A method for detecting herbicides and their metabolites in fruits and vegetables

Abstract

The present invention relates to the field of analytical detection technology, and in particular to a method for detecting herbicides and their metabolites in fruits and vegetables. The present invention uses acidic acetonitrile as an extractant, inorganic salts as dehydration and salting out, and performs qualitative and quantitative detection and analysis of one or more of cyhalofop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, fluazifop-butyl and high-efficiency fluazifop-butyl and their metabolite residues in fruits and vegetables by dispersed solid phase extraction purification-high performance liquid chromatography-tandem mass spectrometry, which can make up for the current lack of detection technology for some herbicides and their metabolites. The analytical detection method provided by the present invention is simple to operate, highly sensitive, and has good repeatability. It can meet the requirements of relevant domestic and foreign laws and regulations, and is suitable for qualitative and quantitative analysis of herbicides and their metabolite residues in fruits and vegetables.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection, and in particular to a method for detecting herbicides and metabolites thereof in fruits and vegetables. Background Art

[0002] In recent years, with the improvement of public awareness of food safety, people are paying more and more attention to the quality and safety of agricultural products. my country has formulated technical standards for the detection of some herbicides, such as GB23200.60-2016 "National Food Safety Standard for the Detection of Clodinafop-butyl Residues in Foods", SN / T4257-2015 "Determination of Residues of Triclosan, Cyfluthrin, Cyclohexanil and Gibberellic Acid in Exported Foods by Liquid Chromatography-Mass Spectrometry / Mass Spectrometry", etc. However, the above methods have not yet had targeted standardized detection methods for herbicides such as clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, triclosan, haloxyfop-butyl and haloxyfop-butyl in plant-derived foods. The only reference detection technical standards have very limited applicability.

[0003] Herbicide pesticides are often used to eradicate broadleaf weeds and are often used in some plant-derived crops. The main methods for determining pesticide residues in vegetables include high performance liquid chromatography, liquid chromatography-tandem mass spectrometry, and gas chromatography-tandem mass spectrometry. For example, the existing technology "Qian Lijuan. Establishment of a method for determining multiple pesticide residues in vegetables by high performance liquid chromatography-tandem mass spectrometry [D]. Nanjing Agricultural University, 2018." selected five different representative vegetable varieties in Nanjing, namely cabbage, Chinese cabbage, tomato, cucumber and green bean, and determined 20 pesticide residues in the five vegetables, including aldicarb and its derivatives (aldicarb sulfone, aldicarb sulfoxide), methomyl, acephate, carbendazim, pyrimethanil, carbaryl, carbofuran and its derivatives (3-hydroxycarbofuran), acetamiprid, pirimicarb, metalaxyl, phoxim, pyrimidine, prochloraz, dimethomorph, fenpropimorph, and avermectin. Based on the QuEChERS method, the vegetable samples were directly extracted with acetonitrile, added with sodium chloride, shaken vigorously and centrifuged, and then directly injected into the machine, and quantified by the external standard method in positive ion multiple reaction monitoring mode; the detection limits of 20 pesticides such as carbendazim were 0.0005-0.005 mg / kg. However, the above detection method lacks a purification step in the pretreatment process, and other impurities in the matrix may affect the determination of the target peak and easily cause contamination of the HPLC-tandem mass spectrometer detector.Existing technology "Gao Qian. LC-MS / MS detection of phenothiazine sedatives, neonicotinoid insecticides, and amide herbicides in food [D]. Hebei Normal University, 2016." A method for simultaneous detection of promethazine and chlorpromazine in poultry eggs using liquid chromatography-tandem mass spectrometry was established using acetonitrile to precipitate protein and as an extractant, ultrasound-assisted extraction, and solid phase extraction for purification. The experiment used ESI positive ion mode, MRM multiple reaction monitoring, 0.1% formic acid water-acetonitrile (V:V=35:65) as the mobile phase, promethazine and chlorpromazine were well separated within 4 minutes, the detection limits (LOD) of promethazine and chlorpromazine were 0.05μg / kg and 0.10μg / kg, respectively, and the quantification limits (LOQ) were 0.17μg / kg and 0.23μg / kg, respectively; a mixed solution of acetonitrile:ethyl acetate (V:V)=4:1 was used as an extractant, ultrasound-assisted extraction, and solid phase extraction was used for purification, and a liquid chromatography-tandem mass spectrometry method was established. -Tandem mass spectrometry technology was used to detect 8 neonicotinoid pesticides in infant food. The experiment adopted ESI positive ion mode, MRM multiple reaction monitoring, 0.1% formic acid water-acetonitrile (V:V=35:65) as the mobile phase, isopromazine and chlorpromazine were well separated within 4 minutes, and the LOD and LOQ were 0.02-6.20μg / kg and 0.07-20.67μg / kg, respectively; petroleum ether (30-60℃) was used as the extractant, and after oscillation-assisted extraction, FlorisilPR solid phase extraction column was used for purification. A method for the simultaneous determination of 10 amide herbicides in fruits and their products by liquid chromatography-tandem mass spectrometry was established. Using ESI positive ion mode, MRM multiple reaction monitoring, and gradient elution, the 10 amide herbicides were well separated within 11 minutes, and the LOD and LOQ were 0.05-4.15μg / kg and 0.17-13.83μg / kg, respectively. However, the above detection method uses many types of organic reagents and has cumbersome steps. The solid phase extraction column used is expensive and needs to be activated with organic reagents. After use, waste disposal is required, which increases the cost and time required for the experiment.

[0004] At present, there is no unified detection method for the residue analysis of six herbicides and their metabolites, including cypermethrin, cyhalofop-butyl, quizalofop-butyl, anthracene, fluazifop-butyl, and haloxyfop-butyl. Therefore, it is very necessary to develop a detection method that can detect the above pesticides at the same time. Summary of the invention

[0005] The object of the present invention is to provide a method for detecting herbicides and their metabolites in fruits and vegetables. The method provided by the present invention can quickly and accurately realize the simultaneous qualitative and quantitative detection of the residues of six herbicides, namely, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, haloxyfop-butyl and haloxyfop-butyl and their metabolites in fruits and vegetables, with high sensitivity and high precision.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides a method for detecting herbicides and their metabolites in fruits and vegetables, comprising the following steps:

[0007] Mixing the sample to be tested, acidic acetonitrile and inorganic salt, performing extraction and separation, and obtaining an extract;

[0008] The extract is mixed with a solid phase extractant, and subjected to dispersed solid phase extraction purification to obtain a sample solution to be tested;

[0009] Detecting the herbicide and its metabolites in the sample liquid by high performance liquid chromatography-tandem mass spectrometry;

[0010] The herbicide includes one or more of clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, haloxyfop-butyl and high-efficiency haloxyfop-butyl;

[0011] The high performance liquid chromatography-tandem mass spectrometry method includes high performance liquid chromatography separation and mass spectrometry detection;

[0012] The conditions for the HPLC separation include: the mobile phase system is a mobile phase A and a mobile phase B; the mobile phase A is acetonitrile, and the mobile phase B is a formic acid-ammonium formate aqueous solution; the elution method is a gradient elution;

[0013] The gradient elution procedure is as follows: 0-1min, the volume fraction of the mobile phase A is 40%; 1-6min, the volume fraction of the mobile phase A increases uniformly from 40% to 90%; 6-7min, the volume fraction of the mobile phase A decreases uniformly from 90% to 40%; 7-8min, the volume fraction of the mobile phase A is 40%;

[0014] The mass spectrometry detection conditions include: ESI ion source, ion source temperature of 250-350°C; curtain gas pressure of 30-40psi, collision gas pressure of 6-10psi, spray gas pressure of 40-50psi, auxiliary heating gas pressure of 35-45psi, positive and negative ion scanning, and multiple reaction monitoring mode.

[0015] Preferably, the metabolites include one or more of clodinafop-butyl, cyanhalofop-butyl, quizalofop-butyl, antineptasulfuron, fluazifop-butyl and 2,4-D.

[0016] Preferably, the chromatographic column for HPLC separation is a BHEC18 chromatographic column; the column temperature is 35° C.; the injection volume is 2 μL; and the flow rate of the mobile phase system is 0.25 to 0.35 mL / min.

[0017] Preferably, the acidic acetonitrile is a formic acid-acetonitrile mixed solution, and the volume fraction of formic acid in the acidic acetonitrile is 0.05-0.15%;

[0018] The ratio of the mass of the sample to be tested to the volume of the acidic acetonitrile is 1 g: 1-2 mL.

[0019] Preferably, the inorganic salt comprises sodium chloride and / or anhydrous magnesium sulfate;

[0020] The mass ratio of the sample to be tested to the inorganic salt is 1:0.4-0.6.

[0021] Preferably, the extraction and separation comprises: using acidic acetonitrile to perform vortex oscillation extraction on the sample to be tested, mixing the obtained extraction system with an inorganic salt, and performing centrifugal separation to obtain a supernatant as the extract.

[0022] Preferably, the rotation speed of the vortex oscillation extraction is 2000-2500 r / min, and the time is 5-10 min;

[0023] The rotation speed of the centrifugal separation is 4000-5000 r / min, and the time is 5-10 min.

[0024] Preferably, the solid phase extractant comprises magnesium sulfate and Florisil, and the mass ratio of magnesium sulfate to Florisil is 1:1;

[0025] The ratio of the volume of the extract to the mass of the solid phase extractant is 1 mL: 20-30 mg.

[0026] Preferably, the dispersed solid phase extraction cleanup comprises sequentially performing vortex mixing and centrifugal separation.

[0027] Preferably, the rotation speed of the vortex mixing is 2000-2500 r / min, and the time is 1-2 min;

[0028] The rotation speed of the centrifugal separation is 4000-5000 r / min, and the time is 5-10 min.

[0029] The invention provides a method for detecting herbicides and metabolites thereof in fruits and vegetables, comprising the following steps: mixing a sample to be tested, acidic acetonitrile and an inorganic salt, performing extraction and separation to obtain an extract; mixing the extract with a solid phase extractant, performing dispersed solid phase extraction purification to obtain a sample liquid to be tested; using high performance liquid chromatography-tandem mass spectrometry to detect the herbicides and metabolites thereof in the sample liquid to be tested; the herbicides include one or more of clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, haloxyfop-butyl and haloxyfop-butyl; the high performance liquid chromatography-tandem mass spectrometry includes high performance liquid chromatography separation and mass spectrometry detection; the conditions for the high performance liquid chromatography separation include: the mobile phase system is a mobile phase A and mobile phase B; the mobile phase A is acetonitrile, and the mobile phase B is formic acid-ammonium formate aqueous solution; the elution mode is gradient elution; the program of the gradient elution is: 0-1min, the volume fraction of the mobile phase A is 40%; 1-6min, the volume fraction of the mobile phase A increases uniformly from 40% to 90%; 6-7min, the volume fraction of the mobile phase A decreases uniformly from 90% to 40%; 7-8min, the volume fraction of the mobile phase A is 40%; the conditions for mass spectrometry detection include: the ion source temperature is 250°C; the air curtain gas pressure is 35psi, the collision gas pressure is 8psi, the spray gas pressure is 50psi, and the auxiliary heating gas pressure is 40psi. Compared with the prior art, the method for detecting pesticide residues in plant-derived agricultural products of the present invention uses acidic acetonitrile and inorganic salts to extract and separate the sample to be tested, and then uses dispersed solid phase extraction (DSPE) technology for purification, which can minimize the interference of substances other than pesticides on the detection results. The pretreatment method adopted by the present invention is simple and fast, has good purification effect, high sensitivity, and good repeatability, and can meet the requirements of relevant domestic and foreign laws and regulations. It is suitable for qualitative analysis and quantitative detection of residues of cyhalofop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, fluazifop-butyl and high-efficiency fluazifop-butyl and their metabolites in fruits and vegetables. In addition, the high-efficiency Liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) conditions can analyze cyhalofop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, fluazifop-butyl and their metabolites within 8 minutes. A detection method for six herbicides and their metabolites in fruit and vegetable matrices has been established, which fills the gap of single detection target of herbicides and their metabolites and the lack of corresponding detection methods for some targets. It can also meet the lower residue limit of 0.2 mg / kg specified in the national standard GB2763-2021 (only fluazifop-butyl and fluazifop-butyl have temporary residue limit regulations, and there are no residue limit regulations for other herbicides and pesticides).As shown in the test results of the embodiment, the quantitative limit of the method provided by the present invention is 0.0005-0.01 mg / kg, the detection limit of the method is 0.0001-0.008 mg / kg, and when the spiked levels are 0.01 mg / kg, 0.05 mg / kg and 0.2 mg / kg respectively, the spiked recovery rate is 89.4-112.6%, and the RSD is 1.7-5.9%, indicating that the detection method provided by the present invention has a low detection limit, high detection accuracy and high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the TIC diagram of twelve pesticides;

[0031] Figure 2 Chromatograms of blank matrix and spiked 10 μg / kg clodinafop-butyl in cabbage;

[0032] Figure 3 Chromatograms of blank matrix and spiked 10 μg / kg quizalofop-p-butyl acid in cabbage;

[0033] Figure 4 Chromatograms of blank matrix and spiked 10 μg / kg cyanofluoric acid in cabbage;

[0034] Figure 5 Chromatograms of blank matrix and spiked 50 μg / kg anabasic acid in cabbage;

[0035] Figure 6 Chromatograms of blank matrix and spiked 10 μg / kg fluazifop-butyl in cabbage;

[0036] Figure 7 Chromatograms of blank matrix and spiked 20 μg / kg 2,4-D in cabbage.

[0037] Figure 8 Chromatograms of blank matrix and spiked 100 μg / kg cyhalofop-butyl in cabbage;

[0038] Fig. 9 Chromatograms of blank matrix and spiked 10 μg / kg high-efficiency halpyr-methyl in cabbage;

[0039] Fig.10 Chromatograms of blank matrix and spiked 10 μg / kg trinexapac-ethyl in cabbage;

[0040] Fig.11 Chromatograms of blank matrix and spiked 10 μg / kg quizalofop-butyl in cabbage;

[0041] Fig.12 Chromatograms of blank matrix and spiked 10 μg / kg halpyrifos-ethyl in cabbage;

[0042] Fig.13The chromatograms of the blank matrix and spiked matrix of cabbage with 10 μg / kg clodinafop-butyl. DETAILED DESCRIPTION

[0043] The present invention provides a method for detecting herbicides and their metabolites in fruits and vegetables, comprising the following steps:

[0044] Mixing the sample to be tested, acidic acetonitrile and inorganic salt, performing extraction and separation, and obtaining an extract;

[0045] The extract is mixed with a solid phase extractant, and subjected to dispersed solid phase extraction purification to obtain a sample solution to be tested;

[0046] Detecting the herbicide and its metabolites in the sample liquid by high performance liquid chromatography-tandem mass spectrometry;

[0047] The herbicide includes one or more of clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, haloxyfop-butyl and high-efficiency haloxyfop-butyl;

[0048] The high performance liquid chromatography-tandem mass spectrometry method includes high performance liquid chromatography separation and mass spectrometry detection;

[0049] The conditions for the HPLC separation include: the mobile phase system is a mobile phase A and a mobile phase B; the mobile phase A is acetonitrile, and the mobile phase B is a formic acid-ammonium formate aqueous solution; the elution method is a gradient elution;

[0050] The gradient elution procedure is as follows: 0-1min, the volume fraction of the mobile phase A is 40%; 1-6min, the volume fraction of the mobile phase A increases uniformly from 40% to 90%; 6-7min, the volume fraction of the mobile phase A decreases uniformly from 90% to 40%; 7-8min, the volume fraction of the mobile phase A is 40%;

[0051] The mass spectrometry detection conditions include: ESI ion source, ion source temperature of 250-350°C; curtain gas pressure of 30-40psi, collision gas pressure of 6-10psi, spray gas pressure of 40-50psi, auxiliary heating gas pressure of 35-45psi, positive and negative ion scanning, and multiple reaction monitoring mode.

[0052] In the present invention, unless otherwise specified, the reagents used are commercially available products well known to those skilled in the art.

[0053] The invention mixes a sample to be tested, acidic acetonitrile and an inorganic salt, performs extraction and separation, and obtains an extract.

[0054] In the present invention, the acidic acetonitrile is preferably a formic acid-acetonitrile mixed solution, and the volume fraction of formic acid in the acidic acetonitrile is preferably 0.05-0.15%, more preferably 0.1%; the ratio of the mass of the sample to be tested to the volume of the acidic acetonitrile is preferably 1g:1-2mL, more preferably 1g:1-1.5mL.

[0055] In the present invention, the inorganic salt preferably includes sodium chloride and / or anhydrous magnesium sulfate, more preferably sodium chloride or anhydrous magnesium sulfate; the mass ratio of the sample to be tested to the inorganic salt is preferably 1:0.4-0.6, more preferably 1:0.4-0.5.

[0056] In the present invention, the extraction and separation preferably includes: using acidic acetonitrile to perform vortex oscillation extraction on the sample to be tested, mixing the obtained extraction system with an inorganic salt, and centrifuging to obtain the supernatant as the extract. In the present invention, the temperature of the vortex oscillation extraction is preferably 4 to 25°C, more preferably 10 to 25°C; the rotation speed of the vortex oscillation extraction is preferably 2000 to 2500r / min, more preferably 2300 to 2500r / min; the time of the vortex oscillation extraction is preferably 5 to 10min, more preferably 8 to 10min. The present invention has no special restrictions on the mixing, as long as the raw materials can be mixed evenly. In the present invention, the rotation speed of the centrifugal separation is preferably 4000 to 5000r / min, more preferably 4500 to 5000r / min; the time of the centrifugal separation is preferably 5 to 10min, more preferably 5 to 8min.

[0057] After obtaining the extract, the present invention mixes the extract with a solid phase extractant, performs dispersed solid phase extraction purification, and obtains a sample solution to be tested.

[0058] In the present invention, the solid phase extractant preferably includes magnesium sulfate and floral silica, and the mass ratio of the magnesium sulfate to floral silica is preferably 1:1-2, more preferably 1:1-1.5; the ratio of the volume of the extract to the mass of the solid phase extractant is preferably 1 mL:20-30 mg, more preferably 1 mL:25 mg.

[0059] In the present invention, the dispersed solid phase extraction purification preferably includes vortex mixing and centrifugal separation in sequence; the rotation speed of the vortex mixing is preferably 2000-2500r / min, more preferably 2300-2500r / min, and the time of the vortex mixing is preferably 1-2min, more preferably 1.5-2min; the rotation speed of the centrifugal separation is 4000-5000r / min, and the time is 5-10min.

[0060] After obtaining the sample liquid to be tested, the present invention adopts high performance liquid chromatography-tandem mass spectrometry to detect the herbicide and its metabolites in the sample liquid to be tested.

[0061] In the present invention, the sample liquid to be tested is preferably filtered before being detected by high performance liquid chromatography-tandem mass spectrometry, and the pore size of the organic filter membrane for filtration is preferably 0.22 μm.

[0062] In the present invention, the HPLC-MS / MS method includes HPLC separation and mass spectrometry detection. In the present invention, the conditions for HPLC separation include: the chromatographic column is preferably a BHEC18 chromatographic column; the column temperature is preferably 30-40°C, more preferably 35°C; the mobile phase system is mobile phase A and mobile phase B; the mobile phase A is acetonitrile, and the mobile phase B is formic acid-ammonium formate aqueous solution; the volume fraction of formic acid in the formic acid-ammonium formate aqueous solution is preferably 0.1%, and the concentration of ammonium formate is preferably 5mmol / L; the elution method is gradient elution; the program of the gradient elution is: 0-1m in, the volume fraction of the mobile phase A is 40%; from 1 to 6 min, the volume fraction of the mobile phase A increases uniformly from 40% to 90%; from 6 to 7 min, the volume fraction of the mobile phase A decreases uniformly from 90% to 40%; from 7 to 8 min, the volume fraction of the mobile phase A is 40%; the flow rate of the mobile phase system is preferably 0.25 to 0.35 mL / min, more preferably 0.3 mL / min; the injection volume is preferably 2 to 3 μL, more preferably 2 to 2.5 μL.

[0063] In the present invention, the conditions for mass spectrometry detection include: ESI ion source, ion source temperature is 250-350°C, preferably 250-300°C; curtain gas pressure is 30-40psi, preferably 35psi; collision gas pressure is 6-10psi, preferably 8psi; spray gas pressure is 40-50psi, preferably 45-50psi; auxiliary heating gas pressure is 35-45psi, preferably 40psi; positive and negative ion scanning and multiple reaction monitoring mode are adopted.

[0064] In the present invention, the high performance liquid chromatography-tandem mass spectrometry detection is preferably performed using liquid chromatography-triple quadrupole tandem mass spectrometry detection.

[0065] In the present invention, the herbicide includes one or more of clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, fluazifop-butyl and high-efficiency fluazifop-butyl; the metabolite preferably includes one or more of clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, fluazifop-butyl and 2,4-D.

[0066] In the present invention, the mass spectrometry conditions of the herbicide and its metabolites are shown in Table 1.

[0067] Table 1 Mass spectrometry parameters of herbicides and their metabolites

[0068] Pesticide name Precursor ion (m / z) Product ion (m / z) Collision energy (V) Declustering voltage(V) Clodinafop-butyl 310 238 / 218 -19 / -29 -80 Cyanofluoric acid 300 228 / 208 -21 / -28 -82 Quizalofop-p-ethyl 343 271 / 243 -19 / -35 -70 Anti-acid 223 135 / 179 -21 / -20 -80 Halpyralid 360 288 / 252 -17 / -34 -97 2,4-D 218.9 160.9 / 124.9 -20 / -36 -101 Cyhalofop-butyl 375 256 / 120 22 / 44 85 Haloxyfop-Phthiophene 376 288 / 91 35 / 36 133 Trinexapac-ethyl 253 69 / 207 30 / 17 97 Quitamilin 429.2 299.3 / 270.9 31 / 38 112 Haloxyfop-Phthiophene 376 316.1 / 288.1 22 / 35 162 Clodinafop-butyl 350 266.2 / 91 19 / 36 166

[0069] In the present invention, the detection of the sample liquid by the high performance liquid chromatography-tandem mass spectrometry preferably includes qualitative analysis and quantitative detection.

[0070] In the present invention, the step of qualitative analysis preferably includes:

[0071] The sample solution to be tested and the mixed standard working solution are measured according to the conditions of high performance liquid chromatography separation and mass spectrometry detection, and the chromatographic retention times of the herbicides and their metabolites in the sample solution to be tested and the mixed standard working solution are recorded. When a chromatographic peak consistent with the retention time of the herbicide and its metabolite standard in a certain standard working solution is detected in the sample solution to be tested (the variation range is within ±2.5%), and the deviation between the relative abundance ratio of the selected monitoring ion pair in the chromatogram of the sample solution to be tested and the relative abundance ratio (k) of the ion of the standard solution of equivalent concentration does not exceed the range specified in Table 2, it can be determined that the corresponding compound is detected in the sample.

[0072] Table 2 Maximum allowable deviation of relative ion abundance in qualitative analysis

[0073] Relative ion abundance / % ＞50 20～50 10～20 ≤10 Allowable relative deviation / % ±20 ±25 ±30 ±50

[0074] In the present invention, the method for preparing the mixed standard working solution preferably comprises:

[0075] Prepare standard stock solutions of herbicides and their metabolites;

[0076] Prepare mixed standard stock solutions of herbicides and their metabolites;

[0077] Prepare mixed standard working solutions of herbicides and their metabolites.

[0078] The present invention prepares a standard stock solution of a herbicide and its metabolites. In the present invention, the standard stock solution is specifically prepared as follows: accurately weigh 10 mg (accurate to 0.01 mg) of a standard substance of the herbicide and its metabolites, respectively, dissolve and dilute to 10 mL with methanol, acetonitrile or acetone, shake well, obtain a standard stock solution, store at -20°C in the dark, and have a shelf life of 12 months.

[0079] In the present invention, the herbicide and its metabolites are clodinafop-butyl standard, cyhalofop-butyl standard, quizalofop-butyl acid standard, antinexamic acid standard, fluazifop-butyl standard, 2,4-D standard, cyhalofop-butyl standard, high-efficiency fluazifop-butyl standard, trinexapac-butyl standard, quizalofop-butyl standard, fluazifop-butyl standard and clodinafop-butyl standard. In the present invention, in the standard stock solutions of the herbicides and their metabolites, the standard stock solution concentrations of clodinafop-butyl, cyhalofop-butyl, 2,4-D, antinexamic acid, cyhalofop-butyl, high-efficiency fluazifop-butyl, fluazifop-butyl and fluazifop-butyl are preferably 1000 mg / L; the standard stock solution concentrations of clodinafop-butyl, quizalofop-butyl acid and quizalofop-butyl are preferably 100 mg / L; the standard stock solution concentrations of trinexapac-butyl are preferably 5000 mg / L; the standard stock solutions of clodinafop-butyl, cyhalofop-butyl, 2,4-D, The solvent in the standard stock solutions of antinexamic acid, cyanamide, quizalofop-butyl and antinexamic acid is preferably acetonitrile; the solvent in the standard stock solutions of high-efficiency fluazifop-p-ethyl, clodinafop-ac-butyl, quizalofop-p-ethyl acid and fluazifop-p-ethyl is preferably methanol; the solvent in the standard stock solution of haloxyfop-p-ethyl is preferably acetone; the standard stock solutions of high-efficiency fluazifop-p-ethyl, fluazifop-p-ethyl and haloxyfop-p-ethyl are preferably purchased from Yuanye Company; the standard stock solutions of clodinafop-ac-butyl, quizalofop-p-ethyl acid and quizalofop-p-ethyl are preferably purchased from First Standard Company; the standard stock solutions of the herbicides and their metabolites are preferably stored at -20°C in the dark.

[0080] After obtaining the standard stock solution of the herbicide and its metabolite, the present invention prepares a mixed standard stock solution of the herbicide and its metabolite. In the present invention, the concentration of 2,4-D in the mixed standard stock solution is preferably 20 mg / L, the concentration of anti-invert acid is preferably 50 mg / L, the concentration of cyhalofop-butyl is preferably 100 mg / L, and the concentration of the other nine pesticides is preferably 10 mg / L. In the present invention, the method for preparing the mixed standard stock solution preferably includes: accurately aspirating the standard stock solution respectively, diluting the volume with acetonitrile, shaking well, and preparing a mixed standard stock solution. In the present invention, the mixed standard stock solution is preferably prepared before use.

[0081] After obtaining the mixed standard stock solution of the herbicide and its metabolites, the present invention prepares the mixed standard working solution of the herbicide and its metabolites.

[0082] In the present invention, the method for preparing the mixed standard working solution preferably comprises:

[0083] Provide blank matrix extract;

[0084] Accurately pipette the mixed standard stock solution respectively, dilute it to the fixed volume with the blank matrix extract, shake well, and use it as the mixed standard working solution to obtain mixed standard working solutions with concentrations of 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 10 μg / L, 20 μg / L and 50 μg / L.

[0085] In the present invention, the blank matrix extract refers to the sample solution to be tested that does not contain the above-mentioned herbicides and their metabolites; the blank fruit or vegetable matrix is ​​used as a raw material and is prepared according to the above-mentioned preparation method of the sample solution to be tested, which will not be repeated here.

[0086] In the present invention, there is no special requirement for the volume of the mixed standard stock solution and the final volume of the blank matrix extract solution, which is based on the final mixed standard working solution of the corresponding concentration. In the present invention, the standard mixed working solution is preferably prepared before use.

[0087] In the present invention, the quantitative detection preferably includes the preparation of a standard curve and the determination of the herbicide and its metabolites in the sample solution to be tested.

[0088] In the present invention, the method for preparing the standard curve preferably comprises the following steps:

[0089] The mixed standard working solution is detected according to the detection conditions of high performance liquid chromatography-tandem mass spectrometry to obtain the chromatographic peak area of ​​the herbicide and its metabolites, and a standard curve is drawn with the mass concentration of the mixed standard working solution as the abscissa and the peak area of ​​the chromatographic peak of the quantitative ion of the herbicide and its metabolite as the ordinate to obtain the standard curve regression equation.

[0090] In the present invention, the standard curve regression equation of the herbicide and its metabolites is shown in Table 3:

[0091] Table 3 Standard curve regression equations for herbicides and their metabolites

[0092]

[0093]

[0094] In the present invention, the determination of the herbicide and its metabolites in the sample liquid to be tested preferably includes the following steps:

[0095] The sample solution to be tested is tested according to the detection conditions of high performance liquid chromatography-tandem mass spectrometry to obtain the chromatographic peak area of ​​the herbicide and its metabolites in the sample solution to be tested;

[0096] The concentration of the components in the test solution is obtained according to the chromatographic peak area of ​​the herbicide and its metabolites and the standard curve regression equation.

[0097] The number of determinations of the sample solution to be tested in the present invention is preferably ≥ 2 times.

[0098] In the present invention, the calculated result is preferably expressed as the arithmetic mean of 6 independent determination results obtained under repeatability conditions. In the present invention, the absolute difference of the 6 independent determination results obtained under repeatability conditions preferably should not exceed 20% of the arithmetic mean.

[0099] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0100] Example 1

[0101] Drawing of standard curve

[0102] (1) Preparation of standard solution

[0103] (1.1) Preparation of pesticide stock solution

[0104] (1.1.1) Clodinafop-butyl standard stock solution: Accurately weigh 10 mg (accurate to 0.01 mg) of the standard substance and dilute to 10 mL with acetonitrile to prepare a standard stock solution with a concentration of approximately 1000 mg / L. Store at -20°C in the dark.

[0105] (1.1.2) Cyanosulfuron standard stock solution: Accurately weigh 10 mg (accurate to 0.01 mg) of the standard substance and dilute to 10 mL with acetonitrile to prepare a standard stock solution with a concentration of about 1000 mg / L. Store at -20°C in the dark.

[0106] (1.3) 2,4-D standard stock solution: Purchase 10 mg of 2,4-D standard substance and dilute to 10 mL with acetonitrile to prepare a standard stock solution with a concentration of about 1000 mg / L. Store at -20°C in the dark.

[0107] (1.4) Standard stock solution of anti-invert acid: Accurately weigh 10 mg (accurate to 0.01 mg) of the standard substance and dilute to 10 mL with acetonitrile to prepare a standard stock solution with a concentration of about 1000 mg / L. Store at -20°C in the dark.

[0108] (1.1.5) Cyanofluoric acid standard stock solution: Accurately weigh 10 mg (accurate to 0.01 mg) of the standard substance and dilute to 10 mL with acetonitrile to prepare a standard stock solution with a concentration of about 1000 mg / L. Store at -20°C in the dark.

[0109] (1.1.6) High-efficiency haloxyfop-p-ethyl standard stock solution: Purchase high-efficiency haloxyfop-p-ethyl solution (1000 mg / L, methanol) produced by Yuanye Company and store it at -20°C in the dark.

[0110] (1.1.7) Clodinafop-butyl standard stock solution: Purchase clodinafop-butyl solution (100 mg / L, methanol) produced by First Standard and store at -20°C in the dark.

[0111] (1.1.8) Quizalofop-p-butyl acid standard stock solution: Purchase quizalofop-p-butyl acid solution (100 mg / L, methanol) produced by First Standard and store at -20°C in the dark.

[0112] (1.1.9) Quitaclonide standard stock solution: Purchase quitaclonide solution (100 mg / L, acetonitrile) produced by First Standard and store at -20°C in the dark.

[0113] (1.1.10) Haloxyfop-ethyl standard stock solution: Purchase Haloxyfop-ethyl solution (1000 mg / L, methanol) produced by Yuanye Company and store it at -20°C away from light.

[0114] (1.1.11) Standard stock solution of trinexapac-ethyl: Purchase 25 mg of trinexapac-ethyl standard substance and dilute to 5 mL with acetonitrile to prepare a standard stock solution with a concentration of about 5000 mg / L. Store at -20°C in the dark.

[0115] (1.1.12) Haloxyfop-butyl standard stock solution: Purchase Haloxyfop-butyl solution (1000 mg / L, acetone) produced by Yuanye Company and store it at -20℃ away from light.

[0116] (1.2) Preparation of mixed standard stock solutions: Pipette appropriate amounts of the above single standard stock solutions to prepare mixed standard stock solutions with concentrations of 20 mg / L for 2,4-D, 50 mg / L for anticoagulant, 100 mg / L for cyhalofop-butyl, and 10 mg / L for the other nine pesticides. The solvent used is acetonitrile.

[0117] (2) Drawing of standard curve

[0118] The cabbage blank matrix was homogenized with a proofing machine and put into a small can for use. 10 g (±0.1 g) of the homogenate was weighed into a centrifuge tube, 10 mL of acidic acetonitrile was added, vortexed at 2500 r / min for 10 min, 4 g of sodium chloride was added, and centrifuged at 5000 r / min for 5 min. The supernatant was the extract; 6 mL of the extract was transferred into a centrifuge tube containing 150 mg of anhydrous magnesium sulfate and 150 mg of floral silica, vortexed at 2500 r / min for 2 min, and centrifuged at 5000 r / min for 5 min. The supernatant was passed through a 0.22 μm microporous organic membrane and put into a small vial to obtain the cabbage blank matrix.

[0119] The mixed standard stock solution was added to the blank matrix of cabbage to prepare a series of standard working solutions with pesticide concentrations of 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 10 μg / L, 20 μg / L and 50 μg / L, respectively. The series of standard working solutions were subjected to high performance liquid chromatography-tandem mass spectrometry detection, and the peak area of ​​the analyte was used as the ordinate (y) and the mass concentration of the pesticide was used as the abscissa (x). A standard curve was drawn to obtain a standard curve regression equation. The instrumental quantitative limit was estimated with a signal-to-noise ratio (S / N) of 7 to 10, and the standard curve regression equation, linear range, correlation coefficient and method quantitative limit are shown in Table 3.

[0120] Wherein, high performance liquid chromatography-tandem mass spectrometry detection is carried out using a liquid chromatography-triple quadrupole tandem mass spectrometry detector; high performance liquid chromatography conditions: BHEC18 (1.7 μm, 2.1×100 mm); mobile phase A: acetonitrile, mobile phase B: formic acid with a volume fraction of 0.1%+5 mmol / L ammonium formate aqueous solution; chromatographic column temperature: 35° C.; injection volume: 2 μL; mobile phase flow rate: 0.3 mL / min; gradient elution program: 0-1 min, the volume fraction of mobile phase A is 40%, the volume fraction of mobile phase A is 60%, 1-6 min, the volume fraction of mobile phase A is increased from 40% to 90% at a uniform rate, the volume fraction of mobile phase B is decreased from 60% to 10% at a uniform rate, 6-7 min, the volume fraction of mobile phase A is decreased from 90% to 40% at a uniform rate, the volume fraction of mobile phase B is increased from 10% to 60% at a uniform rate, 7-8 min, the volume fraction of mobile phase A is 40%, and the volume fraction of mobile phase A is 60%.

[0121] Mass spectrometry conditions: ion source temperature was 250°C; curtain gas was 35 psi, collision gas was 8 psi, spray gas GS1 was 50 psi, and auxiliary heating gas GS2 was 40 psi; the mass spectrometry parameters are shown in Table 1.

[0122] Table 3 Linear equations, linear ranges and correlation coefficients of twelve pesticides

[0123]

[0124]

[0125] As shown in Table 3, the solvent and matrix standard curves of the detection method provided by the present invention have good linearity, the correlation coefficients are all greater than 0.995, the quantitative limit is 0.0001-0.004 mg / kg, the quantitative limit is low, and the detection sensitivity is high.

[0126] Example 2

[0127] Spike recovery

[0128] A blank matrix of cabbage was prepared according to the method of Example 1, and twelve pesticides were added to the blank matrix of cabbage, wherein the 2,4-D spike concentration was 0.02 mg / kg, 0.1 mg / kg and 0.4 mg / kg; the spike concentration of anti-necrotic acid was 0.05 mg / kg, 0.25 mg / kg and 1.0 mg / kg; the spike concentration of cyhalofop-butyl was 0.1 mg / kg, 0.5 mg / kg and 2 mg / kg, and the spike levels of the other nine pesticides were 0.01 mg / kg, 0.05 mg / kg and 0.2 mg / kg, respectively. Six parallels were made for each concentration, and a spike recovery test was performed. The HPLC-MS / MS detection conditions were the same as those in Example 1; the spike recovery results are shown in Table 4.

[0129] Table 4 Recovery of spiked pesticides in cabbage matrix

[0130]

[0131]

[0132] As shown in Table 4, the spiked recoveries of clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, fluazifop-butyl and high-efficiency fluazifop-butyl and their metabolites were 89.4-112.6%, and the RSD was 1.7-5.9%. The spiked recoveries were high, the relative standard deviations were small, and the detection accuracy and precision were high.

[0133] Example 3

[0134] Spike recovery

[0135] A pear blank matrix was prepared according to the method of Example 1 (replacing cabbage with pear), and twelve pesticides were added to the pear blank matrix, wherein the 2,4-D spike concentration was 0.02 mg / kg, 0.04 mg / kg and 0.2 mg / kg; the anti-invert acid spike concentration was 0.05 mg / kg, 0.1 mg / kg and 0.5 mg / kg; the cyhalofop-butyl spike concentration was 0.1 mg / kg, 0.2 mg / kg and 1 mg / kg, and the spike levels of the other nine pesticides were 0.01 mg / kg, 0.02 mg / kg and 0.1 mg / kg, respectively. Six parallels were made for each concentration, and a spike recovery test was performed. The HPLC-MS / MS detection conditions were the same as those in Example 1; the spike recovery results are shown in Table 5.

[0136] Table 5 Recovery of spiked pesticides in pear matrix

[0137]

[0138]

[0139] As shown in Table 5, the spiked recoveries of clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, fluazifop-butyl and high-efficiency fluazifop-butyl and their metabolites in pear matrix were 80.0-119.6%, and the RSD was 0.6-17.3%. The spiked recoveries were high, the relative standard deviations were small, and the detection accuracy and precision were high.

[0140] Example 4

[0141] Determination of method detection limit LOD

[0142] (1) A cabbage blank matrix (blank sample) was prepared according to Example 1.

[0143] (2) Use the matrix standard to calculate the concentration of the blank value and the spiked sample, calculate the LOD value according to formula (1), and calculate the weighted standard deviation (SD) according to formula (2):

[0144] LOD=2×t 0.05(f) ×SD / S……Formula (1)

[0145]

[0146] In formula (2), m is the number of blank sample determinations, and n is the number of repetitions of a certain addition concentration; the sensitivity S=sample concentration average B / minimum addition concentration C (minimum addition concentration C is generally the lowest point of the standard curve or the lowest concentration point that can produce a peak) can be estimated from the addition recovery average and the addition level. The detection limits of various pesticide methods are shown in Table 6; the high performance liquid chromatography-tandem mass spectrometry detection conditions are the same as those in Example 1.

[0147] Table 6 Detection (LOD) values ​​of various pesticide methods in cabbage

[0148] Pesticide name Method detection limit LOD (mg / kg) Method quantification limit*(mg / kg) Clodinafop-butyl 0.0003 0.001 Cyanofluoric acid 0.0001 0.0005 Quizalofop-p-ethyl 0.0004 0.001 Anti-acid 0.001 0.01 Halpyralid 0.0001 0.0005 2,4-D 0.0005 0.001 Cyhalofop-butyl 0.008 0.01 Haloxyfop-Phthiophene 0.0001 0.0005 Trinexapac-ethyl 0.0001 0.0005 Quitamilin 0.0001 0.0005 Haloxyfop-Phthiophene 0.0001 0.0005 Clodinafop-butyl 0.0001 0.0005

[0149] *Note: While ensuring the linear range and accuracy, the quantitative limit of the method is set to the data in the table.

[0150] As shown in Table 6, the detection limit LOD of the detection method provided by the present invention is 0.0001-0.008 mg / kg, the method quantification limit is 0.0005-0.01 mg / kg, the detection limit and quantification limit are low, and the detection sensitivity is high.

[0151] Figure 1 is the TIC diagram of twelve pesticides. Figure 1 It can be seen that under the above detection conditions, the peak shapes and separation of the twelve herbicides and their metabolites were good.

[0152] Figure 2 Chromatograms of blank matrix and spiked 10 μg / kg clodinafop-butyl in cabbage; Figure 3 Chromatograms of blank matrix and spiked 10 μg / kg quizalofop-p-butyl acid in cabbage; Figure 4 Chromatograms of blank matrix and spiked 10 μg / kg cyanofluoric acid in cabbage; Figure 5 Chromatograms of blank matrix and spiked 50 μg / kg anabasic acid in cabbage; Figure 6 Chromatograms of blank matrix and spiked 10 μg / kg fluazifop-butyl in cabbage; Figure 7 Chromatograms of blank matrix and spiked 20 μg / kg 2,4-D in cabbage. Figure 8 Chromatograms of blank matrix and spiked 100 μg / kg cyhalofop-butyl in cabbage; Fig. 9 Chromatograms of blank matrix and spiked 10 μg / kg high-efficiency halpyr-methyl in cabbage; Fig.10 Chromatograms of blank matrix and spiked 10 μg / kg trinexapac-ethyl in cabbage; Fig.11 Chromatograms of blank matrix and spiked 10 μg / kg quizalofop-butyl in cabbage;

[0153] Fig.12 Chromatograms of blank matrix and spiked 10 μg / kg halpyrifos-ethyl in cabbage; Fig.13 The chromatograms of the blank matrix and spiked with 10 μg / kg clodinafop-butyl are shown in Table 1. Figures 2 to 13 It can be seen that the cabbage blank matrix does not contain the target pesticides and each pesticide has a good response value at the spike level of 10 μg / kg (among which, the spike level of 2,4-D is 20 μg / kg, the spike level of anti-necrotic acid is 50 μg / kg, and the spike level of cyhalofop-butyl is 100 μg / kg).

[0154] Example 5

[0155] Determination of method detection limit LOD

[0156] (1) A pear matrix was prepared according to Example 1 (blank sample, cabbage was replaced with pear).

[0157] (2) The detection limit (LOD) of the method in pear matrix was calculated according to the same steps as in Example 4.

[0158] Table 7 Detection (LOD) values ​​of various pesticide methods in pears

[0159]

[0160]

[0161] *Note: While ensuring the linear range and accuracy, the quantitative limit of the method is set to the data in the table.

[0162] As shown in Table 7, the detection limit LOD of the detection method provided by the present invention is 0.0001-0.004 mg / kg, the method quantification limit is 0.0005-0.01 mg / kg, the detection limit and quantification limit are low, and the detection sensitivity is high.

[0163] Example 6

[0164] Matrix Effects

[0165] (1) Peach matrix and kidney bean matrix (blank sample, cabbage was replaced with peach and kidney bean, respectively) were prepared according to Example 1, and blank matrix solution was obtained to prepare matrix standard curve, and acetonitrile was used to prepare solvent standard curve.

[0166] (2) The pesticide concentrations of the prepared matrix standard curve and solvent standard curve were 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 10 μg / L, 20 μg / L and 50 μg / L, respectively.

[0167] (3) The series of standard working solutions are subjected to high performance liquid chromatography-tandem mass spectrometry detection, and a standard curve is drawn with the peak area of ​​the analyte as the ordinate (y) and the mass concentration of the pesticide as the abscissa (x) to obtain a standard curve regression equation. The matrix effect (ME) is calculated according to formula (3) using the linear equations of the matrix standard curve and the pure solvent standard curve obtained respectively.

[0168] SR = k1 / k2*100% ... Formula (3)

[0169] In formula (3), k1 is the slope of the matrix standard curve, and k2 is the slope of the pure solvent standard curve; the linear equations and matrix effects of peach and kidney bean are shown in Table 8. The matrix effect (ME) can be reflected by SR (slope ratio), SR = 1, indicating no matrix effect; 0.8 < SR < 1.2, indicating a weak matrix effect, which can be ignored; when SR > 1.2 or SR < 0.8, it indicates an enhanced matrix effect or a matrix inhibition effect. When SR is 0.5-0.8 or 1.2-1.5, it is a moderate matrix effect; when SR < 0.5 or > 1.5, it is a strong matrix effect.

[0170] Table 8 Linear range and SR of twelve pesticides

[0171]

[0172]

[0173] From the data in Table 8, it can be seen that trinexapac-ethyl has a strong matrix effect in peach and bean matrices. In the peach matrix, only fluazifop-butyl, 2,4-D and trinexapac-ethyl have negligible matrix effects; in the bean matrix, only clodinafop-butyl, fluazifop-butyl, trinexapac-ethyl and clodinafop-butyl have negligible matrix effects. For pesticides with strong and weak matrix effects, matrix standard curves should be prepared for quantification to obtain more accurate data.

[0174] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for detecting herbicides and their metabolites in fruits and vegetables, comprising the following steps: Mixing the sample to be tested, acidic acetonitrile and inorganic salt, performing extraction and separation, and obtaining an extract; The extract is mixed with a solid phase extractant, and subjected to dispersed solid phase extraction purification to obtain a sample solution to be tested; the solid phase extractant comprises magnesium sulfate and floral silica; Detecting the herbicide and its metabolites in the sample liquid by high performance liquid chromatography-tandem mass spectrometry; The herbicides include clodinafop-butyl, cyhalofop-butyl, quizalofop-butyl, trinexapac-ethyl, haloxyfop-butyl and high-efficiency haloxyfop-butyl; The metabolites include one or more of clodinafop-butyl, cyanhalofop-butyl, quizalofop-butyl, antineptasulfuron, fluazifop-butyl and 2,4-D; The high performance liquid chromatography-tandem mass spectrometry method includes high performance liquid chromatography separation and mass spectrometry detection; The conditions for the HPLC separation include: the chromatographic column is a BHE C18 chromatographic column; the mobile phase system is a mobile phase A and a mobile phase B; the mobile phase A is acetonitrile, and the mobile phase B is a formic acid-ammonium formate aqueous solution; the elution method is a gradient elution; The gradient elution procedure is as follows: 0-1 min, the volume fraction of the mobile phase A is 40%; 1-6 min, the volume fraction of the mobile phase A increases uniformly from 40% to 90%; 6-7 min, the volume fraction of the mobile phase A decreases uniformly from 90% to 40%; 7-8 min, the volume fraction of the mobile phase A is 40%; The mass spectrometry detection conditions include: ESI ion source, ion source temperature of 250-350°C; curtain gas pressure of 30-40 psi, collision gas pressure of 6-10 psi, spray gas pressure of 40-50 psi, auxiliary heating gas pressure of 35-45 psi, positive and negative ion scanning, and multiple reaction monitoring mode.

2. The detection method according to claim 1, characterized in that: The column temperature of the HPLC separation is 30-40°C; the injection volume is 2-3 μL; and the flow rate of the mobile phase system is 0.25-0.35 mL / min.

3. The detection method according to claim 1, characterized in that: The acidic acetonitrile is a formic acid-acetonitrile mixed solution, and the volume fraction of formic acid in the acidic acetonitrile is 0.05-0.15%; The ratio of the mass of the sample to be tested to the volume of acidic acetonitrile is 1 g: 1-2 mL.

4. The detection method according to claim 1, characterized in that: The inorganic salt includes sodium chloride and / or anhydrous magnesium sulfate; The mass ratio of the sample to be tested to the inorganic salt is 1:0.4-0.

6.

5. The detection method according to claim 1, 3 or 4, characterized in that: The extraction and separation comprises: using acidic acetonitrile to perform vortex oscillation extraction on the sample to be tested, mixing the obtained extraction system with inorganic salts, and performing centrifugal separation to obtain a supernatant as an extract.

6. The detection method according to claim 5, characterized in that: The rotation speed of the vortex oscillation extraction is 2000-2500 r / min, and the time is 5-10 min; The rotation speed of the centrifugal separation is 4000-5000 r / min, and the time is 5-10 min.

7. The detection method according to claim 1, characterized in that: The mass ratio of magnesium sulfate to florisil is 1:1-2; The ratio of the volume of the extract to the mass of the solid phase extractant is 1 mL: 20-30 mg.

8. The detection method according to claim 1 or 7, characterized in that: The dispersed solid phase extraction cleanup includes sequentially performing vortex mixing and centrifugal separation.

9. The detection method according to claim 8, characterized in that: The vortex mixing speed is 2000-2500 r / min, and the time is 1-2 min; The rotation speed of the centrifugal separation is 4000-5000 r / min, and the time is 5-10 min.

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