Method for determining organophosphorus in vegetables by gas chromatography

Abstract

The invention discloses a method for determining organophosphorus in vegetables by gas chromatography, aiming at different vegetable types, vegetables with standard pesticide residues in different concentration ranges are detected, and detection values corresponding to standard values can be obtained, so that standard curves of pesticide residue-detection values and standard values in different pesticide residue intervals can be obtained; the average value of the difference between the detection value and the standard value of each concentration interval can be obtained at the same time, and the final pesticide residue can be obtained by adding the obtained detection value and the average value of the corresponding standard curve after the vegetables are cleaned and purified, so that the influence of different vegetable matrix effects in the chromatographic analysis process of each pesticide is greatly reduced, and the detection accuracy is improved. The problem that the detection accuracy is easily influenced by different matrixes in the existing measurement mode is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pesticide residue detection, and relates to a method for determining organophosphorus in vegetables by gas chromatography. Background Art

[0002] At present, organochlorine insecticides have been discontinued, and organophosphorus pesticides have become the main pesticide pollution sources of vegetables, with prominent organophosphorus pesticide pollution. This has raised the technical requirements for pesticide residue detection by inspection and testing institutions, especially through chromatographic analysis. There are more and more types of pesticides, and due to the influence of different vegetable matrix effects during the chromatographic analysis of each pesticide, the detection results are either too high or too low, which is a problem often encountered by testing technicians. Therefore, the research on methods to eliminate the interference of matrix, treatment methods, method conditions, etc. during the determination of pesticides by gas chromatography is of great significance for the determination of various pesticides. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for determining organophosphorus in vegetables by gas chromatography, which solves the problem that the existing determination method is easily affected by different matrices and the detection accuracy is affected.

[0004] The technical solution adopted by the present invention is as follows: A method for determining organophosphorus in vegetables by gas chromatography, comprising the following steps: Drawing a standard curve: For different vegetable types, detecting vegetables with different concentration ranges of standard pesticide residues, and drawing a standard curve of pesticide residue amount - detection value and standard value; Washing the sample to be tested and forming a sample solvent; Selecting at least one of a solid phase extraction column, the QuEChERS method, and liquid - liquid extraction for purification according to the type of the sample to be tested; Using gas chromatography to detect the pesticide residue amount and obtaining a detection value. For the corresponding vegetable type, obtaining the concentration range corresponding to the detection value from the standard curve. Within this concentration range, the sum of the average difference between the detection value and the standard value in the standard curve and the detection value is the final pesticide residue amount; Conducting a spike test on the sample to be tested.

[0005] Further, the gas chromatography is detected by tandem mass spectrometry and quantified by the external standard method.

[0006] Further, the gas chromatography tandem mass spectrometry detection uses an Agilent 7890B - 7000C triple quadrupole gas chromatography - mass spectrometry instrument, and a DB - 5 capillary gas chromatography column is used to achieve component separation.

[0007] Further, the solid phase extraction column is a C18 packing solid phase extraction column with a specification of 500mg / 6mL.

[0008] Furthermore, the organophosphorus in vegetables includes one or more of methamidophos, dichlorvos, acephate, omethoate, ethoprophos, cadusafos, phorate, dimethoate, terbufos, chlorpyrifos-methyl, phosphamidon, diazinon, parathion-methyl, fenthion, fenitrothion, malathion, fenthion, chlorpyrifos, parathion, isocarbophos, quinalphos, methidathion, fenamiphos, profenofos, triazophos, phosmet, phosalone, and coumaphos.

[0009] Furthermore, the concentration range interval of the standard curve is 0.03 - 0.06 mg / L.

[0010] Furthermore, the concentration range interval of the standard curve is 0.05 mg / L.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: In the method for determining organophosphorus in vegetables of the present invention, for different vegetable varieties, vegetables with different concentration ranges of pesticide residues in the standard are detected, and the detected values corresponding to the standard values can be obtained. Thus, the standard curves of pesticide residues - detected values and standard values in different pesticide residue intervals can be obtained, and the average value of the difference between the detected value and the standard value in each concentration interval can also be obtained. After the vegetables are washed and purified, the final pesticide residue can be obtained by adding the average value of the corresponding standard curve to the detected value, greatly reducing the influence of different vegetable matrix effects on each pesticide during chromatographic analysis, and solving the problem that the existing determination method is easily affected by different matrices and the detection accuracy is affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings, where: Figure 1 It is a schematic flow chart of a method for determining organophosphorus in vegetables by gas chromatography according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further elaborates on the present invention in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0014] Accordingly, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0015] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0016] As described in the background art, in the method for determining organophosphorus in vegetables of the present invention, for different types of vegetables, vegetables with different concentration ranges of pesticide residues in the standard are detected, and the corresponding detection values of the standard values can be obtained, so that the standard curves of pesticide residues - detection values and standard values in different pesticide residue intervals can be obtained, and the average value of the difference between the detection values and the standard values in each concentration interval can also be obtained at the same time. After the vegetables are washed and purified, the final pesticide residue can be obtained by adding the average value corresponding to the standard curve to the obtained detection value, which greatly reduces the influence of different vegetable matrix effects on each pesticide in the chromatographic analysis process and solves the problem that the existing determination method is easily affected by different matrices and the detection accuracy.

[0017] Based on this, the inventor created a method for determining organophosphorus in vegetables by gas chromatography in this application to solve the above technical problems.

[0018] The features and performance of the present invention will be further described in detail below with reference to the embodiments. Embodiment

[0019] Please refer to Figure 1 , a method for determining organophosphorus in vegetables by gas chromatography, comprising the following steps: S1. Plot the standard curve: For different types of vegetables, detect vegetables with different concentrations of pesticide residues in the standard, and plot the standard curve of pesticide residue - detection value and standard value. Here, that is to say, for each type of vegetable, plot the corresponding standard curve and input it into the system. The standard curve takes the concentration range of pesticide residues as the abscissa, and the detection value and standard value as the ordinate to plot a line graph.

[0020] S2. Wash the sample to be tested and form a sample solvent.

[0021] S3. Select at least one of solid phase extraction column, QuEChERS method, and liquid - liquid extraction for purification according to the type of the sample to be tested. Here, that is to say, one of the above three methods can be selected, or a combination of more than one method can be used. The present invention is not limited thereto.

[0022] S4. Use gas chromatography to detect the pesticide residue and obtain the detection value. For the corresponding vegetable type, obtain the concentration range corresponding to the detection value from the standard curve. Within this concentration range, the sum of the average difference between the detection value and the standard value in the standard curve and the detection value is the final pesticide residue. For example, the vegetables can be Chinese chives, cabbage, etc. For example, when the phosphorus content of the sample to be tested during detection is 0.07 mg / L, the corresponding concentration range in the standard curve is the 0.05 - 0.09 mg / L interval. In the standard curve within this interval, the broken line of the corresponding detection value is 0.05 - 0.09 mg / L, the broken line of the standard value is 0.06 - 0.10 mg / L, and the average difference is 0.01 mg / L. Then the final pesticide residue at this time is 0.06 mg / L.

[0023] S5. Conduct a spiking test on the sample to be tested.

[0024] In the method for determining organophosphorus in vegetables of the present invention, for different types of vegetables, detecting vegetables with different concentrations of pesticide residues in the standard can obtain the detection values corresponding to the standard values, so as to obtain the standard curves of pesticide residue - detection value and standard value in different pesticide residue intervals, and can also obtain the average value of the difference between the detection value and the standard value in each concentration interval at the same time. After the vegetables are washed and purified, the obtained detection value plus the average value of the corresponding standard curve can obtain the final pesticide residue, which greatly reduces the influence of different vegetable matrix effects of each pesticide during chromatographic analysis, and solves the problem that the existing determination methods are easily affected by different matrices and affect the detection accuracy. In addition, attention should be paid to the setting of detection conditions, as well as the maintenance and cleaning of detection instruments.

[0025] In another embodiment, gas chromatography is detected by tandem mass spectrometry and quantified by the external standard method. For example, appropriate amounts of the standard stock solution of organophosphorus pesticides are taken and mixed standard solutions of organophosphorus pesticides with concentrations of 0.001 mg / L, 0.005 mg / L, 0.010 mg / L, 0.020 mg / L, and 0.050 mg / L are prepared with acetone. Operate according to the requirements of the above steps, and draw a standard curve according to the requirements of the external standard method. Using this external standard method, the residues of organophosphorus pesticides in fish bodies are measured.

[0026] In another embodiment, the gas chromatography tandem mass spectrometry detection uses an Agilent 7890B-7000C triple quadrupole gas chromatography-mass spectrometry instrument, and a DB-5 capillary gas chromatography column is used to achieve component separation. The temperature programming of the gas chromatography column is as follows: maintain at 70 °C for 2 min, then increase the temperature to 150 °C at a rate of 25 °C / min, then increase the temperature to 200 °C at a rate of 3 °C / min, and then increase the temperature to 280 °C at a rate of 8 °C / min and maintain for 10 min; the carrier gas is helium, with a purity of ≥99.999%, the column flow rate is 3.5 mL / min, constant flow; the inlet temperature is 260 °C; the injection volume is 1 μL; the injection method is splitless injection, and the split valve is opened after 0.75 min.

[0027] In another embodiment, the solid-phase extraction column is a C18 packing solid-phase extraction column with a specification of 500 mg / 6 mL.

[0028] In another embodiment, the organophosphorus in vegetables includes one or more of methamidophos, dichlorvos, acephate, omethoate, ethoprophos, cadusafos, phorate, dimethoate, terbufos, chlorfenvinphos, phosphamidon, diazinon, methyl parathion, fenthion, fenitrothion, malathion, fenthion, chlorpyrifos, parathion, isocarbophos, quinalphos, methidathion, fenamiphos, profenofos, triazophos, phosmet, phosalone, and cyromazine.

[0029] In another embodiment, the concentration range interval of the standard curve is 0.03 - 0.06 mg / L. Further, the concentration range interval of the standard curve is 0.05 mg / L.

[0030] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made by those skilled in the art within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining organophosphorus in vegetables by gas chromatography, characterized in that, It includes the following steps: Drawing a standard curve: For different vegetable varieties, detecting vegetables with different concentrations of pesticide residues in the standard, and drawing a standard curve of pesticide residue - detection value and standard value; Washing the sample to be tested and forming a sample solvent; Selecting at least one of solid-phase extraction column, QuEChERS method and liquid-liquid extraction for purification according to the type of the sample to be tested; Detecting the pesticide residue by gas chromatography to obtain a detection value. For the corresponding vegetable variety, obtaining the concentration range corresponding to the detection value from the standard curve. Within this concentration range, the sum of the average difference between the detection value and the standard value in the standard curve and the detection value is the final pesticide residue; Conducting a spike test on the sample to be tested.

2. The method for determining organophosphorus in vegetables by gas chromatography according to claim 1, wherein The gas chromatography is detected by tandem mass spectrometry and quantified by the external standard method.

3. A method for determining organophosphorus in vegetables by gas chromatography according to claim 1, characterized in that, The gas chromatography tandem mass spectrometry detection uses an Agilent 7890B-7000C triple quadrupole gas chromatography mass spectrometer, and a DB-5 capillary gas chromatography column is used to achieve component separation.

4. A method for determining organophosphorus in vegetables by gas chromatography according to claim 1, characterized in that, The solid-phase extraction column is a C18 packing solid-phase extraction column with a specification of 500mg / 6mL.

5. The method for determining organophosphorus in vegetables by gas chromatography according to claim 1, characterized in that, The organophosphorus in vegetables includes one or more of methamidophos, dichlorvos, acephate, omethoate, ethoprophos, cadusafos, phorate, dimethoate, terbufos, chlorfenvinphos, phosphamidon, diazinon, methyl parathion, fenthion, fenitrothion, malathion, fenthion, chlorpyrifos, parathion, isocarbophos, quinalphos, methidathion, fenamiphos, profenofos, triazophos, phosmet, phosalone and coumaphos.

6. A method for determining organophosphorus in vegetables by gas chromatography according to any one of claims 1-5, characterized in that, The concentration range interval of the standard curve is 0.03 - 0.06mg / L.

7. A method for determining organophosphorus in vegetables by gas chromatography according to claim 6, characterized in that, The concentration range interval of the standard curve is 0.05mg / L.

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