A method for rapid detection of pesticide residues in vegetables by ion mobility spectrometry with a glass slide as a third party medium

Abstract

The application discloses a method for rapidly detecting pesticide residues in vegetables by ion mobility spectrometry with a slide as a third-party medium, wherein the slide is horizontally placed in a field and is in the same pesticide spraying environment as the vegetables, pesticide is sprayed, vegetable samples and slide samples are collected after 2 hours, the pesticide residues of the two are respectively determined by high performance liquid chromatography tandem mass spectrometry, a simple formula model is established according to the relationship between the two, and the pesticide residues in the vegetables can be deduced from the pesticide residues in the slide according to the formula. Under the premise, the slide samples are directly collected after pesticide spraying for pretreatment, and the pesticide residues in the vegetables are rapidly detected by ion mobility spectrometry. The pretreatment time of the application is short, the traditional multiple extraction, nitrogen blowing, impurity removal, redissolution and other processes using organic reagents are abandoned, the whole sample pretreatment time is reduced from 1-2 hours to 10 minutes, and the whole detection process is about 20 minutes. Meanwhile, the application reflects the pesticide residues in the vegetables by using the third-party medium slide, avoids the matrix effect of the vegetables themselves, and reduces the interference of impurities in the detection process. The detection method is low in cost, simple and rapid in operation, and is suitable for on-site rapid detection of vegetable samples.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food safety detection, and specifically relates to a method for rapidly detecting pesticide residues in vegetables by using a glass slide as a third-party medium in combination with ion mobility spectrometry. BACKGROUND

[0002] About 1 million tons of chemical pesticides are used on vegetables and other crops in China every year, and China has become the second largest pesticide user in the world. Most of the pesticides are directly sprayed on the surface of plants or applied to the roots of plants for absorption and conduction to the body of plants. Due to the inherent chemical properties of pesticides and the overuse or even abuse of pesticides, the quality of fruits and vegetables for daily consumption is greatly threatened by pesticide residues. Countries around the world have strictly controlled the use of pesticides and have formulated various maximum residue limits (MRL) of pesticides on agricultural products to measure whether the pesticide residues in agricultural products exceed the standard.

[0003] The conventional method for detecting pesticide residues in vegetables needs to perform complex pretreatment operations on the vegetable samples. Due to the diversity of pesticide types and components and the complexity of the sample matrix, the pretreatment method for pesticide residue analysis is required to remove as many impurities as possible that exist simultaneously with the target substance, which makes the pretreatment time-consuming, expensive, consumes a large amount of solvent, and causes pollution and waste. A more rapid, simple and inexpensive method for rapidly detecting pesticide residues is increasingly welcomed. SUMMARY

[0004] The application discloses a method for rapidly detecting pesticide residues in vegetables by using a glass slide as a third-party medium in combination with ion mobility spectrometry, which solves the problems of waste of vegetable samples in the existing pesticide residue detection, complex operation process of the vegetable pretreatment method, consumption of a large amount of organic solvent, long time consumption, requirement of professional personnel, and matrix effect.

[0005] In order to achieve the above-mentioned purpose, the application specifically adopts the following technical solutions:

[0006] The method for rapidly detecting pesticide residues in vegetables by using a glass slide as a third-party medium in combination with ion mobility spectrometry comprises the following steps:

[0007] 1) The glass slide is placed in a field environment and sprayed with pesticides at the same time as the vegetables

[0008] The device comprises a simple support and a single-side frosted glass slide. The glass slide is used as a third-party medium, placed horizontally on the support and in the field at a certain height, and sprayed with pesticides at the same time as the vegetables in the field. After the pesticide is applied, an initial residue distribution will form on the surface of the vegetables and the glass slide. The glass slide sample is collected 2 hours after the pesticide on the glass slide is completely dried. The sample capacity is as many as possible according to the planting area in the field.

[0009] 2) Pretreatment of glass slide samples

[0010] Pretreatment of glass slide samples: Put the glass slide sample into a 50mL centrifuge tube, add 10mL ultrapure water, shake well for 5min, then pass the eluent through a 0.22μm organic filter membrane, and finally use ion mobility spectrometry to analyze the extract. The test is set up three times of parallel processing and once of control processing.

[0011] 3) Detection of samples

[0012] Instrument: Tmallus TR1000 ion mobility spectrometer

[0013] Instrument principle and conditions:

[0014] Ion mobility spectrometry is a method in which the molecules of the substance to be tested are heated and vaporized at the inlet, then ionized into ion groups of different charges and sizes by an ionization source in the migration tube. They reach the detector at different speeds under the action of an electric field, forming an ion characteristic spectrum with different migration times. Dry air is used as the drift gas, entering the end of the migration field at a flow rate of 1000mL / min. The electric field strength of the migration field is 300V / cm, the length of the migration tube is 15cm, the inlet temperature and the temperature of the migration tube are 180℃ and 60℃ respectively, the sampling frequency is 16 scans per second, and the analysis time for each sample is set to 80s.

[0015] 4) Result analysis

[0016] The pesticide residue concentration in the glass slide detected by ion mobility spectrometry is substituted into the formula model, and the pesticide residue concentration in the vegetables can be obtained.

[0017] The glass slide as a third-party medium combined with ion mobility spectrometry for rapid detection of pesticide residues in vegetables, characterized in that in step 4), the formula model is composed of the vertical projection area and weight of the vegetables and the glass slide, and the pesticide characteristic factor, and the formula is as follows:

[0018] Wherein, C0 is the concentration of pesticide residues in the slide, X0 is the pesticide loading amount per unit area of the slide, S0 is the pesticide loading area of the slide, M0 is the weight of the slide, Cv is the concentration of pesticide residues in the vegetables, Sv is the pesticide loading area of the vegetables, Mv is the weight of the vegetables, and "r" is the pesticide correction coefficient.

[0019] Compared with the prior art, the present application provides a method for rapidly detecting pesticide residues in vegetables, which has the following beneficial effects:

[0020] 1. The present application provides a new idea for pesticide residue detection by using a slide as a third-party medium to calculate the pesticide residue concentration in vegetables according to the pesticide residue concentration of the slide, and realizes the monitoring of safe production of vegetables by the method.

[0021] 2. The sample pretreatment time of the detection method is short, and the traditional multiple extraction, nitrogen blowing, impurity removal, and redissolution complex procedures using organic reagents are abandoned, and the original sample pretreatment process of about 1.5 hours is reduced to about 20 minutes. At the same time, the matrix effect of the vegetables is avoided, and the interference of impurities in the detection process is reduced. The detection method has low cost, simple and rapid operation, and is suitable for on-site rapid detection of vegetable samples. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0024] A method for rapidly detecting pesticide residues in vegetables by using a slide as a third-party medium combined with ion mobility spectrometry, all materials, instruments and methods are as follows:

[0025] 1. Materials and methods

[0026] 1.1. Materials and reagents

[0027] 10 different formulations of pesticide preparations (4 suspensions: fl uoxastrobin, chlorantraniliprole, propoxur, cymoxanil; 3 water dispersible granules: clothianidin, thiacloprid, hydroprene; 1 wettable powder: thiophanate-methyl; 1 emulsion: bifenthrin; 1 dispersible oil suspension: fl uoxypyr) from corresponding pesticide production companies, single-sided frosted glass slides, HPLC grade acetonitrile purchased from Merck Company in Germany.

[0028] 1.2. Instruments and equipment

[0029] XW-80A vortex mixer, Xinhaimen Bell Instruments Co., Ltd.

[0030] 1.3. Methods

[0031] 1.3.1. Field application

[0032] The single-sided ground glass slides were prepared, placed in a beaker, and then added with sufficient deionized water and placed in an ultrasonic cleaner. Under the action of ultrasonic mechanical oscillation, the dust and other dirt adsorbed on the surface of the glass slide were stripped. Finally, the glass slide was dried and ready for use. We selected 10 pesticides, each prepared into a pesticide formulation at the recommended concentration and double the concentration, and sprayed on three kinds of vegetables. Each treatment was tested 3-5 times in parallel and once in control. To ensure that the pesticide solution is uniformly sprayed on the surface of the vegetables, the person spraying the pesticide should ensure that the spray nozzle moves at a uniform speed and the spray pot pressure remains stable. When applying pesticides, fruits of similar size were marked to ensure that fruits not treated or of different sizes were not collected during harvesting. The weight and surface area of the vegetable fruits were recorded. The glass slides were placed horizontally on a self-made support and evenly placed in the field to ensure that the glass slides and the fruits of the vegetables were under the same pesticide application conditions. After 2 hours of pesticide spraying, cucumber and tomato fruit samples of about 3 kg and sufficient glass slide samples were randomly collected for analysis.

[0033] 1.3.2. Pretreatment of glass slide samples

[0034] Pretreatment of glass slide samples: The glass slide samples were placed in a 50 mL centrifuge tube, 10 mL of ultrapure water was added, shaken well for 5 min, then the eluent was passed through a 0.22 μm organic filter membrane, and finally the extract was directly analyzed by ion mobility spectrometry. The test was set up three times in parallel and once in control.

[0035] 1.3.3. Detection by ion mobility spectrometry

[0036] Instruments and equipment: Xiangwei TR1000 ion mobility spectrometer

[0037] Instrument principle and conditions:

[0038] Ion mobility spectrometry is a method in which the molecules of the substance to be measured are vaporized by heating at the inlet, and then ionized into ion groups of different charges and sizes by an ionization source. The ion groups reach the detector at different speeds under the action of an electric field, thereby forming an ion characteristic spectrum with different migration times. Dry air is used as the drift gas, which enters the end of the migration field at a flow rate of 1000 mL / min. The electric field strength of the migration field is 300 V / cm, the length of the migration tube is 15 cm, the inlet temperature and the temperature of the migration tube are 180°C and 60°C respectively, the sampling frequency is 16 scans per second, the analyte to be analyzed is injected into the sample box and pushed into the heating zone, and the analysis time of each sample is set to 80 s.

[0039] 2. Determination and analysis of results

[0040] The method established by the present application was used to detect 10 pesticides in a glass slide. The results showed that the above-mentioned 10 pesticides could be detected in the glass slide. The pesticide residue concentration detected by ion mobility spectrometry was substituted into the formula to calculate the residual concentration in the vegetables, and the calculated residual concentration in the vegetables was lower than the maximum residue limit required in the national standard. In addition, the calculated residual concentration in the vegetables was in good agreement with the actual measured residual concentration in the vegetables. The instrument method conditions and measurement results of the 10 pesticides are shown in Table 1. The results show the accuracy and stability of the method.

[0041] Table 1. Instrument conditions and measurement results of 10 pesticides

[0042]

[0043]

[0044]

[0045] The concentration unit in the table is mg / kg.

[0046] 3. Conclusion

[0047] The new method of the application uses a glass slide as a third-party medium to rapidly detect pesticide residues in vegetables by ion mobility spectrometry. This method avoids the interference of matrix effects during the pretreatment process of vegetable samples, greatly shortens the pretreatment time, and saves complex operation steps and a large amount of organic solvent consumption. As a low-cost, simple, rapid, mobile, and widely applicable method for rapid detection of pesticide residues and safety evaluation of vegetables, the present application can be widely promoted in some small and medium-sized vegetable production enterprises.

Claims

1. A method for rapid detection of pesticide residues in vegetables by ion mobility spectrometry using a glass slide as a third-party medium, characterized by, 1) The glass slide is placed in the field environment and sprayed with pesticides at the same time as the vegetables: The device includes a simple support and a single-sided frosted glass slide. The glass slide is used as a third-party medium, placed horizontally on the support and in the field at a certain height, and sprayed with pesticides at the same time as the vegetables in the field. After the pesticide is applied, an initial residue distribution will form on the surface of the vegetables and the glass slide. The glass slide sample is collected after the pesticide on the glass slide has completely dried 2 hours after application; The glass slide is placed horizontally on the self-made support and evenly placed in the field to ensure that the glass slide and the fruit of the vegetable are under the same pesticide application conditions; 2) Pretreatment of glass slide samples Glass slide sample pretreatment: Take the glass slide sample and put it into a 50mL centrifuge tube, add 10mL ultrapure water and shake for 5min, then pass the eluent through a 0.22μm organic filter membrane, and finally use ion mobility spectrometry to analyze the extract. The test is set up three times in parallel and once as a control; 3) Sample detection Instrument: Tongfang Weishi TR1000 ion mobility spectrometer Instrument principle and conditions: Ion mobility spectrometry is a method in which the molecules of the substance to be tested are heated and vaporized at the inlet, then ionized by the ionization source in the migration tube to form ion groups of different charges and sizes. They reach the detector at different speeds under the action of the electric field, forming ion characteristic spectra of different migration times; Dry air is used as the drift gas, entering the end of the migration field at a flow rate of 1000mL / min; The electric field strength of the migration field is 300V / cm, the length of the migration tube is 15cm, the inlet temperature and the temperature of the migration tube are 180°C and 60°C respectively, the sampling frequency is 16 scans per second, and the analysis time for each sample is set to 80s; 4) Result analysis The pesticide residue concentration in the glass slide detected by ion mobility spectrometry is substituted into the formula model, and the pesticide residue concentration in the vegetable can be obtained.

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