A gas chromatography-mass spectrometry method for simultaneous detection of tetrachlorobenzene and pentachlorobenzene in chlorothalonil

Abstract

The present invention provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in chlorothalonil. The method comprises: preparing a standard working solution and a sample solution to be tested, the standard working solution contains tetrachlorobenzene and pentachlorobenzene standards, the tetrachlorobenzene includes any one of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene or 1,2,3,4-tetrachlorobenzene or a combination of at least two; the sample solution to be tested contains a chlorothalonil sample; the standard working solution and the sample solution to be tested are separated and detected by gas chromatography and mass spectrometry; and a standard curve is prepared according to the detection results to calculate the content of tetrachlorobenzene and pentachlorobenzene in the sample to be tested. The method can obtain a stable detector response, can achieve good separation and detection of tetrachlorobenzene and pentachlorobenzene in chlorothalonil, and has high selectivity, sensitivity, repeatability and accuracy for the detection of tetrachlorobenzene and pentachlorobenzene in chlorothalonil.

Description

Technical Field

[0001] The invention belongs to the field of analytical chemistry, and specifically relates to a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in chlorothalonil, and in particular to a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in chlorothalonil with good selectivity, high sensitivity and high accuracy. Background Art

[0002] Chlorothalonil, with the chemical name of tetrachloroisophthalonitrile, is a highly effective, low-toxic broad-spectrum, protective fungicide, which is widely used in the prevention and treatment of rust, anthracnose, powdery mildew and downy mildew on fruit trees and vegetables. During the chlorination synthesis process of chlorothalonil technical, tetrachlorobenzene and pentachlorobenzene impurities are generated. Tetrachlorobenzene and pentachlorobenzene, as chlorobenzene compounds, are one of the most common environmental pollutants in the world. They are highly toxic and potentially harmful to human health. They are not easily degraded in the environment and are persistent organic pollutants. They have been listed in the "blacklist" of priority controlled pollutants and hazardous compounds by the US Environmental Protection Agency and the European Union.

[0003] In recent years, the world has paid more and more attention to the quality safety of agricultural products and the safety of the ecological environment. When my country's chlorothalonil entered the foreign market, some countries proposed a limit requirement that the content of tetrachlorobenzene and pentachlorobenzene should not exceed 4 mg / kg, which to a certain extent restricted my country's export trade of chlorothalonil.

[0004] At present, there are many research reports on chlorobenzene compounds in water bodies, soil and other environments in my country, but there are no reports on the research methods of tetrachlorobenzene and pentachlorobenzene in chlorothalonil. Therefore, it is very important to find an efficient and rapid method to detect the content of tetrachlorobenzene and pentachlorobenzene in chlorothalonil.

[0005] CN104062369A discloses a method for detecting chlorobenzene in sludge by ultrasound-assisted dispersion microextraction-gas chromatography, comprising the following steps: (1) preparation of standard solution; (2) ultrasound-assisted extraction; (3) dispersion microextraction; (4) chromatographic analysis. The detection method has high sensitivity and short analysis time, and saves a large amount of toxic reagents, and can be used for the detection of a large number of sludge samples. However, the study does not disclose a method for detecting chlorobenzene compounds in thiophanate-methyl.

[0006] CN108152397A discloses a method for simultaneously detecting hexachlorobutadiene, pentachlorobenzene and hexachlorobenzene in fly ash from garbage incineration, comprising the following steps: (1) sample pretreatment; (2) ultrasonic extraction; (3) purification; (4) gas chromatography-mass spectrometry detection; (5) establishment of a standard curve and acquisition of quantitative results. The detection method is simple to operate and has high sensitivity. It can ensure a good recovery rate while removing impurities, thus filling the gap in the analytical detection method of hexachlorobutadiene in fly ash. However, the detection method in this study cannot be directly used for the detection of chlorobenzene compounds in thiophanate-methyl, and the study does not disclose the detection method of tetrachlorobenzene.

[0007] CN112098564A discloses an HPLC detection method for simultaneously detecting hexachlorobenzene and decachlorobiphenyl in chlorothalonil, comprising the following steps: using a standard working solution prepared from hexachlorobenzene and decachlorobiphenyl standards and a sample solution prepared from a chlorothalonil sample to be tested, using water and acetonitrile as mobile phases, and using a C18 reverse phase chromatographic column to perform HPLC detection, and calculating the contents of hexachlorobenzene and decachlorobiphenyl in the sample to be tested according to the test results. This method can simultaneously detect hexachlorobenzene and decachlorobiphenyl in chlorothalonil at one time, with good separation effect, high sensitivity, high accuracy and precision. However, the study did not disclose the relevant content of the detection of tetrachlorobenzene and pentachlorobenzene in chlorothalonil.

[0008] Based on the above research, there is currently no method for the simultaneous detection of tetrachlorobenzene and pentachlorobenzene in chlorothalonil. Therefore, finding a method with high sensitivity, high selectivity and accuracy to simultaneously detect tetrachlorobenzene and pentachlorobenzene in chlorothalonil is an urgent problem to be solved. Summary of the invention

[0009] In view of the shortcomings of the prior art and the actual needs, the purpose of the present invention is to provide a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in chlorothalonil. The detection method provided by the present invention has the advantages of high sensitivity, good selectivity and high accuracy, and can simultaneously detect the content of tetrachlorobenzene and pentachlorobenzene in chlorothalonil, which has great practical significance.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] The present invention provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in chlorothalonil, the method comprising the following steps:

[0012] (1) preparing a standard working solution and a sample solution to be tested, wherein the standard working solution contains tetrachlorobenzene and pentachlorobenzene standard samples, and the sample solution to be tested contains a thiophanate-methyl sample;

[0013] (2) separating and detecting the standard working solution and the sample solution to be tested described in step (1) by gas chromatography and mass spectrometry;

[0014] (3) preparing a standard curve according to the test results obtained in step (2), and calculating the contents of tetrachlorobenzene and pentachlorobenzene in the sample to be tested;

[0015] The tetrachlorobenzene described in step (1) includes any one of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene or 1,2,3,4-tetrachlorobenzene, or a combination of at least two thereof.

[0016] The detection method provided by the present invention adopts a gas chromatography-mass spectrometry method to detect a thiophanate-methyl sample, which can achieve good separation and accurate detection of tetrachlorobenzene isomers and pentachlorobenzene in thiophanate-methyl, improves the analysis efficiency, and the obtained detection results have high selectivity, sensitivity, repeatability and accuracy.

[0017] At the same time, the detection method can detect tetrachlorobenzene isomers and pentachlorobenzene in chlorothalonil, and realize the separation of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene and 1,2,3,4-tetrachlorobenzene, which has important practical significance for the preparation of chlorothalonil fungicide that meets industry standards.

[0018] Preferably, the chromatographic column of the gas chromatography comprises a DB-5ms (5% phenyl-95% dimethylpolysiloxane) capillary column, or other chromatographic columns with the same stationary phase, preferably a DB-5ms capillary column;

[0019] Preferably, the specification of the chromatographic column is 30×0.25 mm (inner diameter) and the membrane thickness is 0.25 μm.

[0020] Preferably, the gas chromatography injection mode is pulsed splitless injection.

[0021] Preferably, the injection pulse pressure of the gas chromatograph is 50-70 kPa, for example, it can be 50 kPa, 52 kPa, 54 kPa, 56 kPa, 58 kPa, 60 kPa, 62 kPa, 64 kPa, 66 kPa, 68 kPa or 70 kPa, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0022] Preferably, the injection volume of the gas chromatograph is 0.8-1.2 μL, for example, 0.8 μL, 0.9 μL, 1 μL, 1.1 μL or 1.2 μL, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0023] The specific injection volume, method and injection pulse pressure can improve the sensitivity of detecting trace tetrachlorobenzene and pentachlorobenzene in the sample.

[0024] Preferably, the carrier gas of the gas chromatography is helium, and the purity of the helium is ≥99.999%.

[0025] Preferably, the flow rate of the chromatographic column is 0.8-1.2 mL / min, for example, 0.8, 0.9, 1, 1.1 or 1.2 mL / min, but is not limited to the listed values, and other values ​​not listed within the above ranges are also applicable.

[0026] The above-mentioned specific carrier gas and flow rate have no interference with the measurement and have good separation performance and high column efficiency.

[0027] Preferably, the injection port temperature of the gas chromatograph is 260-300°C, for example, it can be 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, 295°C or 300°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0028] The above-mentioned specific injection port temperature can ensure that each component in the sample is completely vaporized.

[0029] Preferably, the temperature of the chromatographic column of the gas chromatography is programmed.

[0030] Preferably, the programmed temperature rise includes a heat preservation stage, a first temperature rise stage and a second temperature rise stage in sequence;

[0031] Preferably, the temperature in the insulation stage is 60-80°C, for example, it can be 60°C, 62°C, 64°C, 68°C, 69°C, 71°C, 73°C, 75°C, 77°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0032] Preferably, the holding time of the insulation stage is 0.5 to 1 min, for example, it can be 0.5 min, 0.6 min, 0.7 min, 0.9 min or 1.0 min, but it is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0033] Preferably, the starting temperature of the first temperature rising stage is the temperature of the temperature keeping stage.

[0034] Preferably, the termination temperature of the first heating stage is 120-130°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0035] Preferably, the heating rate in the first heating stage is 3 to 8°C / min, for example, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min or 8°C / min, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0036] Preferably, the holding time of the first heating stage is 2 to 4 minutes, for example, 2 minutes, 2.5 minutes, 3.0 minutes, or 4.0 minutes, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0037] Preferably, the end temperature of the first heating stage is the start temperature of the second heating stage.

[0038] Preferably, the termination temperature of the second heating stage is 280-320°C, for example, it can be 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C or 320°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0039] Preferably, the heating rate of the second heating stage is 35-45°C / min, for example, it can be 35°C / min, 37°C / min, 39°C / min, 41°C / min, 43°C / min or 45°C / min, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0040] Preferably, the holding time of the second heating stage is 1 to 3 minutes, for example, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes or 3 minutes, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0041] The combination of the above-mentioned specific parameters can reduce the peak broadening phenomenon caused by the solvent effect on the early eluting components during the splitless injection process, and realize the effective chromatographic separation of the tetrachlorobenzene isomers 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene in chlorothalonil within a suitable time, and the results are more accurate.

[0042] Preferably, the ionization mode of the mass spectrometer includes electron bombardment ionization.

[0043] Preferably, the electron energy of the electron bombardment ionization is 60-80eV, for example, it can be 60eV, 62eV, 64eV, 66eV, 68eV, 70eV, 72eV, 74eV, 76eV, 78eV or 80eV, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0044] Preferably, the GC-MSD interface temperature in the mass spectrometer is 280°C to 320°C, for example, it can be 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C or 320°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0045] Preferably, the ion source temperature in the mass spectrometer is 220-240°C, for example, it can be 220°C, 222°C, 224°C, 226°C, 228°C, 230°C, 232°C, 234°C, 236°C, 238°C or 240°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0046] Preferably, the quadrupole temperature in the mass spectrometer is 140-160°C, for example, it can be 140°C, 142°C, 144°C, 146°C, 148°C, 150°C, 152°C, 154°C, 156°C, 158°C or 160°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0047] Preferably, the multiplier voltage in the mass spectrometer is an automatically tuned value.

[0048] Preferably, the solvent delay time in the mass spectrum is 10.0 to 15.0 min, for example, it can be 10 min, 10.5 min, 11 min, 11.5 min, 12 min, 12.5 min, 13 min, 13.5 min, 14 min, 14.5 min or 15 min, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0049] Preferably, the detector closing time in the mass spectrometer is 19.0 to 21.0 min, for example, it can be 19.0 min, 19.3 min, 19.5 min, 19.7 min, 19.9 min, 20.1 min, 20.3 min, 20.5 min, 20.7 min or 21.0 min, but is not limited to the above-listed values, and other unlisted values ​​within the above-mentioned numerical ranges are also applicable.

[0050] The above-mentioned specific detector off time can prevent high concentration of thiophanate-methyl matrix from contaminating the mass spectrometer detector, thereby obtaining a more stable and sensitive detector response.

[0051] Preferably, the mass spectrometer is scanned in selected ion monitoring mode (SIM);

[0052] Preferably, the start time, quantitative ions and qualitative ions of each group of detected ions in the selected ion monitoring mode are as shown in Table 1 below:

[0053] Table 1

[0054]

[0055] The above-mentioned specific quantitative ions and qualitative ions can improve the selectivity, sensitivity and qualitative accuracy of detection.

[0056] Preferably, the gas chromatography-mass spectrometry detection method adopts external standard method for quantification.

[0057] In the present invention, the preparation method of the standard working solution in step (1) can be prepared by the following steps:

[0058] 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene standards were placed in volumetric flasks respectively, solvent was added to dissolve by shaking and the volume was fixed to obtain a single standard stock solution; the single standard stock solutions were then mixed and diluted to obtain standard working solutions of different concentrations.

[0059] Preferably, the solvent comprises toluene.

[0060] Preferably, the mixing comprises the following steps: taking a single standard stock solution in the same container, and diluting it to obtain an intermediate dilution.

[0061] Preferably, different volumes of the intermediate dilution solution are taken for further dilution to obtain standard working solutions of different concentrations.

[0062] Preferably, the solvent comprises toluene.

[0063] The toluene has better solubility for chlorothalonil and its impurities tetrachlorobenzene and pentachlorobenzene, and has no interference with the determination of tetrachlorobenzene and pentachlorobenzene in the sample, and can improve the accuracy and sensitivity of the detection.

[0064] Preferably, the concentration of the single standard stock solution is 60-140 μg / mL, for example, it can be 60 μg / mL, 70 μg / mL, 80 μg / mL, 90 μg / mL, 100 μg / mL, 110 μg / mL, 120 mg / mL, 130 μg / mL or 140 μg / mL, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0065] Preferably, the concentration of the intermediate diluent is 4 to 6 μg / mL, for example, 4 μg / mL, 4.5 μg / mL, 5 μg / mL, 5.5 μg / mL or 6 μg / mL, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0066] Preferably, the concentration range of the standard working solutions of different concentrations is consistent with the concentration range of the corresponding components in the sample solution to be tested.

[0067] Preferably, the concentration of 1,2,3,5-tetrachlorobenzene in the standard working solution is 0.01 to 0.2 μg / mL, for example, 0.01 μg / mL, 0.02 μg / mL, 0.03 μg / mL, 0.04 μg / mL, 0.05 μg / mL, 0.06 μg / mL, 0.07 μg / mL, 0.08 μg / mL, 0.09 μg / mL, 0.1 μg / mL, 0.11 μg / mL, 0.12 μg / mL, 0.13 μg / mL, 0.14 μg / mL, 0.15 μg / mL, 0.16 μg / mL, 0.17 μg / mL, 0.18 μg / mL, 0.19 μg / mL or 0.2 μg / mL, but is not limited to the listed values, and other values ​​not listed within the above numerical ranges are equally applicable.

[0068] Preferably, the concentration of 1,2,4,5-tetrachlorobenzene in the standard working solution is 0.01-0.2 μg / mL, for example, 0.01 μg / mL, 0.02 μg / mL, 0.03 μg / mL, 0.04 μg / mL, 0.05 μg / mL, 0.06 μg / mL, 0.07 μg / mL, 0.08 μg / mL, 0.09 μg / mL, 0.1 μg / mL, 0.11 μg / mL, 0.12 μg / mL, 0.13 μg / mL, 0.14 μg / mL, 0.15 μg / mL, 0.16 μg / mL, 0.17 μg / mL, 0.18 μg / mL, 0.19 μg / mL or 0.2 μg / mL, but is not limited to the listed values, and other values ​​not listed within the above numerical ranges are also applicable. .

[0069] Preferably, the concentration of 1,2,3,4-tetrachlorobenzene in the standard working solution is 0.01-0.2 μg / mL, for example, 0.01 μg / mL, 0.02 μg / mL, 0.03 μg / mL, 0.04 μg / mL, 0.05 μg / mL, 0.06 μg / mL, 0.07 μg / mL, 0.08 μg / mL, 0.09 μg / mL, 0.1 μg / mL, 0.11 μg / mL, 0.12 μg / mL, 0.13 μg / mL, 0.14 μg / mL, 0.15 μg / mL, 0.16 μg / mL, 0.17 μg / mL, 0.18 μg / mL, 0.19 μg / mL or 0.2 μg / mL, but is not limited to the listed values, and other values ​​not listed within the above numerical ranges are also applicable. .

[0070] Preferably, the concentration of pentachlorobenzene in the standard working solution is 0.01-0.2 μg / mL, for example, 0.01 μg / mL, 0.02 μg / mL, 0.03 μg / mL, 0.04 μg / mL, 0.05 μg / mL, 0.06 μg / mL, 0.07 μg / mL, 0.08 μg / mL, 0.09 μg / mL, 0.1 μg / mL, 0.11 μg / mL, 0.12 μg / mL, 0.13 μg / mL, 0.14 μg / mL, 0.15 μg / mL, 0.16 μg / mL, 0.17 μg / mL, 0.18 μg / mL, 0.19 μg / mL or 0.2 μg / mL, but is not limited to the listed values, and other values ​​not listed within the above numerical ranges are equally applicable.

[0071] The concentration and dilution multiple of the specific single standard stock solution in the present invention facilitate the preparation of a standard working solution that is close to the content range of the component to be tested in the sample to be tested, and can ensure that the standard working solution is accurately prepared while using less solvent and standard sample, which can effectively reduce the use of toxic and harmful reagents.

[0072] The concentration range of the specific standard stock solution in the present invention can improve the accuracy of quantification.

[0073] Preferably, the method for preparing the test sample solution in step (1) comprises the following steps: diluting the thiophanate-methyl sample with a solvent, dissolving it by shaking under ultrasound, cooling it to room temperature of 18 to 28° C., and shaking it well to obtain the test sample solution.

[0074] Preferably, the ultrasound time is 10 to 15 minutes, for example, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0075] Preferably, the power of the ultrasound is 30 to 50 kHz, for example, it can be 30 kHz, 32 kHz, 34 kHz, 36 kHz, 38 kHz, 40 kHz, 42 kHz, 44 kHz, 46 kHz, 48 kHz or 50 kHz, but is not limited to the listed values, and other unlisted values ​​within the above numerical ranges are also applicable.

[0076] Preferably, the diluting solvent comprises toluene.

[0077] Preferably, the concentration of the thiophanate-methyl sample in the sample solution to be tested is 15-25 mg / mL, for example, it can be 15 mg / mL, 16 mg / mL, 17 mg / mL, 18 mg / mL, 19 mg / mL, 20 mg / mL, 21 mg / mL, 22 mg / mL, 23 mg / mL, 24 mg / mL or 25 mg / mL, but is not limited to the listed values, and other values ​​not listed within the above numerical ranges are also applicable.

[0078] The concentration and dilution ratio of the above-mentioned specific test sample solution can meet the needs of sensitive detection of tetrachlorobenzene and pentachlorobenzene in the chlorothalonil sample, and can ensure complete dissolution of the sample under the premise of small weighing error and small amount of reagent used.

[0079] As a preferred technical solution, the present invention provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in chlorothalonil, the method comprising the following steps:

[0080] (1) 1,2,3,5-tetrachlorobenzene standard, 1,2,4,5-tetrachlorobenzene standard, 1,2,3,4-tetrachlorobenzene standard and pentachlorobenzene standard were mixed with toluene respectively, and ultrasonically dissolved to prepare a single standard stock solution; then mixed and diluted to obtain standard working solutions of different concentrations;

[0081] Take a sample of thiophanate-methyl, add toluene, shake and dissolve under ultrasound, and cool to obtain a sample solution to be tested;

[0082] (2) separating and detecting the standard working solution and the sample solution to be tested described in step (1) by gas chromatography and mass spectrometry;

[0083] The gas chromatography conditions are as follows: the temperature of the chromatographic column is programmed to rise, 60-80°C for 0.5-1 min, then rise to 120-130°C at 3-8°C / min, and hold for 2-4 min, then rise to a final column temperature of 280-320°C at 35-45°C / min, and hold for 1-3 min; the carrier gas is helium, purity ≥99.999%, flow rate 0.8-1.2 ml / min. The injection port temperature is 260-300°C; the injection volume is 0.8-1.2 μL; the injection method is pulsed splitless injection, and the pulse pressure is 50-70 kPa;

[0084] The mass spectrometry conditions were set as follows: the ionization mode was electron impact ionization (EI), the ionization energy was 60-80 eV, the GC-MSD interface temperature was 280-320 °C; the ion source temperature was 220-240 °C; the quadrupole temperature was 140-160 °C; the multiplier voltage was the automatic tuning value; the solvent delay time was 10.0-15.0 min; the detector off time was 19.0-21.0 min; the mass spectrometry scanning mode was the selected ion monitoring mode, and the start time of each group of detection ions in the selected ion monitoring mode, the quantitative ion and the qualitative ion setting parameters were The data are as follows: the starting detection time of tetrachlorobenzene is 10-15min; the starting detection time of pentachlorobenzene is 18-18.6min; the mass-to-charge ratio of the quantitative ion of tetrachlorobenzene is 216m / z; the mass-to-charge ratio of the first qualifier ion of tetrachlorobenzene is 214m / z; the mass-to-charge ratio of the second qualifier ion of tetrachlorobenzene is 218m / z; the mass-to-charge ratio of the quantitative ion of pentachlorobenzene is 250m / z; the mass-to-charge ratio of the first qualifier ion of pentachlorobenzene is 248m / z; the mass-to-charge ratio of the second qualifier ion of pentachlorobenzene is 252m / z;

[0085] (3) preparing a standard curve according to the test results obtained in step (2), and calculating the contents of tetrachlorobenzene and pentachlorobenzene in the thiophanate-methyl sample;

[0086] In a second aspect, the present invention provides an application of the gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl as described in the first aspect in the preparation of thiophanate-methyl fungicide.

[0087] The detection method provided by the invention has good selectivity, high sensitivity and a wide range of applications.

[0088] Compared with the prior art, the present invention has the following beneficial effects:

[0089] The present invention optimizes gas chromatography operating conditions and mass spectrometry conditions, so that the gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl provided by the present invention has the advantages of high selectivity, high sensitivity, repeatability and high accuracy.

[0090] The method described in the invention is used for detection. In the obtained detection results, the relative standard deviation of tetrachlorobenzene is between 1.9 and 6.8%, and the recovery rate of spike addition is between 97.2 and 103.2%. The relative standard deviation of pentachlorobenzene is between 1.8 and 5.9%, and the recovery rate of spike addition is between 98.1 and 102.8%. The method has good linear relationship, and the concentrations of tetrachlorobenzene and pentachlorobenzene in the range of 0.01 to 0.2 μg / mL show good linear correlation with the quantitative ion peak area. The method has high sensitivity, and the detection limits (LOD) of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene are all 0.05 mg / kg, and the quantitation limits (LOQ) are all 0.2 mg / kg. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 is the selected ion chromatogram of the 0.1 μg / mL standard working solution in Example 1, wherein peak 1-1,2,3,5-tetrachlorobenzene, peak 2-1,2,4,5-tetrachlorobenzene, peak 3-1,2,3,4-tetrachlorobenzene, peak 4-pentachlorobenzene;

[0092] Figure 2 is the selected ion chromatogram of the 0.05 μg / mL standard working solution in Example 1, wherein Peak 1-1,2,3,5-tetrachlorobenzene, Peak 2-1,2,4,5-tetrachlorobenzene, Peak 3-1,2,3,4-tetrachlorobenzene, Peak 4-pentachlorobenzene;

[0093] Figure 3 is the selected ion chromatogram of the 0.025 μg / mL standard working solution in Example 1, wherein Peak 1-1,2,3,5-tetrachlorobenzene, Peak 2-1,2,4,5-tetrachlorobenzene, Peak 3-1,2,3,4-tetrachlorobenzene, Peak 4-pentachlorobenzene;

[0094] Figure 4 It is the selected ion chromatogram of the first detection of the sample solution in Example 1, wherein Peak 1-1,2,3,5-tetrachlorobenzene, Peak 2-1,2,4,5-tetrachlorobenzene, Peak 3-1,2,3,4-tetrachlorobenzene, Peak 4-pentachlorobenzene;

[0095] Figure 5 It is the selected ion chromatogram of the second detection of the sample solution in Example 1, wherein Peak 1-1,2,3,5-tetrachlorobenzene, Peak 2-1,2,4,5-tetrachlorobenzene, Peak 3-1,2,3,4-tetrachlorobenzene, Peak 4-pentachlorobenzene;

[0096] Figure 6 This is the standard curve of 1,2,3,5-tetrachlorobenzene;

[0097] Figure 7 This is the standard curve of 1,2,4,5-tetrachlorobenzene;

[0098] Figure 8 This is the standard curve of 1,2,3,4-tetrachlorobenzene;

[0099] Fig. 9 This is the standard curve of pentachlorobenzene. DETAILED DESCRIPTION

[0100] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0101] In the following examples, the gas chromatograph-mass spectrometer was Agilent 7890B / 5977B;

[0102] The chromatographic column was a DB-5ms capillary column with specifications of 30 × 0.25 mm (inner diameter) and a film thickness of 0.25 μm;

[0103] The balance was purchased from METTLER TOLEDO, model ME204 / 02;

[0104] 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene standards were purchased from Dr. Ehrenstorfer, with a mass fraction of not less than 98.0%;

[0105] The samples of chlorothalonil were all from Jiangsu Xinhe Agricultural Chemical Co., Ltd., and the model was 98.5% chlorothalonil technical drug;

[0106] Other materials and reagents were obtained from commercial sources unless otherwise specified.

[0107] Preparation of standard working solutions: Accurately weigh 0.01 g (accurate to 0.0001 g) of 1,2,3,5-tetrachlorobenzene standard, 1,2,4,5-tetrachlorobenzene standard, 1,2,3,4-tetrachlorobenzene standard and pentachlorobenzene standard into four 100 mL volumetric flasks, add appropriate amount of toluene and ultrasonically dissolve, cool to room temperature and dilute to scale with toluene, shake well, and prepare a single standard stock solution of 100 μg / mL; use a pipette to take each of the above single standard stock solutions 2.5 mL of the mixed solution was placed in a 50 mL volumetric flask, diluted to the mark with toluene, and shaken to prepare an intermediate dilution of 5.0 μg / mL; 2 mL, 1 mL, and 0.5 mL of the mixed intermediate dilution were taken out with a pipette, respectively placed in three 100 mL volumetric flasks, diluted to the mark with toluene, and shaken to prepare a series of standard working solutions of 0.1 μg / mL (C1), 0.05 μg / mL (C2), and 0.025 μg / mL (C3) for use.

[0108] Preparation of the sample solution to be tested: Weigh 0.2 g (accurate to 0.0001 g) of chlorothalonil sample and place it in a stoppered glass bottle. Use a pipette to add 10 mL of toluene, shake it in an ultrasonic bath for 10 min to dissolve it, cool it to 25°C, shake it well and set aside.

[0109] Example 1

[0110] The present embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the gas chromatography conditions are set as follows: the chromatographic column temperature is programmed to maintain at 70°C for 0.5 min, then to 125°C at 5°C / min, maintained for 3 min, then to a final column temperature of 300°C at 40°C / min, maintained for 2 min; the carrier gas is helium with a purity of ≥99.999% and a flow rate of 1.0 mL / min. The injection port temperature was 280°C; the injection volume was 1.0 μL; the injection mode was pulsed splitless injection, and the pulse pressure was 68 kPa; the mass spectrometry conditions were set as follows: the ionization mode was electron impact ionization (EI), the ionization energy was 70 eV, and the GC-MSD interface temperature was 300°C; the ion source temperature was 230°C; the quadrupole temperature was 150°C; the multiplier voltage was the automatic tuning value; the solvent delay time was 12.0 min; the detector off time was 19.5 min; the mass spectrometry scanning mode was selected ion monitoring mode (SIM), and the retention time, quantitative ion and qualitative ion and their abundance ratio of each component are shown in Table 1.

[0111] Table 1

[0112]

[0113] Under the above-mentioned gas chromatography-mass spectrometry operating conditions, after the instrument baseline is stable, several injections of C2 standard working solution are continuously injected in SIM mode until the relative change in the peak area of ​​two adjacent injections of tetrachlorobenzene (pentachlorobenzene) is less than 10%, and then the injection and determination are carried out in the order of C3, C2, C1, the first sample solution to be tested, the second sample solution to be tested, C3, C2, and C1.

[0114] The results are as follows Figure 1-5 As shown, Figure 1 The test results of the standard working solution of 0.1μg / mL are as follows: Figure 2 The standard working solution is 0.05 μg / mL. Figure 3 The test result of the standard working solution of 0.025μg / mL is Figure 4 The test result of the sample solution to be tested for the first time is: Figure 5This is the test result of the second test of the sample solution. It can be seen that the retention times of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene in the sample solution are consistent with those of the standard working solutions of different concentrations, and the peaks are sharp and symmetrical. There are no interfering chromatographic peaks around the test object, and the separation of each component is good, especially the difficult-to-separate components 1,2,3,5-tetrachlorobenzene and 1,2,4,5-tetrachlorobenzene are well separated, indicating that the detection method provided by the present invention has good selectivity and high accuracy.

[0115] Example 2

[0116] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein except that the initial temperature of the chromatographic column is maintained at 60° C. for 0.5 min, the other parameter settings and operations are the same as those in Example 1.

[0117] Example 3

[0118] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein except that the initial temperature of the chromatographic column is maintained at 80° C. for 1 min, the other parameter settings and operations are the same as those in Example 1.

[0119] Example 4

[0120] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the final column temperature in the programmed temperature rise of the chromatographic column is 320° C.; the other parameter settings and operations are the same as those in Example 1.

[0121] Example 5

[0122] The present embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the temperature rising stage in the programmed temperature rising of the chromatographic column is set to be maintained at 75°C for 0.7 min, then heated to 130°C at 10°C / min, maintained for 2 min, and then heated to a final column temperature of 280°C at 35°C / min, the other parameter settings and operations are the same as those in Example 1.

[0123] Example 6

[0124] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein except that the column flow rate is 0.8 mL / min, the other parameter settings and operations are the same as those in Example 1.

[0125] Example 7

[0126] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein except that the column flow rate is 1.2 mL / min, the other parameter settings and operations are the same as those in Example 1.

[0127] Example 8

[0128] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the solvent removal delay time is 10 minutes, and the other parameter settings and operations are the same as those in Example 1.

[0129] Example 9

[0130] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the mass spectrometry conditions are set to a GC-MSD interface temperature of 280°C and an ion source temperature of 210°C, and the other parameter settings and operations are the same as those in Example 1.

[0131] Example 10

[0132] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the injection volume is 1.2 μL and the pulse pressure is 60 kPa; the other parameter settings and operations are the same as those in Example 1.

[0133] Embodiment 11

[0134] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the final column temperature in the programmed temperature rise of the chromatographic column is 270° C.; the other parameter settings and operations are the same as those in Example 1.

[0135] Example 12

[0136] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the chromatographic column is a DB-1 chromatographic column; the other parameter settings and operations are the same as those in Example 1.

[0137] Embodiment 13

[0138] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein the initial temperature of the chromatographic column is maintained at 100° C. for 2 min; the other parameter settings and operations are the same as those in Example 1.

[0139] Embodiment 14

[0140] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein except that the column flow rate is 1.5 mL / min, the other parameter settings and operations are the same as those in Example 1.

[0141] Embodiment 15

[0142] This embodiment provides a gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, wherein except that the detector closing time is 21.5 min; the other parameter settings and operations are the same as those in Example 1.

[0143] Statistics of test results of various embodiments

[0144] (1) Drawing of standard curve and calculation of results

[0145] The test results in Examples 1-15 were calculated to obtain the contents of tetrachlorobenzene and pentachlorobenzene in the sample solution to be tested, wherein the calculation process is as follows:

[0146] Calculate the average peak area of ​​the quantitative ion of each component in the standard solution measured twice before and after, draw the standard working curve with the standard solution concentration as the horizontal axis and the average peak area of ​​the quantitative ion as the vertical axis, and fit the linear regression equation.

[0147] According to the peak area of ​​the quantitative ions of tetrachlorobenzene (3 isomeric compounds) and pentachlorobenzene in the sample solution, the mass concentration x of tetrachlorobenzene (3 isomeric compounds) and pentachlorobenzene can be obtained from the standard curve. i The mass fractions of tetrachlorobenzene (3 isomeric compounds) and pentachlorobenzene in the sample are calculated according to formula (1):

[0148]

[0149] Where:

[0150] ω1—mass fraction of tetrachlorobenzene isomers and pentachlorobenzene in the sample, expressed in mg / kg;

[0151] x i —The mass concentration of tetrachlorobenzene isomers and pentachlorobenzene in the sample solution calculated from the standard curve, μg / mL;

[0152] 10—The volume of toluene solvent used to dissolve the sample, mL;

[0153] m—mass of the sample, g.

[0154] The results are shown in Table 2:

[0155] Table 2

[0156]

[0157]

[0158] From the data results of Examples 1 to 10 in Table 2, it can be seen that the detection method provided by the present invention has a small effect on the detection results when the experimental conditions change within the preferred range, the coefficient of variation of the results is small, and the detection method has high robustness.

[0159] It can be seen from the data results of Examples 11 to 15 in Table 2 that, compared with Examples 1-10, the results of Examples 11-15 have low precision and large differences in results.

[0160] By comparing Example 1 and Example 11, it can be seen that the final column temperature in the programmed temperature rise of the chromatographic column has a great influence on the measurement result. If the final column temperature is too low, the high boiling point components in the sample, including the main component, cannot flow out of the column.

[0161] By comparing Example 1 and Example 12, it can be seen that the selection of the chromatographic column has a great influence on the measurement results. When the DB-1 chromatographic column is selected for separation, the components in the sample flow out too fast and the impurity components cannot be effectively separated, especially the separation of 1,2,3,5-tetrachlorobenzene and 1,2,4,5-tetrachlorobenzene is poor.

[0162] By comparing Example 1 and Example 14, it can be seen that the flow rate of the chromatographic column has a great impact on the measurement results, because the flow rate of the chromatographic column is too high, resulting in poor component separation, especially the separation effect of 1,2,3,5-tetrachlorobenzene and 1,2,4,5-tetrachlorobenzene will be seriously affected.

[0163] By comparing Example 1 and Example 15, it can be seen that the setting of the detector closing time has a great influence on the measurement results. If the detector closing time is set too late, thiophanate-methyl will enter the analysis system, contaminate the ion source, and deteriorate the detection sensitivity and repeatability.

[0164] (2) Linear correlation and detection limit and quantification limit test:

[0165] Prepare 0.2 μg / mL, 0.1 μg / mL, 0.05 μg / mL, 0.025 μg / mL, 0.01 μg / mL, etc. 5 concentration levels of tetrachlorobenzene and pentachlorobenzene mixed standard solutions, and inject them according to the chromatography-mass spectrometry conditions and steps in Example 1, measure the peak area, plot the standard curve with the concentration of the standard solution as the abscissa and the quantitative ion peak area as the ordinate, and establish a linear equation.

[0166] The linear range, linear equation and linear correlation coefficient (r 2 ) See Table 3, standard curve diagram see Figure 6 (1,2,3,5-Tetrachlorobenzene standard curve), Figure 7 (1,2,4,5-Tetrachlorobenzene standard curve), Figure 8 (1,2,3,4-Tetrachlorobenzene standard curve) and Fig. 9 (Petrochlorobenzene standard curve).

[0167] A low concentration of tetrachlorobenzene and pentachlorobenzene mixed standard solution was added to the blank sample, and the sample was injected according to the chromatography-mass spectrometry conditions and steps in Example 1, the peak area was determined, and the determination was repeated 7 times for each concentration. The results were calculated according to the standard curve obtained from the linear correlation test. The spiked level corresponding to 3 times the signal-to-noise ratio was taken as the detection limit (LOD), and the spiked level corresponding to 10 times the signal-to-noise ratio was taken as the quantification limit (LOQ). The detection limits and quantification limits of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene are shown in Table 3.

[0168] Table 3

[0169]

[0170]

[0171] The results show that the concentrations of tetrachlorobenzene and pentachlorobenzene in the range of 0.01 to 0.2 μg / mL show a good linear correlation with the quantitative ion peak area, indicating that the method provided by the present invention has a good linear relationship.

[0172] The detection limits (LOD) of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene were all 0.05 mg / kg, and the quantification limits (LOQ) were all 0.2 mg / kg. This indicates that the method provided by the present invention has high sensitivity and can meet the detection requirements of tetrachlorobenzene and pentachlorobenzene in chlorothalonil samples.

[0173] (3) Precision test and recovery test:

[0174] Three levels of tetrachlorobenzene and pentachlorobenzene mixed standard solutions were added to the same sample with known content. The amount of each component standard sample added is shown in Table 4. The sample was injected according to the chromatography-mass spectrometry conditions and steps in Example 1. Six parallel measurements were performed for each level. The relative standard deviation and average recovery rate of each level were calculated to examine the precision and accuracy of the method. The precision and recovery test results are shown in Table 4.

[0175] Table 4

[0176]

[0177]

[0178] The results show that the relative standard deviation of tetrachlorobenzene isomers is between 1.9% and 6.8%, and the recovery rate of spiked addition is between 97.2% and 103.2%; the relative standard deviation of pentachlorobenzene is between 1.8% and 5.9%, and the recovery rate of spiked addition is between 98.1% and 102.8%, indicating that the method provided by the present invention has high precision and accuracy.

[0179] The applicant declares that the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0180] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl, characterized in that: The method comprises the following steps: (1) preparing a standard working solution and a sample solution to be tested, wherein the standard working solution contains tetrachlorobenzene and pentachlorobenzene standard samples, and the sample solution to be tested contains thiophanate-methyl test sample; (2) separating and detecting the standard working solution and the sample solution described in step (1) by gas chromatography and mass spectrometry; (3) preparing a standard curve according to the test results obtained in step (2), and calculating the contents of tetrachlorobenzene and pentachlorobenzene in the chlorothalonil sample; The tetrachlorobenzene described in step (1) includes any one of 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene or 1,2,3,4-tetrachlorobenzene, or a combination of at least two thereof; The method for preparing the standard working solution in step (1) comprises the following steps: dissolving 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene standards in a solvent; The method for preparing the sample solution to be tested in step (1) comprises the following steps: diluting the thiophanate-methyl sample with a solvent; The solvents of the standard working solution and the sample solution to be tested include toluene.

2. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The chromatographic column of the gas chromatograph comprises a DB-5ms capillary column.

3. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The gas chromatograph is injected in a pulsed splitless manner.

4. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 3, characterized in that: The injection pulse pressure of the gas chromatograph is 50-70 kPa.

5. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 3, characterized in that: The injection volume of the gas chromatograph is 0.8 to 1.2 μL.

6. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 3, characterized in that: The carrier gas of the gas chromatography is helium, and the purity of the helium is ≥99.999%.

7. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 3, characterized in that: The column flow rate of the gas chromatograph is 0.8-1.2 mL / min.

8. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 3, characterized in that: The injection port temperature of the gas chromatograph is 260°C to 300°C.

9. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The temperature of the chromatographic column of the gas chromatography is programmed.

10. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 9, characterized in that: The programmed temperature rise includes a temperature keeping stage, a first temperature rise stage and a second temperature rise stage in sequence.

11. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The temperature in the insulation stage is 60-80°C.

12. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The holding time of the heat preservation stage is 0.5 to 1 min.

13. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The starting temperature of the first temperature rising stage is the temperature of the temperature keeping stage.

14. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The termination temperature of the first temperature rising stage is 120-130°C.

15. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The heating rate of the first heating stage is 3-8°C / min.

16. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The holding time of the first heating stage is 2 to 4 minutes.

17. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The end temperature of the first heating stage is the start temperature of the second heating stage.

18. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The end temperature of the second temperature rising stage is 280-320°C.

19. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in chlorothalonil according to claim 10, characterized in that: The heating rate of the second heating stage is 35-45°C / min.

20. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 10, characterized in that: The holding time of the second heating stage is 1 to 3 minutes.

21. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The ionization mode of the mass spectrometer includes electron bombardment ionization.

22. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 21, characterized in that: The electron energy of the electron bombardment ionization is 60-80 eV.

23. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The GC-MSD interface temperature in the mass spectrometer is 280-320°C.

24. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The ion source temperature in the mass spectrometer is 220-240°C.

25. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The temperature of the quadrupole in the mass spectrometer is 140-160°C.

26. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The multiplier voltage in the mass spectrometer is an automatic tuning value.

27. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The solvent delay time in the mass spectrum is 10.0 to 15.0 min.

28. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The detector closing time in the mass spectrometer is 19.0 to 21.0 minutes.

29. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The mass spectrometer is scanned in a selected ion monitoring mode.

30. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The starting detection time of the tetrachlorobenzene is 10 to 15 minutes.

31. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The starting detection time of pentachlorobenzene is 18 to 18.6 minutes.

32. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The mass-to-charge ratio of the quantification ion of tetrachlorobenzene is 216 m / z.

33. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The mass-to-charge ratio of the first qualifier ion of tetrachlorobenzene is 214 m / z.

34. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The mass-to-charge ratio of the second qualifier ion of tetrachlorobenzene is 218 m / z.

35. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The mass-to-charge ratio of the quantification ion of pentachlorobenzene is 250 m / z.

36. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The mass-to-charge ratio of the first qualifier ion of pentachlorobenzene is 248 m / z.

37. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 29, characterized in that: The mass-to-charge ratio of the second qualifier ion of pentachlorobenzene is 252 m / z.

38. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The gas chromatography-mass spectrometry detection method adopts external standard method for quantification.

39. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The preparation method of the standard working solution in step (1) comprises the following steps: dissolving 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene standard samples in a solvent, and then mixing and diluting to obtain standard working solutions of different concentrations.

40. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 39, characterized in that: The concentration range of the components to be detected in the standard working solutions of different concentrations is consistent with the concentration range of the corresponding components in the sample solution to be detected.

41. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 39, characterized in that: The concentration of 1,2,3,5-tetrachlorobenzene in the standard working solution is 0.01-0.2 μg / mL.

42. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 39, characterized in that: The concentration of 1,2,4,5-tetrachlorobenzene in the standard working solution is 0.01-0.2 μg / mL.

43. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 39, characterized in that: The concentration of 1,2,3,4-tetrachlorobenzene in the standard working solution is 0.01-0.2 μg / mL.

44. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 39, characterized in that: The concentration of pentachlorobenzene in the standard working solution is 0.01-0.2 μg / mL.

45. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The method for preparing the sample solution to be tested in step (1) comprises the following steps: diluting the thiophanate-methyl sample with a solvent, dissolving it by shaking under ultrasound, cooling it to 18-28° C., and shaking it well to obtain the sample solution to be tested.

46. ​​The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 45, characterized in that: The ultrasonic time is 10 to 15 minutes.

47. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 45, characterized in that: The power of the ultrasound is 30-50kHz.

48. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 45, characterized in that: The concentration of the thiophanate-methyl sample in the sample solution to be tested is 15-25 mg / mL.

49. The gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl according to claim 1, characterized in that: The method comprises the following steps: (1) 1,2,3,5-tetrachlorobenzene standard, 1,2,4,5-tetrachlorobenzene standard, 1,2,3,4-tetrachlorobenzene standard and pentachlorobenzene standard were mixed with toluene respectively, dissolved by ultrasonication to prepare a single standard stock solution; then mixed and diluted to obtain a standard working solution; Take a sample of thiophanate-methyl, add toluene, shake and dissolve under ultrasound, and cool to obtain a sample solution to be tested; (2) separating and detecting the standard working solution and the sample solution described in step (1) by gas chromatography and mass spectrometry; The gas chromatography conditions were set as follows: the temperature of the chromatographic column was programmed to rise from 60 to 80°C for 0.5 to 1 min, then to 120 to 130°C at 3 to 8°C / min, and then to a final column temperature of 280 to 320°C at 35 to 45°C / min, and then to 1 to 3 min; the carrier gas was helium with a purity of ≥99.999% and a flow rate of 0.8 to 1.2 ml / min; the injection port temperature was 260 to 300°C; the injection volume was 0.8 to 1.2 µL; the injection method was pulsed splitless injection, and the pulse pressure was 50 to 70 kPa; The mass spectrometry conditions were set as follows: the ionization mode was electron impact ionization, the ionization energy was 60-80 eV, the GC-MSD interface temperature was 280-320 °C; the ion source temperature was 220-240 °C; the quadrupole temperature was 140-160 °C; the multiplier voltage was the automatic tuning value; the solvent delay time was 10.0-15.0 min; The mass spectrometry scanning mode is a selected ion monitoring mode, and the starting time, quantitative ion and qualitative ion setting parameters of each group of detection ions in the selected ion monitoring mode are as follows: the starting detection time of tetrachlorobenzene is 10 to 15 minutes; the starting detection time of pentachlorobenzene is 18 to 18.6 minutes; the mass-to-charge ratio of the quantitative ion of tetrachlorobenzene is 216m / z; the mass-to-charge ratio of the first qualitative ion of tetrachlorobenzene is 214m / z; the mass-to-charge ratio of the second qualitative ion of tetrachlorobenzene is 218m / z; the mass-to-charge ratio of the quantitative ion of pentachlorobenzene is 250m / z; the mass-to-charge ratio of the first qualitative ion of pentachlorobenzene is 248m / z; the mass-to-charge ratio of the second qualitative ion of pentachlorobenzene is 252m / z; (3) A standard curve is prepared according to the test results obtained in step (2), and the contents of tetrachlorobenzene and pentachlorobenzene in the chlorothalonil sample are obtained by calculation.

50. Use of the gas chromatography-mass spectrometry detection method for simultaneously detecting tetrachlorobenzene and pentachlorobenzene in thiophanate-methyl as claimed in any one of claims 1 to 49 in the preparation of thiophanate-methyl fungicide.

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