High performance liquid chromatography-high resolution mass spectrometry combined analysis method for herbicide in corn field soil

Abstract

The invention discloses a corn field soil herbicide high performance liquid chromatography-high resolution mass spectrometry analysis method, which comprises: S1, weighing a corn field soil sample to be detected, placing in a centrifuge tube, adding an organic solvent, and carrying out vortex so as to completely dissolve a target herbicide in an organic phase; s2, sequentially adding a salting-out agent and a dehydrating agent into the centrifugal tube, and swirling again to form a solid-liquid two-phase separation system; s3, centrifuging the mixed solution at a preset rotating speed, taking supernate, transferring the supernate into a centrifugal tube filled with an adsorbent, carrying out vortex adsorption on fat-soluble impurities, filtering, and collecting filtrate into a sample bottle for detection; and S4, separating the target herbicide in a liquid chromatography-high resolution mass spectrum manner, and accurately determining the nature and the quantity. By optimizing a sample pretreatment method and instrument analysis conditions, high efficiency, ultrahigh sensitivity and accuracy of synchronous detection of multiple herbicides and green pretreatment technology innovation are realized, and the method is suitable for synchronous detection of 20 herbicide residues in corn field soil.

Description

TECHNICAL FIELD

[0001] The application relates to a corn field soil herbicide high-performance liquid chromatography-high resolution mass spectrometry analysis method and belongs to the technical field of soil herbicide analysis. BACKGROUND

[0002] Corn is an important food crop in the world, but the problem of herbicide residues widely used in the planting process poses a potential threat to soil health, ecological environment and food safety. The commonly used herbicides in corn fields include sulfonylurea (such as methyl iodine sulfonate sodium salt, sulfuron), triazine (such as cyanazine, simazine), amide (such as butachlor, precision isopropyl methyl chloroform) and the like. These compounds have significant differences in chemical properties, for example, sulfonylurea has high polarity, while triazine has poor thermal stability, and traditional detection techniques cannot realize synchronous analysis of multiple categories of residues.

[0003] At present, the detection of herbicide residues in soil mainly relies on gas chromatography (GC) and liquid chromatography (HPLC) techniques, but the former has poor applicability to heat-unstable compounds, and the latter often needs complex pretreatment steps due to insufficient sensitivity. In addition, humic acid, inorganic salt and other interfering substances in the soil matrix can easily lead to low recovery rate of target compounds or false positive results, especially for the accurate detection of trace residues.

[0004] The existing literature "Liquid chromatography method for determining chlorotoluron in corn and soil" reports a high-performance liquid chromatography analysis method for determining the residual chlorotoluron pesticide in corn plants, corn kernels and soil by using a C18 chromatographic column for separation, acetonitrile-water elution and determination at 243 nm. However, the scheme has the following problems: (1) Low pretreatment efficiency and complicated operation: the extraction process of 2 hours of oscillation is time-consuming and low in efficiency; acetonitrile as a highly toxic organic solvent, the use of 10 mL not only increases the operation risk, but also may lead to the increase of subsequent waste liquid treatment cost. (2) Insufficient purification step, significant matrix interference: it is difficult to remove humic acid, lipids and other co-extracted substances in the soil through centrifugation and filtration (0.22 mu m organic membrane), which may lead to matrix effect (such as ion suppression or enhancement) in liquid chromatography detection, affecting the quantitative accuracy. (3) Limited detection sensitivity and selectivity: ultraviolet detector is easily disturbed by other co-eluted compounds, while mass spectrometry (such as LC-MS / MS or HRMS) can improve selectivity through characteristic ions. (4) Poor universality and expandability: the method is only for chlorotoluron, and does not cover other 19 herbicides (such as sulfonylurea, triazine) commonly used in corn fields, which cannot meet the actual needs of synchronous analysis of multiple residues.

[0005] The existing document "Solid phase extraction-high performance liquid chromatography method for detecting the residual amount of mesotrione in corn, sugarcane and soil" reports a method for establishing a SAX solid phase column extraction, high phase liquid chromatography (HPLC) method for detecting the residual amount of mesotrione in corn, sugarcane and soil. However, the scheme has the following problems: (1) The pretreatment step is complicated and the solvent consumption is large: the scheme uses 20g of soil sample and 40mL of acetonitrile as the extraction system, which has the problem of excessive use of organic solvent. This not only significantly increases the experimental cost, but also produces a large amount of organic waste liquid, which does not meet the development requirements of green chemistry. At the same time, the technology needs to be adjusted to pH (sodium carbonate is adjusted to pH=8), which increases the operation steps and introduces new salt interference factors. (2) The purification efficiency is insufficient to affect the detection accuracy: the existing technology only uses salting-out stratification (NaCl+MgSO4) for purification, and the removal effect of humic acid, lipids and other interfering substances in the soil matrix is limited. (3) Low chromatographic separation efficiency: the technology uses a 250mm long chromatographic column with a high flow rate of 1mL / min, which has a high column efficiency in theory, but the actual separation effect is not good. In the detection of mesotrione, the separation degree of mesotrione from the common humic acid impurities in the soil is only 1.2 (the USP standard requires >1.5), and the 30-minute analysis period is too long. (4) Lack of multi-component detection capability: the method is only developed for a single compound of mesotrione, which cannot meet the actual detection needs.

[0006] The existing document "Detection of tebuconazole and pyraclostrobin residues in corn plants and soil and their dissipation dynamics" reports a high performance liquid chromatography-tandem mass spectrometry (LC-MS / MS) method using acetonitrile extraction. However, the scheme has the following problems: (1) Limited selection of extraction solvent: acetonitrile is used as a single extraction agent, which has good solubility for moderately polar compounds, but it is difficult to effectively extract herbicides with strong polarity (such as methyl iodine sulfonate sodium salt) or high hydrophobicity (such as fluroxypyr). (2) Purification method is missing: the existing technology only uses 0.22μm filter membrane filtration for purification, without introducing an adsorbent purification step. The complex components such as humic acid and plant residues in corn soil matrix will seriously interfere with the ionization of the target, seriously affecting the quantitative accuracy. (3) The pretreatment time is too long: the existing method uses 60 minutes of oscillation extraction, combined with a standing stratification step, and the pretreatment time of a single sample is more than 90 minutes. Compared with the vortex-assisted extraction technology, the efficiency is greatly reduced, which is difficult to meet the demand of large-scale soil monitoring. (4) Salt-out agent is missing: no salt-out agent such as sodium chloride is introduced to optimize the phase separation, resulting in a blurred acetonitrile-water phase interface and a prolonged stratification time.

[0007] By analyzing the existing documents, it can be seen that the current detection technology has three major defects:

[0008] (1) The ability to detect multiple components simultaneously is insufficient. Existing methods are difficult to achieve effective separation and accurate quantification of 20 herbicides (including polar / nonpolar and acid / basic compounds) with significant differences in physicochemical properties, such as sulfonylureas, triazines, and amides.

[0009] (2) The matrix interference is severe. Traditional pretreatment methods are not effective in purifying complex soil matrices, resulting in significant ion suppression during mass spectrometry detection.

[0010] (3) The sensitivity and throughput of the methods are limited. Conventional detection methods are difficult to meet the needs of modern agricultural residue monitoring in terms of detection limit (generally higher than 0.01 mg / kg), analysis time (usually more than 30 minutes / sample) and method stability (RSD>15%).

[0011] Based on the above, developing a detection method that can simultaneously detect multiple herbicides, has high sensitivity and anti-interference capabilities has become an urgent technical challenge to be solved. Summary of the Invention

[0012] Based on the above, this invention provides a high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-MS / MS) method for analyzing herbicides in cornfield soil. By innovatively constructing HPLC-MS / MS technology, it overcomes the key technical difficulties of simultaneous extraction and trace residue enrichment detection of heterogeneous herbicides. It can simultaneously extract 20 herbicides from cornfield soil, providing reliable technical support for the assessment of cornfield soil environmental quality.

[0013] The technical solution of this invention is: a method for analyzing herbicides in cornfield soil using high-performance liquid chromatography-high-resolution mass spectrometry, comprising:

[0014] S1 Sample Extraction: Weigh the soil sample from the cornfield to be tested into a centrifuge tube, add organic solvent, vortex, and make the target herbicide fully dissolve in the organic phase;

[0015] S2 Salting out and dehydration: Add salting out agent and dehydrating agent to the centrifuge tube in sequence, vortex again to form a solid-liquid two-phase separation system;

[0016] S3 Centrifugation and Purification: Centrifuge the mixture at a predetermined speed, transfer the supernatant to a centrifuge tube containing adsorbent, vortex to adsorb lipid-soluble impurities, filter, and collect the filtrate into a sample bottle for testing;

[0017] S4 herbicide determination: The target herbicide was separated, accurately identified, and quantified using liquid chromatography-high resolution mass spectrometry.

[0018] Preferably, the organic solvent is an ethyl acetate solution, the salting-out agent is sodium chloride, the dehydrating agent is anhydrous magnesium sulfate, and the adsorbent is C. 18Adsorbents. Ethyl acetate was chosen as the extraction solvent based on its extensive solubility for a variety of chemically distinct herbicides, while possessing low toxicity and volatility. Sodium chloride was used for salting-out effect, enhancing the separation of organic and aqueous phase. Anhydrous magnesium sulfate was used for adsorbing water, further improving the purity and concentration of target compounds in organic layer. 18 Adsorbents were chosen based on their effective adsorption capacity for humic acid, lipids and other interferents in soil matrix, thus reducing the interference of matrix effect on mass spectrometry detection.

[0019] Preferably, the analysis conditions of liquid chromatography-high resolution mass spectrometry are as follows:

[0020] Chromatographic conditions: chromatographic column: Agilent Eclipse XDB-C18 (4.6 mm x 150 mm, 5 μm), mobile phase: methanol and 5 mmol / L ammonium formate aqueous solution (volume ratio 80:20), flow rate: 0.3 mL / min, column temperature: 30℃, injection volume: 5 μL;

[0021] Mass spectrometry conditions: mass spectrometer: Thermo Scientific TM Orbitrap Exploris TM 240 high-resolution mass spectrometer, ion source: electrospray ionization (ESI), positive and negative ion switching mode, scan mode: Full MS, resolution 120,000 (Full MS), scan range: m / z 100-1000, spray voltage: 3500V, ion transfer tube temperature: 320℃, sheath gas and auxiliary gas pressure: 35Arb and 7Arb, auxiliary gas heating temperature: 350℃.

[0022] Preferably, the mobile phase is prepared by mixing methanol and 5 mmol / L ammonium formate at a volume ratio of 80:20. The optimization of the ratio of the mobile phase aims to balance the retention time of polar and non-polar compounds, and ensure the effective separation of 20 herbicides on the chromatographic column.

[0023] Preferably, the target herbicides include fluroxypyr-meptyl, fluroxypyr-meptyl, butachlor, cyprazole, S- metamifop, terbuthylazine, simazine, triallate, metribuzin, simazine, cyanazine, iodosulfuron-methyl-sodium, bentazone, mesotrione, sulcotrione, florasulam, cloransulam, pyrimethanil and foramsulfuron.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] 1. The present application realizes the synchronous and efficient detection of multiple herbicides. Based on high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS), the present application first establishes a synchronous detection method for 20 different chemical structures (including sulfonylurea, triazine, amide, pyrimidine, etc.) herbicides in corn field soil. By optimizing the proportion of the mobile phase (methanol: 5mmol ammonium formate = 80:20) and selecting the chromatographic column (Eclipse XDB-C18), the efficient separation of multiple components in complex matrix is realized, avoiding the repeated operation of traditional single standard method or group detection method, and significantly improving the detection efficiency.

[0026] 2. The present application has ultra-high sensitivity and accuracy. Combined with the accurate mass number determination (mass accuracy <3ppm) of Orbitrap Exploris 240 high resolution mass spectrometer and the stable separation performance of Vanquish Flex liquid chromatograph, the detection limit (LOD) of the present application for 20 kinds of herbicides is 0.0001-0.0060mg / kg, and the quantification limit (LOQ) is 0.02mg / kg, which has higher sensitivity than the traditional LC-MS / MS method, and the high resolution mass spectrometer uses accurate ion mass for qualitative and quantitative analysis, effectively avoiding the generation of false positive data. Through the matrix purification treatment of the adsorbent, the target recovery rate is stably maintained at 88.66%-108.23% (RSD≤5.78%), which effectively overcomes the interference problem of soil organic matter. 18

[0027] 3. The present application solves the technical problems of low extraction efficiency and large impurity interference. The present application uses "salting-out-adsorption synergistic purification" technology (sodium chloride + anhydrous magnesium sulfate + C18), which simplifies the traditional solid phase extraction column purification process to one-step vortex centrifugation treatment, reduces the amount of organic solvent (only 10mL of ethyl acetate is needed), and completes the pretreatment within 30 minutes. This method has broken through the technical problems of low extraction efficiency and large impurity interference of trace herbicides in high humic acid soil samples.

[0028] In summary, the present application optimizes the sample pretreatment method and instrument analysis conditions, realizes the efficiency, ultra-high sensitivity and accuracy of synchronous detection of multiple herbicides, and innovates the green pretreatment technology. The method is not only suitable for the detection of 20 kinds of herbicide residues in corn field soil, but also can be applied to the field of environmental monitoring and food safety evaluation in other crop planting areas. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The flow chart of the pretreatment of soil samples;

[0030] Figure 2 Effect of different extractants on the recovery rate of 20 kinds of herbicides in soil matrix, the addition level is 0.2mg / kg;​

[0031] Figure 3 The influence of different purifying agents on the recovery rate of 20 herbicides in soil matrix at an addition level of 0.2 mg / kg;

[0032] Figures 4 to 11 The standard curve of 20 herbicides and the matrix standard curve. DETAILED DESCRIPTION

[0033] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a number of different ways beyond the specific embodiments described herein and with modifications thereof, without departing from the scope of the present application, and it is understood that similar improvements can be made by those skilled in the art in light of the foregoing description. Therefore, the present application is not limited by the specific implementation disclosed below.

[0034] Example 1: Analysis method of herbicides in corn field soil by high performance liquid chromatography-high resolution mass spectrometry

[0035] Reference Figure 1 The method comprises the following steps:

[0036] S1 sample extraction: accurately weigh 10 g of soil sample into a 50 mL centrifuge tube, add 10 mL of ethyl acetate solution, and mix well by vortex mixer (2500 rpm) for 10 min to dissolve the target herbicide in the organic phase;

[0037] S2 salting-out and dehydration: add 1 g of sodium chloride (salting-out agent) and 1 g of anhydrous magnesium sulfate (dehydrating agent) into the above centrifuge tube in turn, vortex again for 10 min (2500 rpm) to form a solid-liquid two-phase separation system, and promote the target to further enrich in the organic layer;

[0038] S3 centrifugation and purification: centrifuge the mixed solution at 5000 rpm for 10 min, transfer 1 mL of supernatant to a centrifuge tube containing 50 mg of C18 adsorbent, vortex for 1 min to adsorb fat-soluble impurities, then filter through a 0.22 μm organic filter membrane, and collect the filtrate in a sample bottle for testing;

[0039] S4 herbicide determination: separate, accurately identify and quantify the target herbicide by liquid chromatography-high resolution mass spectrometry, and the analysis conditions of the liquid chromatography-high resolution mass spectrometry are as follows:

[0040] Chromatographic conditions: Column: Agilent Eclipse XDB-C18(4.6 mm x 150 mm, 5 μm), mobile phase: methanol and 5 mmol / L ammonium formate aqueous solution (volume ratio 80:20), flow rate: 0.3 mL / min, column temperature: 30 °C, injection volume: 5 μL;

[0041] Mass spectrometric conditions: Mass spectrometer: Thermo Scientific TM Orbitrap Exploris TM 240 high-resolution mass spectrometer, ion source: electrospray ionization (ESI), positive and negative ion switching mode, scanning mode: Full MS, resolution 120,000 (Full MS), scanning range: m / z 100-1000, spray voltage: 3500 V, ion transfer tube temperature: 320 °C, sheath gas and auxiliary gas pressure: 35 Arb and 7 Arb, auxiliary gas heating temperature: 350 °C.

[0042] Example 2: Condition optimization

[0043] (1) Optimization of extractant for the analysis method

[0044] Three different extractants (methanol, acetonitrile and ethyl acetate, each with a usage of 10 mL) were used for the extraction of soil samples, aiming to explore the influence of these extractants on the recovery rate of twenty target analytes in soil matrix. The comparison results of extraction efficiency ( Figure 2 ) showed that, in general, ethyl acetate had a higher extraction recovery rate of target herbicides in soil, so it was determined as the best extractant. When the extractant was ethyl acetate, the recovery rate of twenty herbicides was 84.29% to 101.49%. Therefore, ethyl acetate was used as the extractant for twenty herbicides in soil matrix.

[0045] (2) Optimization of purifying agent for the analysis method

[0046] By comparing the purification efficiency of PSA, C 18 and GCB three adsorption materials, it was found that C 18 performed best in terms of matrix purification ability and added recovery rate ( Figure 3 ), so it was selected as the purifying agent for target herbicides. When the purifying agent was C 18 , the recovery rate of twenty herbicides was 86.48% to 103.45%.

[0047] Example 2: Method validation

[0048] Preparation of standard solution: accurately weigh a certain amount of fluroxypyr-methyl, fluroxypyr-meptyl, and 20 kinds of herbicide standard products such as butachlor into a volumetric flask (100 mL), and prepare a 100 μg / mL standard solution mother liquor by constant volume with acetonitrile. Take 10 mL of the prepared 20 kinds of mother liquor into a 50 mL volumetric flask, and constant volume to obtain a 20 μg / mL mixed standard solution. Gradient dilution of the mixed standard solution obtains a series of standard solution with concentrations of 0.01, 0.02, 0.1, 0.2, 0.5, 1, and 2 μg / mL. The system standard solution with 7 concentrations is filtered through an organic filter membrane (0.22 μm) for HPLC-HRMS determination.

[0049] Preparation of matrix matching standard solution: take 1 mL of the prepared series of standard solution into a pear-shaped flask and spin dry; the blank soil sample is treated according to the pretreatment method Figure 1 . Take 1 mL of the supernatant and add it into the pear-shaped flask with the spin-dried standard solution, and manually vortex for 2 min. The solution is filtered through a 0.22 μm filter membrane to obtain a series of matrix matching standard solution with concentrations of 0.01, 0.02, 0.1, 0.2, 0.5, 1, and 2 μg / mL, which is determined by HPLC-HRMS.

[0050] Addition recovery experiment: the mixed standard solution of 20 kinds of herbicides is added to the blank soil sample to make the addition level of the 20 kinds of herbicides 0.02, 0.2, and 2 mg / kg, respectively. The soil sample is extracted and purified according to the sample pretreatment method Figure 1 , and detected by HPLC-HRMS to calculate the addition recovery rate and relative standard deviation.

[0051] The present application tests the recovery rate and relative standard deviation of 20 kinds of herbicides at different addition levels to verify the reliability of the method. The experimental results show that the standard curves and matrix matching standard curves of the 20 kinds of herbicides all exhibit good linear relationships (Table 1), and the correlation coefficients (R 2 ) are all greater than 0.993. At the three addition levels of 0.02 mg / kg, 0.2 mg / kg, and 2 mg / kg, the average recovery rate of the target substances is in the range of 83.48%-112.78% (Table 2), and the relative standard deviation (RSD) is ≤8.78%. For example, the average recovery rate of butachlor at the addition level of 0.02 mg / kg is 108.23%, and the RSD is 4.68%; the average recovery rate of cyanazine at the addition level of 2 mg / kg is 85.90%, and the RSD is 3.01%.

[0052] The matrix effect evaluation showed that the soil matrix had a weak inhibitory effect on butachlor, fluthiacet-methyl, isopropyl amine, simazine, metribuzin, flumetsulam and foramsulfuron, with matrix effect values of -19.15%, -12.16%, -11.31%, -2.40%, -16.19%, -5.70% and -8.02%, respectively. The medium matrix inhibition effect of fluroxypyr, terbuthylazine and sulfentrazone in the soil matrix was -33.13%, -23.51% and -47.25%, respectively. The weak enhancement effect of chlorflurenol, cyanazine, iodosulfuron-methyl-sodium, flumetralin, sulfometuron-methyl and nicosulfuron in the soil matrix was 14.16%, 15.83%, 14.91%, 12.65%, 1.84% and 8.77%, respectively. The medium matrix enhancement effect of fluroxypyr, simazine, bentazone and mesotrione in the soil matrix was 33.62%, 30.20%, 25.48% and 21.23%, respectively.

[0053] Table 12 Linear equation, correlation coefficient (R2) and matrix effect of 20 herbicides 2

[0054]

[0055]

[0056] Table 2 Recovery and relative standard deviation of 20 herbicides in soil at different addition levels (Guizhou soil)

[0057]

[0058]

[0059] Example 4: Application Case

[0060] To verify the universality and reliability of the established high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) method for detecting 20 target herbicides in corn field soil, the applicant not only used the typical corn field soil samples in Kedu Town, Pingtang County, Qian Nan Buyi and Miao Autonomous Prefecture, Guizhou Province as the main research object to develop and verify the method, but also specially selected corn field soil samples in Yongning County, Yinchuan City, Ningxia Hui Autonomous Region which had significant differences in geographical environment and soil properties to conduct an addition recovery test.

[0061] ​The results of the 20 target herbicide addition recovery tests in the soil samples in Yongning County of Yinchuan City in Ningxia Hui Autonomous Region are shown in Table 3. The experimental results show that at the three addition levels of 0.02 mg / kg, 0.2 mg / kg and 2 mg / kg, the average recovery rates of the 20 target herbicides are in the range of 77.80%-108.05%, and the relative standard deviation (RSD) is ≤8.06%.

[0062] Table 3 Recovery rates and relative standard deviations of 20 herbicides in soil at different addition levels (soil in Yongning County of Yinchuan City in Ningxia Hui Autonomous Region)

[0063]

[0064]

[0065]

[0066] The application case proves that the HPLC-HRMS method can effectively simultaneously detect the residues of the 20 herbicides in the soil in different typical corn production areas, and provides reliable technical support for the investigation of the use status of herbicides in corn fields, the environmental behavior research and the ecological risk assessment in the whole country.

[0067] The above-described embodiments only express several embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HDMS) method for the analysis of herbicides in cornfield soil, characterized in that, include: S1 Sample Extraction: Weigh the soil sample from the cornfield to be tested into a centrifuge tube, add organic solvent, vortex, and make the target herbicide fully dissolve in the organic phase; S2 Salting out and dehydration: Add salting out agent and dehydrating agent to the centrifuge tube in sequence, vortex again to form a solid-liquid two-phase separation system; S3 Centrifugation and Purification: Centrifuge the mixture at a predetermined speed, transfer the supernatant to a centrifuge tube containing adsorbent, vortex to adsorb lipid-soluble impurities, filter, and collect the filtrate into a sample bottle for testing; S4 herbicide determination: The target herbicide was separated, accurately identified, and quantified using liquid chromatography-high resolution mass spectrometry.

2. The analytical method according to claim 1, characterized in that, The organic solvent is ethyl acetate solution, the salting-out agent is sodium chloride, the dehydrating agent is anhydrous magnesium sulfate, and the adsorbent is C. 18 Adsorbent.

3. The analytical method according to claim 1, characterized in that, The analytical conditions for the liquid chromatography-high resolution mass spectrometry are as follows: Chromatographic conditions: Column: Agilent Eclipse XDB-C18, mobile phase: methanol and 5 mmol / L ammonium formate aqueous solution, flow rate: 0.3 mL / min, equilibration column temperature: 30℃, injection volume: 5 μL; Mass spectrometry conditions: Mass spectrometer: Thermo Scientific TM Orbitrap Exploris TM 240 high-resolution mass spectrometer, ion source: electrospray ionization, positive and negative ion switching mode, scanning mode: Full MS, resolution 120,000, scanning range: m / z 100-1000, spray voltage: 3500V, ion transmission tube temperature: 320℃, sheath gas and auxiliary gas pressure: 35Arb and 7Arb, auxiliary gas heating temperature: 350℃.

4. The analytical method according to claim 3, characterized in that, The mobile phase was prepared by mixing methanol and 5 mmol / L ammonium formate at a volume ratio of 80:

20.

5. The analytical method according to claim 1, characterized in that, The target herbicides include isooctyl chlorpyrifos, fluroxypyr, butachlor, fluthiamethoxam, S-metolachlor, terbufos, cypermethrin, chlormequat chloride, metribuzin, simazine, cyanazine, sodium methyl iodosulfuron, bentazon, mesotrione, sulfadiazine, diflubenzuron, pyrazosulfuron, sulfadiazine, nicosulfuron, and formamide sulfuron.

Images