Method for Separating and Detecting Dichlorvos and Methyldichlorvos Isomers by Supercritical Fluid Chromatography Tandem Mass Spectrometry
The separation and quantitative analysis of pyrophyte and methyl pyrophyte isomers by supercritical fluid chromatography tandem mass spectrometry solves the problem of ineffective separation and quantification in the prior art, and achieves efficient and rapid isomer detection.
Patent Information
- Application Number
- CN202310070900.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-07
- Publication Date
- 2025-07-18
- Estimated Expiration
- 2043-02-07
AI Technical Summary
The prior art cannot effectively isolate and quantitatively analyze the cistrans isomers of pyrophylla and methyl pyrophylla, resulting in inaccurate detection of pesticide residues.
Supercritical fluid chromatography tandem mass spectrometry was used to use silica gel with cellulose-tris (3,5-dichlorophenylcarbamate) covalently bonded on the surface as the filler, and ethanol and supercritical CO2 were mobile phases. Combined with gradient elution and mass spectrometry detection, isomers were separated and quantified.
The rapid resolution and quantitative analysis of pyrophyte and methylpyrophyte isomers were achieved, with good resolution, high sensitivity and accuracy, and the detection limit was less than 0.021 mg/kg.
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Figure CN115902070B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for separating and detecting dichlorvos and methyl dichlorvos isomers by supercritical fluid chromatography tandem mass spectrometry, belonging to the technical field of analytical chemistry. Background Art
[0002] Cis-trans isomerism is an important stereoisomerism phenomenon and belongs to the problem of diastereoisomerism. Due to the factors restricting rotation in the compound molecule, the arrangement of each group in space is different, resulting in cis-trans isomers. The properties of these isomers are not completely the same, and their dissipation and fate in the environment are often significantly different. There may be huge differences in their activities, toxicities, as well as absorption, metabolism, degradation, etc. in the natural environment and organisms.
[0003] Dichlorvos and methyl dichlorvos are highly toxic to humans and livestock and belong to highly toxic pesticide varieties. The molecular structures of dichlorvos and methyl dichlorvos contain C = C bonds and have a pair of cis-trans isomers, and the structures are as follows:
[0004]
[0005] At present, the pesticides sold on the market are all mixtures of cis-trans isomers of dichlorvos and methyl dichlorvos, and there is a small amount of residue after use in crop planting and storage processes. In the prior art, only the total amount of dichlorvos and methyl dichlorvos can be determined during the detection of dichlorvos and methyl dichlorvos. For example, the literature "Analysis of 29 Organophosphorus Pesticide Residues in Tobacco by Gas Chromatography-Mass Spectrometry" (Acta Tabacaria Sinica, 2008, 14(Z1)) discloses a method for detecting the residues of organophosphorus pesticides in tobacco. After the sample pretreatment, this method uses gas chromatography-mass spectrometry for analysis, and can realize the analysis of the residue amount of dichlorvos in tobacco. However, due to the lack of specific selectivity of gas chromatography and the corresponding chromatographic column for dichlorvos isomers, the cis-trans isomers of dichlorvos cannot be separated and quantitatively analyzed. Since there are certain differences in the activities of the cis-trans isomers of dichlorvos and methyl dichlorvos, it is very necessary to establish a method for determining the content of dichlorvos and methyl dichlorvos isomers for the development and production of single isomer products, the quality control of products by manufacturers, and the control of the residues of cis-trans isomers of dichlorvos and methyl dichlorvos in agricultural products. Summary of the Invention
[0006] The purpose of the present invention is to provide a method for separating and detecting dichlorvos and methyl dichlorvos isomers by supercritical fluid chromatography tandem mass spectrometry, which can realize the quantitative analysis of dichlorvos and methyl dichlorvos isomers in the sample to be tested.
[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is:
[0008] A method for separating and detecting dichlorvos and methyl dichlorvos isomers, comprising the following steps:
[0009] 1) Pretreat the sample to be tested to obtain a solution to be tested;
[0010] 2) Detect the solution to be tested by supercritical fluid chromatography tandem mass spectrometry;
[0011] 3) Calculate the contents of different isomers of dichlorvos and methyl dichlorvos in the sample to be tested according to the standard working curve;
[0012] In step 2), the chromatographic column used for supercritical fluid chromatography detection is packed with silica gel covalently bonded with cellulose tris(3,5-dichlorophenylcarbamate) on the surface, and the mobile phase used is ethanol and supercritical CO2. Tris(3,5-dichlorophenylcarbamate) outside the cellulose cavity in the chromatographic column can recognize isomers containing specific functional groups (benzene ring and phosphate group structure) through dipole-dipole or π-π interactions under the action of ethanol and supercritical CO2, realizing good separation of compounds containing both benzene ring and phosphate group.
[0013] Preferably, the chromatographic column is a Chiralpak IC-3 column, with a length of 100 mm, an inner diameter of 3.0 mm, and a packing particle size of 3 μm.
[0014] Preferably, the column temperature of the chromatographic column used for supercritical fluid chromatography detection is 35-45 °C.
[0015] Preferably, the back pressure of the supercritical fluid chromatography is 1900-2100 psi.
[0016] Preferably, the mobile phase is ethanol and supercritical CO2; gradient elution is used for liquid chromatography detection. From 0 to 0.5 min, the volume ratio of ethanol to CO2 is 99%:1.0%. From 0.5 to 3.0 min, the volume ratio of ethanol to CO2 linearly changes from 99%:1.0% to 90%:10%. From 3.0 to 3.5 min, the volume ratio of ethanol to CO2 linearly changes from 90%:10% to 99%:1.0%. From 3.5 to 5.0 min, the volume ratio of ethanol to CO2 is 99%:1.0%; the flow rate of the mobile phase is 1.8-2.0 mL / min.
[0017] Preferably, the compensation solvent is a mixed solution of formic acid and methanol, in which the volume fraction of formic acid is 0.1% and the flow rate is 0.2 mL / min.
[0018] Depending on the different samples to be tested, the pretreatment methods are also different, but all can be processed according to the pretreatment methods used for the detection of organic substances in the samples to be tested in the prior art. The sample to be tested is a chlorfenvinphos and methylchlorfenvinphos product or an agricultural product. When the sample to be tested is a chlorfenvinphos and methylchlorfenvinphos product, the pretreatment required includes the steps of diluting the chlorfenvinphos and methylchlorfenvinphos product and filtering it. When the sample to be tested is an agricultural product, the pretreatment includes the steps of extracting the sample to be tested and purifying the extract. For example, an improved QuEChERS method can be used to pretreat agricultural products to extract chlorfenvinphos and methylchlorfenvinphos in agricultural products to reduce matrix interference.
[0019] The agricultural product is tobacco or grain.
[0020] The pretreatment includes the following steps: crushing the sample to be tested and extracting it with an organic solvent, then adding an extraction salt, mixing well and centrifuging, taking the supernatant and purifying it with an adsorbent containing spherical carbon, and centrifuging again to take the supernatant to obtain the sample solution to be tested. Spherical carbon has excellent carbon content and pore structure, and at the same time has a large surface area. Compared with other purifying agents, it can better remove pigments and purify the matrix.
[0021] In mass spectrometry detection, the quantitative ion pairs of chlorfenvinphos and methylchlorfenvinphos are 358.9 / 155.0 and 331.1 / 127.1 respectively; the qualitative ion pairs are 358.9 / 205.1 and 331.1 / 205.1 respectively. The declustering voltages of the quantitative ion pairs and qualitative ion pairs of chlorfenvinphos are both 28V, and the collision energies are 12V and 30V respectively; the declustering voltages of the quantitative ion pairs and qualitative ion pairs of methylchlorfenvinphos are both 28V, and the collision energies are 20V and 16V respectively.
[0022] Preferably, the mass spectrometry detection conditions are: the ion source is an electrospray ionization source (ESI); the scanning mode is positive ion scanning; the capillary voltage is 2.6 - 2.8 KV; the ion source temperature is 140 - 150 °C; the desolvation gas temperature is 320 - 340 °C; the desolvation gas flow rate is 580 - 620 L / h; the cone gas flow rate is 40 - 50 L / h.
[0023] The method for separating and detecting chlorfenvinphos and methylchlorfenvinphos isomers of the present invention uses supercritical fluid chromatography tandem mass spectrometry, selects a chromatographic column filled with silica gel covalently bonded with cellulose tris(3,5-dichlorophenylcarbamate) on the surface, uses ethanol and supercritical CO2 as the mobile phase, and quantifies the cis and trans isomers of chlorfenvinphos and methylchlorfenvinphos by tandem mass spectrometry, which can realize the rapid separation and detection of the cis and trans isomers of chlorfenvinphos and methylchlorfenvinphos and reduce false positive results.
[0024] The method for separating and detecting chlorfenvinphos and methylchlorfenvinphos isomers of the present invention has a fast quantitative analysis speed for the cis- and trans-isomers of chlorfenvinphos and methylchlorfenvinphos. The time-consuming can be shortened to within 5 minutes. Supercritical fluid chromatography uses low-viscosity carbon dioxide as the main mobile phase, allowing the use of higher flow rates to obtain a faster separation speed. The packing material of the chromatographic column used is sub-2μm particles. Compared with the chromatographic column using sub-5μm particles, this chromatographic column has a faster separation speed. The detection limits of the cis- and trans-isomers of chlorfenvinphos and methylchlorfenvinphos are between 0.010 and 0.021 mg / kg, with high sensitivity and accuracy, and good resolution of the isomers. Brief Description of the Drawings
[0025] Figure 1 It is the selected ion chromatogram of the matrix mixed standard working solution in Example 1.
[0026] Figure 2 It is the selected ion chromatogram of the matrix mixed standard working solution in Comparative Example 1.
[0027] Figure 3 It is the selected ion chromatogram of the matrix mixed standard working solution in Comparative Example 2.
[0028] Figure 4 It is the selected ion chromatogram of the matrix mixed standard working solution in Comparative Example 3. Detailed Description of the Invention
[0029] The method for separating and detecting chlorfenvinphos and methylchlorfenvinphos isomers provided by the present invention includes the following steps:
[0030] 1) Pretreat the sample to be tested to obtain a solution to be tested;
[0031] 2) Detect the solution to be tested by supercritical fluid chromatography-tandem mass spectrometry;
[0032] 3) Calculate the contents of the cis-isomers and / or trans-isomers of chlorfenvinphos and methylchlorfenvinphos in the sample to be tested according to the standard working curve;
[0033] In step 2), the chromatographic column used in the supercritical fluid chromatography detection uses silica gel covalently bonded with cellulose tris(3,5-dichlorophenylcarbamate) as the packing material, and the mobile phase used is ethanol and supercritical CO2.
[0034] In the specific embodiment of the present invention, when the sample to be tested is an agricultural product, the pretreatment method is an improved QuEChERS method, including the following steps: after crushing the sample to be tested, extract it with an organic solvent, then add an extraction salt, mix well and centrifuge, take the supernatant and purify it with an adsorbent, and take the supernatant again after centrifugation to obtain the solution to be tested.
[0035] The organic solvent is acetonitrile. The extraction salt consists of the following components by weight: 5 parts of anhydrous magnesium sulfate, 1 part of sodium chloride, 1 part of sodium citrate, and 0.5 part of disodium hydrogen citrate. The mass ratio of the sample to be measured to the extraction salt is 2:7.5. The adsorbent consists of the following components: 150 mg of anhydrous magnesium sulfate, 25 mg of PSA, and 2.5 mg of spherical carbon.
[0036] In a specific embodiment of the present invention, the flow rate of the mobile phase during supercritical fluid chromatography detection is 2.0 mL / min.
[0037] In a specific embodiment of the present invention, the injection volume during supercritical fluid chromatography detection is 5 μL.
[0038] In a specific embodiment of the present invention, the mobile phase is ethanol and supercritical CO2.
[0039] In a specific embodiment of the present invention, the elution is gradient elution. From 0 to 0.5 min, the volume ratio of ethanol to CO2 is 99%:1.0%. From 0.5 to 3.0 min, the volume ratio of ethanol to CO2 linearly changes from 99%:1.0% to 90%:10%. From 3.0 to 3.5 min, the volume ratio of ethanol to CO2 linearly changes from 90%:10% to 99%:1.0%. From 3.5 to 5.0 min, the volume ratio of ethanol to CO2 is 99%:1.0%.
[0040] In a specific embodiment of the present invention, the compensation solvent is a mixed solution of formic acid and methanol, where the volume fraction of formic acid is 0.1% and the flow rate is 0.2 mL / min.
[0041] In a specific embodiment of the present invention, the back pressure of the supercritical fluid chromatography is 2000 psi.
[0042] In a specific embodiment of the present invention, the detection results are analyzed by the external standard method to calculate the contents of chlorpyrifos and methyl chlorpyrifos isomers in the sample to be measured.
[0043] In a specific embodiment of the present invention, in step 3), the standard working curve is determined by the method of the prior art. And according to the difference of chlorpyrifos and methyl chlorpyrifos isomers to be detected, a standard working curve of chlorpyrifos and methyl chlorpyrifos cis-isomers or a standard working curve of chlorpyrifos and methyl chlorpyrifos trans-isomers can be established; if the contents of chlorpyrifos and methyl chlorpyrifos cis-isomers and chlorpyrifos and methyl chlorpyrifos trans-isomers are determined simultaneously, standard working curves for both need to be established separately. The standard working solution used to determine the standard working curve is prepared according to the method in the prior art. To eliminate the influence of the matrix of the sample to be measured, the standard solutions used to determine the standard working curve are all matrix-mixed standard working solutions.
[0044] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.
[0045] The acetonitrile used in Example 1 and Example 2 was a chromatographic grade reagent, sodium citrate and sodium chloride were both analytical pure reagents, and the distilled water met the requirements of grade 1 water in GB / T 6682; the standard solutions of E-chlorfenvinphos, Z-chlorfenvinphos, E-methylchlorfenvinphos and Z-methylchlorfenvinphos (100 μg / mL) were purchased from Tianjin Aladdin Co., Ltd.; the mass spectrometer used was a Waters TQS quadrupole tandem mass spectrometer; the weighing was performed using a Swiss Mettler AE 163 electronic balance (sensitivity: 0.0001 g).
[0046] Example 1
[0047] The method for separating and detecting chlorfenvinphos and methylchlorfenvinphos isomers in this example includes the following steps:
[0048] 1) Prepare a blank sample matrix solution as follows: Accurately weigh 2 g of the ground grain blank sample into a 50 mL capped centrifuge tube, add 10 mL of water, add 10 mL of acetonitrile after soaking, and then place the centrifuge tube on a vortex mixer and oscillate at a rate of 2000 rpm for 5 min. Then add 5 g of anhydrous magnesium sulfate, 1 g of sodium chloride, 1 g of sodium citrate and 0.5 g of disodium hydrogen citrate to the centrifuge tube, immediately place it on a vortex mixer and oscillate at a rate of 2000 rpm for 5 min, and then centrifuge at a rate of 6000 rpm for 3 min; Pipette 1.0 mL of the supernatant into a 1.5 mL centrifuge tube, add 150 mg of anhydrous magnesium sulfate, 25 mg of PSA and 2.5 mg of spherical carbon, oscillate at a rate of 2000 rpm on a vortex mixer for 2 min, and centrifuge at a rate of 6000 rpm for 3 min; Aspirate the supernatant and filter it through a 0.45 μm organic phase filter membrane, and the obtained filtrate is the blank sample matrix solution for standby.
[0049] 2) Prepare a matrix-mixed standard working solution as follows: Pipette 0.1 mL of the standard solutions of E-chlorfenvinphos, Z-chlorfenvinphos, E-methylchlorfenvinphos and Z-methylchlorfenvinphos (100 μg / mL) into a 10 mL volumetric flask respectively, dissolve with acetonitrile and make up to the mark to prepare a standard stock solution (1.0 μg / mL); Pipette 50 μL, 100 μL, 200 μL, 500 μL, 1000 μL, 2000 μL of the secondary standard stock solution into 6 10 mL volumetric flasks respectively, make up to the mark with acetonitrile to obtain standard working solutions; Then pipette 500 μL of the above standard working solutions and mix them with 500 μL of the blank sample matrix solution respectively to prepare matrix-mixed standard working solutions.
[0050] 3) Inject the matrix-mixed standard working solutions with various concentrations prepared in step 2) into a supercritical fluid chromatography-tandem mass spectrometry for detection, record the selected ion peak areas of cis-isomers of chlorfenvinphos and methylchlorfenvinphos (Z-chlorfenvinphos and Z-methylchlorfenvinphos) and trans-isomers of chlorfenvinphos and methylchlorfenvinphos (E-chlorfenvinphos and E-methylchlorfenvinphos). The obtained selected ion chromatogram is shown in Figure 1 ; Then, using the concentration value of each isomer as the independent variable and its corresponding selected ion peak area as the dependent variable, calculate a univariate linear regression equation as the standard working curve. The specific detection results are shown in Table 1.
[0051] Table 1 Detection Results of Matrix-Mixed Standard Working Solutions
[0052] Isomer Retention time (min) Linear regression equation Linear correlation coefficient Linear range (ng / mL) Detection limit (mg / kg) E-chlorfenvinphos 2.55 Y = 14.44X + 60.86 0.9986 5~200 0.011 Z-chlorfenvinphos 2.89 Y = 18.84X + 60.68 0.9978 5~200 0.010 E-methylchlorfenvinphos 2.73 Y = 4.43X + 10.24 0.9975 5~200 0.021 Z-methylchlorfenvinphos 3.14 Y = 5.04X + 23.08 0.9943 5~200 0.020
[0053] Supercritical fluid chromatography-tandem mass spectrometry detection conditions:
[0054] Chromatographic conditions: Chromatographic column: Chiralpak IC-3 column with a specification of 100 mm × 3.0 mm, 3.0 µm; Mobile phase: ethanol and supercritical CO2, Flow rate: 2.0 mL / min; Gradient elution; Column temperature: 40 °C; Injection volume: 5 µL; From 0 - 0.5 min, the volume ratio of ethanol to CO2 is 99%:1.0%, from 0.5 - 3.0 min, the volume ratio of ethanol to CO2 linearly changes from 99%:1.0% to 90%:10%, from 3.0 - 3.5 min, the volume ratio of ethanol to CO2 linearly changes from 90%:10% to 99%:1.0%, from 3.5 - 5.0 min, the volume ratio of ethanol to CO2 is 99%:1.0%; The compensation solvent is a mixed solution of formic acid and methanol, where the volume fraction of formic acid is 0.1% and the flow rate is 0.2 mL / min.
[0055] Mass spectrometry conditions: Ion source is an electrospray ionization source (ESI); Scanning mode is positive ion scanning; Capillary voltage is 2.6 KV; Ion source temperature is 140 °C; Desolvation gas temperature is 320 °C; Desolvation gas flow rate is 580 L / h; Cone gas flow rate is 40 L / h; The quantitative ion pairs of chlorfenvinphos and methylchlorfenvinphos are 358.9 / 155.0 and 331.1 / 127.1 respectively; The qualitative ion pairs are 358.9 / 205.1 and 331.1 / 205.1 respectively. The declustering voltages of the quantitative ion pairs and qualitative ion pairs of chlorfenvinphos are both 28 V, and the collision energies are 12 V and 30 V respectively; The declustering voltages of the quantitative ion pairs and qualitative ion pairs of methylchlorfenvinphos are both 28 V, and the collision energies are 20 V and 16 V respectively.
[0056] 4) Pretreatment of the sample to be tested: Accurately weigh 2 g of the ground grain sample to be tested into a 50 mL centrifuge tube with a lid, add 10 mL of distilled water, add 10 mL of acetonitrile after soaking, then place the centrifuge tube on a vortex mixer and oscillate at a rate of 2000 rpm for 5 min. Then add 5 g of anhydrous magnesium sulfate, 1 g of sodium chloride, 1 g of sodium citrate and 0.5 g of disodium hydrogen citrate to the centrifuge tube, immediately place it on the vortex mixer and oscillate at a rate of 2000 rpm for 5 min, and then centrifuge at a rate of 6000 rpm for 3 min; Transfer 1.0 mL of the supernatant to a 1.5 mL centrifuge tube, add 150 mg of anhydrous magnesium sulfate, 25 mg of PSA and 2.5 mg of spherical carbon, oscillate at a rate of 2000 rpm on the vortex mixer for 2 min, and centrifuge at a rate of 6000 rpm for 3 min. Absorb the supernatant and filter it through a 0.45 μm organic phase filter membrane, and dilute it 2-fold with acetonitrile to obtain the solution to be tested;
[0057] 5) Perform supercritical fluid chromatography tandem mass spectrometry (LC-MS / MS) on the solution to be tested obtained in step 4) according to the chromatographic conditions and mass spectrometry conditions in step 3), and separate each elution peak according to the quantitative ion pairs, qualitative ion pairs and elution peak retention times of the isomers in Table 1.
[0058] Record the selected ion peak areas corresponding to the cis isomers of chlorfenvinphos and methylchlorfenvinphos and the trans isomers of chlorfenvinphos and methylchlorfenvinphos respectively, substitute the selected ion peak areas corresponding to each isomer obtained into the unary linear regression equation obtained in step 3), and obtain that the concentrations of E-chlorfenvinphos and Z-chlorfenvinphos in the solution to be tested are 7.0 ng / mL and 7.0 ng / mL respectively. Furthermore, the contents of Z-chlorfenvinphos, methylchlorfenvinphos, E-chlorfenvinphos and methylchlorfenvinphos in the grain sample to be tested are all 0.035 mg / kg.
[0059] To judge the accuracy of the method in this example, take 2 g of the grain sample and add 0.1 mL of the standard stock solution so that the added amounts of E-chlorfenvinphos, Z-chlorfenvinphos, E-methylchlorfenvinphos and Z-methylchlorfenvinphos in the sample are all 0.05 mg / kg. Perform sample pretreatment according to step 4), and perform analysis according to the chromatographic conditions and mass spectrometry conditions in step 3). Measure the selected ion peak areas of each isomer, substitute them into the standard curve obtained in step 3), and obtain that the contents of E-chlorfenvinphos, Z-chlorfenvinphos, E-methylchlorfenvinphos and Z-methylchlorfenvinphos in the sample at this time are 0.077, 0.080, 0.046 and 0.044 mg / kg respectively. That is, the spike recoveries of the target substances are 90.5%, 94.1%, 92.0% and 88.0%, indicating that the method in this example is accurate.
[0060] Example 2
[0061] The method for separating and detecting dichlorvos and methyl dichlorvos isomers in this example is completely the same as that in Example 1, except that the sample to be tested is another tobacco sample.
[0062] Neither E-dichlorvos, methyl dichlorvos, Z-dichlorvos nor methyl dichlorvos was detected in the tobacco sample in Example 2.
[0063] Comparative Example 1
[0064] The method for separating and detecting dichlorvos and methyl dichlorvos isomers in this example is completely the same as that in Example 1, except that the chromatographic column used is Chiralpak OD-3. On the total ion chromatogram, the four isomers cannot be completely separated. See Figure 2 。
[0065] Comparative Example 2
[0066] The method for separating and detecting dichlorvos and methyl dichlorvos isomers in this example is completely the same as that in Example 1, except that the chromatographic column used is Chiralpak IA-3. On the total ion chromatogram, the four isomers cannot be completely separated. See Figure 3 。
[0067] Comparative Example 3
[0068] The method for separating and detecting dichlorvos and methyl dichlorvos isomers in this example is completely the same as that in Example 1, except that the chromatographic column used is Chiralpak IG-3. On the total ion chromatogram, the four isomers cannot be completely separated. See Figure 4 。
Claims
1. A method for separating and detecting chlorfenvinphos and methyl chlorfenvinphos isomers by supercritical fluid chromatography-tandem mass spectrometry, characterized in that: It includes the following steps: 1) Pretreat the sample to be tested to obtain a test solution; The pretreatment includes the following steps: crush the sample to be tested and extract it with an organic solvent, then add extraction salt, mix well and centrifuge, take the supernatant and purify it with an adsorbent containing spherical carbon, and take the supernatant after centrifugation again to obtain the test solution; 2) Detect the test solution by supercritical fluid chromatography-tandem mass spectrometry. The chromatographic column used is packed with silica gel covalently bonded with cellulose tris(3,5-dichlorophenylcarbamate) on the surface, and the mobile phase used is ethanol and supercritical CO2; the chromatographic column is a Chiralpak IC-3 column. The column temperature of the chromatographic column used for supercritical fluid chromatography detection is 35-45 °C. Supercritical fluid chromatography detection adopts gradient elution. From 0 to 0.5 min, the volume ratio of ethanol to CO2 is 99%:1.0%. From 0.5 to 3.0 min, the volume ratio of ethanol to CO2 linearly changes from 99%:1.0% to 90%:10%. From 3.0 to 3.5 min, the volume ratio of ethanol to CO2 linearly changes from 90%:10% to 99%:1.0%. From 3.5 to 5.0 min, the volume ratio of ethanol to CO2 is 99%:1.0%; the flow rate of the mobile phase is 1.8-2.0 mL / min. In mass spectrometry detection, the quantitative ion pairs of chlorfenvinphos and methylchlorfenvinphos are 358.9 / 155.0 and 331.1 / 127.1 respectively; the qualitative ion pairs are 358.9 / 205.1 and 331.1 / 205.1 respectively; the declustering voltages of the quantitative ion pairs and qualitative ion pairs of chlorfenvinphos are both 28 V, and the collision energies are 12 V and 30 V respectively; the declustering voltages of the quantitative ion pairs and qualitative ion pairs of methylchlorfenvinphos are both 28 V, and the collision energies are 20 V and 16 V respectively. 3) Calculate the contents of chlorfenvinphos and methylchlorfenvinphos isomers in the sample to be tested according to the standard working curve.
2. The method for separating and detecting dichlorvos and methyl dichlorvos isomers according to claim 1, characterized in that: The Chiralpak IC-3 column has a length of 100 mm, an inner diameter of 3.0 mm, and a packing particle size of 3 μm.
3. The method for separating and detecting dichlorvos and methyl dichlorvos isomers according to claim 1, characterized in that: The sample to be tested is a chlorfenvinphos and methylchlorfenvinphos product or agricultural product.
4. The method for separating and detecting dichlorvos and methyl dichlorvos isomers according to claim 3, characterized in that: The agricultural product is tobacco or grain.
5. The method for separating and detecting isomers of chlorfenvinphos and methylchlorfenvinphos according to claim 1, characterized in that: The mass spectrometry detection conditions are: the ion source is an electrospray ionization source (ESI); the scanning mode is positive ion scanning; the capillary voltage is 2.6-2.8 KV; the ion source temperature is 140-150 °C; the desolvation gas temperature is 320-340 °C; the desolvation gas flow rate is 580-620 L / h; the cone gas flow rate is 40-50 L / h.