A gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in chlorothalonil

Abstract

The present invention provides a gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl. The gas chromatography-mass spectrometry detection method comprises: preparing a hexachlorobenzene-decachlorobiphenyl standard working solution and a thiophanate-methyl sample solution; separating and detecting the hexachlorobenzene-decachlorobiphenyl standard working solution and the thiophanate-methyl sample solution by gas chromatography and mass spectrometry, wherein the gas chromatography adopts a DB-5ms capillary column and is performed in a split injection mode; obtaining a hexachlorobenzene standard curve and a decachlorobiphenyl standard curve according to the detection results of the gas chromatography and mass spectrometry, and obtaining the content of ultra-trace hexachlorobenzene and decachlorobiphenyl in the thiophanate-methyl sample solution in combination with the standard curve. The gas chromatography-mass spectrometry detection method can simultaneously and sensitively and rapidly measure the content of ultra-trace hexachlorobenzene and decachlorobiphenyl in high-purity thiophanate-methyl, saves analysis costs, has high analysis efficiency, and is suitable for the determination of ultra-trace hexachlorobenzene and decachlorobiphenyl content in large quantities of thiophanate-methyl products.

Description

Technical Field

[0001] The invention belongs to the field of analytical chemistry, and in particular relates to a gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl. Background Art

[0002] Chlorothalonil is a highly effective, low-toxic, broad-spectrum, low-residue protective fungicide, which is widely used in the prevention and control of fungal diseases in agriculture and forestry. Hexachlorobenzene and decachlorobiphenyl are by-product impurities formed during the production of chlorothalonil technical. They are persistent and difficult to degrade organic pollutants, which are easily accumulated in organisms and the environment, and are harmful substances that can cause cancer and are harmful to the human body.

[0003] Both the national standard of chlorothalonil and the FAO standard of the International Food and Agriculture Organization have listed it as a key control item and put forward strict requirements: the content of hexachlorobenzene is not more than 40mg / kg, and the content of decachlorobiphenyl is not more than 30mg / kg. However, in the actual market trade, with the increasing attention paid to environmental protection and human health around the world, chlorothalonil products with hexachlorobenzene and decachlorobiphenyl content not more than 10mg / kg have become a new market demand in recent years. Even in the process of chlorothalonil registration in foreign markets, some countries have put forward access requirements of not more than 2mg / kg. All these show that the control trend of hexachlorobenzene and decachlorobiphenyl in chlorothalonil is becoming more and more stringent, making the production and export of chlorothalonil in my country face more severe challenges. Therefore, the production of high-purity ultra-trace hexachlorobenzene and decachlorobiphenyl chlorothalonil has become the goal pursued by various manufacturers at present, and at the same time, it also puts forward higher requirements on the sensitivity and accuracy of the detection methods of hexachlorobenzene and decachlorobiphenyl in chlorothalonil.

[0004] At present, there are many methods for the simultaneous detection of hexachlorobenzene and decachlorobiphenyl in chlorothalonil in China, including standard methods and other research methods. The standard methods include the high performance liquid chromatography method in the national standard of chlorothalonil and the gas chromatography-mass spectrometry method in FAOSpecification 288 / TC (April 2020). Other research methods include the method of determining the impurities hexachlorobenzene and decachlorobiphenyl in chlorothalonil by gas chromatography-mass spectrometry.

[0005] CN112098564A discloses an HPLC detection method for simultaneously detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl. Among the various detection methods, the detection sensitivity of liquid chromatography cannot meet the requirements of ultra-trace determination. Although FAO gas chromatography-mass spectrometry has high sensitivity and selectivity, because it determines trace impurities in thiophanate-methyl, in order to improve the sensitivity, a large amount of thiophanate-methyl sample matrix is ​​introduced into the mass spectrometer detector in the method, which can easily lead to rapid contamination of the ion source in a short time, and the sensitivity and repeatability decrease rapidly. In order to ensure high sensitivity, the ion source needs to be frequently cleaned, which has high maintenance costs and affects the analysis efficiency. On the other hand, in order to reduce the influence of the non-split injection solvent effect, the method adopts a lower initial temperature and a long analysis time.

[0006] Among the current research methods, one method is to use gas chromatography-mass spectrometry to determine the impurities hexachlorobenzene and decachlorobiphenyl in chlorothalonil. However, the chromatographic and mass spectrometric operating conditions are not ideal, and the sensitivity is low. It is not suitable for the detection of hexachlorobenzene and decachlorobiphenyl below 2 mg / kg. In addition, the problem of the impact of ion source contamination on the detection also exists.

[0007] Therefore, these current methods are difficult to meet the high sensitivity, repeatability, accuracy and rapid detection requirements of manufacturers for trace amounts of hexachlorobenzene and decachlorobiphenyl in batches of chlorothalonil products. How to provide a highly sensitive, stable, repeatable, accurate and rapid detection method for trace amounts of hexachlorobenzene and decachlorobiphenyl in chlorothalonil has become an urgent problem to be solved. Summary of the invention

[0008] In view of the shortcomings of the prior art, the object of the present invention is to provide a gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in chlorothalonil. The method has high detection sensitivity and continuous stability, good selectivity and repeatability, and fast analysis speed, which can meet the production enterprise's requirements for accurate control of trace amounts of hexachlorobenzene and decachlorobiphenyl in continuous large quantities of chlorothalonil. At the same time, it has low pollution to the mass spectrometer detector, reduces frequent and cumbersome instrument maintenance, and can improve analysis efficiency and save analysis costs.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl, the gas chromatography-mass spectrometry detection method comprising:

[0011] Prepare HCB-DCB standard working solution and thiophanate-methyl sample solution.

[0012] The hexachlorobenzene-decachlorobiphenyl standard working solution and the thiophanate-methyl sample solution are separated and detected by gas chromatography and mass spectrometry, wherein the gas chromatography adopts a DB-5ms capillary column and is carried out in a split injection mode, and the injection split ratio in the gas chromatography is (5-10):1, including but not limited to 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0013] In a specific experiment, the split ratio can be adjusted within a certain range according to the sample concentration and injection volume.

[0014] The present invention adopts a split injection method and sets a suitable split ratio range, which can ensure that the sensitivity meets the detection requirements while avoiding the influence of the solvent effect on the detection. At the same time, a higher initial temperature can be used to shorten the detection time and reduce the pollution to the instrument system.

[0015] A hexachlorobenzene standard curve and a decachlorobiphenyl standard curve are obtained according to the detection results of the gas chromatography and mass spectrometry, and the contents of ultra-trace hexachlorobenzene and decachlorobiphenyl in the chlorothalonil sample solution are obtained by combining the hexachlorobenzene standard curve and the decachlorobiphenyl standard curve.

[0016] The gas chromatography and mass spectrometry detection method described in the present invention can sensitively detect ultra-trace amounts of hexachlorobenzene and decachlorobiphenyl. Since the detected content is at an ultra-trace level, a sufficient injection amount is required to meet the detection limit requirement. However, a mass spectrometer is a precision instrument. Too much injection amount is likely to contaminate the detector, resulting in inaccurate subsequent detection and affecting the accuracy of instrument detection. Therefore, by split injection, the split ratio is accurately adjusted to enable it to meet the purpose of ultra-trace precise quantification, while overcoming the contamination problem of the mass spectrometer detector in industrial production, and ensuring the accuracy of the instrument during the detection process.

[0017] The method provided by the present invention can simultaneously detect the contents of ultra-trace hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl at one time, thereby improving the analysis efficiency. The gas chromatography-mass spectrometry detection method is adopted, and the method has high detection sensitivity and continuous stability, good selectivity and repeatability, and fast analysis speed, and can meet the production enterprise's continuous large-scale accurate control requirements of ultra-trace hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl. At the same time, the pollution to the mass spectrometer detector is low, and the frequent and cumbersome instrument maintenance is reduced, which can improve the analysis efficiency and save the analysis cost.

[0018] In the present invention, the trace amount is: the component content is one part per million, 10 -6 g / g~10 -4 g / g, that is, 1μg / g~100μg / g, commonly known as 1ppm~100ppm; when the concentration of the component to be tested is less than 10 -6 g / g, this kind of analysis is called ultra-trace analysis. Correspondingly, the trace component content is one ten-thousandth, 10 -4g / g~10 -2 g / g, i.e. 100μg / g~10000μg / g; constant, 10 -2 g / g~1g / g, i.e. 10 4 μg / g~10 6 μg / g.

[0019] As a preferred technical solution of the present invention, the temperature control method in the gas chromatography adopts a programmed temperature increase method.

[0020] Preferably, the programmed temperature increase includes first-order temperature increase and second-order temperature increase.

[0021] Preferably, the initial temperature of the programmed temperature column is 135°C to 145°C, including but not limited to 135°C, 138°C, 140°C, 142°C or 145°C.

[0022] Preferably, the initial temperature holding time of the column during the programmed temperature increase is 0.5 min to 1.5 min, including but not limited to 0.5 min, 0.8 min, 1.0 min, 1.2 min or 1.5 min.

[0023] Preferably, the first-order heating rate of the programmed temperature is 35°C / min to 45°C / min, including but not limited to 35°C / min, 38°C / min, 40°C / min, 42°C / min, 44°C / min or 45°C / min.

[0024] Preferably, the first-order endpoint temperature of the programmed temperature rise is 235°C to 245°C, including but not limited to 235°C, 238°C, 240°C, 243°C or 245°C.

[0025] Preferably, the second-order heating rate of the programmed temperature is 15°C / min to 25°C / min, including but not limited to 15°C / min, 17°C / min, 19°C / min, 20°C / min, 23°C / min or 25°C / min.

[0026] Preferably, the final column temperature of the programmed temperature increase is 300°C to 320°C, including but not limited to 300°C, 305°C, 310°C, 315°C or 320°C.

[0027] Preferably, the final column temperature holding time of the programmed temperature increase is 2 min to 3 min, including but not limited to 2 min, 2.3 min, 2.5 min, 2.8 min or 3 min.

[0028] The combination of specific column temperature parameters set by the present invention can achieve effective separation of hexachlorobenzene and decachlorobiphenyl, with more accurate results and shorter analysis time.

[0029] Preferably, the carrier gas of the gas chromatography is helium with a purity of ≥99.999%.

[0030] Preferably, the flow rate of the helium gas is 0.8 mL / min to 1.2 mL / min, including but not limited to 0.8 mL / min, 0.9 mL / min, 1.0 mL / min, 1.1 mL / min or 1.2 mL / min.

[0031] The flow rate of the specific carrier gas set by the present invention has good separation and high column efficiency.

[0032] Preferably, the injection port temperature of the gas chromatograph is 280°C to 300°C, including but not limited to 280°C, 285°C, 290°C, 295°C or 300°C.

[0033] The injection port temperature set in the present invention can ensure that each component in the sample is completely vaporized.

[0034] Preferably, the injection volume of the gas chromatography is 0.5 μL to 1.5 μL, including but not limited to 0.5 μL, 0.8 μL, 1.0 μL, 1.2 μL or 1.5 μL.

[0035] The sample injection volume provided by the present invention can ensure high sensitivity in detecting ultra-trace amounts of hexachlorobenzene and decachlorobiphenyl.

[0036] As a preferred technical solution of the present invention, the ionization mode of the mass spectrometer is electron bombardment ionization.

[0037] Preferably, the ionization energy of the electron bombardment ionization is 60eV to 80eV, including but not limited to 60eV, 65eV, 70eV, 75eV or 80eV.

[0038] Preferably, the GC-MSD interface temperature of the mass spectrometer is 280°C to 320°C, including but not limited to 280°C, 290°C, 300°C, 310°C or 320°C.

[0039] Preferably, the ion source temperature of the mass spectrometer is 220°C to 240°C, including but not limited to 220°C, 225°C, 230°C, 235°C or 240°C.

[0040] Preferably, the quadrupole temperature of the mass spectrometer is 140°C to 160°C, including but not limited to 140°C, 145°C, 150°C, 155°C or 160°C.

[0041] Preferably, the multiplier voltage of the mass spectrometer is an automatically tuned value.

[0042] Preferably, the solvent delay time of the mass spectrometer is 2.0 min to 3.0 min, including but not limited to 2.0 min, 2.3 min, 2.6 min, 2.8 min or 3.0 min.

[0043] Preferably, the detector closing time of the mass spectrometer is 0.12 min to 0.25 min after the retention time of hexachlorobenzene. For example, the retention time of hexachlorobenzene is 3.71 min. The detector closing time includes but is not limited to 3.83 min, 3.85 min, 3.87 min, 3.89 min, 3.91 min, 3.93 min or 3.96 min.

[0044] The specific detector shutdown time set in the present invention can prevent high-concentration thiophanate-methyl matrix from contaminating the mass spectrometer detector, obtain a more stable and sensitive detector response, and reduce the frequency of instrument maintenance.

[0045] Preferably, the mass spectrometry scanning mode of the mass spectrometer is a selected ion monitoring mode.

[0046] Preferably, the starting detection time of hexachlorobenzene is 2.0 min to 3.0 min, including but not limited to 2.0 min, 2.1 min, 2.3 min, 2.5 min, 2.7 min, 2.9 min or 3.0 min, the mass-to-charge ratio of the quantitative ion of hexachlorobenzene is 286, the mass-to-charge ratio of the first qualifier ion of hexachlorobenzene is 284, and the mass-to-charge ratio of the second qualifier ion of hexachlorobenzene is 288.

[0047] Preferably, the starting detection time of decachlorobiphenyl is 6.0 min to 7.0 min, including but not limited to 6.0 min, 6.1 min, 6.3 min, 6.5 min, 6.7 min, 6.9 min or 7.0 min, the mass-to-charge ratio of the quantitative ion of decachlorobiphenyl is 498, the mass-to-charge ratio of the first qualifier ion of decachlorobiphenyl is 496, and the mass-to-charge ratio of the second qualifier ion of decachlorobiphenyl is 500.

[0048] Preferably, the concentration of hexachlorobenzene in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL, including but not limited to 0.001 μg / mL, 0.002 μg / mL, 0.005 μg / mL, 0.02 μg / mL or 0.05 μg / mL, etc.

[0049] Preferably, the concentration of decachlorobiphenyl in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL, including but not limited to 0.001 μg / mL, 0.002 μg / mL, 0.005 μg / mL, 0.02 μg / mL or 0.05 μg / mL, etc.

[0050] In a specific test, the concentration range of the HCB-DCB standard working solution should be consistent with the concentration range of the components to be measured in the actual sample.

[0051] Preferably, the solvent of the hexachlorobenzene-decachlorobiphenyl standard working solution is xylene.

[0052] Preferably, the preparation of the sample solution comprises: diluting the thiophanate-methyl sample with xylene, dissolving by shaking under ultrasound, and cooling to obtain the thiophanate-methyl sample solution.

[0053] Preferably, the concentration of thiophanate-methyl technical in the thiophanate-methyl sample solution is 15 mg / mL to 25 mg / mL, including but not limited to 15 mg / mL, 17 mg / mL, 19 mg / mL, 20 mg / mL, 21 mg / mL, 23 mg / mL or 25 mg / mL, etc.

[0054] Preferably, the ultrasonication time is 10 min to 15 min, including but not limited to 10 min, 12 min, 14 min or 15 min.

[0055] Preferably, the cooling temperature is 25°C to 30°C, including but not limited to 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, etc.

[0056] As a preferred technical solution of the present invention, the specific steps of the gas chromatography-mass spectrometry detection method include:

[0057] (1) Mixing a hexachlorobenzene standard sample with xylene, ultrasonically dissolving and fixing the volume to obtain a hexachlorobenzene single standard stock solution, wherein the concentration of the hexachlorobenzene single standard stock solution is 80 μg / mL to 120 μg / mL, including but not limited to 80 μg / mL, 90 μg / mL, 100 μg / mL, 110 μg / mL or 120 μg / mL.

[0058] (2) Mixing the decachlorobiphenyl standard sample with xylene, ultrasonically dissolving and fixing the volume to obtain a decachlorobiphenyl single standard stock solution, wherein the concentration of the decachlorobiphenyl single standard stock solution is 80 μg / mL to 120 μg / mL, including but not limited to 80 μg / mL, 90 μg / mL, 100 μg / mL, 110 μg / mL or 120 μg / mL.

[0059] (3) The hexachlorobenzene single standard stock solution and the decachlorobiphenyl single standard stock solution are respectively mixed with xylene, fixed to volume, and prepared into a mixed intermediate dilution. The concentration of hexachlorobenzene in the mixed intermediate dilution is 0.8 μg / mL to 1.2 μg / mL, including but not limited to 0.8 μg / mL, 0.9 μg / mL, 1.0 μg / mL, 1.1 μg / mL or 1.2 μg / mL. The concentration of decachlorobiphenyl in the mixed intermediate dilution is 0.8 μg / mL to 1.2 μg / mL, including but not limited to 0.8 μg / mL, 0.9 μg / mL, 1.0 μg / mL, 1.1 μg / mL or 1.2 μg / mL.

[0060] (4) taking the mixed intermediate dilution solution and preparing a hexachlorobenzene-decachlorobiphenyl standard working solution, wherein the concentration of hexachlorobenzene in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL, and the concentration of decachlorobiphenyl in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL.

[0061] (5) diluting the thiophanate-methyl sample with xylene, oscillating in an ultrasonic wave for 10 to 20 minutes to dissolve it, and cooling it to 25° C. to 30° C. to obtain the thiophanate-methyl sample solution having a thiophanate-methyl original drug concentration of 15 mg / mL to 25 mg / mL.

[0062] (6) Setting gas chromatography conditions, using the DB-5ms capillary column and performing split injection, the split ratio of the split injection is (5-10):1, the temperature control method of the gas chromatography adopts a programmed temperature increase method, the initial temperature of the column is 135°C-145°C, maintained at the initial temperature of the column for 0.5min-1.5min, heated to the first-order terminal temperature of 235°C-245°C at a first-order heating rate of 35°C / min-45°C / min, heated to the final column temperature of 300°C-320°C at a second-order heating rate of 15°C / min-25°C / min, maintained at the final column temperature for 2min-3min, the carrier gas is helium, the flow rate of the helium is 0.8mL / min-1.2mL / min, the injection port temperature is 280°C-300°C, and the injection volume is 0.5μL-1.5μL.

[0063] (7) Setting mass spectrometry conditions: the ionization mode is electron impact ionization, the ionization energy is 60 eV to 80 eV, the GC-MSD interface temperature is 280° C. to 320° C., the ion source temperature is 220° C. to 240° C., the quadrupole temperature is 140° C. to 160° C., the multiplier voltage is an automatic tuning value, the solvent delay time is 2.0 min to 3.0 min, the mass spectrometer detector closing time is 0.12 min to 0.25 min after the retention time of hexachlorobenzene, and the mass spectrometry scanning mode is a selected ion monitoring mode.

[0064] (8) The starting detection time of hexachlorobenzene is 2.0 min to 3.0 min, the mass-to-charge ratio of the quantitative ion of hexachlorobenzene is 286, the mass-to-charge ratio of the first qualifier ion of hexachlorobenzene is 284, and the mass-to-charge ratio of the second qualifier ion of hexachlorobenzene is 288. The starting detection time of decachlorobiphenyl is 6.0 min to 7.0 min, the mass-to-charge ratio of the quantitative ion of decachlorobiphenyl is 498, the mass-to-charge ratio of the first qualifier ion of decachlorobiphenyl is 496, and the mass-to-charge ratio of the second qualifier ion of decachlorobiphenyl is 500.

[0065] (9) A hexachlorobenzene standard curve and a decachlorobiphenyl standard curve are obtained according to the detection results of the gas chromatography and mass spectrometry, and the contents of ultra-trace hexachlorobenzene and decachlorobiphenyl in the chlorothalonil sample solution are obtained by combining the hexachlorobenzene standard curve and the decachlorobiphenyl standard curve.

[0066] It should be noted that the scientific and technical terms and abbreviations used in the present invention have the meanings generally understood by those skilled in the art.

[0067] GC-MSD: gas chromatography-mass spectrometry.

[0068] FAO Specification 288 / TC (April 2020): FAO Specification 288 / TC (April 2020): Pesticide Specification and Evaluation Standards, Chlorothalonil.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] (1) The split injection mode and split ratio range provided by the present invention can ensure that the sensitivity meets the detection requirements while avoiding the expansion and tailing of the hexachlorobenzene peak caused by the solvent effect of the non-split injection, thereby reducing the pollution caused by a large amount of sample matrix entering the chromatography-mass spectrometry detection system. In addition, the non-split injection is adopted, usually to reduce the influence of the solvent effect on the hexachlorobenzene detection, a lower column initial temperature is required, but because the boiling points of hexachlorobenzene and decachlorobiphenyl differ greatly, the lower column initial temperature will cause the retention time of decachlorobiphenyl in the column to increase, which is not conducive to the sensitive detection of decachlorobiphenyl, and the analysis time is long. The split injection can adopt a higher initial temperature, shorten the detection time, and is conducive to the sensitive detection of decachlorobiphenyl.

[0071] (2) The combination of specific column temperature parameters, specific carrier gas and flow rate set in the present invention can achieve effective separation of hexachlorobenzene and decachlorobiphenyl, with more accurate results and shorter analysis time.

[0072] (3) The specific detector shut-off time set in the present invention solves the problem of serious and rapid contamination of the mass spectrometry detection system by a large amount of thiophanate-methyl matrix in the process of detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl by gas chromatography-mass spectrometry, improves the sustainability and stability of high sensitivity, facilitates the sensitive and accurate detection of ultra-trace hexachlorobenzene and decachlorobiphenyl in large quantities of thiophanate-methyl, improves the detection efficiency, and reduces the maintenance cost of the instrument.

[0073] (4) The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl provided by the present invention has high sensitivity, good repeatability, high accuracy and good linearity, and can achieve ultra-trace detection level.

[0074] High sensitivity: The detection limit (LOD) of hexachlorobenzene is 0.005mg / kg, reaching 0.005ppm, and the quantification limit (LOQ) is 0.01mg / kg, reaching 0.01ppm. The detection limit of decachlorobiphenyl is 0.01mg / kg, reaching 0.01ppm, and the quantification limit is 0.02mg / kg, reaching 0.02ppm.

[0075] Good repeatability: the relative standard deviation of hexachlorobenzene is between 3.3% and 5.7%, and the relative standard deviation of decachlorobiphenyl is between 3.1% and 6.5%.

[0076] High accuracy: the recovery rate of hexachlorobenzene is between 98.1% and 102.3%, and the recovery rate of decachlorobiphenyl is between 99.1% and 103.0%.

[0077] Good linear relationship: The concentrations of hexachlorobenzene and decachlorobiphenyl in the range of 0.001μg / mL to 0.05μg / mL showed good linear correlation with the quantitative ion peak area, and the correlation coefficients were all 0.9999.

[0078] The method provided by the present invention can simultaneously detect the contents of ultra-trace hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl at one time, thereby improving the analysis efficiency. The method provided by the present invention has high sensitivity and continuous stability, good repeatability, accuracy and rapidity, reduces frequent and cumbersome instrument maintenance, improves the analysis efficiency and saves the analysis cost, and is suitable for the determination of ultra-trace hexachlorobenzene and decachlorobiphenyl contents in large quantities of thiophanate-methyl products of production enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 This is the total ion chromatogram (TIC) of the hexachlorobenzene-decachlorobiphenyl standard sample with a concentration of 2 μg / mL, where peak 1 is hexachlorobenzene and peak 2 is decachlorobiphenyl.

[0080] Figure 2 This is the selected ion chromatogram (SIM) of the hexachlorobenzene-decachlorobiphenyl standard working solution with a concentration of 0.05 μg / mL in Example 1, wherein peak 1 is hexachlorobenzene and peak 2 is decachlorobiphenyl.

[0081] Figure 3 This is the selected ion chromatogram (SIM) of the hexachlorobenzene-decachlorobiphenyl standard working solution with a concentration of 0.02 μg / mL in Example 1, wherein peak 1 is hexachlorobenzene and peak 2 is decachlorobiphenyl.

[0082] Figure 4 This is the selected ion chromatogram (SIM) of the hexachlorobenzene-decachlorobiphenyl standard working solution with a concentration of 0.005 μg / mL in Example 1, wherein peak 1 is hexachlorobenzene and peak 2 is decachlorobiphenyl.

[0083] Figure 5 This is the selected ion chromatogram (SIM) of the determination of hexachlorobenzene and decachlorobiphenyl in the thiophanate-methyl sample solution 1 injected for the first time in Example 1, wherein Peak 1 is hexachlorobenzene and Peak 2 is decachlorobiphenyl.

[0084] Figure 6 This is the selected ion chromatogram (SIM) of the determination of hexachlorobenzene and decachlorobiphenyl in the second injection of thiophanate-methyl sample solution 1 in Example 1, wherein peak 1 is hexachlorobenzene and peak 2 is decachlorobiphenyl.

[0085] Figure 7 The standard curve of hexachlorobenzene in test example 1, the linear equation is y=80948.25x+15.83, the correlation coefficient (r 2 ) is 0.9999.

[0086] Figure 8The standard curve of decachlorobiphenyl in test example 1, the linear equation is y=41594.92x+2.35, the correlation coefficient (r 2 ) is 0.9999. DETAILED DESCRIPTION

[0087] 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.

[0088] In the following examples, the gas chromatography-mass spectrometer is Agilent 7890B / 5977B.

[0089] The chromatographic column is a DB~5ms capillary column with a specification of 30m×0.25mm (inner diameter) and a film thickness of 0.25μm.

[0090] The balance was purchased from Mettler-Toledo, model ME204 / 02.

[0091] The hexachlorobenzene standard sample and the decachlorobiphenyl standard sample were purchased from Dr. Ehrenstorfer (Dr Standard Products Company, Germany), and the mass fraction was not less than 98.0%.

[0092] All samples of thiophanate-methyl were from Jiangsu Xinhe Agricultural Chemical Co., Ltd., and the model was 98.5% thiophanate-methyl technical.

[0093] Other materials and reagents were obtained from commercial sources unless otherwise specified.

[0094] Reagent preparation and total ion spectrum scanning:

[0095] (1) Hexachlorobenzene single standard stock solution:

[0096] Accurately weigh 0.01 g (accurate to 0.0001 g) of hexachlorobenzene standard sample and place it in a 100 mL volumetric flask. Add appropriate amount of xylene and ultrasonically dissolve it. After cooling to room temperature, add xylene to the scale and shake well to prepare a 100 μg / mL hexachlorobenzene single standard stock solution.

[0097] (2) Decachlorobiphenyl single standard stock solution:

[0098] Accurately weigh 0.01 g (accurate to 0.0001 g) of decachlorobiphenyl standard and place it in a 100 mL volumetric flask. Add an appropriate amount of xylene and dissolve it by ultrasonication. After cooling to room temperature, add xylene to the scale and shake well to prepare a 100 μg / mL decachlorobiphenyl single standard stock solution.

[0099] (3) Mixing intermediate dilution:

[0100] Use a pipette to take 1 mL of the hexachlorobenzene single standard stock solution and the decachlorobiphenyl single standard stock solution respectively into a 100 mL volumetric flask, dilute to the scale with xylene, shake well, and prepare a mixed intermediate dilution of 1.0 μg / mL.

[0101] (4) Hexachlorobenzene-decachlorobiphenyl standard working solution:

[0102] Use a pipette to take 5 mL, 2 mL, and 0.5 mL of the mixed intermediate dilution solution, respectively, and place them in three 100 mL volumetric flasks, dilute to the scale with xylene, shake well, and prepare hexachlorobenzene-decachlorobiphenyl standard working solutions with concentrations of 0.05 μg / mL (C1), 0.02 μg / mL (C2), and 0.005 μg / mL (C3) for use.

[0103] Use a pipette to take 5 mL of the hexachlorobenzene-decachlorobiphenyl standard working solution with a concentration of 0.02 μg / mL and place it in a 50 mL volumetric flask, dilute it to the scale with xylene, shake well, and make a hexachlorobenzene and decachlorobiphenyl standard working solution with a concentration of 0.002 μg / mL (C4).

[0104] Use a pipette to take 5 mL of the hexachlorobenzene-decachlorobiphenyl standard working solution with a concentration of 0.02 μg / mL and place it in a 100 mL volumetric flask, dilute it to the scale with xylene, shake well, and make a hexachlorobenzene-decachlorobiphenyl standard working solution with a concentration of 0.001 μg / mL (C5).

[0105] (5) Preparation of thiophanate-methyl sample solution:

[0106] 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 xylene. Oscillate in ultrasound for 10 min to dissolve it. Cool to 25°C and shake well to obtain the chlorothalonil sample solution.

[0107] (6) Total ion chromatographic scan of 2 μg / mL hexachlorobenzene-decachlorobiphenyl standard

[0108] The total ion chromatogram (TIC) of a hexachlorobenzene-decachlorobiphenyl standard sample is scanned, wherein the sample detected by the total ion chromatogram is a 2 μg / mL hexachlorobenzene-decachlorobiphenyl solution, and the specific steps include:

[0109] Use a pipette to take 2 mL of the hexachlorobenzene single standard stock solution and the decachlorobiphenyl single standard stock solution respectively into a 100 mL volumetric flask, dilute to the scale with xylene, and shake well to prepare the 2 μg / mL hexachlorobenzene-decachlorobiphenyl standard solution.

[0110] Set the instrument conditions and gas chromatography conditions: the temperature of the chromatographic column is programmed, the initial column temperature is 140°C, the initial column temperature is maintained for 1.0 min, the temperature is increased to the first-order terminal temperature of 240°C at a first-order heating rate of 40°C / min, and then increased to the final column temperature of 320°C at a second-order heating rate of 20°C / min, and the final column temperature is maintained for 2 min; the carrier gas is helium, purity ≥99.999%, flow rate 1.0 mL / min. The injection port temperature is 280°C; the injection volume is 1.0 μL; the injection method is split injection, and the split ratio is 5:1.

[0111] Mass spectrometry detection conditions: ionization mode is electron impact ionization (EI), ionization energy is 70 eV, GC-MSD interface temperature is 300℃; ion source temperature is 230℃; quadrupole temperature is 150℃; multiplier voltage is automatic tuning value; solvent delay time is 2.5min; mass spectrometry scanning mode is full scan mode (TIC).

[0112] Injection sequence: After the instrument baseline is stable, inject several injections of 2 μg / mL HCB-DCB standard solution in TIC mode.

[0113] Figure 1 This is the total ion chromatogram (TIC) of the hexachlorobenzene-decachlorobiphenyl standard sample with a concentration of 2 μg / mL, where peak 1 is hexachlorobenzene and peak 2 is decachlorobiphenyl.

[0114] Example 1

[0115] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0116] Set the instrument conditions and gas chromatography conditions: the temperature of the chromatographic column is programmed, the initial column temperature is 140°C, the initial column temperature is maintained for 1.0 min, the temperature is increased to the first-order terminal temperature of 240°C at a first-order heating rate of 40°C / min, and then increased to the final column temperature of 320°C at a second-order heating rate of 20°C / min, and the final column temperature is maintained for 2 min; the carrier gas is helium, purity ≥99.999%, flow rate 1.0 mL / min. The injection port temperature is 280°C; the injection volume is 1.0 μL; the injection method is split injection, and the split ratio is 5:1.

[0117] Mass spectrometry detection conditions: ionization mode is electron impact ionization (EI), ionization energy is 70 eV, GC-MSD interface temperature is 300℃; ion source temperature is 230℃; quadrupole temperature is 150℃; multiplier voltage is automatic tuning value; solvent delay time is 2.5min; mass spectrometry detector closing time is 0.12min after the retention time of hexachlorobenzene; mass spectrometry scanning mode is selected ion monitoring mode (SIM), and the retention time, quantitative ion and qualitative ion of each component are shown in Table 1.

[0118] Table 1

[0119]

[0120] Injection sequence: After the instrument baseline is stable, continuously inject several injections of C2 hexachlorobenzene-decachlorobiphenyl standard working solution in SIM mode until the relative change in the peak area of ​​two adjacent injections of hexachlorobenzene and decachlorobiphenyl is less than 10%. Then, inject and measure in the order of C3, C2, C1, chlorothalonil sample solution 1, chlorothalonil sample solution 1, C3, C2, C1.

[0121] Figure 2 , Figure 3 , Figure 4 They are the selected ion chromatograms (SIM) of the hexachlorobenzene-decachlorobiphenyl standard working solutions with concentrations of 0.05 μg / mL (C1), 0.02 μg / mL (C2), and 0.005 μg / mL (C3) in Example 1, wherein peak 1-hexachlorobenzene; peak 2-decachlorobiphenyl; Figure 5 , Figure 6 They are respectively the selected ion chromatograms (SIM) of hexachlorobenzene-decachlorobiphenyl determination in the first test sample solution 1 and the second test sample solution 1, wherein peak 1 is hexachlorobenzene; peak 2 is decachlorobiphenyl.

[0122] Drawing of standard curve:

[0123] The average peak area of ​​the quantitative ion of each component in the hexachlorobenzene-decachlorobiphenyl standard working solution measured twice was calculated, and the standard working curve was drawn with the concentration of the hexachlorobenzene-decachlorobiphenyl standard working solution as the horizontal axis and the average peak area of ​​the quantitative ion as the vertical axis, and the linear regression equation was fitted.

[0124] Calculation results:

[0125] According to the peak area of ​​the quantitative ions of hexachlorobenzene and decachlorobiphenyl in the sample solution, the mass concentration x of hexachlorobenzene and decachlorobiphenyl can be obtained from the standard curve. i , the mass fraction of hexachlorobenzene and decachlorobiphenyl in the sample is calculated according to formula (1):

[0126]

[0127] Where:

[0128] ω1: Mass fraction of hexachlorobenzene and decachlorobiphenyl in the sample, expressed in mg / kg.

[0129] x i : Mass concentration of hexachlorobenzene and decachlorobiphenyl in sample solution calculated from the standard curve, μg / mL.

[0130] 10: Volume of xylene solvent used to dissolve the sample, mL.

[0131] m: mass of the sample, g.

[0132] Example 2

[0133] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0134] The only difference from Example 1 is that in the method described in this embodiment, the initial temperature is 135°C and maintained for 0.5 min, and the temperature is increased to the first-order endpoint temperature of 245°C at a first-order heating rate of 45°C / min; the detector closing time of the mass spectrometer is 0.25 min after the retention time of hexachlorobenzene, and the other conditions remain consistent with Example 1.

[0135] The specific gas chromatography conditions are as follows: the temperature of the chromatographic column is programmed, the initial column temperature is 135°C, the initial column temperature is maintained for 0.5 min, the temperature is increased to the first-order terminal temperature of 245°C at a first-order heating rate of 45°C / min, and then increased to the final column temperature of 320°C at a second-order heating rate of 20°C / min, and the final column temperature is maintained for 2 min; the carrier gas is helium, the purity is ≥99.999%, the flow rate is 1.0 mL / min. The injection port temperature is 280°C; the injection volume is 1.0 μL; the injection method is split injection, and the split ratio is 5:1.

[0136] Mass spectrometry detection conditions: ionization mode is electron impact ionization (EI), ionization energy is 70 eV, GC-MSD interface temperature is 300℃; ion source temperature is 230℃; quadrupole temperature is 150℃; multiplier voltage is automatic tuning value; solvent delay time is 2.5min; mass spectrometry detector shut-off time is 0.25min after the retention time of hexachlorobenzene; mass spectrometry scanning mode is selected ion monitoring mode (SIM).

[0137] Example 3

[0138] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0139] The only difference from Example 1 is that in the method described in this embodiment, the initial column temperature is 145°C, the initial column temperature is maintained for 1.5 min, the temperature is increased to a first-order terminal temperature of 245°C at a first-order heating rate of 45°C / min, and then increased to a final column temperature of 310°C at a second-order heating rate of 15°C / min, and the final column temperature is maintained for 2.5 min; the detector closing time of the mass spectrometer is 0.2 min after the retention time of hexachlorobenzene, and the other conditions remain consistent with Example 1.

[0140] The specific gas chromatography conditions are as follows: the temperature of the chromatographic column is programmed, the initial column temperature is 145°C, the initial column temperature is maintained for 1.5 min, the temperature is increased to the first-order terminal temperature of 245°C at a first-order heating rate of 45°C / min, and then increased to the final column temperature of 310°C at a second-order heating rate of 15°C / min, and the final column temperature is maintained for 2.5 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 is 280°C; the injection volume is 1.0 μL; the injection method is split injection, and the split ratio is 5:1.

[0141] Mass spectrometry detection conditions: ionization mode is electron impact ionization (EI), ionization energy is 70 eV, GC-MSD interface temperature is 300℃; ion source temperature is 230℃; quadrupole temperature is 150℃; multiplier voltage is automatic tuning value; solvent delay time is 2.5min; mass spectrometry detector shut-off time is 0.2min after the retention time of hexachlorobenzene; mass spectrometry scanning mode is selected ion monitoring mode (SIM).

[0142] Example 4

[0143] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0144] The only difference from Example 1 is that in the method described in this embodiment, the initial column temperature is 138°C, the initial column temperature is maintained for 1.2 min, the temperature is increased to a first-order terminal temperature of 235°C at a first-order heating rate of 35°C / min, and then increased to a final column temperature of 300°C at a second-order heating rate of 25°C / min, the final column temperature is maintained for 3 min, and the other conditions remain consistent with Example 1.

[0145] The specific gas chromatography conditions are as follows: the temperature of the chromatographic column is programmed, the initial column temperature is 138°C, the initial column temperature is maintained for 1.2 min, the temperature is increased to the first-order terminal temperature of 235°C at a first-order heating rate of 35°C / min, and then the temperature is increased to the final column temperature of 300°C at a second-order heating rate of 25°C / min, and the final column temperature is maintained for 3 min; the carrier gas is helium, the purity is ≥99.999%, the flow rate is 1.0 mL / min. The injection port temperature is 280°C; the injection volume is 1.0 μL; the injection method is split injection, and the split ratio is 5:1.

[0146] Example 5

[0147] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0148] The only difference from Example 1 is that the flow rate in the method described in this example is 0.8 mL / min, the injection port temperature is 300° C., and the other conditions remain the same as in Example 1.

[0149] The specific gas chromatography conditions are as follows: the temperature of the chromatographic column is programmed, the initial column temperature is 140°C, the initial column temperature is maintained for 0.5 min, the temperature is increased to the first-order terminal temperature of 240°C at a first-order heating rate of 40°C / min, and then the temperature is increased to the final column temperature of 320°C at a second-order heating rate of 20°C / min, and the final column temperature is maintained for 2 min; the carrier gas is helium, the purity is ≥99.999%, and the flow rate is 0.8 mL / min. The injection port temperature is 300°C; the injection volume is 1.0 μL; the injection method is split injection, and the split ratio is 5:1.

[0150] The remaining step conditions are the same as in Example 1.

[0151] Example 6

[0152] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0153] The only difference from Example 1 is that the flow rate in the method described in this example is 1.2 mL / min, the injection port temperature is 290° C., and the other conditions remain the same as in Example 1.

[0154] Set the instrument conditions and gas chromatography conditions: the temperature of the chromatographic column is programmed, the initial column temperature is 140°C, the initial column temperature is maintained for 0.5 min, the temperature is increased to the first-order terminal temperature of 240°C at a first-order heating rate of 40°C / min, and then increased to the final column temperature of 320°C at a second-order heating rate of 20°C / min, and the final column temperature is maintained for 2 min; the carrier gas is helium, with a purity of ≥99.999%, and a flow rate of 1.2 mL / min. The injection port temperature is 290°C; the injection volume is 0.5 μL; the injection method is split injection, and the split ratio is 5:1.

[0155] The remaining step conditions are the same as in Example 1.

[0156] Example 7

[0157] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl, wherein the solvent removal delay time is 2.0 min, the detector closing time of the mass spectrometer is 0.16 min after the retention time of hexachlorobenzene, and the remaining step conditions are the same as those in Example 1.

[0158] Example 8

[0159] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl, wherein except for the GC-MSD interface temperature of 280°C, the ion source temperature of 240°C and the solvent delay time of 3.0 min, the remaining step conditions are the same as those in Example 1.

[0160] Example 9

[0161] This embodiment provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0162] The only difference from Example 1 is that the injection volume in the method described in this example is 1.5 μL, the split ratio is 10:1, and the other conditions are consistent with Example 1.

[0163] Set the instrument conditions and gas chromatography conditions: the temperature of the chromatographic column is programmed, the initial column temperature is 140°C, the initial column temperature is maintained for 0.5 min, the temperature is increased to the first-order terminal temperature of 240°C at a first-order heating rate of 40°C / min, and then increased to the final column temperature of 320°C at a second-order heating rate of 20°C / min, and the final column temperature is 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 is 280°C; the injection volume is 1.5 μL; the injection method is split injection, and the split ratio is 10:1.

[0164] Example 10

[0165] This comparative example provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0166] The only difference from Example 1 is that the detector closing time of the mass spectrometer in the method described in this example is: hexachlorobenzene retention time + 0.30 min, and the other conditions are consistent with Example 1.

[0167] Embodiment 11

[0168] This comparative example provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0169] The only difference from Example 1 is that the detector closing time of the mass spectrometer in the method described in this example is: hexachlorobenzene retention time + 0.07 min, and the other conditions are consistent with Example 1.

[0170] Comparative Example 1

[0171] This comparative example provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0172] The only difference from Example 1 is that the chromatographic column in the method described in this embodiment adopts a DB-1 chromatographic column, and the other conditions remain the same as in Example 1.

[0173] Comparative Example 2

[0174] This comparative example provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0175] The only difference from Example 1 is that the method described in this example adopts splitless injection, and the other conditions remain the same as those in Example 1.

[0176] Comparative Example 3

[0177] This comparative example provides a gas chromatography-mass spectrometry method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl.

[0178] The only difference from Example 1 is that the split ratio used in the method described in this example is 15:1, and the other conditions remain the same as in Example 1.

[0179] Test result statistics:

[0180] The results of the determination of the contents of hexachlorobenzene and decachlorobiphenyl in the samples to be tested in Examples 1 to 11 and Comparative Examples 1 to 3 are shown in Table 2:

[0181] Table 2

[0182]

[0183] From the data results of Examples 1 to 9 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.

[0184] The comparison results of Example 1 and Example 10 show that when the detector shutdown time is set too late, it has a great impact on the measurement results. The thiophanate-methyl will enter the ion source and ionize, causing contamination of the ion source and interference of the matrix with the detection, affecting the sensitivity, repeatability and accuracy of the detection.

[0185] The comparison results between Example 1 and Example 11 show that when the detector closing time is set too early, it has a great impact on the measurement result, affects the integration of hexachlorobenzene, and has a great impact on the accuracy of the hexachlorobenzene quantitative result.

[0186] The comparison results of Example 1 and Comparative Example 1 show that the selection of the chromatographic column has a great influence on the determination results. When the DB-1 chromatographic column is selected for separation, the components in the sample flow out too fast, and hexachlorobenzene and the impurity components in the sample cannot be effectively separated, which affects the repeatability and accuracy of the hexachlorobenzene quantification.

[0187] The comparison results of Example 1 and Comparative Example 2 show that when the sample is not injected by split flow, the solvent effect has a great influence on the determination of hexachlorobenzene. The hexachlorobenzene peak is affected by the solvent effect, the peak is expanded and tailed, and the peak separation is poor, making it difficult to achieve accurate quantification of hexachlorobenzene.

[0188] The comparison results of Example 1 and Comparative Example 3 show that the split ratio is too large, the detection sensitivity is reduced, and the detection requirements of ultra-trace hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl cannot be met.

[0189] Test Example 1

[0190] This test example provides a linear correlation test of the gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in chlorothalonil:

[0191] Prepare hexachlorobenzene-decachlorobiphenyl standard working solutions at five concentration levels: 0.05 μg / mL, 0.02 μg / mL, 0.005 μg / mL, 0.002 μg / mL, and 0.001 μg / mL.

[0192] Injection sequence: According to the gas chromatography-mass spectrometry conditions in Example 1, after the instrument baseline is stable, several injections of C2 hexachlorobenzene-decachlorobiphenyl standard working solution are continuously injected in SIM mode until the relative change of the peak area of ​​two adjacent injections of hexachlorobenzene and decachlorobiphenyl is less than 10%, and then the injection is measured in the order of C5, C4, C3, C2, and C1. The peak area is measured, and the concentration of the hexachlorobenzene-decachlorobiphenyl standard working solution is used as the horizontal axis and the quantitative ion peak area is used as the vertical axis. The standard curve is drawn and a linear equation is established.

[0193] The linear range, linear equation and linear correlation coefficient (r 2 ) See Table 3, standard curve diagram see Figure 7 and Figure 8 .

[0194] Table 3

[0195] Compound Linear range (μg / mL) Linear equations <![CDATA[Correlation coefficient (r 2 )]]> Hexachlorobenzene 0.001～0.05 y=80948.25x+15.83 0.9999 Decachlorobiphenyl 0.001～0.05 y=41594.92x+2.35 0.9999

[0196] like Figure 7 The results showed that the concentration of hexachlorobenzene showed a good linear correlation with the quantitative ion peak area in the range of 0.001 μg / mL to 0.05 μg / mL, and the correlation coefficient (r 2 ) is 0.9999; Figure 8 The results showed that the concentration of decachlorobiphenyl in the range of 0.001 μg / mL to 0.05 μg / mL showed a good linear correlation with the quantitative ion peak area, and the correlation coefficient (r 2 ) is 0.9999. This indicates that the method provided by the present invention has a good linear relationship.

[0197] Test Example 2

[0198] This test example provides a detection limit and quantification limit test of the gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in chlorothalonil:

[0199] A low concentration of hexachlorobenzene-decachlorobiphenyl standard working solution was added to the blank sample, and the amount added was shown in Table 4. The sample was injected according to the chromatography-mass spectrometry conditions and steps in Example 1, and the peak area was determined. The measurement was repeated 7 times for each concentration, and the results were calculated according to the standard curve obtained from the linear correlation test. The spiked level corresponding to the signal-to-noise ratio of 3:1 was taken as the detection limit, and the spiked level corresponding to the signal-to-noise ratio of 10:1 was taken as the quantification limit.

[0200] The test data of detection limit and quantification limit of decachlorobiphenyl method are shown in Table 4.

[0201] Table 4

[0202]

[0203] The results showed that the detection limit of hexachlorobenzene was 0.005 mg / kg, and the quantification limit was 0.01 mg / kg; the detection limit of decachlorobiphenyl was 0.01 mg / kg, and the quantification limit was 0.02 mg / kg, which met the requirements for the determination of ultra-trace amounts of hexachlorobenzene and decachlorobiphenyl in samples.

[0204] Test Example 3

[0205] This test example provides a precision test and recovery test for a gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in chlorothalonil:

[0206] Three levels of HCB-DCB standard working solutions were added to the same sample with known content. The amount of each component standard sample added is shown in Table 5. The sample was injected according to the chromatography-mass spectrometry conditions and steps in Example 1. Five 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 5.

[0207] Table 5

[0208]

[0209] The results show that the relative standard deviation of hexachlorobenzene is between 3.3% and 5.7%, and the recovery rate of spiked addition is between 98.1% and 102.3%; the relative standard deviation of decachlorobiphenyl is between 3.1% and 6.5%, and the recovery rate of spiked addition is between 99.1% and 103.0%, indicating that the method provided by the present invention has high precision and accuracy.

[0210] Method comparison test:

[0211] The contents of hexachlorobenzene and decachlorobiphenyl in the thiophanate-methyl spiked solution in Test Example 3 were analyzed by high performance liquid chromatography in the national standard of thiophanate-methyl in GB / T9551-2017 and gas chromatography-mass spectrometry in FAO Specification 288 / TC (April 2020), respectively. Five parallel measurements were performed at each level. The analysis results are shown in Tables 6 and 7.

[0212] Table 6 shows the contents of decachlorobiphenyl and 10-decachlorobiphenyl in the thiophanate-methyl spiked solution obtained by the HPLC method in GB / T9551-2017.

[0213] Table 6

[0214]

[0215] Table 7 shows the contents of decachlorobiphenyl and 10-decachlorobiphenyl in the thiophanate-methyl spiked solution obtained by gas chromatography-mass spectrometry according to FAO Specification 288 / TC (April 2020).

[0216] Table 7

[0217]

[0218] The comparison results of Table 5, Table 6 and Table 7 show that the detection method provided by the present invention is better than the high performance liquid chromatography method in the national standard of thiophanate-methyl and the gas chromatography-mass spectrometry method in FAO Specification 288 / TC (April 2020) in determining hexachlorobenzene and decachlorobiphenyl using the gas chromatography-mass spectrometry detection method provided by the present invention, especially when the low content level is determined, the detection sensitivity, repeatability and accuracy are good. The high performance liquid chromatography method in GB / T9551-2017 has low detection sensitivity. The FAO Specification 288 / TC (April 2020) method has the highest method sensitivity, but in the actual detection process, due to the contamination of the thiophanate-methyl matrix, the detection response value will continue to decline, resulting in a decrease in precision. When the contamination is serious, the detection sensitivity will not be able to meet the needs of ultra-trace detection.

[0219] The applicant declares that the present invention uses the above-mentioned embodiment to illustrate the gas chromatography-mass spectrometry detection method of hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl of the present invention, but the present invention is not limited to the above-mentioned embodiment, that is, it does not mean that the present invention must rely on the above-mentioned embodiment to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0220] The preferred embodiments of the present invention are described in detail above. However, 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.

[0221] 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 method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl, characterized in that: The gas chromatography-mass spectrometry detection method comprises: Prepare HCB-DCB standard working solution and chlorothalonil sample solution; The solvent of the hexachlorobenzene-decachlorobiphenyl standard working solution is xylene; The hexachlorobenzene-decachlorobiphenyl standard working solution and the thiophanate-methyl sample solution are separated and detected by gas chromatography and mass spectrometry, wherein the gas chromatography adopts a DB-5ms capillary column and is carried out in a split injection mode, and the injection split ratio in the gas chromatography is (5-10):1; A hexachlorobenzene standard curve and a decachlorobiphenyl standard curve are obtained according to the detection results of the gas chromatography and mass spectrometry, and the contents of ultra-trace hexachlorobenzene and decachlorobiphenyl in the chlorothalonil sample solution are obtained by combining the hexachlorobenzene standard curve and the decachlorobiphenyl standard curve.

2. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The temperature control method of the gas chromatography adopts a programmed temperature increase method.

3. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The programmed temperature increase includes a first-order temperature increase and a second-order temperature increase.

4. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The initial temperature of the column in the programmed temperature increase is 135°C to 145°C.

5. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The initial temperature holding time of the column in the programmed temperature increase is 0.5 min to 1.5 min.

6. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The first-order heating rate of the programmed temperature heating is 35°C / min to 45°C / min.

7. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The first-order endpoint temperature of the programmed temperature rise is 235°C to 245°C.

8. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The second-order heating rate of the programmed temperature heating is 15°C / min to 25°C / min.

9. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The final column temperature of the programmed temperature increase is 300°C to 320°C.

10. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 2, characterized in that: The final column temperature holding time of the programmed temperature increase is 2 min to 3 min.

11. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The carrier gas of the gas chromatography is helium.

12. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 11, characterized in that: The flow rate of the helium gas is 0.8 mL / min to 1.2 mL / min.

13. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The injection port temperature of the gas chromatograph is 280°C to 300°C.

14. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The injection volume of the gas chromatograph is 0.5 μL to 1.5 μL.

15. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The ionization mode of the mass spectrometer is electron bombardment ionization.

16. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 15, characterized in that: The ionization energy of the electron bombardment ionization is 60eV to 80eV.

17. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The GC-MSD interface temperature of the mass spectrometer is 280°C to 320°C.

18. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The ion source temperature of the mass spectrometer is 220°C to 240°C.

19. The method for detecting hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl by gas chromatography-mass spectrometry according to claim 1, characterized in that: The quadrupole temperature of the mass spectrometer is 140°C to 160°C.

20. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The multiplier voltage of the mass spectrometer is an automatic tuning value.

21. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The solvent delay time of the mass spectrometer is 2.0 min to 3.0 min.

22. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The detector closing time of the mass spectrometer is 0.12min to 0.25min after the retention time of hexachlorobenzene.

23. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The mass spectrometry scanning mode of the mass spectrometer is a selected ion monitoring mode.

24. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The starting detection time of hexachlorobenzene is 2.0 min to 3.0 min, the mass-to-charge ratio of the quantitative ion of hexachlorobenzene is 286, the mass-to-charge ratio of the first qualifier ion of hexachlorobenzene is 284, and the mass-to-charge ratio of the second qualifier ion of hexachlorobenzene is 288.

25. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The starting detection time of decachlorobiphenyl is 6.0 min to 7.0 min, the mass-to-charge ratio of the quantitative ion of decachlorobiphenyl is 498, the mass-to-charge ratio of the first qualifier ion of decachlorobiphenyl is 496, and the mass-to-charge ratio of the second qualifier ion of decachlorobiphenyl is 500.

26. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The concentration of hexachlorobenzene in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL.

27. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The concentration of decachlorobiphenyl in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL.

28. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The preparation of the thiophanate-methyl sample solution comprises: The thiophanate-methyl sample was diluted with xylene, dissolved by shaking under ultrasound, and cooled to obtain the thiophanate-methyl sample solution.

29. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 28, characterized in that: The concentration of thiophanate-methyl technical in the thiophanate-methyl sample solution is 15 mg / mL to 25 mg / mL.

30. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 28, characterized in that: The ultrasonic time is 10 min to 15 min.

31. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 28, characterized in that: The cooling temperature is 25°C to 30°C.

32. The gas chromatography-mass spectrometry detection method for hexachlorobenzene and decachlorobiphenyl in thiophanate-methyl according to claim 1, characterized in that: The specific steps of the gas chromatography-mass spectrometry detection method include: (1) mixing a hexachlorobenzene standard sample with xylene, dissolving by ultrasonication and fixing the volume to obtain a hexachlorobenzene single standard stock solution, wherein the concentration of the hexachlorobenzene single standard stock solution is 80 μg / mL to 120 μg / mL; (2) mixing the decachlorobiphenyl standard sample with xylene, dissolving by ultrasonication and fixing the volume to obtain a decachlorobiphenyl single standard stock solution, wherein the concentration of the decachlorobiphenyl single standard stock solution is 80 μg / mL to 120 μg / mL; (3) respectively taking the hexachlorobenzene single standard stock solution and the decachlorobiphenyl single standard stock solution and mixing them with xylene, fixing the volume, and preparing a mixed intermediate dilution solution; (4) taking the mixed intermediate dilution solution and preparing a hexachlorobenzene-decachlorobiphenyl standard working solution, wherein the concentration of hexachlorobenzene in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL, and the concentration of decachlorobiphenyl in the hexachlorobenzene-decachlorobiphenyl standard working solution is 0.001 μg / mL to 0.05 μg / mL; (5) diluting the thiophanate-methyl sample with xylene, shaking in an ultrasonic wave for 10 to 15 minutes to dissolve it, and cooling to 25° C. to 30° C. to obtain the thiophanate-methyl sample solution having a thiophanate-methyl technical concentration of 15 mg / mL to 25 mg / mL; (6) Setting gas chromatography conditions, using the DB-5ms capillary column and performing split injection, the split ratio of the split injection is (5-10):1, the temperature control method of the gas chromatography adopts a programmed temperature increase method, the column initial temperature is 135°C-145°C, maintained at the column initial temperature for 0.5min-1.5min, heated to the first-order terminal temperature of 235°C-245°C at a first-order heating rate of 35°C / min-45°C / min, heated to the final column temperature of 300°C-320°C at a second-order heating rate of 15°C / min-25°C / min, maintained at the final column temperature for 2min-3min, the carrier gas is helium, the flow rate of helium is 0.8mL / min-1.2mL / min, the injection port temperature is 280°C-300°C, and the injection volume is 0.5μL-1.5μL; (7) Setting the mass spectrometry conditions: the ionization mode is electron impact ionization, the ionization energy is 60 eV to 80 eV, the GC-MSD interface temperature is 280°C to 320°C, the ion source temperature is 220°C to 240°C, the quadrupole temperature is 140°C to 160°C, the multiplier voltage is the automatic tuning value, the solvent delay time is 2.0 min to 3.0 min, the detector closing time of the mass spectrometer is 0.12 min to 0.25 min after the retention time of hexachlorobenzene, and the mass spectrometry scanning mode is the selected ion monitoring mode; (8) The starting detection time of hexachlorobenzene is 2.0 min to 3.0 min, the mass-to-charge ratio of the quantitative ion of hexachlorobenzene is 286, the mass-to-charge ratio of the first qualifier ion of hexachlorobenzene is 284, and the mass-to-charge ratio of the second qualifier ion of hexachlorobenzene is 288; the starting detection time of decachlorobiphenyl is 6.0 min to 7.0 min, the mass-to-charge ratio of the quantitative ion of decachlorobiphenyl is 498, the mass-to-charge ratio of the first qualifier ion of decachlorobiphenyl is 496, and the mass-to-charge ratio of the second qualifier ion of decachlorobiphenyl is 500; (9) A hexachlorobenzene standard curve and a decachlorobiphenyl standard curve are obtained according to the detection results of the gas chromatography and mass spectrometry, and the contents of ultra-trace hexachlorobenzene and decachlorobiphenyl in the chlorothalonil sample solution are obtained by combining the hexachlorobenzene standard curve and the decachlorobiphenyl standard curve.

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