coefficient R<supgt;2< / supgt> = 0.9920. The gas chromatogram obtained by the method provided by the present invention has complete, clear peaks and high resolution, and has high sensitivity and accuracy.

Description

Technical Field

[0001] The invention relates to a method for detecting 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water by using gas chromatography, belonging to the technical field of pesticide detection. Background Art

[0002] 3-Chloro-2-fluoro-5-(trifluoromethyl)pyridine is a pyridine derivative with the molecular formula C 6 H 2 CIF 4 N, CAS registration number is 72537-17-8, and is often used as a pesticide intermediate.

[0003] In my country, the production and application of pyridine derivatives are increasing year by year. However, due to the stable structure of pyridine derivatives, they are difficult to biodegrade and have certain biological toxicity. Contact or inhalation of pyridine derivatives can irritate the eyes and upper respiratory tract. Long-term inhalation can cause dizziness, headache, insomnia, digestive tract dysfunction and other symptoms. Direct discharge into the soil or water environment can have a negative impact on environmental organisms. Therefore, quantitative detection of pyridine derivative residues in the environment is very important for environmental safety monitoring of their production and application sites.

[0004] At present, my country has not yet formulated a detection standard for 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine, and the qualitative and quantitative detection methods of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water are still blank. In order to avoid soil and water environmental pollution in the production and application areas of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine, it is necessary to establish a qualitative and quantitative detection method for 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water environments. Summary of the invention

[0005] In order to address the gaps in the prior art, the present invention provides a method for detecting the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water environments. Specifically, the present invention provides a method for detecting 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water using gas chromatography.

[0006] The technical solution adopted to achieve the purpose of the present invention is:

[0007] A method for detecting 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water using gas chromatography, the method comprising the following steps:

[0008] (1) Accurately weigh 0.10038 g of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard sample into a 100 mL volumetric flask, dissolve it in acetonitrile and make up to volume, shake well, and prepare a standard stock solution with a concentration of 1000.09 mg / L; take an appropriate amount of the standard stock solution and dilute it in acetonitrile to prepare a series of standard working solutions with different concentrations of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine.

[0009] (2) subjecting the series of standard working solutions prepared in step (1) to gas chromatography analysis to obtain the peak areas of the series of standard working solutions with different concentrations of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine, and plotting a calibration curve and a linear regression equation of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine with the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine as the abscissa and the peak area as the ordinate.

[0010] (3) The soil sample and water sample to be tested are subjected to gas chromatography analysis after pretreatment to obtain the peak area of ​​3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the sample. The peak area is substituted into the above linear regression equation for calculation to obtain the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the corresponding sample.

[0011] In step (1), the concentration range of the series of standard working solutions is 0.50 to 10.0 μg / L.

[0012] Preferably, the concentrations of the series of standard working solutions are 0.50 μg / L, 1.00 μg / L, 2.00 μg / L, 4.00 μg / L, 6.00 μg / L, 8.00 μg / L, and 10.0 μg / L.

[0013] The soil sample pretreatment step is: weigh 10-15g of the soil sample to be tested into a 250mL conical flask, add 50mL of acetonitrile, shake for 15-20min, take the supernatant after standing, and filter it with a 0.22μm filter membrane to obtain the soil sample solution to be tested.

[0014] The pretreatment steps of the water sample are as follows: 10 mL of the water sample to be tested is drawn into a colorimetric tube, excess potassium chloride is added to saturate it, 10 mL of acetonitrile is added to mix evenly, the supernatant is taken out, an appropriate amount of anhydrous sodium sulfate is added to remove excess water, and the water sample solution to be tested is obtained by filtering with a 0.22 μm filter membrane.

[0015] The gas chromatography analysis adopts HP-INNOWAX, 30m×0.25mm, 0.25μm chromatographic column and ECD detector.

[0016] The gas chromatography analysis conditions are:

[0017] Injection volume: 1.0 μL;

[0018] Split ratio: pulse is not split;

[0019] Temperature: vaporization chamber 250°C; detector 300°C; column box: initial temperature 60°C, hold for 10 min, increase the temperature to 120°C at a rate of 10°C / min, hold for 0 min, increase the temperature to 260°C at a rate of 50°C / min, hold for 5 min;

[0020] Gas: Carrier gas (N 2 )1mL / min; tail blowing (N 2 )30mL / min; Pressure: 5.18psi.

[0021] The method showed a linear relationship in the concentration range of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the range of 0.50 to 10.0 μg / L, with a linear regression equation of y=22.51x+10.76 and a linear correlation coefficient of R 2 =0.9920.

[0022] The LOD of this method for 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine is 100.63 ng / L, and the LOQ is 602.76 ng / L.

[0023] The beneficial effects of the present invention are:

[0024] 1. This method fills the gap in the current 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine content detection method and provides a detection method with good specificity, high efficiency, convenience, stability and reliability.

[0025] 2. This method has a peak at about 12.5min. The target peak has no interference peak at this time point, and the separation effect is good. 3-Chloro-2-fluoro-5-(trifluoromethyl)pyridine has a good linear relationship in the range of 0.50μg / L to 10.0μg / L. The linear regression equation is y=22.51x+10.76, and the linear correlation coefficient is R 2 =0.9920; RSD of target peak R.T. 0.15%, RSD Area The detection limit of this method for 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine is 100.63 ng / L, and the quantitative limit is 602.76 ng / L, which can still achieve the purpose of detection when the concentration of the sample to be tested is low.

[0026] 3. The present invention can effectively detect the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water environment, and provides a reliable technical solution for soil and water environment monitoring in the production and application areas of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine, thereby avoiding environmental pollution caused by the irregular discharge of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine. The method has the advantages of simple operation, rapidity, good repeatability, high accuracy and precision, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a calibration curve diagram of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine;

[0028] Figure 2 This is a typical spectrum of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine (8.00 μg / L);

[0029] Figure 3 It is a typical repetitive spectrum of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine (4.00 μg / L);

[0030] Figure 4 This is a typical spectrum of the detection limit of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine (0.20μg / L);

[0031] Figure 5 This is a typical spectrum of the quantification limit of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine (1.00 μg / L);

[0032] Figure 6 This is a typical graph of the recovery rate of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine added in soil (blank control);

[0033] Figure 7 This is a typical graph of the recovery rate of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil (0.1 mg / L);

[0034] Figure 8 This is a typical graph of the recovery rate of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil (1.00 mg / L);

[0035] Fig. 9 This is a typical graph of the recovery rate of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine added to water (blank control);

[0036] Fig.10 This is a typical graph of the recovery rate of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine added to water (0.1 mg / L);

[0037] Fig.11This is a typical graph of the recovery rate of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in water (10.0 mg / L). DETAILED DESCRIPTION

[0038] The following is a description of the method for analyzing and detecting the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water environments using gas chromatography according to the present invention through specific examples.

[0039] The main instruments, equipment and reagents used in the following examples and test cases include but are not limited to:

[0040] 1. Main instruments and equipment

[0041] Gas chromatograph: Agilent 8860, ECD detector;

[0042] Electronic balance: Mettler-Toledo (China) Co., Ltd., XSE205DU;

[0043] Electronic balance: Mettler-Toledo (China) Co., Ltd., MS1602S / 01;

[0044] Constant temperature culture oscillator: Shanghai Zhicheng Analytical Instrument Manufacturing Co., Ltd., ZWY-240;

[0045] Commonly used glass instruments such as volumetric flasks and pipettes.

[0046] 2. Main reagents

[0047] 3-Chloro-2-fluoro-5-(trifluoromethyl)pyridine standard, purity 99.63%;

[0048] Acetonitrile: chromatographic grade, ANPELInc.;

[0049] Potassium chloride: analytical grade, Tianjin Zhiyuan Chemical Reagent Co., Ltd.;

[0050] Anhydrous sodium sulfate: analytical grade.

[0051] 3. Samples to be tested

[0052] 1) Soil sample to be tested

[0053] The soil used in this test was purchased from the Institute of Pesticide Control of the Ministry of Agriculture and Rural Affairs, Jilin Province Gongzhuling Black Soil T2020005. The soil was air-dried and passed through a 1.0 mm sieve and stored at room temperature away from light for later use.

[0054] The preparation steps of the soil sample to be tested are as follows: weigh 10g of the prepared black soil into a 250mL conical flask, add 1mL of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard working solution diluted with acetonitrile to a concentration of 0.1mg / L, vortex mix, and prepare a soil sample to be tested with a theoretical concentration of 0.01mg / kg.

[0055] 2) Water sample to be tested

[0056] This experiment uses UP water as a representative of environmental water. UP water comes from the tap water of this laboratory and is prepared by an ultrapure water machine and can be used at any time. The resistivity of UP water is 18.2MΩ×cm.

[0057] The preparation steps of the water sample to be tested are as follows: take 1 mL of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard working solution diluted with acetonitrile to a concentration of 100 μg / L into a 100 mL volumetric flask, and make up to volume with UP water to obtain a water sample to be tested with a theoretical concentration of 1.0 μg / L.

[0058] Embodiment 1:

[0059] Gas chromatography detection of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil:

[0060] (1) Accurately weigh 0.10038 g of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard sample into a 100 mL volumetric flask, dissolve it in acetonitrile and make up to volume, shake well, and prepare a standard stock solution with a concentration of 1000.09 mg / L; take an appropriate amount of the standard stock solution and dilute it with acetonitrile to prepare a series of standard working solutions with concentrations of 0.50 μg / L, 1.00 μg / L, 2.00 μg / L, 4.00 μg / L, 6.00 μg / L, 8.00 μg / L, and 10.0 μg / L of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine.

[0061] (2) The series of standard working solutions prepared in step (1) were subjected to gas chromatography analysis. The analysis results are shown in Table 1. The concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine was used as the abscissa and the peak area was used as the ordinate to obtain a calibration curve and a linear regression equation for 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine. The linear fitting curve is shown in Table 1. Figure 1 When the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine is in the range of 0.50μg / L to 10.0μg / L, the concentration x and peak area y are linearly related. The linear regression equation y=22.51x+10.76, the linear correlation coefficient R 2 =0.9920.

[0062] Table 1: Gas chromatography analysis results of a series of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard working solutions

[0063]

[0064] (3) Pretreatment of soil samples: Weigh 10 g of the soil sample to be tested into a 250 mL conical flask, add 50 mL of acetonitrile, shake for 15 min, let stand, take the supernatant and filter it with a 0.22 μm filter membrane to obtain the soil sample solution to be tested.

[0065] (4) Sample determination and calculation: The soil sample solution to be tested in step (3) is subjected to gas chromatography analysis to obtain the peak area of ​​3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the soil sample. The peak area is substituted into the above linear regression equation for calculation to obtain the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the soil sample.

[0066] The instrument operating conditions of the gas chromatography are:

[0067] Detector: ECD;

[0068] Chromatographic column: HP-INNOWAX, 30m×0.25mm, 0.25μm

[0069] Injection volume: 1.0 μL;

[0070] Split ratio: pulse is not split;

[0071] Temperature: vaporization chamber 250°C; detector 300°C; column box: initial temperature 60°C, hold for 10 min, increase the temperature to 120°C at a rate of 10°C / min, hold for 0 min, increase the temperature to 260°C at a rate of 50°C / min, hold for 5 min;

[0072] Gas: carrier gas (N2) 1 mL / min; tail gas (N2) 30 mL / min; pressure: 5.18 psi.

[0073] Embodiment 2:

[0074] Except for the pretreatment step of the soil sample to be tested, the remaining steps are the same as those in Example 1.

[0075] The pretreatment of the soil sample to be tested in this embodiment is as follows: weigh 12 g of the soil sample to be tested into a 250 mL conical flask, add 50 mL of acetonitrile, shake for 14 min, let stand, take the supernatant and filter it with a 0.22 μm filter membrane to obtain the soil sample solution to be tested.

[0076] Embodiment 3:

[0077] Except for the pretreatment step of the soil sample to be tested, the remaining steps are the same as those in Example 1.

[0078] The pretreatment of the soil sample to be tested in this embodiment is as follows: weigh 15 g of the soil sample to be tested into a 250 mL conical flask, add 50 mL of acetonitrile, shake for 20 min, let stand, take the supernatant and filter it with a 0.22 μm filter membrane to obtain the soil sample solution to be tested.

[0079] Embodiment 4:

[0080] Gas chromatography detection of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in water:

[0081] Step (1) and step (2) are the same as in Example 1.

[0082] (3) Pretreatment of the water sample to be tested: Pipette 10 mL of the water sample to be tested into a colorimetric tube, add excess potassium chloride to saturate it, add 10 mL of acetonitrile and mix well, take out the supernatant and add an appropriate amount of anhydrous sodium sulfate to remove excess water, and filter with a 0.22 μm filter membrane to obtain the water sample solution to be tested.

[0083] (4) Sample determination and calculation: The water sample solution to be tested in step (3) is subjected to gas chromatography analysis to obtain the peak area of ​​3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the water sample, and the peak area is substituted into the above linear regression equation for calculation to obtain the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the water sample.

[0084] The instrument operating conditions of the gas chromatography are:

[0085] Detector: ECD;

[0086] Chromatographic column: HP-INNOWAX, 30m×0.25mm, 0.25μm

[0087] Injection volume: 1.0 μL;

[0088] Split ratio: pulse is not split;

[0089] Temperature: vaporization chamber 250°C; detector 300°C; column box: initial temperature 60°C, hold for 10 min, increase the temperature to 120°C at a rate of 10°C / min, hold for 0 min, increase the temperature to 260°C at a rate of 50°C / min, hold for 5 min;

[0090] Gas: carrier gas (N2) 1 mL / min; tail gas (N2) 30 mL / min; pressure: 5.18 psi.

[0091] Experimental example:

[0092] 1. Exclusivity

[0093] The GC analysis method established by the present invention was used to measure water blank samples, water added recovery rate samples, soil blank samples, and soil added recovery rate samples. The results are shown in Figure 6-Figure 11 Comparing the spectra of blank samples of water and soil and samples with added recovery rate, 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine peaked at 12.5min, and the blank sample had no interfering peak at this time point. The results showed that this method has good specificity for PyF.

[0094] 2. Repeatability

[0095] The 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard working solution with a concentration of 4.00 μg / L in Example 1 was selected for the method repeatability test, and the injection was repeated 6 times. The results are shown in Table 2. The RSDR.T. of the target peak was 0.15%, and the RSDArea was 3.36%, both less than 5.00%, indicating that this method can be used for the qualitative and quantitative analysis of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine.

[0096] Table 2: Repeatability test results

[0097]

[0098]

[0099] 3. Limit of detection and limit of quantification

[0100] The standard working solution of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine diluted with acetonitrile to a concentration of 0.20 μg / L was selected for the detection limit test, and the standard working solution of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine with a concentration of 1.00 μg / L was used for the quantification limit test. The injections were repeated 3 times, and the LOD and LOQ were calculated by S / N. The average results of the 3 analyses were shown in Table 3. The LOD of this method for 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine was 100.63 ng / L, and the LOQ was 602.76 ng / L.

[0101] Table 3: Limits of detection and quantification

[0102] Number of measurements Analytical concentration (μg / L) S / N LOD(ng / L) LOQ(ng / L) 1 0.20 6.566 91.38 - 2 0.20 6.087 98.57 - 3 0.20 5.360 111.94 - 1 1.00 16.109 - 620.77 2 1.00 17.314 - 577.57 3 1.00 16.395 - 609.94 average value - - 100.63 602.76

[0103] 4. Recovery rate of soil and water samples

[0104] 4.1 Recovery rate of soil sample addition

[0105] Weigh 10g of black soil in two 250mL conical flasks, add 1mL of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard working solution with concentrations of 0.1mg / L and 1.0mg / L respectively, vortex mix, and prepare two soil recovery samples with concentrations of 0.01mg / kg and 0.1mg / kg respectively. Add 50mL of acetonitrile to the conical flask, shake for 15min, take the supernatant after standing and filter with 0.22μm filter membrane (high concentration is diluted 5 times with acetonitrile), and determine the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine according to the gas chromatography conditions of the present invention. Each concentration sample is made in parallel for 5 times, and a soil blank test is performed at the same time.

[0106] The analysis results are shown in Table 4. Figure 6-Figure 8 The average recovery rates of two different concentrations of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil were 84.5% and 95.2%, respectively, and the standard deviations of the recovery rates were 9.3% and 6.3%, respectively.

[0107] Table 4: Recovery results of soil addition

[0108]

[0109] 4.2 Recovery rate of water sample addition

[0110] Get 1mL concentration respectively and be 0.1mg / L and 10mg / L 3-chloro-2-fluoro-5-(trifluoromethyl) pyridine standard working solution in 100mL volumetric flask, use UP water constant volume, obtain the water body recovery rate sample of 1.0μg / L and 100μg / L respectively.Get 10mL water body recovery rate sample in colorimetric tube, add excessive potassium chloride to make it saturated, add 10mL acetonitrile to mix, take out supernatant and add appropriate amount of anhydrous sodium sulfate to remove excess moisture, use 0.22μm membrane filtration (high concentration acetonitrile dilution 20 times), by gas chromatographic condition determination of the present invention wherein 3-chloro-2-fluoro-5-(trifluoromethyl) pyridine concentration.Each concentration sample is all made in parallel 5 parts, does water body blank test simultaneously.

[0111] The analysis results are shown in Table 5. Figure 9-11 The average recovery rates of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine at two different concentrations in water were 89.5% and 103.6%, respectively, and the standard deviations of the recovery rates were 10.5% and 7.0%, respectively.

[0112] Table 5: Recovery results of water addition

[0113]

[0114]

[0115] The above specific implementations are only preferred embodiments of the present invention and are not intended to limit the present invention in other forms. Any person skilled in the art may use the above disclosed technical contents to change or modify them into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for detecting the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water using gas chromatography, characterized in that: The method steps are as follows: (1) Accurately weigh 0.10038 g of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine standard sample into a 100 mL volumetric flask, dissolve it in acetonitrile and make it up to volume, shake it well, and prepare a standard stock solution with a concentration of 1000.09 mg / L; take an appropriate amount of the standard stock solution and perform gradient dilution with acetonitrile to prepare a series of standard working solutions with different concentrations of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine; (2) subjecting the series of standard working solutions prepared in step (1) to gas chromatography analysis to obtain the peak areas of the series of standard working solutions with different concentrations of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine, and plotting a calibration curve and a linear regression equation of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine with the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine as the abscissa and the peak area as the ordinate; (3) The soil sample and water sample to be tested are subjected to gas chromatography analysis after pretreatment to obtain the peak area of ​​3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the sample, and the peak area is substituted into the above linear regression equation for calculation to obtain the concentration of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in the corresponding sample; In the step (1), the concentration range of the series of standard working solutions is 0.50 to 10.0 μg / L; The soil sample pretreatment step is: weigh 10-15g of the soil sample to be tested into a 250mL conical flask, add 50mL of acetonitrile, shake for 15-20min, take the supernatant after standing, filter with a 0.22μm filter membrane to obtain the soil sample solution to be tested; The pretreatment steps of the water sample are as follows: 10 mL of the water sample to be tested is drawn into a colorimetric tube, excess potassium chloride is added to saturate it, 10 mL of acetonitrile is added to mix evenly, the supernatant is taken out, an appropriate amount of anhydrous sodium sulfate is added to remove excess water, and the water sample solution to be tested is obtained by filtering with a 0.22 μm filter membrane; The gas chromatography analysis uses HP-INNOWAX, 30m×0.25mm, 0.25μm chromatographic column, ECD detector; The gas chromatography analysis conditions are: Injection volume: 1.0 μL; Split ratio: pulse is not split; Temperature: vaporization chamber 250°C; detector 300°C; column box: initial temperature 60°C, hold for 10 min, increase the temperature to 120°C at a rate of 10°C / min, hold for 0 min, increase the temperature to 260°C at a rate of 50°C / min, hold for 5 min; Gas: carrier gas N2: 1 mL / min; tail gas N2: 30 mL / min; pressure: 5.18 psi.

2. The method for detecting the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water by gas chromatography according to claim 1, characterized in that: The concentrations of the series of standard working solutions are 0.50 μg / L, 1.00 μg / L, 2.00 μg / L, 4.00 μg / L, 6.00 μg / L, 8.00 μg / L, and 10.0 μg / L.

3. The method for detecting the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water by gas chromatography according to claim 1, characterized in that: The linear regression equation of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine is y=22.51x+10.76, and the linear correlation coefficient is R2=0.9920.

4. The method for detecting the content of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in soil and water by gas chromatography according to claim 1, characterized in that: The detection limit of the method for 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine is 100.63 ng / L, and the quantification limit is 602.76 ng / L.

Images