A mixed blank matrix for vegetable pesticide residue analysis and its application

Abstract

The invention discloses a mixed blank matrix for vegetable pesticide residue analysis and detection and its application, including the preparation of blank matrix and the preparation of mixed blank matrix, the raw materials of mixed blank matrix are calculated by weight: 20-30 parts of Chinese cabbage, 20-40 parts of cucumber, 10-40 parts of spinach, 5-30 parts of cauliflower; after the blank matrix and the mixed blank matrix are pre-treated, the matrix matching standard solution establishes a standard curve, and the pure solvent standard curve is established at the same time; the corresponding matrix effect is calculated using the slope; the matrix matching degree is calculated; the practicality of the mixed blank matrix is ​​evaluated. The mixed blank matrix can reduce or eliminate the matrix effect, and is suitable for the simultaneous determination of the residual amounts of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in 8 different vegetables (cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, green onion, green vegetables), which can improve work efficiency, reduce the time cost caused by the blindness of obtaining blank matrix, and reduce the maintenance cost of the instrument.

Description

Technical Field

[0001] The invention relates to the field of vegetable pesticide residue analysis and detection, and in particular to a mixed blank matrix used in vegetable pesticide residue analysis and detection and an application thereof. Background Art

[0002] In modern agriculture, the use of pesticides can increase crop yields, but excessive and unreasonable use of pesticides will cause the pesticide residue content to exceed the limit standard. Pesticide residue detection is a means of agricultural product safety supervision, and the accuracy and reliability of its analysis results are an important guarantee for the quality and safety of agricultural products.

[0003] However, during the detection process, the existence of matrix effects will seriously affect the accuracy and reliability of the test results. Therefore, reducing or eliminating matrix effects has become an indispensable part of pesticide residue detection.

[0004] Regarding the matrix effect, the matrix matching standard curve correction method is currently a solution that takes into account economy, feasibility and high accuracy. However, in actual testing work, it is necessary to conduct dozens or even hundreds of pesticide residues analysis on a large number of samples of various types. The matrix matching standard curve method is too labor-intensive and inefficient; and it is difficult to obtain blank samples that do not contain target analytes; at the same time, more sample matrices entering the instrument will increase the maintenance cost of the system. Therefore, it is of great significance to develop a universal mixed blank matrix.

[0005] The invention discloses a mixed blank matrix for pesticide residue analysis and detection. Experiments have shown that the mixed blank matrix can be used for simultaneous determination of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in 8 kinds of different vegetables (cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables). The mixed blank matrix can improve work efficiency, reduce time cost caused by blindness in obtaining blank matrices and reduce maintenance cost of instruments. Summary of the invention

[0006] The purpose of the present invention is to provide a mixed blank matrix for use in the analysis and detection of vegetable pesticide residues. One mixed blank matrix can replace blank matrices of multiple vegetables (cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables). A standard curve matched by the mixed blank matrix can replace multiple single standard curves. It can effectively compensate for the enhancement or weakening of the matrix effect, improve work efficiency, reduce the time cost caused by the blindness of obtaining the blank matrix, and reduce the maintenance cost of the instrument.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] 1) Preparation of blank matrices of cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables and preparation of mixed blank matrices;

[0009] 2) The above 8 different blank matrices and mixed blank matrices were pre-treated according to QuEChERS in GB 23200.113-2018 standard, and the matrix matching standard solution calibration method was used. The target analytes were dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole. At the same time, ethyl acetate was used to prepare a pure solvent standard curve, and all test solutions were added with internal standard heptachlor epoxide B, and the corresponding standard curve was established using gas chromatography-triple quadrupole tandem mass spectrometry;

[0010] 3) Calculation and evaluation of matrix effect value: The matrix effect value was calculated by the ratio of the slope of the standard curve of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in the above 8 different blank matrices to that of the corresponding pure solvents.

[0011]

[0012] Meffect——matrix effect value;

[0013] Maritix - slope of the standard curve for different analytes in a blank vegetable matrix;

[0014] Msolvent - slope of the standard curve of the analyte in pure solvent;

[0015] Evaluation of matrix effect: when the matrix effect value is 0.9-1.1, the matrix effect is not obvious; when the matrix effect is greater than 1.1, it is a matrix enhancement effect; when the matrix effect is less than 0.9, it is a matrix weakening effect; 4) Calculation and evaluation of matrix matching;

[0016] Dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in 8 different blank matrices of vegetables and the corresponding mixed blank matrices;

[0017] 4) The matrix matching degree is calculated by the ratio of the slopes of the standard curves;

[0018]

[0019] Msimilarity——matrix matching degree;

[0020] Maritix – the slope of the standard curve of the corresponding analyte in a certain blank matrix vegetable;

[0021] Mmix – slope of the standard curve of the corresponding analyte in the mixed blank matrix;

[0022] Matrix similarity evaluation: When the matrix similarity is 0.9-1.1, the matching degree is high, and the mixed blank matrix can replace a certain blank matrix;

[0023] 5) Evaluate the practicality of the mixed blank matrix through spike recovery experiments;

[0024] 500 μL of mixed standard solution (containing dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole with a concentration of 5 μg / mL) was added to 8 different vegetables. The mixed matrix was matched with the standard solution, and the contents of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in the 8 different vegetables were determined by instrumentation. The corresponding recoveries were calculated to see whether they met the requirements of GB / T27404-2008 "Laboratory Quality Control Specification for Physical and Chemical Testing of Food".

[0025] In step 1) of the present invention, the blank matrix of cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables is a blank matrix without the target substance, and the raw materials included in the mixed blank matrix are calculated by weight: 20-30 parts of Chinese cabbage, 20-40 parts of cucumber, 10-40 parts of spinach, and 5-30 parts of cauliflower;

[0026] Pretreatment in step 2): refer to standard GB 23200.113-2018, accurately weigh 10g of sample and place it in a 50mL plastic centrifuge tube, add 10mL acetonitrile, add extraction salt bag (containing 1g sodium chloride, 4g magnesium sulfate, 0.5g disodium hydrogen citrate, 1g sodium citrate and ceramic homogenizer), cover the centrifuge tube cap, shake vigorously for 1min, and centrifuge at 4200r / min for 5min. Pipette 6mL of supernatant into a centrifuge tube, add purification bag (containing 150mg PSA, 885mg magnesium sulfate and 15mg GCB), and vortex mix for 1min. Centrifuge at 4200r / min for 5min, accurately pipette 2.0mL of supernatant into a 10mL test tube, and blow nitrogen to nearly dryness in a 40℃ water bath. Add 1mL of ethyl acetate to dissolve, then add 20μL of internal standard (concentration of heptachlor epoxide B 5μg / mL), and pass through a 0.22μm organic phase microporous filter.

[0027] Instrument conditions were as follows: capillary column: DB-1701 (30m×0.25mm, 0.25μm), column temperature: 40℃ for 1 min, then programmed to 120℃ at 40℃ / min, then to 240℃ at 5℃ / min, and finally to 300℃ at 12℃ / min, maintained for 6 min; injection port temperature: 280℃; injection volume: 1μL; carrier gas: high-purity helium, flow rate: 1.0mL / min; injection mode: splitless injection; electron bombardment source: 70eV; ion source temperature: 280℃; transfer line temperature: 280℃; solvent delay: 5min (can be adjusted according to the peak time of the target); multiple reaction monitoring, retention time, quantitative ion pairs, qualitative ion pairs and collision energy of 11 target analytes.

[0028] In step 5), the spike recovery was calculated to evaluate the practicality of the mixed blank matrix. 500 μL of mixed standard solution (containing dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole at a concentration of 5 μg / mL) was added to 8 different vegetables, and the mixed matrix was used to match the standard solution.

[0029] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0030] (1) By using the mixed blank matrix of the present invention, there is no need to calibrate the matrix matching standard solution for each vegetable, which can reduce a large amount of data processing in the later stage, improve work efficiency, reduce the time cost caused by the blindness of obtaining the blank matrix, and reduce the maintenance cost of the instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A bar graph showing the matching degree between a single blank matrix and a mixed blank matrix A in Example 1 of the present invention.

[0032] Figure 2 A bar graph showing the matching degree between a single blank matrix and a mixed blank matrix B in Example 2 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Embodiment 1:

[0035] 1) Material preparation

[0036] Preparation of blank matrices of cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables and preparation of mixed blank matrices: 8 different blank matrix vegetables were all from the blank matrix planting base of Xiangyun Taixing Agricultural Science and Technology Development Co., Ltd.; the mixed blank matrix A included the following components in parts by weight: 30 parts of Chinese cabbage, 30 parts of cucumber, 35 parts of spinach and 5 parts of broccoli.

[0037] 7890B-7000D triple quadrupole gas chromatograph-mass spectrometer, DB-1701 chromatographic column (specifications: 30m×0.25mm, 0.25μm) (Agilent Technologies, USA); ME204T electronic analytical balance (sensitivity 0.0001g, METTLERTOLEDO); 3k15 centrifuge (Sigma, Germany); Mx-s adjustable mixer (DLAB); LC-DCY-24SY nitrogen blowdown instrument (Shanghai Lichen Bangxi Instrument Technology Co., Ltd.).

[0038] Dichlorvos (CAS No.: 62-73-7, concentration: 1000μg / mL, Tanmo Quality Inspection Technology Co., Ltd.); chlorfenapyr (CAS No.: 42509-80-8, concentration: 1000μg / mL, Tianjin Alta Technology Co., Ltd.); pirimicarb (CAS No.: 23103-98-2, concentration: 1000μg / mL, Beijing Tanmo Quality Inspection Technology Co., Ltd.); metalaxyl (CAS No.: 57837-19-1, concentration: 1000μg / mL, Tanmo Quality Inspection Technology Co., Ltd.); chlorpyrifos (C AS number: 2921-88-2, concentration: 1000μg / mL, Tanmo Quality Inspection Technology Co., Ltd.); triadimefon (CAS number: 43121-43-3, concentration: 1000μg / mL, Tanmo Quality Inspection Technology Co., Ltd.); procymidone (CAS number: 32809-16-8, concentration: 1000μg / mL, Tanmo Quality Inspection Technology Co., Ltd.); myclobutanil (CAS number: 88671-89-0, concentration: 1000μg / mL, Beijing Tanmo Quality Inspection Technology Co., Ltd.); propiconazole (CAS number : 60207-90-1, concentration: 1000μg / mL, Tianjin Alta Technology Co., Ltd.); bifenthrin (CAS No.: 82657-04-3, concentration: 1000μg / mL, Tanmo Quality Inspection Technology Co., Ltd.); etoxazole (CAS No.: 153233-91-1, concentration: 1000μg / mL, Tanmo Quality Inspection Technology Co., Ltd.); acetonitrile, ethyl acetate (chromatographic grade, Thermo Fisher Scientific (China) Co., Ltd.); heptachlor epoxide B (CAS No.: 1024-57-3, purity: 99 .1%, Tanmo Quality Inspection Technology Co., Ltd.); anhydrous magnesium sulfate, sodium citrate (superior grade, Tianjin Guangfu Fine Chemical Research Institute); sodium chloride (analytical grade, Sichuan Xilong Science Co., Ltd.); disodium hydrogen citrate (99.0%, Ron's reagent); ethylenediamine-N-propyl silane silica gel (PSA) (40-60μm, Yuexu Technology); graphitized carbon black (GCB) (100μm, Yuexu Technology); ceramic homogenizer (Agilent Technologies, USA); microporous filter membrane (organic phase): 13mm×0.22μm (Tianjin Jinteng Co., Ltd.).

[0039] 2) Establish the corresponding standard curve

[0040] The analytical method QuEChERS-gas chromatography-triple quadrupole tandem mass spectrometry was used to determine the residues of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in 8 kinds of vegetables (cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion, and green vegetables). The corresponding standard curve was established using matrix-matched standard solutions and pure solvent ethyl acetate.

[0041] Pretreatment: Refer to standard GB 23200.113-2018: Accurately weigh 10g of sample and place it in a 50mL plastic centrifuge tube, add 10mL acetonitrile, add extraction salt bag (containing 1g sodium chloride, 4g magnesium sulfate, 0.5g disodium hydrogen citrate, 1g sodium citrate and ceramic homogenizer), cover the centrifuge tube, shake vigorously for 1min, and centrifuge at 4200r / min for 5min. Pipette 6mL of supernatant into a centrifuge tube, add purification bag (containing 150mg PSA, 885mg magnesium sulfate and 15mg GCB), and vortex mix for 1min. Centrifuge at 4200r / min for 5min, accurately pipette 2.0mL of supernatant into a 10mL test tube, blow nitrogen in a 40℃ water bath until nearly dry. Add 1mL ethyl acetate to dissolve, then add 20μL internal standard (concentration of heptachlor epoxide B 5μg / mL), and pass through a 0.22μm organic phase microporous filter.

[0042] Instrument conditions are as follows: capillary column: DB-1701 (30m×0.25mm, 0.25μm), column temperature: 40℃ for 1min, then programmed to 120℃ at 40℃ / min, then to 240℃ at 5℃ / min, and finally to 300℃ at 12℃ / min, and maintained for 6min; injection port temperature: 280℃; injection volume: 1μL; carrier gas: high-purity helium, flow rate: 1.0mL / min; injection mode: splitless injection; electron bombardment source: 70eV; ion source temperature: 280℃; transfer line temperature: 280℃; solvent delay: 5min (can be adjusted according to the peak time of the target); multiple reaction monitoring, retention time, quantitative ion pair, qualitative ion pair and collision energy of 11 target analytes, monitoring conditions are shown in Table 1.

[0043] Table 1 Multiple reaction monitoring (MRM) conditions for 11 target analytes

[0044]

[0045]

[0046] The standard curves were prepared using cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion, green vegetable blank matrix and mixed blank matrix A. In the mass concentration range of 10-500 μg / L working solution, the linear relationship was good, all greater than 0.99, and the slope statistics are shown in Table 2.

[0047] Table 2 Slope statistics of different matrices

[0048]

[0049]

[0050] 3) Calculation of matrix effect value

[0051] Eight different blank matrices were used for matrix matching working curves. The determination indicators were dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole. The matrix effect value was calculated by the ratio of the slope of the corresponding standard curve to the slope of the corresponding pure solvent standard curve, as shown in Table 3.

[0052]

[0053] Meffect——matrix effect value;

[0054] Maritix - slope of the standard curve for different analytes in a blank vegetable matrix;

[0055] Msolvent - slope of the standard curve of the analyte in pure solvent;

[0056] Evaluation of matrix effect: When the matrix effect value is 0.9-1.1, the matrix effect is not obvious; when the matrix effect is greater than 1.1, it is a matrix enhancement effect; when the matrix effect is less than 0.9, it is a matrix weakening effect. From the results, it can be seen that the matrix effect values ​​of 11 target substances (dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole) are greater than 1.1 in 8 different blank matrix vegetables except procymidone, which is a matrix enhancement effect. The matrix effect of procymidone is not obvious except in spinach, and the matrix effect values ​​of the rest are 0.8, which are all matrix weakening effects.

[0057] Table 3 Matrix effect values ​​of 8 blank matrices

[0058]

[0059]

[0060] 4) Matrix matching calculation and evaluation

[0061] Eight different blank matrices were used to perform matrix matching working curves. The determination indicators were dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole. The matrix matching degree was calculated by the ratio of the slope of the corresponding standard curve to the slope of the standard curve of the mixed blank matrix A.

[0062]

[0063] Msimilarity——matrix matching degree;

[0064] Maritix - slope of the standard curve for different analytes in a blank vegetable matrix;

[0065] Mmix – slope of the standard curve of different analytes in mixed blank matrix;

[0066] Matrix matching evaluation: When the matrix similarity is between 0.9 and 1.1, the matching degree is high and they can replace each other.

[0067] Eight different blank matrices were used to match the matrix working curve. The determination indicators were dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole. The matching degree of the corresponding standard curve slope with the mixed blank matrix A was between 0.9 and 1.1, which was a high matching degree. See Table 4 and Figure 1 .

[0068] In short, when the analytical method QuEChERS-gas chromatography-triple quadrupole tandem mass spectrometry is used to determine the residue contents of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in different vegetables (including cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables), the mixed blank matrix A can be used for matrix matching curve, without the need to use cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables for one-to-one matrix matching, which can improve work efficiency, reduce cost problems caused by the blindness of obtaining blank matrices, and reduce the maintenance cost of the instrument.

[0069] Table 4 Matching degree between 8 blank matrices and mixed blank matrix A

[0070]

[0071] 5) Evaluating the practicality of mixed blank matrices

[0072] The practicability of mixed blank matrix A was evaluated by spike recovery experiments. 500 μL of mixed standard solution (containing dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin, and etoxazole at a concentration of 5 μg / mL) was added to 8 different vegetables, and the mixed matrix A was used to match the standard solution. The recovery rates are shown in Table 5.

[0073] Table 5 Recovery rate (%) of the standard curve prepared with mixed matrix A

[0074]

[0075]

[0076] Mixed standard solutions were added to 8 different vegetable matrices, and the recoveries of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole were determined simultaneously, ranging from 77.1% to 113.8%, which met the requirements of GB / T 27404-2008 "Laboratory Quality Control Specification for Physical and Chemical Testing of Food".

[0077] It shows that when dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, cypermethrin and etoxazole are determined in 8 different vegetables, the mixed blank matrix A can be used to prepare the standard curve, which can improve work efficiency, reduce the time cost caused by the blindness of obtaining blank matrix and reduce the maintenance cost of the instrument.

[0078] Example 2

[0079] 1) Material preparation

[0080] The mixed blank matrix B includes the following components in parts by weight: 30 parts of Chinese cabbage, 30 parts of cucumber, 10 parts of spinach and 30 parts of broccoli.

[0081] The rest is the same as in Example 1.

[0082] 2) Establish the corresponding standard curve

[0083] Same as Example 1

[0084] The standard curves were prepared using cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion, green vegetable blank matrix and mixed blank matrix B. In the mass concentration range of 10-500 μg / L working solution, the linear relationship was good, all greater than 0.99, and the slope statistics are shown in Table 2.

[0085] 3) Calculation of matrix effect value

[0086] Same as Example 1.

[0087] 4) Evaluation of matrix matching

[0088] Same as Example 1.

[0089] Eight different blank matrices were used to match the matrix working curve. The determination indicators were dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole. The matching degree of the corresponding standard curve slope with the mixed blank matrix B was between 0.9 and 1.1, which was a high matching degree. See Table 6 and Figure 2 .

[0090] In short, when the analytical method QuEChERS-gas chromatography-triple quadrupole tandem mass spectrometry is used to determine the residue contents of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in different vegetables (including cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables), the mixed blank matrix B can be used for matrix matching curve, without the need to use cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables for one-to-one matrix matching, which can greatly save labor and time costs.

[0091] Table 6 Matching degree between single blank matrix and mixed blank matrix B

[0092]

[0093]

[0094] 5) Evaluating the practicality of mixed blank matrices

[0095] The practicality of mixed blank matrix B was evaluated by spike recovery experiments. 500 μL of mixed standard solution (containing dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole at a concentration of 5 μg / mL) was added to 8 different vegetables, and the mixed matrix B was used to match the standard solution. The recovery rates are shown in Table 7.

[0096] Table 7 Recovery rate of standard curve prepared by mixed matrix B (%)

[0097]

[0098] The recoveries of 8 different samples when simultaneously determining dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, cypermethrin and etoxazole were between 72.1% and 110.5%, which met the requirements of GB / T27404-2008 "Laboratory Quality Control Specifications for Physical and Chemical Testing of Food".

[0099] It shows that when dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, cypermethrin and etoxazole are determined in 8 different vegetables, the mixed blank matrix B can be used to prepare the standard curve, which can improve work efficiency, reduce the time cost caused by the blindness of obtaining blank matrix and reduce the maintenance cost of the instrument.

[0100] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should fall within the protection scope determined by the claims of the present invention.

Claims

1. A mixed blank matrix for use in the analysis and detection of vegetable pesticide residues, characterized in that: The following steps are involved: 1) Preparation of blank matrices of cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables and preparation of mixed blank matrices; The raw materials of the mixed blank matrix are calculated by weight as follows: 20-30 parts of Chinese cabbage, 20-40 parts of cucumber, 10-40 parts of spinach, and 5-30 parts of cauliflower; 2) After pretreatment of the blank matrix and mixed blank matrix, the target analyte is determined using the matrix-matched standard solution to establish a standard curve, and a pure solvent standard curve is also established; 3) Calculation and evaluation of matrix effect values; 4) Calculation and evaluation of matrix matching: Calculate according to the following formula: Msimilarity——matrix matching degree; Maritix – the slope of the standard curve of the corresponding analyte in a certain blank matrix vegetable; Mmix – slope of the standard curve of the corresponding analyte in the mixed blank matrix; Matrix similarity evaluation: When the matrix similarity is 0.9-1.1, the matching degree is high, and the corresponding mixed blank matrix can replace a certain blank matrix; 5) Evaluate the practicality of mixed blank matrices.

2. A mixed blank matrix for use in vegetable pesticide residue analysis and detection according to claim 1, characterized in that: The cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables described in step 1) are blank matrices, that is, they do not contain the target analyte or the concentration is below the detection limit.

3. A mixed blank matrix for use in vegetable pesticide residue analysis and detection according to claim 1, characterized in that: Step 2) blank matrix vegetables are cucumber, Chinese cabbage, spinach, cauliflower, lettuce, celery, onion and green vegetables; The target analytes were dichlorvos, chlorfenapyr, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin, and etoxazole; Different blank matrix vegetables and mixed blank matrix QuEChERS were pretreated, and pure solvent standard curves were prepared with ethyl acetate. Internal standard heptachlor epoxide B was added to all test solutions, and the corresponding standard curves were established by gas chromatography-triple quadrupole tandem mass spectrometry.

4. A mixed blank matrix for use in the analysis and detection of vegetable pesticide residues according to claim 1, characterized in that: The calculation of the matrix effect value in step 3) is: the ratio of the slope of the standard curve of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole in different blank matrix vegetables to the slope of the standard curve of the corresponding pure solvent.

5. A mixed blank matrix for use in the analysis and detection of vegetable pesticide residues according to claim 1, characterized in that: Step 5) The practicality of the mixed blank matrix was evaluated by performing a spike recovery experiment.

6. Application of a mixed blank matrix for the analysis and detection of vegetable pesticide residues in the detection of dichlorvos, chlorpyrifos, pirimicarb, metalaxyl, chlorpyrifos, triadimefon, procymidone, myclobutanil, propiconazole, bifenthrin and etoxazole.

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