A method for determining the residue of pyraflufen-ethyl in tea
Through the methods of acetic acid-acetonitrile solution extraction, solid-phase extraction column purification and liquid chromatography tandem mass spectrometer detection, the accuracy and stability of flupyroxone residue detection in tea was solved, and efficient flupyroxone residue determination in tea was achieved.
Patent Information
- Application Number
- CN202211712083.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-29
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2042-12-29
AI Technical Summary
The prior art lacks stable and suitable methods for detecting flupyramidone residues in tea, making it difficult to conduct risk assessment, and flupyramidone is easily disturbed during the extraction and analysis of tea.
Sample extraction was performed using 1% acetic acid-acetonitrile solution and mixed salt, purified using GCB/NH2 solid-phase extraction column, tested in combination with liquid chromatography tandem mass spectrometer, and quantitative analysis was performed by internal standard method and matrix calibration solution.
It provides an accurate, stable and strong anti-interference detection method for flupyramidone residue detection in tea, which is suitable for a variety of teas, with low detection limits and wide applicability, and can meet a variety of testing needs.
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Figure CN115980222B_ABST
Abstract
Description
[Technical Field]
[0001] The present invention belongs to the technical field of analytical chemistry, and specifically relates to a method for determining the residue of pyroxasulfone in tea leaves. [Background Art]
[0002] As weeds gradually develop resistance to traditional herbicides, alternative products that are relatively safe and highly effective in weed control are an urgent need in current agricultural production. HPPD (4-hydroxyphenylpyruvate dioxygenase) is one of the most important herbicide action targets at present, and HPPD-inhibiting herbicides are currently a research and development hotspot in the global pesticide industry. In recent years, various HPPD-inhibiting herbicides have been emerging in an endless stream, and the biosafety of new herbicides represented by triketones has gradually attracted the attention of health departments and environmental protection agencies in various countries.
[0003] Pyroxasulfone belongs to triketone HPPD inhibitors. By inhibiting the activity of HPPD, it prevents HPPA (4-hydroxyphenylpyruvate) from being converted into HGA (homogentisic acid), thereby hindering the normal synthesis of tocopherol and plastoquinone in weeds, affecting the biosynthesis of carotenoids, promoting the albino of plant meristematic and new tissues, and causing the death of weed plants. In order to improve the safety of herbicides for crops, herbicides are often mixed with safeners such as cloquintocet or mefenpyr-diethyl for application. Since the market launch of the new herbicide pyroxasulfone in 2015, the market has grown rapidly, with sales reaching 100 million US dollars in the first year of market launch, and a compound growth rate of 47% from 2015 to 2019. Currently, it is widely used worldwide. Pyroxasulfone belongs to a relatively low-toxic botanical pesticide, which is widely absorbed and distributed in mammalian bodies, mainly distributed in the liver and kidneys, and excreted through urine. This herbicide is extremely toxic to aquatic organisms and has long-term continuous effects. High doses of pyroxasulfone can cause severe hepatotoxicity and nephrotoxicity, and may cause harm to fertility or fetuses. In 2017, the Pest Management Regulatory Agency of Health Canada formulated the maximum residue limit of pyroxasulfone for raw agricultural products, etc. In 2021, the US Environmental Protection Agency stipulated the residue limit of pyroxasulfone in crops such as lemongrass. Countries around the world pay more and more attention to the limit requirements and content detection of pyroxasulfone. In 2020, China stipulated the temporary limit of pyroxasulfone in grains in GB2763-2021.
[0004] With the continuous attention of various countries to the pesticide flupyradifurone, it is imperative to evaluate the residue risk of flupyradifurone in tea and establish the maximum residue limit (MRL). However, at present, there are few mature and stable detection methods for flupyradifurone residues in tea, which makes it difficult to carry out the detection work of flupyradifurone residues in tea and also difficult to conduct risk assessment. Flupyradifurone has a relatively small relative molecular mass, is slightly soluble in methanol, is difficult to extract, and is easily interfered by impurities in the sample during the analysis process. Moreover, there are many interfering substances in tea, and the analysis is inherently difficult. Conventional tea detection methods are obviously not applicable to flupyradifurone. Therefore, it is urgent to establish an accurate and stable detection method for the content of flupyradifurone in tea. [Summary of the Invention]
[0005] The purpose of the present invention is to solve the above deficiencies and provide a method for determining the residue amount of flupyradifurone in tea by liquid chromatography-tandem mass spectrometry after extraction and purification. This determination method is accurate, stable, has strong anti-interference ability and wide applicability, and can meet various test requirements.
[0006] To achieve the above purpose, a method for determining the residue amount of flupyradifurone in tea is designed, including the following steps: 1) Sample pretreatment: After the sample is crushed by a pulverizer, it is mixed evenly and put into a clean and dry self-sealing bag, sealed and reserved; 2) Sample extraction: Take an appropriate amount of the sample, and extract it with a 1% acetic acid-acetonitrile solution and a mixed salt to obtain a sample extract; 3) Sample purification: The sample extract obtained in step 2) is purified by a GCB / NH2 solid-phase extraction column to obtain an analysis solution for injection; 4) Preparation of matrix calibration solution: Weigh a negative sample without flupyradifurone, and prepare a negative sample extract without internal standard according to steps 1), 2), and 3) for preparing a flupyradifurone matrix calibration solution; 5) Use liquid chromatography-tandem mass spectrometry to determine the concentration of flupyradifurone in the analysis solution for injection obtained in step 3) and the matrix calibration solution obtained in step 4); 6) Calculate the concentration of flupyradifurone in the sample according to the concentration of flupyradifurone in the analysis solution for injection of the sample and the matrix calibration solution obtained in step 5).
[0007] Further, in step 1), after the sample is crushed by a pulverizer, if the particle size of the sample is still uneven, the crushed sample is first sieved through a 2 mm sieve and then mixed evenly.
[0008] Further, in step 2), before weighing the sample, mix the sample again, accurately weigh 2 g of the sample into a 50 mL centrifuge tube, add 0.2 mL of 1 mg / L triphenyl phosphate (TPP) internal standard solution, add 10 mL of water, vortex to disperse the sample into the aqueous solution, and soak for 20 min; add 20 mL of 1% acetic acid - acetonitrile solution, fix the centrifuge tube on a horizontal shaker, shake and extract at a speed of 250 - 300 times / min for 15 min, then add a mixed salt composed of 6 g of anhydrous magnesium sulfate and 1.5 g of sodium acetate, quickly mix evenly for 1 min to prevent caking, and then centrifuge at 8000 r / min at 4°C for 5 min.
[0009] Further, in step 3), activate the GCB / NH2 solid phase extraction column with 10 mL of acetonitrile - toluene solution with a volume ratio of 3:1, and do not retain the effluent; accurately transfer 10 mL of the supernatant in step 2) to a centrifuge tube, add 3.33 mL of toluene, mix evenly and transfer to the small column, and collect the effluent; after all the sample solution has flowed out, elute and collect with 15 mL of acetonitrile - toluene solution with a volume ratio of 3:1, and combine the above two effluents; under the condition of 40°C, rotary evaporate the sample solution to near dryness, then blow to dry with nitrogen, re - dissolve with acetone and make the volume up to 1 mL, and then centrifuge at 10000 r / min for 3 min; take 0.1 mL of the supernatant and mix evenly with 0.4 mL of 80% methanol - aqueous solution for detection by liquid chromatography - tandem mass spectrometry.
[0010] Further, in step 4), if the sample is positive, prepare a negative sample extract without adding the internal standard according to steps 1), 2), and 3), and then according to the concentration of the target residue in the sample, absorb an appropriate amount of the fluroxypyr standard intermediate solution and triphenyl phosphate (TPP) internal standard solution, and prepare a matrix standard solution with the same concentration for on - machine analysis to calculate the actual residue of the target in the sample.
[0011] Further, in step 5), the determination conditions of the liquid chromatography - tandem mass spectrometry are as follows:
[0012] a) The liquid chromatography analytical column uses a Poroshell 120 EC - C18 column with a specification of column length 10 cm, column inner diameter 3.0 mm, and particle size 2.7 μm;
[0013] b) The liquid chromatography guard column uses a Poroshell 120 EC - C18 column with a specification of column length 5 mm, column inner diameter 3.0 mm, and particle size 2.7 μm;
[0014] c) The liquid chromatography column temperature is set at 40°C;
[0015] d) Injection volume: 20 μL;
[0016] e) Flow rate: 0.4 L / min;
[0017] f) Mobile phase:
[0018]
[0019] g) Run time: 15 min;
[0020] h) Mass spectrometry parameters are shown in the following table:
[0021] Ion source type Electrospray ionization ion source Ionization mode Positive mode Capillary voltage V 4000 Drying gas temperature °C 300 Drying gas flow rate L / min 40 Nebulizing gas pressure psi 45 psi Scanning mode Selected ion monitoring Selected ion m / z 400.2 / 324.2，400.2 / 228 。
[0022] Furthermore, in step 6), the amount of flufenpyr-ethyl in the sample solution obtained by liquid chromatography-tandem mass spectrometry is quantified by the internal standard method, and the internal standard is triphenyl phosphate; at the same time, matrix calibration conversion is performed through the detection result of the amount of flufenpyr-ethyl in the matrix calibration solution, and the actual content of flufenpyr-ethyl in the sample is calculated.
[0023] Furthermore, in step 6), it is determined whether flufenpyr-ethyl is detected in the sample by comparing the retention time of the chromatographic peak in the sample solution with the retention time of flufenpyr-ethyl in the standard solution and the relative abundances of each ion pair; then, calibration of the matrix effect is performed according to the matrix calibration solution, and quantification is performed by the internal standard method.
[0024] Furthermore, the flufenpyr-ethyl refers to a compound with CAS No. 352010-68-5 and molecular formula C 19 H 20 F3NO5.
[0025] Compared with the prior art, the present invention fills the gap in the detection method of flufenpyr-ethyl in tea in the market, and provides a method for determining the content of flufenpyr-ethyl in tea. The sample is extracted with a 1% acetic acid-acetonitrile solution assisted by mixed salts, purified by a solid-phase extraction column, and then detected by liquid chromatography-tandem mass spectrometry. Quantification is performed by the internal standard method, and the actual content is corrected by the matrix calibration solution. This determination method is accurate, stable, has strong anti-interference ability, is fast and has wide applicability. It is applicable to various teas such as green tea, black tea, and oolong tea. The lowest quantification concentration is relatively low, which is 0.01 mg / kg, and it can meet various test requirements and is worthy of popularization and application. [Description of the Drawings]
[0026] Figure 1 It is the mass spectrometry diagram of flufenpyr-ethyl and the internal standard triphenyl phosphate obtained by using liquid chromatography-tandem mass spectrometry to detect the content of flufenpyr-ethyl in a black tea sample in Example 2 of the present invention. [Detailed Embodiments]
[0027] The present invention belongs to the accurate determination of the content of pyroxasulfone in tea in the field of analytical chemistry. The principle is as follows: The sample is extracted with a 1% acetic acid-acetonitrile solution assisted by a mixed salt, purified by a solid-phase extraction column, and then detected by a liquid chromatography-tandem mass spectrometer. The internal standard method is used for quantification, and the actual content is corrected with a matrix calibration solution.
[0028] The determination method includes the following steps: 1) Sample pretreatment: After the sample is crushed by a pulverizer, if the particle size of the sample is still uneven, the crushed sample is first screened through a 2-mm sieve, mixed evenly, placed in a clean and dry self-sealing bag, and sealed for standby; 2) Sample extraction: Take 2 g of the sample, extract it with a 1% acetic acid-acetonitrile solution and a mixed salt to obtain a sample extract; 3) Sample purification: The sample extract is purified by a GCB / NH2 solid-phase extraction column to obtain an analysis solution for injection; 4) Preparation of the matrix calibration solution: Weigh a negative sample without pyroxasulfone, and prepare a negative sample extract without internal standard according to steps 1), 2), and 3) for preparing the pyroxasulfone matrix calibration solution; 5) Use a liquid chromatography-tandem mass spectrometer to measure the concentration of pyroxasulfone in the analysis solution for injection obtained in step 3) and the matrix calibration solution obtained in step 4); 6) Calculate the concentration of pyroxasulfone in the sample based on the concentration of pyroxasulfone in the analysis solution for injection of the sample and the matrix calibration solution obtained in step 5).
[0029] Among them, in step 2), the sample is mixed again before weighing, 2 g of the sample is accurately weighed into a 50-mL centrifuge tube, 0.2 mL of a 1-mg / L triphenyl phosphate (TPP) internal standard solution is added, 10 mL of water is added, and the sample is vortexed to disperse it in the aqueous solution and soaked for 20 min; 20 mL of a 1% acetic acid-acetonitrile solution is added, the centrifuge tube is fixed on a horizontal shaker, and shaken at a speed of 250-300 times per minute for 15 min. Then, a mixed salt (6 g of anhydrous magnesium sulfate and 1.5 g of sodium acetate) is added, and quickly mixed for 1 min to prevent caking. Then, it is centrifuged at a speed of 8000 r / min at 4 °C for 5 min.
[0030] In step 3), a GCB / NH2 solid-phase extraction column is activated with 10 mL of an acetonitrile-toluene (volume ratio 3:1) solution, and the effluent is not retained; 10 mL of the supernatant is accurately transferred to a centrifuge tube, 3.33 mL of toluene is added, mixed evenly and then transferred to the small column, and the effluent is collected; after all the sample solution has flowed out, it is eluted and collected with 15 mL of an acetonitrile-toluene (volume ratio 3:1) solution, and the above two effluents are combined; under the condition of 40 °C, the sample solution is rotary evaporated to near dryness, and then blown to dry with nitrogen, redissolved with acetone and fixed volume to 1 mL, and then centrifuged at a speed of 10000 r / min for 3 min; 0.1 mL of the supernatant is mixed evenly with 0.4 mL of an 80% methanol-aqueous solution for detection by a liquid chromatography-tandem mass spectrometer.
[0031] In step 4), if the sample is positive, prepare a negative sample extract without internal standard according to steps 1), 2), and 3). Then, according to the concentration of the target residue in the sample, pipette an appropriate amount of the pyraflufen-ethyl standard intermediate solution and the triphenyl phosphate (TPP) internal standard solution to prepare a matrix standard solution with the same concentration for on-machine analysis to calculate the actual residue of the target in the sample. Prepare and use it immediately.
[0032] In step 5), the determination conditions of the liquid chromatography-tandem mass spectrometer are as follows:
[0033] a) The liquid chromatography analytical column uses a Poroshell 120 EC-C18 column with a specification of column length 10 cm, column inner diameter 3.0 mm, and particle size 2.7 μm;
[0034] b) The liquid chromatography guard column uses a Poroshell 120 EC-C18 column with a specification of column length 5 mm, column inner diameter 3.0 mm, and particle size 2.7 μm;
[0035] c) The liquid chromatography column temperature is set at 40 °C;
[0036] d) Injection volume: 20 μL;
[0037] e) Flow rate: 0.4 L / min;
[0038] f) Mobile phase:
[0039]
[0040] g) Running time: 15 min;
[0041] h) The mass spectrometry parameters are shown in the following table:
[0042] Ion source type Electrospray ionization ion source Ionization mode Positive mode Capillary voltage (V) 4000 Drying gas temperature (°C) 300 Drying gas flow rate (L / min) 40 Nebulizing gas pressure (psi) 45 psi Scanning mode Selected ion monitoring Selected ion m / z 400.2 / 324.2，400.2 / 228
[0043] In step 6), the amount of pyraflufen-ethyl in the sample solution obtained by the liquid chromatography-tandem mass spectrometer is quantified by the internal standard method. The internal standard is triphenyl phosphate, and the matrix calibration conversion is performed through the amount of pyraflufen-ethyl in the matrix calibration solution to calculate the actual content of pyraflufen-ethyl in the sample. Pyraflufen-ethyl refers to the compound with CAS number 352010-68-5 and molecular formula C 19 H 20 F3NO5.
[0044] The following further illustrates the present invention with specific embodiments:
[0045] Example 1: Determination of pyraflufen-ethyl residue in green tea
[0046] 1. Preparation of the sample solution:
[0047] Break the green tea into pieces with a crusher, sieve through a 2-mm sieve, mix well, put it into a clean and dry self-sealing bag, and seal for later use. Mix the sample again before weighing, accurately weigh 2 g of the sample into a 50-mL centrifuge tube, add 0.2 mL of 1 mg / L triphenyl phosphate (TPP) internal standard solution, add 10 mL of water, vortex to disperse the sample into the aqueous solution, and soak for 20 min. Add 20 mL of 1% acetic acid-acetonitrile solution, fix the centrifuge tube on a horizontal shaker, shake and extract at a speed of 250 - 300 times / min for 15 min, then add mixed salts (6 g of anhydrous magnesium sulfate and 1.5 g of sodium acetate), quickly mix well for 1 min to prevent caking, and then centrifuge at 8000 r / min at 4°C for 5 min; activate the GCB / NH2 solid-phase extraction column with 10 mL of acetonitrile-toluene (volume ratio 3:1) solution, and do not retain the effluent. Accurately transfer 10 mL of the supernatant to a centrifuge tube, add 3.33 mL of toluene, mix well and transfer to the small column, and collect the effluent. After all the sample solution has flowed out, elute and collect with 15 mL of acetonitrile-toluene (volume ratio 3:1) solution, and combine the above two effluents. Under the condition of 40°C, rotary evaporate the sample solution to nearly dry, then blow to dry with nitrogen, re-dissolve with acetone and make the volume up to 1 mL, and then centrifuge at 10000 r / min for 3 min. Take 0.1 mL of the supernatant and mix it evenly with 0.4 mL of 80% methanol-aqueous solution for detection by liquid chromatography-tandem mass spectrometry.
[0048] 2. Set the instrument parameters:
[0049] a) The liquid chromatography analytical column uses a Poroshell 120 EC-C18 column with a specification of column length 10 cm, column inner diameter 3.0 mm, and particle size 2.7 μm;
[0050] b) The liquid chromatography guard column uses a Poroshell 120 EC-C18 column with a specification of column length 5 mm, column inner diameter 3.0 mm, and particle size 2.7 μm;
[0051] c) The liquid chromatography column temperature is set at 40°C;
[0052] d) Injection volume: 20 μL;
[0053] e) Flow rate: 0.4 L / min;
[0054] f) Mobile phase:
[0055]
[0056] g) Running time: 15 min;
[0057] h) The mass spectrometry parameters are shown in the following table:
[0058] Ion source type Electrospray ionization ion source Ionization mode Positive mode Capillary voltage (V) 4000 Drying gas temperature (°C) 300 Drying gas flow rate (L / min) 40 Nebulizing gas pressure (psi) 45 psi Scanning mode Selected ion monitoring Selected ion m / z 400.2 / 324.2，400.2 / 228
[0059] 3. Qualitative and Quantitative
[0060] 1) Qualitative: By comparing the retention time of the chromatographic peak in the sample solution with the retention time of flupyradifurone in the standard solution and the relative abundances of each ion pair, determine whether flupyradifurone is detected in the sample.
[0061] 2) Quantitative: Calibrate the matrix effect according to the matrix calibration solution and use the internal standard method for quantification.
[0062] 4. Calculation
[0063] Calculate the content of flupyradifurone in the sample according to the concentration of flupyradifurone in the sample extraction solution. After detection, no flupyradifurone was detected in this green tea sample.
[0064] Example 2: Determination of Flupyradifurone Residue in Black Tea
[0065] 1. Preparation of Sample Solution
[0066] Break the black tea with a pulverizer and pass it through a 2 mm sieve. Mix well and put it into a clean and dry self-sealing bag, seal it for later use. Mix the sample again before weighing. Accurately weigh 2 g of the sample into a 50 mL centrifuge tube, add 0.2 mL of 1 mg / L triphenyl phosphate (TPP) internal standard solution, add 10 mL of water, vortex to disperse the sample into the aqueous solution, and soak for 20 min. Add 20 mL of 1% acetic acid-acetonitrile solution, fix the centrifuge tube on a horizontal shaker, and shake and extract at a speed of 250 - 300 times / min for 15 min. Then add mixed salts (6 g of anhydrous magnesium sulfate and 1.5 g of sodium acetate), quickly mix well for 1 min to prevent caking, and then centrifuge at 8000 r / min at 4°C for 5 min; Activate the GCB / NH2 solid-phase extraction column with 10 mL of acetonitrile-toluene (volume ratio 3:1) solution, and do not retain the effluent. Accurately transfer 10 mL of the supernatant to a centrifuge tube, add 3.33 mL of toluene, mix well and transfer it to the small column, and collect the effluent. After all the sample solution has flowed out, elute and collect with 15 mL of acetonitrile-toluene (volume ratio 3:1) solution, and combine the above two effluents. Under the condition of 40°C, rotary evaporate the sample solution to near dryness, then blow it to dry with nitrogen, redissolve it with acetone and dilute to 1 mL, and centrifuge at 10000 r / min for 3 min. Take 0.1 mL of the supernatant and mix it evenly with 0.4 mL of 80% methanol-aqueous solution for detection by liquid chromatography-tandem mass spectrometry.
[0067] 2. Set Instrument Parameters:
[0068] a) The liquid chromatography analysis column uses a Poroshell 120 EC-C18 column with a specification of column length 10 cm, column inner diameter 3.0 mm, and particle size 2.7 μm;
[0069] b) The liquid chromatography guard column uses a Poroshell 120 EC-C18 column with a specification of a column length of 5 mm, an inner column diameter of 3.0 mm, and a particle size of 2.7 μm;
[0070] c) The liquid chromatography column temperature is set at 40 °C;
[0071] d) Injection volume: 20 μL;
[0072] e) Flow rate: 0.4 L / min;
[0073] f) Mobile phase:
[0074]
[0075] g) Running time: 15 min;
[0076] h) The mass spectrometry parameters are shown in the following table:
[0077] Ion source type Electrospray ionization ion source Ionization mode Positive mode Capillary voltage (V) 4000 Drying gas temperature (°C) 300 Drying gas flow rate (L / min) 40 Nebulizing gas pressure (psi) 45 psi Scanning mode Selected ion monitoring Selected ion m / z 400.2 / 324.2，400.2 / 228
[0078] 3. Qualitative and quantitative
[0079] 1) Qualitative: By comparing the retention time of the chromatographic peak in the sample solution with the retention time of fluroxypyr in the standard solution and the relative abundances of each ion pair, it is determined whether fluroxypyr is detected in the sample.
[0080] 2) Quantitative: Calibrate the matrix effect according to the matrix calibration solution, and use the internal standard method for quantification.
[0081] 4. Calculation
[0082] According to the concentration of fluroxypyr in the sample extraction solution, calculate the content of fluroxypyr in the sample. After detection, the content of fluroxypyr in this black tea sample is 0.021 mg / kg.
[0083] The present invention is not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.
Claims
1. A method for determining the residue amount of pyraflufen-ethyl in tea, characterized in that, It includes the following steps: 1) Sample pretreatment: After the sample is crushed by a pulverizer, it is mixed evenly and filled into a clean and dry self-sealing bag, sealed for standby; 2) Sample extraction: Take an appropriate amount of the sample, extract it with 1% acetic acid-acetonitrile solution and mixed salts to obtain a sample extract; 3) Sample purification: Purify the sample extract obtained in step 2) through a GCB / NH2 solid-phase extraction column to obtain an analytical solution for injection; 4) Preparation of matrix calibration solution: Weigh a negative sample without fluroxypyr, and prepare a negative sample extract without internal standard according to steps 1), 2), and 3) for preparing the fluroxypyr matrix calibration solution; 5) Use a liquid chromatography-tandem mass spectrometer to determine the concentration of fluroxypyr in the analytical solution for injection obtained in step 3) and the matrix calibration solution obtained in step 4); 6) Calculate the concentration of fluroxypyr in the sample based on the concentrations of fluroxypyr in the analytical solution for injection of the sample and the matrix calibration solution obtained in step 5); In step 5), the determination conditions of the liquid chromatography-tandem mass spectrometer are as follows: a) The liquid chromatography analytical column uses a Poroshell 120 EC-C18 column, with a specification of column length 10 cm, column inner diameter 3.0 mm, and particle size 2.7 μm; b) The liquid chromatography guard column uses a Poroshell 120 EC-C18 column, with a specification of column length 5 mm, column inner diameter 3.0 mm, and particle size 2.7 μm; c) The liquid chromatography column temperature is set at 40 °C; d) Injection volume: 20 μL; e) Flow rate: 0.4 L / min; f) Mobile phase: g) Running time: 15 min; h) The mass spectrometry parameters are shown in the following table: 。 2. The method according to claim 1, characterized in that: In step 1), after the sample is crushed by a pulverizer, if the particle size of the sample is still uneven, the crushed sample is first passed through a 2 mm sieve and then mixed evenly.
3. The method according to claim 1, wherein: In step 2), the sample is mixed evenly again before weighing. Accurately weigh 2 g of the sample into a 50 mL centrifuge tube, add 0.2 mL of 1 mg / L triphenyl phosphate TPP internal standard solution, add 10 mL of water, vortex to disperse the sample into the aqueous solution, and soak for 20 min; add 20 mL of 1% acetic acid-acetonitrile solution, fix the centrifuge tube on a horizontal shaker, and shake and extract at a speed of 250 - 300 times / min for 15 min. Then add a mixed salt composed of 6 g of anhydrous magnesium sulfate and 1.5 g of sodium acetate, mix quickly for 1 min to prevent caking, and then centrifuge at a speed of 8000 r / min at 4 °C for 5 min.
4. The method according to claim 1, wherein: In step 3), activate the GCB / NH2 solid-phase extraction column with 10 mL of acetonitrile-toluene solution with a volume ratio of 3:1, and do not retain the effluent; accurately transfer 10 mL of the supernatant in step 2) to a centrifuge tube, add 3.33 mL of toluene, mix well and transfer it to the small column, and collect the effluent; after all the sample solution has flowed out, elute and collect with 15 mL of acetonitrile-toluene solution with a volume ratio of 3:1, and combine the two effluents; under the condition of 40 °C, rotary evaporate the sample solution to near dryness, then blow it to dry with nitrogen, re-dissolve it with acetone and make the volume up to 1 mL, and centrifuge at a speed of 10000 r / min for 3 min; take 0.1 mL of the supernatant and mix it evenly with 0.4 mL of 80% methanol-aqueous solution for detection by liquid chromatography-tandem mass spectrometry.
5. The method according to claim 1, characterized in that: In step 6), the amount of fluroxypyr in the sample solution obtained by liquid chromatography-tandem mass spectrometry is quantified by the internal standard method, and the internal standard is triphenyl phosphate; at the same time, the matrix calibration conversion is carried out through the detection result of the amount of fluroxypyr in the matrix calibration solution, and the actual content of fluroxypyr in the sample is calculated.
6. The method according to claim 1, wherein: In step 6), determine whether fluroxypyr is detected in the sample by comparing the retention time of the chromatographic peak in the sample solution with the retention time of fluroxypyr in the standard solution and the relative abundances of each ion pair; then calibrate the matrix effect according to the matrix calibration solution and quantify by the internal standard method.
7. The method according to claim 1, characterized in that: The diflupyrrol is CAS No. 352010-68-5, molecular formula C 19 H 20 Compounds of F3NO5.