Detection Method for Dithiocarbamate Pesticides

Abstract

The detection method of dithiocarbamate pesticides provided by the present disclosure includes: mixing a lanthanide metal coordination polymer with a solvent to obtain a dispersion containing the lanthanide metal coordination polymer; mixing the dispersion, the dithiocarbamate pesticides or the detection object containing the dithiocarbamate pesticides with the solvent evenly to obtain a homogeneous system; performing fluorescence excitation on the homogeneous system, and realizing the detection of the dithiocarbamate pesticides by measuring the fluorescence spectrum for the specific response of the dithiocarbamate pesticides and combining the principal component analysis method. The present disclosure uses the lanthanide metal coordination polymer as a fluorescence sensor, and utilizes the fluorescence inner filter effect existing between it and the dithiocarbamate pesticides to cause fluorescence quenching of the fluorescence sensor, thereby establishing a rapid detection method for the dithiocarbamate pesticides. The detection time only needs 5 minutes, and the detection process is simple and environmentally friendly.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of pesticide detection, and particularly relate to a method for detecting dithiocarbamate pesticides. Background Art

[0002] Dithiocarbamate pesticides (DTCs) are insoluble in most solvents. The most commonly used method for detecting DTCs at present is the dithiocarbamate acid hydrolysis method proposed by Keppel in 1969. Its principle is based on the hydrolysis of dithiocarbamate in an acidic aqueous solution of SnCl 2 to generate CS 2 , and then combined with instruments such as a spectrophotometer or gas chromatography for detection. However, this method can only measure the total residue of DTCs, and cannot measure a specific DTC. Moreover, the detection process is time-consuming and laborious, requires the use of other solvents, and causes certain pollution to the environment.

[0003] On the other hand, there are currently related methods for detecting dithiocarbamate pesticides based on the catalytic effect of tyrosinase on catechol dyes. However, such methods have a long detection time (generally about 30 minutes), and the stability of the enzyme catalyst is poor, affecting the detection effect. Summary of the Invention

[0004] The present disclosure aims to solve at least one of the technical problems in the related art to some extent.

[0005] For this purpose, the embodiments of the present disclosure provide a simple, rapid and environmentally friendly method for detecting dithiocarbamate pesticides, including:

[0006] Mixing a lanthanide metal coordination polymer with a solvent to obtain a dispersion containing the lanthanide metal coordination polymer;

[0007] Mixing the dispersion, a dithiocarbamate pesticide or a test substance containing a dithiocarbamate pesticide with the solvent uniformly to obtain a homogeneous system; performing fluorescence excitation on the homogeneous system, and detecting dithiocarbamate pesticides by measuring the specific response of the fluorescence spectrum to different dithiocarbamate pesticides.

[0008] In some embodiments, the lanthanide metal coordination polymer is synthesized by self-assembly between a lanthanide metal and a nucleotide and prepared by a stirring method.

[0009] Further, the nucleotide is adenosine triphosphate, adenosine monophosphate or guanosine monophosphate.

[0010] In some embodiments, the solvent is water.

[0011] In some embodiments, the dispersion contains a lanthanide metal coordination polymer for detecting the concentration of the dithiocarbamate pesticides.

[0012] Further, the dithiocarbamate pesticides are thiram, zinc dimethyldithiocarbamate, ferbam or sodium dimethyldithiocarbamate.

[0013] In some embodiments, the dispersion contains a plurality of lanthanide metal coordination polymers to form a fluorescence array. By measuring the specific response of the fluorescence array to different dithiocarbamate pesticides and combining with the principal component analysis method, the types and concentrations of different dithiocarbamate pesticides are detected.

[0014] Further, the dithiocarbamate pesticides are a mixture of multiple ones among thiram, zinc dimethyldithiocarbamate, ferbam and sodium dimethyldithiocarbamate.

[0015] In some embodiments, the mass ratio of the lanthanide metal coordination polymer in the homogeneous system to the lanthanide metal coordination polymer in the dispersion is 0.1 - 5:100.

[0016] In some embodiments, the reaction time of the dispersion with the dithiocarbamate pesticides or the analyte is 5 min.

[0017] The principle of the detection method provided by the embodiments of the present disclosure is as follows: The ultraviolet absorption spectrum of the dithiocarbamate pesticides overlaps with the fluorescence excitation spectrum of the material, and the fluorescence of the material is quenched through the fluorescence inner filter effect.

[0018] The beneficial effect of the detection method provided by the embodiments of the present disclosure is as follows: In the embodiments of the present disclosure, through simple stirring and based on the self-assembly effect, a lanthanide metal coordination polymer is synthesized, and the fluorescence detection of the lanthanide metal coordination polymer pesticide is realized through the direct interaction between the dithiocarbamate pesticide molecule and the lanthanide metal coordination polymer. Description of the Drawings

[0019] Figure 1 In [the figure], A and B are respectively the XPS spectrum and SEM image of ATP-Tb prepared in the detection method of the embodiments of the present disclosure.

[0020] Figure 2 In [the figure], A and B are respectively the XPS spectrum and SEM image of AMP-Tb prepared in the detection method of the embodiments of the present disclosure.

[0021] Figure 3 In [the figure], A and B are respectively the XPS spectrum and SEM image of GMP-Tb prepared in the detection method of the embodiments of the present disclosure.

[0022] Figure 4The fluorescence spectrum of ATP-Tb in the detection method of the embodiments of the present disclosure in the presence of thiram at different concentrations.

[0023] Figure 5 The relationship diagram of the fluorescence intensity F and the logarithm of the thiram concentration log[Thiram] in the detection method of the embodiments of the present disclosure.

[0024] Figure 6 In A, the ultraviolet-visible absorption spectra of four kinds of pesticides containing dithiocarbamate pesticides and paraquat obtained by the detection method of the embodiments of the present disclosure. Figure 6 In B, the fluorescence excitation spectra of ATP-Tb, AMP-Tb, and GMP-Tb obtained by the detection method of the embodiments of the present disclosure.

[0025] Figure 7 The PCA score plot for identifying five pesticides by using the detection method of the embodiments of the present disclosure. Detailed implementation manners

[0026] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application.

[0027] On the contrary, the present application covers any alternatives, modifications, equivalent methods and solutions made within the spirit and scope of the present application as defined by the claims. Further, in order to enable the public to have a better understanding of the present application, some specific details are described in detail in the following detailed description of the present application. Those skilled in the art can fully understand the present application without the description of these details.

[0028] The detection method of dithiocarbamate pesticides provided by the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings, specifically including the following steps:

[0029] (1) Preparation of lanthanide metal coordination polymers:

[0030] (1-1) Respectively prepare adenosine triphosphate (ATP) solution, adenosine monophosphate (AMP) solution, and guanosine monophosphate (GMP) solution with a molar concentration of 3 mmol / L using ultrapure water, and prepare terbium chloride hexahydrate solution with a molar concentration of 8 mmol / L using 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution (concentration: 0.1 mol / L, pH = 7.4).

[0031] (1-2) Pipette 4 mL of ATP solution into a 20 mL brown storage bottle, then add 4 mL of terbium chloride hexahydrate solution, and stir vigorously in the dark at room temperature for 3 h. After stirring, centrifuge the reaction solution at 10000 rpm. After 10 min, remove the supernatant, add 5 mL of ultrapure water to wash the precipitate thoroughly, repeat three times, and then freeze-dry to obtain ATP-Tb. Add 4 mL of ultrapure water to ATP-Tb, vortex and ultrasonicate to disperse it evenly, and obtain a dispersion containing ATP-Tb for later use.

[0032] (1-3) Prepare dispersions containing AMP-Tb and GMP-Tb for later use according to the operation in step (1-2).

[0033] Characterization of the structure and properties of ATP-Tb: Use a scanning electron microscope and an X-ray photoelectron spectrometer to characterize the structural morphology and elemental composition of solid ATP-Tb. The XPS spectra and SEM images of ATP-Tb are shown in Figure 1 A and B in Figure 1 As can be seen from 3 / 2 (1277.1 eV), Tb3d 5 / 2 (1241.9 eV), O(1s)(531.2 eV) and P(2p)(133.4 eV).

[0034] Characterization of the structure and properties of AMP-Tb: Use a scanning electron microscope and an X-ray photoelectron spectrometer to characterize the structural morphology and elemental composition of solid AMP-Tb. The XPS spectra and SEM images of AMP-Tb are shown in Figure 2 A and B in Figure 2 As can be seen from 3 / 2 (1277.1 eV), Tb 3d 5 / 2 (1241.8 eV), O(1s)(531.8 eV) and P(2p)(133.1 eV).

[0035] Characterization of the structure and properties of GMP-Tb: Use a scanning electron microscope and an X-ray photoelectron spectrometer to characterize the structural morphology and elemental composition of solid GMP-Tb. The XPS spectra and SEM images of GMP-Tb are shown in Figure 3 A and B in Figure 3 As can be seen from 3 / 2 (1277.1 eV), Tb 3d 5 / 2(1242.0 eV), O(1s) (531.2 eV) and P(2p) (133.4 eV).

[0036] (2) Fluorescence detection of thiram: Fluorescence detection of thiram was carried out using the dispersion containing ATP-Tb, the dispersion containing AMP-Tb, and the dispersion containing GMP-Tb respectively. Taking the ATP-Tb as an example for illustration, the detection steps for AMP-Tb and GMP-Tb are the same as those for ATP-Tb. The specific steps for fluorescence detection of thiram using the dispersion containing ATP-Tb are as follows:

[0037] Prepare a 2 mmol / L thiram stock solution and gradually dilute it into thiram solutions with different concentrations. According to the relative fluorescence intensity change rate F R =(F 0 -F) / F 0 to optimize the detection conditions (F 0 is the fluorescence intensity of the system without the lanthanide metal coordination polymer, and F is the fluorescence intensity of the system with the lanthanide metal coordination polymer), including the dosage of ATP-Tb (0.1% - 5%, the concentration of the dispersion containing the lanthanide metal coordination polymer prepared in step (1) is counted as 100%, if the dispersion is diluted by half, the concentration becomes 50%, and so on), the reaction time of thiram with ATP-Tb (0 min - 20 min). Take the detection conditions corresponding to the maximum relative fluorescence intensity change rate F R as the optimal detection conditions (in this example, the optimal detection conditions are that the dosage of ATP-Tb is 0.1% and the reaction time of thiram with ATP-Tb is 5 min);

[0038] Under the optimal detection conditions, add 25 μL of thiram solution and 5 μL of ATP-Tb dispersion into a 2 mL centrifuge tube and mix them, then add 490 μL of ultrapure water to obtain a homogeneous system with a final volume of 500 μL. Keep the rotation speed at 600 rpm at room temperature and shake the centrifuge tube for 15 min. Record the fluorescence spectrum under 290 nm excitation (for the dispersion containing AMP-Tb, record the fluorescence spectrum under 300 nm excitation; for the dispersion containing GMP-Tb, record the fluorescence spectrum under 270 nm excitation), see Figure 4 Figure A, which is the fluorescence spectrum of ATP-Tb in the presence of different concentrations of thiram (the molar concentration range of thiram is 0 μmol / L - 150 μmol / L). Subsequently, obtain the standard curve of the fluorescence intensity F versus the logarithm of the thiram concentration log[Thiram] by linear fitting, see Figure 4 Figure B. The equation of this standard curve is: F = -8270.961log[Thiram] + 18826.766, and the linearity of the curve R 2= 0.9954, which is greater than 0.99, indicating high detection sensitivity and good response. Substituting the fluorescence intensity used in the detection into the obtained standard curve, the concentration of thiram can be deduced.

[0039] (3) Detection of five dithiocarbamate pesticides: Select four DTCs (thiram, ziram, ferbam, and sodium dimethyldithiocarbamate) and one non-DTC pesticide paraquat. Prepare sodium dimethyldithiocarbamate and paraquat solutions (2 mmol / L) with ultrapure water as the solvent; prepare thiram, ziram, and ferbam solutions (2 mmol / L) with acetonitrile as the solvent. Detection process: In a 2 mL plastic centrifuge tube, successively add 25 μL of the dispersion containing lanthanide metal coordination polymer prepared in step (1) (usage 5%) and 25 μL of a DTCs pesticide solution, then add 450 μL of ultrapure water to obtain a homogeneous system with a final volume of 500 μL. Keep the rotation speed at 600 rpm at room temperature, shake the centrifuge tube for 5 min, measure and record the fluorescence spectrum, and plot the curve of the absorption spectrum of the five pesticides changing with the excitation spectrum (see Figure 6 A in Figure 6 , and plot the curve of the fluorescence spectrum of the three lanthanide metal coordination polymers changing with the excitation spectrum (see Figure 6 B in R . It can be seen that there is varying degrees of overlap between the absorption spectra of the five pesticides and the excitation spectra of the three lanthanide metal coordination polymers. Therefore, their fluorescence can be quenched through the fluorescence inner filter effect. Subsequently, the relative fluorescence intensity change rate F Figure 7 is processed using the PCA method for data dimensionality reduction and extraction of the main characteristic components to obtain the PCA score plot. See

[0040] . In the figure, the five pesticides are clearly distributed in different regions, achieving the intuitive identification of the five pesticides. 3+ In summary, the embodiments of the present disclosure are based on the self-assembly between lanthanide metal ions (such as Tb 3+ etc.) and nucleotides (such as ATP, AMP, or GMP etc.), and lanthanide metal nucleotide coordination polymers (such as ATP-Tb, AMP-Tb, or GMP-Tb) are synthesized by a simple one-step stirring method. Due to the fluorescence inner filter effect (IFE) between dithiocarbamate pesticides (such as thiram, ziram, ferbam, or sodium dimethyldithiocarbamate etc.) and lanthanide metal nucleotide coordination polymers, their fluorescence can be quenched. Based on this principle, a rapid fluorescence detection method for dithiocarbamate pesticides is established, and the detection time is only 5 min. The detection limit (LOD) of this method is 0.093 In addition, the non-selectivity of IFE results in interference in detection by substances with similar absorption properties. Three fluorescent coordination polymers, ATP-Tb, GMP-Tb, and AMP-Tb, are selected to form a fluorescent array. Four dithiocarbamate pesticides (DTCs) and one non-DTC pesticide, paraquat, are chosen as experimental objects. By measuring the specific responses of the fluorescent array to different pesticides and combining with the principal component analysis method (PCA), the identification of five pesticides is achieved.

[0041] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms must be directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0042] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A detection method for dithiocarbamate pesticides, characterized in that, it includes: Mixing a lanthanide metal coordination polymer with a solvent to obtain a dispersion containing the lanthanide metal coordination polymer; Mixing the dispersion, a dithiocarbamate pesticide or a detection object containing a dithiocarbamate pesticide with the solvent uniformly to obtain a homogeneous system; performing fluorescence excitation on the homogeneous system, and detecting the specific response of the dithiocarbamate pesticide by measuring the fluorescence spectrum, so as to realize the detection of the dithiocarbamate pesticide, wherein the ultraviolet absorption spectrum of the dithiocarbamate pesticide overlaps with the fluorescence excitation spectrum of the lanthanide metal coordination polymer, and the fluorescence of the lanthanide metal coordination polymer is quenched through the fluorescence inner filter effect; The lanthanide metal coordination polymer is prepared by self-assembly between a lanthanide metal and a nucleotide and synthesized by a stirring method. The nucleotide is adenosine triphosphate, adenosine monophosphate or guanosine monophosphate. The preparation steps of the lanthanide metal coordination polymer include: Preparing a nucleotide solution with a molar concentration of 3 mmol / L and a terbium chloride hexahydrate solution with a molar concentration of 8 mmol / L; Mixing 4 mL of the nucleotide solution with 4 mL of the terbium chloride hexahydrate solution, stirring in the dark at room temperature for 3 h, then centrifuging the reaction solution, washing the precipitate after removing the supernatant to obtain the lanthanide metal coordination polymer.

2. The detection method according to claim 1, characterized in that, the solvent used is water.

3. The detection method according to claim 1, characterized in that, the dispersion contains a kind of lanthanide metal coordination polymer for realizing the concentration detection of the dithiocarbamate pesticide.

4. The detection method according to claim 3, characterized in that, the dithiocarbamate pesticide is thiram, zinc dimethyldithiocarbamate, ferbam or sodium dimethyldithiocarbamate.

5. The detection method according to claim 1, characterized in that, the dispersion contains a variety of lanthanide metal coordination polymers to form a fluorescence array. By measuring the specific response of the fluorescence array to different dithiocarbamate pesticides and combining the principal component analysis method, the types and concentrations of different dithiocarbamate pesticides are detected.

6. The detection method according to claim 5, characterized in that, the dithiocarbamate pesticide is a mixture of multiple ones among thiram, zinc dimethyldithiocarbamate, ferbam and sodium dimethyldithiocarbamate.

7. The detection method according to claim 1, characterized in that, the reaction time between the dispersion and the dithiocarbamate pesticide or the detection object is 5 min.

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