CN109813689B - Method for detecting carbamate pesticide based on CdTe quantum dot paper chip substrate - Google Patents
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Abstract
The invention relates to the field of paper chip sensing, in particular to a method for detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate. The invention discloses a method for detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate, which comprises the following steps: (1) synthesizing CdTe quantum dots; (2) synthesizing a tetra- (4-pyridyl) zinc porphyrin self-assembly solution; (3) preparing a CdTe quantum dot paper chip substrate; (4) manufacturing a standard color comparison card of the carbamate pesticide; (5) detecting the concentration of the carbamate pesticide in a sample to be detected; compared with the existing carbamate pesticide detection method, the method has the characteristics of simple preparation, quick field detection, low cost, high response speed, high sensitivity and high selectivity, and the CdTe quantum dot paper chip substrate has a specific reaction on the carbamate pesticide and can be used for detecting the carbamate pesticide in a complex matrix water sample.
Description
Technical Field
The invention relates to the field of paper chip sensing, in particular to a method for detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate.
Background
China is a big agricultural country and is also the country producing and using most pesticides. The pesticide plays an important role in preventing and controlling diseases, insects, grass and other harmful organisms in agriculture and forestry, but simultaneously the pesticide can remain in crops and environment to cause pollution to food and environment. The European food safety agency stipulates that the maximum residual quantity of pesticides in food is 10 mug/L. The food which is mistakenly eaten with the pesticide residue is easy to cause symptoms such as acute poisoning, so that the research on the analysis method of the pesticide residue in the food is strengthened, and the method has very important significance.
The water-soluble quantum dots serving as excellent fluorescent nano materials have the advantages of high stability, long fluorescence life, good biocompatibility and the like. The fluorescent probe is used as a high-efficiency fluorescent probe for environmental monitoring, medical diagnosis, clinical medicine and the like by utilizing the fluorescent characteristic of the fluorescent probe. The nano porphyrin has good color sensitivity and photosensitivity, and is an ideal model compound for researching a sensor sensitive element. Porphyrin compounds and nano porphyrin are excellent quantum dot fluorescence quenchers, and the combination of porphyrin and quantum dots is widely applied to food and drug analysis. The traditional pesticide residue detection method comprises liquid chromatography, gas chromatography and mass spectrometry, an enzyme inhibition method and the like, which all involve complex and precise instruments, complicated operation flows and the like, so that the application of the method is limited to a certain extent, and the method is not enough to meet the requirement of rapid field detection of pesticide residue, therefore, a simple, economic and rapid pesticide residue detection method which can carry out instrument-free field detection is needed to be established.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a method for detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate, which not only can detect the carbamate pesticides quickly and highly sensitively, but also can realize instrument-free on-site instant detection.
In order to achieve the purpose, the method for detecting the carbamate pesticide based on the CdTe quantum dot paper chip substrate comprises the following steps:
(1) synthesis of CdTe quantum dot
Dissolving cadmium dichloride and N-acetyl-L-cysteine in pure water, uniformly mixing, then sequentially adding sodium tellurite and sodium borohydride, and finally reacting in an oven to obtain fluorescent CdTe quantum dots;
(2) synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
Dissolving tetra- (4-pyridyl) zinc porphyrin in a tetrahydrofuran solution to obtain a tetra- (4-pyridyl) zinc porphyrin tetrahydrofuran solution, adding the tetra- (4-pyridyl) zinc porphyrin tetrahydrofuran solution into a hexadecyl trimethyl ammonium bromide aqueous solution, uniformly stirring, clarifying the solution from turbidity, and stopping reaction to obtain a tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
(3) preparation of CdTe quantum dot paper chip substrate
Dropwise adding the CdTe quantum dots on a paper base material, and obtaining a CdTe quantum dot paper chip substrate after the paper base material absorbs and fixes the CdTe quantum dots;
(4) making standard colour comparison card for carbamate pesticide
Preparing a mixed solution of carbamate pesticides with different concentrations and a tetra- (4-pyridyl) zinc porphyrin self-assembly solution, sequentially dropwise adding the mixed solution on a CdTe quantum dot paper chip substrate, observing in an ultraviolet dark box, reacting the carbamate pesticides with different concentrations with the CdTe quantum dot paper chip substrate to generate different colors, photographing each CdTe quantum dot paper chip substrate, and finishing to obtain a standard carbamate pesticide colorimetric card;
(5) detecting the concentration of carbamate pesticide in a sample to be detected
And (3) preparing a sample and the tetra- (4-pyridyl) zinc porphyrin self-assembly solution into a mixed solution, dropwise adding the mixed solution on a paper chip substrate, wherein the paper chip substrate has color response to the sample, and contrasting the standard color comparison card of the carbamate pesticide obtained in the step (4) to obtain the concentration of the carbamate pesticide in the sample.
Preferably, in the step (1), the pH value of the mixed solution of cadmium dichloride and N-acetyl-L-cysteine is adjusted to 4.5-4.8, the temperature of an oven is controlled to be 180-220 ℃, and the CdTe quantum dots which emit green light and have the wavelength of 540-560 nm are obtained.
Preferably, the concentration of the tetra- (4-pyridyl) zinc porphyrin self-assembly solution in the step (4) and the step (5) is 17.5-18.0 mu M.
Preferably, the mixed solution in the step (4) is 0 μ g/L of carbamate pesticide and 17.85 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 1 μ g/L of carbamate pesticide and 17.85 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 5 μ g/L of carbamate pesticide and 17.85 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 10 μ g/L of carbamate pesticide and 17.85 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 15 μ g/L of carbamate pesticide and 17.85 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 20 μ g/L of carbamate pesticide and 17.85 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution.
Preferably, in the step (4), the pictures with different colors, which are generated by the reaction of the carbamate pesticides with different concentrations and the paper chip substrate, are introduced into the graphic processing software to extract the color values in the pictures, and the standard color comparison card of the carbamate pesticides is simulated by using the color values.
Preferably, in the step (1), the ratio of the amounts of the cadmium dichloride, the N-acetyl-L-cysteine and the sodium tellurite is as follows: 2.0: 3.8-4.2: 1.0.
Preferably, in the step (2), the amount ratio of the tetra- (4-pyridyl) zinc porphyrin to the hexadecyl trimethyl ammonium bromide is 1: 66.5-67.0.
Preferably, in the step (3), the concentration of the CdTe quantum dots is 20-30 μmol/L.
Preferably, in the step (3), the CdTe quantum dots are dripped in 8-10 uL in the step (2), the paper substrate is circular filter paper with the diameter of 4-6 mm, and the paper chip substrate dripped with the CdTe quantum dots is placed in an oven at 36-39 ℃ and dried for 5-7 minutes.
Preferably, the particle size of the nano porphyrin in the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is 70-90 nm.
The invention has the advantages that: compared with the existing carbamate pesticide detection method, the method for detecting the carbamate pesticide based on the CdTe quantum dot paper chip substrate has the characteristics of simple preparation, quick field detection, low cost, high response speed, high sensitivity and high selectivity, and the CdTe quantum dot paper chip substrate has a specific reaction on the carbamate pesticide and can be used for detecting the carbamate pesticide in a complex matrix water sample.
Drawings
FIG. 1 is a schematic diagram of the mechanism of detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate according to the invention;
FIG. 2 is a transmission electron microscope photograph of a tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
FIG. 3 is a transmission electron microscope image of the addition of a tetra- (4-pyridyl) zinc porphyrin self-assembly solution to a CdTe quantum dot paper chip substrate;
FIG. 4 is a feasibility test chart for detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate according to the invention; FIG. 4A is the color of a paper chip substrate with CdTe quantum dots immobilized; FIG. 4B is a color reaction diagram after addition of tetra- (4-pyridyl) zinc porphyrin to a paper chip substrate; FIG. 4C is a color reaction diagram after a mixed solution of a carbamate pesticide and tetra- (4-pyridyl) zinc porphyrin is added to the substrate of the paper chip;
FIG. 5 is a standard colorimetric card for preparing metolcarb, wherein FIGS. 5A to 5F correspond to colors generated by metolcarb of 0 μ G/L, 1 μ G/L, 5 μ G/L, 10 μ G/L, 15 μ G/L and 20 μ G/L in sequence, and FIG. 5G is a blank control (color of a substrate of a paper chip); FIGS. 5A-5G are standard color charts of the meta-tolyl-N-methylcarbamate obtained by extracting color values of FIGS. 5A-5G;
FIG. 6 is a standard colorimetric card for carbofuran prepared according to the present invention, FIGS. 6A-6F correspond to colors generated by carbofuran of 0 μ G/L, 1 μ G/L, 5 μ G/L, 10 μ G/L, 15 μ G/L, 20 μ G/L in sequence, and FIG. 6G is a blank control (color of the substrate of the paper chip);
FIG. 7 is a standard colorimetric card for carbaryl preparation, FIGS. 6A to 6F correspond to colors of carbaryl of 0. mu.g/L, 1. mu.g/L, 5. mu.g/L, 10. mu.g/L, 15. mu.g/L and 20. mu.g/L in sequence, and FIG. 6G is a blank control (color of a paper chip substrate);
FIG. 8 is a specificity chart of detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate according to the invention; FIGS. 8A to 8I are color reaction diagrams of blank, acetochlor, deltamethrin, cartap, trichlorfon, dichlorvos, systemic phosphorus, dimethoate, metolcarb and tetra- (4-pyridyl) zinc porphyrin which are mixed and then dripped on a paper chip substrate in sequence; FIGS. 8A-8I are color chart diagrams obtained by extracting color values of FIGS. 8A-8I in sequence;
FIG. 9 is a graph of detection of metolcarb in a complex matrix based on a CdTe quantum dot paper chip substrate, and FIG. 9A is a colorimetric cartograph of metolcarb in a human plasma matrix; FIG. 9B is a chart of metacarb in bovine serum matrix; FIG. 9C is a color chart of metolcarb in apple juice base; FIG. 9D is a chart of metacarb in Chinese cabbage juice base; FIG. 9E is a colorimetric cartograph of metolcarb in the Longjing tea matrix;
FIG. 10 is a diagram of accurate detection of carbofuran in a complex matrix based on a CdTe quantum dot paper chip substrate, and FIG. 10A is a color chart of carbofuran in a human plasma matrix; FIG. 10B is a chart of a color chart of carbofuran in bovine serum base; FIG. 10C is a chart of a color chart of carbofuran in apple juice base; FIG. 10D is a chart of a color chart of carbofuran in cabbage juice base; FIG. 10E is a chart of a color chart of carbofuran in Longjing tea matrix;
FIG. 11 is a diagram of accurate detection of carbaryl in a complex matrix based on a CdTe quantum dot paper chip substrate, and FIG. 11A is a colorimetric card diagram of carbaryl in a human plasma matrix; FIG. 10B is a color chart of carbaryl in bovine serum substrate; FIG. 11C is a chart of a color chart of carbaryl in apple juice matrix; FIG. 11D is a chart of a color chart of carbaryl in a cabbage juice base; figure 11E is a colorimetric cartograph of carbaryl in longjing tea matrix.
Detailed Description
For a better understanding of the present invention, reference will now be made in detail to the present invention, examples of which are illustrated in the accompanying drawings.
In order to solve the problems of complex operation and long analysis time of instruments in the prior art for detecting carbamate pesticides, the invention provides a method for detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate, and particularly relates to a method for preparing standard colorimetric cards of carbamate pesticides with different concentrations by utilizing the principle that the fluorescence color of CdTe quantum dots can be changed by using a mixed solution of the carbamate pesticides and a tetra- (4-pyridyl) zinc porphyrin self-assembly solution, and the concentration of the carbamate pesticides to be detected is judged by contrasting the color with the standard colorimetric cards. Preferred embodiments of the method for detecting carbamate-based pesticides using self-assembled porphyrins according to the present invention will be described in detail below with reference to specific examples.
Example 1
The method for detecting the metolcarb based on the CdTe quantum dot paper chip substrate comprises the following steps:
(1) synthesis of CdTe quantum dot
Dissolving cadmium dichloride (0.1096g) and N-acetyl-L-cysteine (0.1567g) in 40mL of ultrapure water, stirring at normal temperature and pressure for 15 minutes, adjusting the pH of the solution to 4.60 by using a sodium hydroxide solution, then filling nitrogen, stirring in an ice bath for 20 minutes, adding sodium tellurite (0.0532g, 2.5mM), and stirring for 15 minutes; adding sodium borohydride (0.0109g), stirring for 15 min, placing the solution into a reaction kettle, reacting for 50 min in an oven at 200 deg.C, cooling to room temperature to obtain green light with emission wavelength of 550nm and concentration of 2.51 × 10-5mol/L CdTe quantum dots.
(2) Synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
0.0037g of tetrakis- (4-pyridyl) zinc porphyrin solid powder was weighed and dissolved in 5mL of tetrahydrofuran solution to obtain a concentration of 1.14X 10-3And (3) a tetrahydrofuran solution of tetra- (4-pyridyl) zinc porphyrin in mol/L. Cetyl trimethyl bromide (0.0732g) is dissolved in 40mL of aqueous solution, 2.8mL of tetra- (4-pyridyl) zinc porphyrin tetrahydrofuran solution is added, stirring is carried out for 10 minutes at normal temperature and normal pressure, the solution becomes clear from turbidity, and the reaction stops. 7.5X 10-5As shown in figure 2, the transmission electron microscope representation of the mol/L tetra- (4-pyridyl) zinc porphyrin self-assembly solution shows that the solution is a nanorod with the particle size of 70-90 nm.
(3) Preparation of CdTe quantum dot paper chip substrate
Sucking 10 μ L of CdTe quantum dots (25.1 μ M) with a pipette, dripping onto 3 pieces of circular filter paper with diameter of 5mm to obtain 3 CdTe quantum dot paper chip substrates, oven drying the 3 CdTe quantum dot paper chip substrates at 37 deg.C for about 4 min, observing the paper chip substrates in a 365nm ultraviolet dark box to obtain green color, and taking pictures.
(4) Standard colorimetric card for making metolcarb
Preparing a solution I: 0 mug/L metolcarb and 17.85 muM tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution II: 1 mug/L metolcarb and 17.85 muM tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution three: 5 mug/L metolcarb and 17.85 muM tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution four: 10 ug/L metolcarb and 17.85 uM tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution five: 15 μ g/L of metolcarb and 17.85 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution six: 20 μ g/L metolcarb and 17.85 μ M tetrakis- (4-pyridyl) zinc porphyrin self-assembly solution;
and (3) sucking 10 mu L of the solutions by using a liquid-transferring gun, dripping the solutions from one to six on a CdTe quantum dot paper chip substrate respectively, observing different color changes in an ultraviolet dark box, taking a picture in a 365nm ultraviolet dark box, storing the picture, guiding the picture into Photoshop software, extracting color values RGB on the picture, and simulating color dots by using the values to obtain the standard colorimetric card of the metolcarb.
With reference to the metacarb standard colorimetric card shown in FIG. 5, FIGS. 5A to 5F correspond to colors produced by metacarb of 0. mu.g/L, 1. mu.g/L, 5. mu.g/L, 10. mu.g/L, 15. mu.g/L and 20. mu.g/L in this order, and FIG. 5G is a blank control (color of the substrate of the paper chip).
Referring to fig. 1 and 4, it can be seen from fig. 1 that the tetra- (4-pyridyl) zinc porphyrin can quench the fluorescence of the CdTe quantum dots, and the mixed solution of the carbamate pesticide and the tetra- (4-pyridyl) zinc porphyrin can change the fluorescence color of the CdTe quantum dots. FIG. 4A shows the color of the paper chip substrate with CdTe quantum dots fixed; as shown in fig. 4B, the fluorescence quenching of the CdTe quantum dots changed from green to dark green after the tetra- (4-pyridyl) zinc porphyrin was added to the paper chip substrate, and the paper chip substrate was observed with a transmission electron microscope as shown in fig. 3; as shown in figure 4C, the mixed solution of the carbamate pesticide and the tetra- (4-pyridyl) zinc porphyrin is added to the paper chip substrate, the color of the paper chip substrate is changed from green to light green, and the color of the paper chip substrate is changed along with the difference of the concentration of the carbamate pesticide in the mixed solution, as shown in figure 5, the concentration of the metolcarb in the mixed solution is increased from 0 mug/L to 20 mug/L, the color of the paper chip substrate is changed from dark green to yellow green, then changed to light green, and finally changed to green, so that the effect of visually detecting the metolcarb on paper is achieved.
(5) Detecting metolcarb concentration of a sample
Mixing the sample with 17.85 mu M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dropwise adding the mixture on a paper chip substrate, wherein the paper chip substrate has color response to the sample, and obtaining the concentration of the metolcarb in the sample by contrasting with a standard colorimetric card of metolcarb.
In order to verify that the method for detecting the metolcarb based on the CdTe quantum dot paper chip substrate can accurately detect the metolcarb in a complex matrix (human plasma, bovine serum, apple juice, Chinese cabbage juice and Longjing tea), and a complex matrix verification test is carried out. The specific process is that the human plasma matrix: preparing 0 mu g/L of metolcarb and 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin, 1 mu g/L of metolcarb and 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin, 5 mu g/L of metolcarb and 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin, 10 mu g/L of metolcarb and 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin, 15 mu g/L of metolcarb and 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin, 20 mu g/L of metolcarb and 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin in human plasma, respectively;
the preparation process of bovine serum, apple juice, Chinese cabbage juice, Longjing tea matrix and human plasma matrix is the same, and is not described herein again.
The results are shown in fig. 9, fig. 9A is a colorimetric cartogram of metolcarb in human plasma matrix; FIG. 9B is a chart of metacarb in apple juice base; FIG. 9C is a color chart of metolcarb in Chinese cabbage juice base; figure 9D is a colorimetric cartograph of metolcarb in longjing tea matrix. As can be seen from FIG. 9, the method for detecting the metolcarb based on the CdTe quantum dot paper chip substrate can accurately detect the metolcarb in a complex substrate, and is less interfered by the substrate.
In order to verify the specificity of the method for detecting the metolcarb by utilizing the CdTe quantum dot-based paper chip substrate, a specificity selection test of carbamate pesticides is carried out, the specific process is that 10 mu L of mixed solution of other pesticides (acetochlor, deltamethrin, cartap, trichlorfon, dichlorvos, systemic phosphorus and dimethoate) and tetra- (4-pyridyl) zinc porphyrin self-assembly solution (17.85 mu M) with the concentration of 5 mu g/L is absorbed by a liquid transfer gun on the paper chip substrate, the fluorescent recovery is not obvious, the mixed solution is still dark green, and 10 mul of the mixed solution of 5 mug/L of metolcarb and tetra- (4-pyridyl) zinc porphyrin self-assembly solution (17.85 muM) is added to the paper chip substrate, the paper chip is changed from dark green to yellow green, and the photoshop software is used for extracting the color value RGB on the picture, as shown in figure 8.
Example 2
The detection of carbofuran based on CdTe quantum dot paper chip substrate includes the following steps:
(1) preparation of paper chip substrate and tetra- (4-pyridyl) zinc porphyrin self-assembly solution
The preparation of the paper chip substrate and the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is the same as that of example 1.
(2) Standard colour comparison card for making carbofuran
Mixing metolcarb (1-20 mug/L) with different concentrations with a tetra- (4-pyridyl) zinc porphyrin self-assembly solution (17.85 mu M), sucking 10 mu L of the mixed solution by a liquid-transferring gun, dropwise adding the mixed solution on a paper chip substrate, observing different color changes in an ultraviolet dark box, and as shown in a graph 6, changing the color of the paper chip substrate from dark green to yellow green, then changing to light green, finally changing to green to achieve the purpose of visually detecting the metolcarb on the paper, photographing and storing the picture in a 365nm ultraviolet dark box, introducing the picture into Photoshop software to extract color values RGB on the picture, and simulating the color points by using the values to obtain a standard colorimetric card of the metolcarb;
with reference to the standard color comparison card of carbofuran shown in FIG. 6, FIGS. 6A-6F correspond to the colors generated by carbofuran of 0 μ G/L, 1 μ G/L, 5 μ G/L, 10 μ G/L, 15 μ G/L, and 20 μ G/L in sequence, and FIG. 6G is a blank control (color of the substrate of the paper chip).
(5) Detecting the carbofuran concentration of the sample
And mixing the sample with 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dropwise adding the mixture onto a paper chip substrate, wherein the paper chip substrate has color response to the sample, and contrasting with a carbofuran standard colorimetric card to obtain the concentration of the carbofuran concentration in the sample.
In order to verify that the method for detecting carbofuran based on the CdTe quantum dot paper chip substrate can accurately detect carbofuran in a complex matrix (human plasma, bovine serum, apple juice, Chinese cabbage juice and Longjing tea), a complex matrix verification test is carried out. The specific process is that the human plasma matrix: in human plasma, 0. mu.g/L carbofuran and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 1. mu.g/L carbofuran and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 5. mu.g/L carbofuran and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 10. mu.g/L carbofuran and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 15. mu.g/L carbofuran and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 20. mu.g/L carbofuran and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin were prepared, respectively.
The preparation process of bovine serum, apple juice, Chinese cabbage juice, Longjing tea matrix and human plasma matrix is the same, and is not described herein again.
The results are shown in fig. 10, fig. 10A is a color chart of carbofuran in human plasma matrix; FIG. 10B is a chart of a color chart of carbofuran in apple juice base; FIG. 10C is a chart of a color chart of carbofuran in cabbage juice base; fig. 10D is a chart of the color chart of carbofuran in the longjing tea matrix. As can be seen from FIG. 10, the detection of carbofuran based on the detection of the CdTe quantum dot paper chip substrate can accurately detect carbofuran in a complex substrate, and is slightly interfered by the substrate.
Example 3
A method for detecting carbaryl based on CdTe quantum dot paper chip substrate detection comprises the following steps:
(1) preparation of paper chip substrate and tetra- (4-pyridyl) zinc porphyrin self-assembly solution
The preparation of the paper chip substrate and the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is the same as that of example 1.
(2) Standard colorimetric card for manufacturing carbaryl
Mixing carbaryl (1-20 mu g/L) with different concentrations with a tetra- (4-pyridyl) zinc porphyrin self-assembly solution (17.85 mu M), sucking 10 mu L of the mixed solution by using a liquid-transferring gun, dropwise adding the mixed solution on a paper chip substrate, observing different color changes in an ultraviolet dark box, and as shown in a figure 7, leading the color of the paper chip substrate to be changed from dark green to yellow green along with the increase of the concentration of the carbaryl, then to be changed into light green, finally to be changed into green, achieving the visual detection of the carbaryl on the paper, photographing and storing the picture in a 365nm ultraviolet dark box, leading the picture into Photoshop software, extracting color values RGB on the picture, and simulating the color to obtain a standard colorimetric card of the carbaryl by using the values;
in combination with the standard colorimetric card for carbaryl shown in FIG. 7, FIGS. 7A to 7F correspond to colors generated by carbaryl of 0. mu.g/L, 1. mu.g/L, 5. mu.g/L, 10. mu.g/L, 15. mu.g/L and 20. mu.g/L in this order, and FIG. 7G is a blank control (color of the substrate of the paper chip).
(5) Detecting the carbofuran concentration of the sample
Mixing the sample with 17.85 mu M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dripping the mixture on a paper chip substrate, wherein the paper chip substrate has color response to the sample, and contrasting with a standard colorimetric card of carbaryl to obtain the concentration of the carbofuran in the sample.
In order to verify that the carbaryl can be accurately detected in a complex matrix (human plasma, bovine serum, apple juice, cabbage juice and Longjing tea) based on the detection of the CdTe quantum dot paper chip substrate, a complex matrix verification test is carried out. The specific process is that the human plasma matrix: in human plasma, 0. mu.g/L carbaryl and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 1. mu.g/L carbaryl and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 5. mu.g/L carbaryl and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 10. mu.g/L carbaryl and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 15. mu.g/L carbaryl and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin, 20. mu.g/L carbaryl and 17.85. mu.M tetra- (4-pyridyl) zinc porphyrin were prepared, respectively.
The preparation process of bovine serum, apple juice, Chinese cabbage juice, Longjing tea matrix and human plasma matrix is the same, and is not described herein again.
The results are shown in fig. 10, fig. 10A is a color chart of carbaryl in human plasma matrix; FIG. 10B is a chart of a color chart of carbaryl in apple juice matrix; FIG. 10C is a chart of the color chart of carbaryl in the cabbage juice base; figure 10D is a colorimetric cartograph of carbaryl in longjing tea matrix. As can be seen from FIG. 10, the method for detecting carbaryl based on the CdTe quantum dot paper chip substrate can accurately detect carbaryl in a complex substrate, and is little interfered by the substrate.
Examples 1 to 3 describe methods for detecting metolcarb, carbofuran, and carbaryl on the basis of CdTe quantum dot paper chip substrates, but the methods are not limited to the detection of metolcarb, carbofuran, and carbaryl.
The above examples only show 3 embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for detecting carbamate pesticides based on a CdTe quantum dot paper chip substrate is characterized by comprising the following steps:
(1) synthesis of CdTe quantum dot
Dissolving cadmium dichloride and N-acetyl-L-cysteine in pure water, uniformly mixing, then sequentially adding sodium tellurite and sodium borohydride, and finally reacting in an oven to obtain fluorescent CdTe quantum dots;
(2) synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
Dissolving tetra- (4-pyridyl) zinc porphyrin in a tetrahydrofuran solution to obtain a tetra- (4-pyridyl) zinc porphyrin tetrahydrofuran solution, adding the tetra- (4-pyridyl) zinc porphyrin tetrahydrofuran solution into a hexadecyl trimethyl ammonium bromide aqueous solution, uniformly stirring, clarifying the solution from turbidity, and stopping reaction to obtain a tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
(3) preparation of CdTe quantum dot paper chip substrate
Dropwise adding the CdTe quantum dots on a paper base material, and obtaining a CdTe quantum dot paper chip substrate after the paper base material absorbs and fixes the CdTe quantum dots;
(4) making standard colour comparison card for carbamate pesticide
Preparing a mixed solution of carbamate pesticides with different concentrations and a tetra- (4-pyridyl) zinc porphyrin self-assembly solution, sequentially dropwise adding the mixed solution on a CdTe quantum dot paper chip substrate, observing in an ultraviolet dark box, reacting the carbamate pesticides with different concentrations with the CdTe quantum dot paper chip substrate to generate different colors, photographing each CdTe quantum dot paper chip substrate, and finishing to obtain a standard carbamate pesticide colorimetric card;
(5) detecting the concentration of carbamate pesticide in a sample to be detected
And (3) preparing a sample and the tetra- (4-pyridyl) zinc porphyrin self-assembly solution into a mixed solution, dropwise adding the mixed solution on a paper chip substrate, wherein the paper chip substrate has color response to the sample, and contrasting the standard color comparison card of the carbamate pesticide obtained in the step (4) to obtain the concentration of the carbamate pesticide in the sample.
2. The method for detecting the carbamate pesticide based on the CdTe quantum dot paper chip substrate as claimed in claim 1, wherein the pH of the mixed solution of the cadmium dichloride and the N-acetyl-L-cysteine in the step (1) is adjusted to 4.5-4.8, the temperature of the oven is controlled to be 180-220 ℃, and the CdTe quantum dots which emit green light and have the emission wavelength of 540-560 nm are obtained.
3. The method for detecting carbamate pesticides based on CdTe quantum dot paper chip substrate as claimed in claim 1 or 2, wherein the concentration of the tetra- (4-pyridyl) zinc porphyrin self-assembly solution in the steps (4) and (5) is 17.5-18.0 μ M.
4. The method for detecting carbamate pesticides based on CdTe quantum dot paper chip substrate as claimed in claim 3, wherein the mixed solution in the step (4) is 0 μ g/L carbamate pesticide and 17.85 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 1 μ g/L carbamate pesticide and 17.85 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 5 μ g/L carbamate pesticide and 17.85 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 10 μ g/L carbamate pesticide and 17.85 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, 15 μ g/L carbamate pesticide and 17.85 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, respectively, 20 mu g/L of carbamate pesticide and 17.85 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution.
5. The method for detecting carbamate pesticides based on the CdTe quantum dot paper chip substrate as claimed in claim 1, wherein in the step (4), the carbamate pesticides with different concentrations react with the paper chip substrate to generate different colors of photos, the photos are imported into graphic processing software to extract color values in the pictures, and the standard color comparison card of the carbamate pesticides is simulated by the color values.
6. The method for detecting carbamate pesticides based on CdTe quantum dot paper chip substrate as claimed in claim 2, wherein in step (1), the ratio of the amounts of the cadmium dichloride, the N-acetyl-L-cysteine and the sodium tellurite is as follows: 2.0: 3.8-4.2: 1.0.
7. The method for detecting carbamate pesticides based on CdTe quantum dot paper chip substrate as claimed in claim 1, wherein in step (2), the quantitative ratio of tetra- (4-pyridyl) zinc porphyrin to cetyl trimethylammonium bromide is 1 (66.5-67.0).
8. The method for detecting the carbamate pesticide based on the CdTe quantum dot paper chip substrate as claimed in claim 1, wherein the concentration of the CdTe quantum dots in the step (3) is 20-30 μmol/L.
9. The method for detecting the carbamate pesticide based on the CdTe quantum dot paper chip substrate as claimed in claim 1, wherein in the step (3), the CdTe quantum dots are dripped in 8-10 uL in the step (2), the paper substrate is circular filter paper with the diameter of 4-6 mm, and the paper chip substrate dripped with the CdTe quantum dots is placed in an oven at 36-39 ℃ for 5-7 minutes.
10. The method for detecting carbamate pesticides based on CdTe quantum dot paper chip substrate as claimed in claim 1, wherein the particle size of the nano porphyrin in the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is 70-90 nm.
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