CN109799212B - Method for detecting organophosphorus pesticide based on CdTe-ZnCdSe double-quantum dot paper chip substrate - Google Patents
Method for detecting organophosphorus pesticide based on CdTe-ZnCdSe double-quantum dot paper chip substrate Download PDFInfo
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Abstract
The invention relates to the field of paper chip sensing, in particular to a method for detecting organophosphorus pesticide based on a CdTe-ZnCdSe double-quantum dot paper chip substrate. The method for detecting the organophosphorus pesticide based on the CdTe-ZnCdSe double quantum dot paper chip substrate comprises the following steps: (1) synthesizing CdTe quantum dots; (2) synthesizing ZnCdSe quantum dots; (3) preparing a CdTe-ZnCdSe double-quantum dot paper chip substrate; (4) synthesizing a tetra- (4-pyridyl) zinc porphyrin self-assembly solution; (5) preparing an organophosphorus pesticide standard colorimetric card; (6) detecting the concentration of the organophosphorus pesticide in the sample; the invention has the characteristics of simple preparation, quick field detection, low cost, high response speed and high sensitivity and selectivity, and compared with single quantum, the fluorescence color of the mixed double-quantum dot solution is influenced by the quencher to be more easily distinguished on a paper chip, thereby improving the detection sensitivity.
Description
Technical Field
The invention relates to the field of paper chip sensing, in particular to a method for detecting organophosphorus pesticide based on a CdTe-ZnCdSe double-quantum dot paper chip substrate.
Background
The organophosphorus pesticide is one of the most common pesticides in China, and after the organophosphorus pesticide remained on crops, fruits and vegetables enters the human body, the organophosphorus pesticide can cause excessive acetylcholine to generate symptoms such as nervous disorder and even cause irreparable damage to the human body. With the wide application of organophosphorus pesticides in the aspects of cultivation of crops and fruits and vegetables in China, the development of a novel rapid, simple and highly sensitive organophosphorus pesticide trace residue detection method is urgent.
The detection means of the organophosphorus pesticides from initial biological determination to gas chromatography-mass spectrometry (GC-MS), Gas Chromatography (GC), capillary electrophoresis, liquid chromatography-mass spectrometry (HPLC-MS), High Performance Liquid Chromatography (HPLC), and the existing more common chemical sensor method and immunoassay technology have some defects to different degrees and cannot be widely applied.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a method for detecting organophosphorus pesticide based on a CdTe-ZnCdSe double-quantum dot paper chip substrate, which not only can quickly and highly sensitively detect organophosphorus pesticide, but also can realize instrument-free field instant detection.
In order to achieve the purpose, the CdTe-ZnCdSe double-quantum-dot paper chip substrate designed by the invention is characterized by comprising a paper base material and CdTe-ZnCdSe double-quantum dots fixed on the paper base material, wherein the CdTe-ZnCdSe double-quantum dots are prepared by mixing CdTe quantum dots and ZnCdSe quantum dots.
Preferably, the concentration of the CdTe quantum dots is 143-146 nmol/L, the concentration of the ZnCdSe quantum dots is 318-422 nmol/L, and the volume ratio of the CdTe quantum dots to the ZnCdSe quantum dots is 1-2: 1 to 2.
As a preferable scheme, the CdTe-ZnCdSe double-quantum dot paper chip substrate further comprises a paper support, and the CdTe-ZnCdSe double-quantum dot paper chip substrate is fixed on the paper support through a hydrophobic adhesive tape.
4. A preparation method of a CdTe-ZnCdSe double 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 ZnCdSe quantum dots
Reacting ZnCl2Dissolving N-acetyl-L-cysteine in pure water, mixing, and sequentially adding CdCl2And NaHSe to obtain a mixed solution, and finally placing the mixed solution in a reaction kettle for reaction to obtain the fluorescent ZnCdSe quantum dots;
(3) preparation of CdTe-ZnCdSe double quantum dot paper chip substrate
And mixing the CdTe quantum dots and the ZnCdSe quantum dots, and then dropwise adding the mixture on a paper base material, wherein the paper base material absorbs and fixes the CdTe quantum dots and the ZnCdSe quantum dots to obtain the CdTe-ZnCdSe quantum dot paper chip substrate.
Preferably, the CdTe quantum dots emit purple red fluorescence and the emission wavelength is 630-640 nm.
Preferably, the ZnCdSe quantum dots emit yellowish green fluorescence with emission wavelength of 480-500 nm.
7. A method for detecting organophosphorus pesticide based on a CdTe-ZnCdSe double-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 ZnCdSe quantum dots
Reacting ZnCl2Dissolving N-acetyl-L-cysteine in pure water, mixing, and sequentially adding CdCl2And NaHSe to obtain a mixed solution, and finally placing the mixed solution in a reaction kettle for reaction to obtain the fluorescent ZnCdSe quantum dots;
(3) preparation of CdTe-ZnCdSe double quantum dot paper chip substrate
Mixing CdTe quantum dots and ZnCdSe quantum dots, and dripping the mixture on a paper base material, wherein the paper base material absorbs and fixes the CdTe quantum dots and the ZnCdSe quantum dots to obtain a CdTe-ZnCdSe quantum dot paper chip substrate;
(4) synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
Dissolving tetra- (4-pyridyl) zinc porphyrin in an N, N-dimethylformamide solution to obtain a tetra- (4-pyridyl) zinc porphyrin solution, adding the tetra- (4-pyridyl) zinc porphyrin solution into dodecyl trimethyl ammonium bromide, uniformly stirring, and stopping reaction to obtain a tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
(5) standard colorimetric card for preparing organophosphorus pesticide
Preparing a mixed solution of organophosphorus pesticides with different concentrations and a tetra- (4-pyridyl) zinc porphyrin self-assembly solution, sequentially dropwise adding the mixed solution on a CdTe-ZnCdSe double-quantum dot paper chip substrate, observing in an ultraviolet dark box, reacting the organophosphorus pesticides with different concentrations with the CdTe-ZnCdSe double-quantum dot paper chip substrate to generate different colors, photographing each CdTe-ZnCdSe double-quantum dot paper chip substrate, and finishing to obtain an organophosphorus pesticide standard colorimetric card;
(6) detecting organophosphorus pesticide concentration of sample
And mixing the sample with the tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dropwise adding the mixture to a double-quantum-dot paper chip substrate, wherein the double-quantum-dot paper chip substrate responds to the sample in color, and contrasting with an organophosphorus pesticide standard colorimetric card to obtain the concentration of the organophosphorus pesticide in the sample.
As a preferred scheme, the CdTe quantum dots in the step (1) emit purple red fluorescence with the emission wavelength of 630-640 nm; and (2) the ZnCdSe quantum dots emit light yellow green fluorescence with the emission wavelength of 480-500 nm.
Preferably, the concentration of the CdTe quantum dots is 143-146 nmol/L, the concentration of the ZnCdSe quantum dots is 318-422 nmol/L, and the volume ratio of the CdTe quantum dots to the ZnCdSe quantum dots is 1-2: 1 to 2.
Preferably, in the step (5), the concentration of the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is 0.46-0.48 mu mol/L, and the concentration of the organophosphorus pesticide is 0-50 mu g/L.
The invention has the advantages that: compared with the existing detection method of organophosphorus pesticides, the method for detecting organophosphorus pesticides based on the CdTe-ZnCdSe double-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 compared with single-quantum single color, the fluorescence color of the mixed double-quantum-dot solution is influenced by a quencher and is easier to generate color discrimination on the paper chip, so that the detection sensitivity is improved.
Drawings
FIG. 1 is a schematic diagram of the mechanism of the method for detecting organophosphorus pesticide based on CdTe-ZnCdSe double quantum dot paper chip substrate of the invention;
FIG. 2 is a transmission electron microscope image of a tetra- (4-pyridyl) zinc porphyrin self-assembly solution of the present invention;
FIG. 3 is a transmission electron microscope image of a tetra- (4-pyridyl) zinc porphyrin self-assembly solution and CdTe-ZnCdSe double quantum dots according to the present invention;
FIG. 4 is a diagram of a feasibility test for detecting organophosphorus pesticide based on a double quantum dot paper chip substrate according to the present invention; 4A is the color of the double-quantum dot paper chip substrate, 4B is the dark purple color picture formed by the double-quantum dot fluorescence quenching after the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is added into the double-quantum dot paper chip substrate, and 4C is the color change from dark purple to red after the tetra- (4-pyridyl) zinc porphyrin self-assembly solution (0.47 mu M) and dimethoate (50 mu g/L) mixed solution are added into the double-quantum dot paper chip substrate;
FIG. 5 is a standard color chart of Dimethoate prepared according to the present invention; FIGS. 5A-5F are sequential illustrations of color produced by Dimethoate at 0. mu.g/L, 1. mu.g/L, 5. mu.g/L, 10. mu.g/L, 20. mu.g/L, and 50. mu.g/L;
FIG. 6 is a comparison chart of Dimethoate detection based on CdTe single quantum dots or ZnCdSe single quantum dots paper chip, FIG. 6A is a color change chart of the CdTe quantum dots paper chip substrate, and FIG. 6B is a color change chart of the ZnCdSe quantum dots paper chip substrate;
FIG. 7 shows the specificity of the double quantum dot-nano porphyrin fluorescence paper chip sensor for visually detecting organophosphorus pesticide. 7A is a blank comparison graph of a double-quantum dot paper chip substrate, 7B is a color change graph of dimethoate detected by the double-quantum dot paper chip substrate, 7C is a comparison graph of fluorescence quenching after a tetra- (4-pyridyl) zinc porphyrin self-assembly solution (0.47 mu M) is dripped, and 7D-7G are color change graphs of deltamethrin, metolcarb, cartap and acetochlor detected by the double-quantum dot paper chip substrate in sequence;
FIG. 8 is a standard color chart of dichlorvos prepared in accordance with the present invention; FIGS. 8A-8E correspond in sequence to the colors produced by 1 μ g/L, 5 μ g/L, 10 μ g/L, 20 μ g/L, 50 μ g/L of DDVP;
FIG. 9 is a standard color chart for systematic phosphorus absorption prepared by the present invention; FIGS. 9A-9E correspond, in order, to the colors produced by 1 μ g/L, 5 μ g/L, 10 μ g/L, 20 μ g/L, and 50 μ g/L of DDVP;
FIG. 10 shows the results of the analysis of training set and prediction set for detecting three organophosphorus pesticides in complex matrix based on PLSDA model. 10A is the analysis result of the dimethoate training set, 10A is the analysis result of the dimethoate prediction set, 10B is the analysis result of the dichlorvos training set, 10B is the analysis result of the dichlorvos prediction set, 10C is the analysis result of the systemic phosphorus training set, and 10C is the analysis result of the systemic phosphorus prediction set.
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 existing technology for detecting organophosphorus pesticides, the invention provides a method for detecting organophosphorus pesticides based on a CdTe-ZnCdSe double-quantum dot paper chip substrate, and specifically, the invention utilizes the principle that the mixed solution of organophosphorus pesticides and tetra- (4-pyridyl) zinc porphyrin self-assembly solution can change the fluorescence color of CdTe-ZnCdSe double-quantum dots to prepare a standard colorimetric card of organophosphorus pesticides, and judges the concentration of organophosphorus pesticides to be detected by contrasting the color with the standard colorimetric card. The following will explain in detail the preferred mode of the method for detecting organophosphorus pesticide based on CdTe-ZnCdSe double quantum dot paper chip substrate of the present invention by specific examples.
Example 1
The method for preparing the CdTe-ZnCdSe double quantum dot paper chip substrate comprises the following steps:
(1) synthesis of CdTe quantum dot
Cadmium dichloride (0.1142g, 12.5mM) and N-acetyl-L-cysteine (0.0979g, 15mM) are dissolved in 40mL of ultrapure water, stirred for 15 minutes at normal temperature and normal pressure, then the solution is adjusted to pH 8.00 by using a sodium hydroxide solution, then the solution is filled with nitrogen, stirred in an ice bath for 20 minutes, added with sodium tellurite (0.0216g, 2.5mM), stirred for 15 minutes, added with hydroboration (0.0113g, 7.5mM), stirred for 15 minutes, finally the solution is put into a reaction kettle, reacted in an oven at 200 ℃ for 50 minutes and cooled to room temperature, and purple CdTe quantum dots with the emission wavelength of 635nm are obtained.
(2) Synthesis of ZnCdSe quantum dots
Reacting ZnCl2(6.4mM) and N-acetyl-L-cysteine (19.2mM) were dissolved in ultrapure water, the reaction was stirred for 20min under ice bath and atmospheric pressure, and then the mixture was treated with sodium hydroxide solutionAdjusting the pH of the reaction mixture to 9.70, adding CdCl2(0.064mM) and nitrogen sparged to continue stirring in the ice bath for 5 min. Then adding NaHSe (0.64mM), continuing stirring for 5min, finally placing the reaction mixed solution in a reaction kettle, and reacting for 65min at 200 ℃ to prepare the light yellow green ZnCdSe quantum dot with the emission wavelength of 490 nm.
(3) Preparation of CdTe-ZnCdSe double quantum dot paper chip substrate
Mixing CdTe quantum dots and ZnCdSe quantum dots in the same volume to obtain CdTe-ZnCdSe double quantum dots, sucking 10 mu LCdTe-ZnCdSe double quantum dots by a liquid transfer gun, dripping the CdTe-ZnCdSe double quantum dots on 3 circular filter papers with the diameter of 5mm, placing the 3 circular filter papers in an oven at 37 ℃ for drying for about 4 minutes until the circular filter papers are slightly dried to obtain 3 CdTe-ZnCdSe double quantum dot paper chip substrates, taking red in an ultraviolet dark box at 365nm, and taking a picture and storing the picture.
Example 2
The method for detecting dimethoate based on the CdTe-ZnCdSe double-quantum dot paper chip substrate comprises the following steps:
(1) synthesis of CdTe quantum dot
Cadmium dichloride (0.1142g, 12.5mM) and N-acetyl-L-cysteine (0.0979g, 15mM) are dissolved in 40mL of ultrapure water, stirred for 15 minutes at normal temperature and normal pressure, then the solution is adjusted to pH 8.00 by using a sodium hydroxide solution, then the solution is filled with nitrogen, stirred in an ice bath for 20 minutes, added with sodium tellurite (0.0216g, 2.5mM), stirred for 15 minutes, added with hydroboration (0.0113g, 7.5mM), stirred for 15 minutes, finally the solution is put into a reaction kettle, reacted in an oven at 200 ℃ for 50 minutes and cooled to room temperature, and purple CdTe quantum dots with the emission wavelength of 635nM of 145nM are obtained.
(2) Synthesis of ZnCdSe quantum dots
Reacting ZnCl2(6.4mM) and N-acetyl-L-cysteine (19.2mM) were dissolved in ultrapure water, the reaction was stirred for 20min under ice bath and atmospheric pressure, the pH of the mixture was then adjusted to 9.70 with sodium hydroxide solution, and CdCl was added2(0.064mM) and nitrogen sparged to continue stirring in the ice bath for 5 min. Then adding NaHSe (0.64mM), continuing stirring for 5min, finally placing the reaction mixed solution in a reaction kettle, reacting for 65min at 200 ℃ to obtain light yellow-green ZnCd with the emission wavelength of about 490nM of 420nMAnd (4) Se quantum dots.
(3) Preparation of CdTe-ZnCdSe double quantum dot paper chip substrate
Mixing CdTe quantum dots and ZnCdSe quantum dots in the same volume to obtain CdTe-ZnCdSe double quantum dots, sucking 10 mu LCdTe-ZnCdSe double quantum dots by a liquid transfer gun, dripping the CdTe-ZnCdSe double quantum dots on 3 circular filter papers with the diameter of 5mm, placing the 3 circular filter papers in an oven at 37 ℃ for drying for about 4 minutes until the circular filter papers are slightly dried to obtain 3 CdTe-ZnCdSe double quantum dot paper chip substrates, taking red in an ultraviolet dark box at 365nm, and taking a picture and storing the picture.
(4) Synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
Dissolving tetra- (4-pyridyl) zinc porphyrin in N, N-Dimethylformamide (DMF) solution to obtain 8.5 × 10-5M in tetra- (4-pyridyl) zinc porphyrin solution. And (3) sucking 500 mu L of tetra- (4-pyridyl) zinc porphyrin solution into a 14mL centrifuge tube, adding 9.5mL of 0.1M Dodecyl Trimethyl Ammonium Bromide (DTAB), performing ultrasonic treatment for 10min, then performing hot water bath at 70 ℃ for 15min to obtain 17.85 mu M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, and storing the solution in a dark place, wherein the transmission electron microscope characterization of the tetra- (4-pyridyl) zinc porphyrin self-assembly solution shows that the nanorod with the particle size of 60-100 nm is formed as shown in figure 2.
(5) Standard colour comparison card for making dimethoate
Preparing a solution I: 0 μ g/L dimethoate and 0.47 μ M tetrakis- (4-pyridyl) zinc porphyrin self-assembly solution;
solution II: 1 μ g/L dimethoate and 0.47 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution three: 5 μ g/L Dimethoate and 0.47 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution four: 10 μ g/L Dimethoate and 0.47 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution five: 20 μ g/L Dimethoate and 0.47 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution six: 50 μ g/L Dimethoate and 0.47 μ M tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
sucking 10 microliter of the above solutions by a liquid-transferring gun, dripping the solutions one to six respectively on a CdTe-ZnCdSe double quantum dot paper chip substrate, 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 a Dimethoate standard colorimetric card. With reference to the standard colorimetric card for Dimethoate shown in FIG. 5, FIGS. 5A to 5F correspond to colors produced by Dimethoate of 0. mu.g/L, 1. mu.g/L, 5. mu.g/L, 10. mu.g/L, 20. mu.g/L, and 50. mu.g/L, in this order.
Referring to fig. 1 and fig. 3, it can be seen from fig. 1 that the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is dripped on the CdTe-ZnCdSe double quantum dot paper chip substrate, the fluorescence of the double quantum dots is quenched through the fluorescence resonance energy transfer and photoinduced electron transfer, the color of the paper changes from red to dark purple, however, the tetra- (4-pyridyl) zinc quinoline self-assembly forms a sensitized micelle system, the stable structure can be efficiently formed by combining with the electron-rich groups in the organophosphorus pesticide through the electron adsorption, the spatial position between the nano porphyrin wrapped by the organophosphorus pesticide molecules and the double quantum dots changes, and the fluorescence performance of the double quantum dots can be recovered. As shown in FIG. 4, the color of the double quantum dot paper chip substrate is red as shown in FIG. 4A, the double quantum dot fluorescence is quenched to form dark purple after the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is added into the double quantum dot paper chip substrate (as shown in FIG. 4B), and the mixed solution of the tetra- (4-pyridyl) zinc porphyrin self-assembly solution (0.47 μ M) and dimethoate (50 μ g/L) is added into the double quantum dot paper chip substrate to change from dark purple to red (as shown in FIG. 4C). As shown in a combined figure 5, the organophosphorus pesticides with different concentrations are mixed with the nano porphyrin and are dripped on the double quantum dot paper chip substrate to generate different color changes, the color on the paper changes from dark purple to light purple, then to light red and finally to red along with the increase of the concentration of the organophosphorus pesticides, so that the purpose of visually detecting the organophosphorus pesticides on the paper is achieved.
(6) Detecting the concentration of Dimethoate in a sample
And mixing the sample with the 0.47 mu M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dropwise adding the mixture onto a double-quantum dot paper chip substrate, wherein the double-quantum dot paper chip substrate has color response to the sample, and contrasting with a dimethoate standard colorimetric card to obtain the concentration of dimethoate in the sample.
The invention adopts double quantum dots as the paper chip substrate, because the double quantum dots can combine the luminescence characteristics of two quantum dots compared with single quantum single color, more color intervals can be generated for more accurately analyzing organophosphorus pesticides with different concentrations, the sensitivity of the probe is improved, the fluorescence color of the mixed double quantum dot solution is more easily distinguished after being influenced by a quencher, samples with different concentrations can be identified on the fluorescence color, and a single quantum comparison experiment is carried out for verifying the identification superiority of the double quantum ratio single quantum on the fluorescence color, the specific process is that the prepared CdTe quantum dot paper chip substrate and ZnCdSe quantum dot paper chip substrate are respectively dripped with dimethoate (1-50 mu g/L) and tetra- (4-pyridyl) zinc porphyrin self-assembly solution (0.47 mu M) with different concentrations on the CdTe quantum dot paper chip substrate and the ZnCdSe quantum dot paper chip substrate The solution was mixed and the results are shown in FIG. 6, with no apparent color discrimination. Fig. 6A is a color change diagram of a CdTe quantum dot paper chip substrate, and fig. 6B is a color change diagram of a ZnCdSe quantum dot paper chip substrate. As can be seen, the CdTe single quantum paper chip substrate or ZnCdSe single quantum paper chip substrate does not produce obvious color distinction on dimethoate (1-50 mug/L) with different concentrations.
In order to verify the specificity of detecting the organophosphorus pesticide based on the double-quantum-dot paper chip substrate, a specific selection test of the organophosphorus pesticide is carried out, the specific process is that 10 mu L of mixed solution of other pesticides (deltamethrin, metolcarb, cartap and acetochlor) with the concentration of 20 mu G/L and tetra- (4-pyridyl) zinc porphyrin self-assembly solution (0.47 mu M) is absorbed by a liquid-transferring gun on the double-quantum-dot paper chip substrate, as shown in figures 7D-7G, no obvious fluorescence recovery is generated, the mixed solution is still dark purple, 10 mu L of mixed solution of dimethoate with the concentration of 10 mu G/L and tetra- (4-pyridyl) zinc porphyrin self-assembly solution (0.47 mu M) is added on the double-quantum-dot paper chip substrate, the mixed solution is changed from dark purple to light red (as shown in figure 7B), the photoshop software is used for extracting the color value RGB on the picture, wherein 7A is a blank comparison graph of the double-quantum-dot paper chip substrate, FIG. 7C is a control chart of fluorescence quenching after dropwise addition of a tetra- (4-pyridyl) zinc porphyrin self-assembly solution (0.47. mu.M).
In addition, the dimethoate in complex matrixes (apple juice and Chinese cabbage juice) with different concentrations is dripped on the double-quantum dot paper chip substrate, and the color distinction of the complex matrixes still has different degrees, so that the method for detecting the organophosphorus pesticide based on the double-quantum dot paper chip substrate can accurately detect the dimethoate in the complex matrixes and is slightly interfered by the matrixes.
Example 3
The method for detecting dichlorvos based on the CdTe-ZnCdSe double-quantum dot paper chip substrate comprises the following steps of:
(1) synthesis of CdTe quantum dot fluorescent probe
(2) Synthesis of ZnCdSe quantum dot fluorescent probe
(3) Preparation of double quantum dot paper chip substrate
(4) Synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
The above steps (1) to (4) are the same as the steps (1) to (4) of example 2, and are not described again here.
(5) Making standard colour comparison card of dichlorvos
Solution one: 1 mu g/L of dichlorvos and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution II: 5 mu g/L of dichlorvos and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution three: 10 mu g/L of dichlorvos and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution four: 20 mu g/L of dichlorvos and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution five: 50 mu g/L of dichlorvos and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
sucking 10 mu L of the above solutions by using a liquid-transferring gun, dripping the solutions one to six respectively on a CdTe-ZnCdSe double quantum dot paper chip substrate, 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 to extract color values RGB on the picture, and simulating color dots by using the values to obtain the standard color comparison card of the dichlorvos. With reference to the standard colorimetric card for dichlorvos shown in FIG. 8, FIGS. 8A to 8E correspond to colors generated by dichlorvos of 1. mu.g/L, 5. mu.g/L, 10. mu.g/L, 20. mu.g/L, and 50. mu.g/L in sequence.
(6) Detecting the concentration of dichlorvos in a sample
Mixing a sample and 0.47 mu M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dropwise adding the mixture on a double-quantum-dot paper chip substrate, wherein the double-quantum-dot paper chip substrate has color response to the sample, and contrasting a standard color comparison card of the dichlorvos to obtain the concentration of the dichlorvos in the sample.
Example 4
A method for detecting systemic phosphorus based on a CdTe-ZnCdSe double quantum dot paper chip substrate comprises the following steps:
(1) synthesis of CdTe quantum dot fluorescent probe
(2) Synthesis of ZnCdSe quantum dot fluorescent probe
(3) Preparation of double quantum dot paper chip substrate
(4) Synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
The above steps (1) to (4) are the same as the steps (1) to (4) of example 2, and are not described again here.
(5) Making standard colorimetric card for absorbing phosphorus
Preparing a solution I: 0 mug/L of systemic phosphorus and 0.47 muM of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution II: 1 mu g/L of systemic phosphorus and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution three: 5 mu g/L of systemic phosphorus and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution four: a self-assembly solution of systemic phosphorus and 0.47 mu M tetra- (4-pyridyl) zinc porphyrin at 10 mu g/L;
solution five: 20 μ g/L of systemic phosphorus and 0.47 μ M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
solution six: 50 mu g/L of systemic phosphorus and 0.47 mu M of tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
sucking 10 microliter of the above solutions by a liquid-transferring gun, dripping the solutions one to six respectively on a CdTe-ZnCdSe double quantum dot paper chip substrate, 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 an internal phosphorus absorption standard colorimetric card. With reference to the systematic phosphorus absorption standard colorimetric card shown in FIG. 9, FIGS. 9A to 9E correspond to colors produced by dichlorvos of 1. mu.g/L, 5. mu.g/L, 10. mu.g/L, 20. mu.g/L and 50. mu.g/L in this order.
(6) Detecting the systemic phosphorus concentration of a sample
And mixing the sample with the 0.47 mu M tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dropwise adding the mixture on a double-quantum dot paper chip substrate, wherein the double-quantum dot paper chip substrate has color response to the sample, and contrasting with a standard colorimetric card for absorbing the phosphorus to obtain the concentration of the absorbed phosphorus in the sample.
The systematic phosphorus in complex matrixes (apple juice and Chinese cabbage juice) with different concentrations is dripped on a double quantum dot paper chip substrate, color distinction of different degrees still exists, a PS (polystyrene) software is used for extracting RGB (red, green, blue) values, a data array is established by RGB (red, green, blue) detected by dimethoate, dichlorvos and the systematic phosphorus in the complex matrixes, pattern recognition Partial Least Squares (PLSDA) is used for carrying out data modeling discriminant analysis, and the result shows that the method has good discriminant results on different organophosphorus pesticides in different matrixes, as shown in figure 10.
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 (2)
1. A method for detecting organophosphorus pesticide based on a CdTe-ZnCdSe double-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 ZnCdSe quantum dots
Reacting ZnCl2Dissolving N-acetyl-L-cysteine in pure water, mixing,CdCl is added in turn2And NaHSe to obtain a mixed solution, and finally placing the mixed solution in a reaction kettle for reaction to obtain the fluorescent ZnCdSe quantum dots;
(3) preparation of CdTe-ZnCdSe double quantum dot paper chip substrate
Mixing CdTe quantum dots and ZnCdSe quantum dots, and dripping the mixture on a paper base material, wherein the paper base material absorbs and fixes the CdTe quantum dots and the ZnCdSe quantum dots to obtain a CdTe-ZnCdSe quantum dot paper chip substrate;
(4) synthesis of tetra- (4-pyridyl) zinc porphyrin self-assembly solution
Dissolving tetra- (4-pyridyl) zinc porphyrin in an N, N-dimethylformamide solution to obtain a tetra- (4-pyridyl) zinc porphyrin solution, adding the tetra- (4-pyridyl) zinc porphyrin solution into dodecyl trimethyl ammonium bromide, uniformly stirring, and stopping reaction to obtain a tetra- (4-pyridyl) zinc porphyrin self-assembly solution;
(5) standard colorimetric card for preparing organophosphorus pesticide
Preparing a mixed solution of organophosphorus pesticides with different concentrations and a tetra- (4-pyridyl) zinc porphyrin self-assembly solution, sequentially dropwise adding the mixed solution on a CdTe-ZnCdSe double-quantum dot paper chip substrate, observing in an ultraviolet dark box, reacting the organophosphorus pesticides with different concentrations with the CdTe-ZnCdSe double-quantum dot paper chip substrate to generate different colors, photographing each CdTe-ZnCdSe double-quantum dot paper chip substrate, and finishing to obtain an organophosphorus pesticide standard colorimetric card;
(6) detecting organophosphorus pesticide concentration of sample
Mixing a sample and the tetra- (4-pyridyl) zinc porphyrin self-assembly solution, dropwise adding the mixture on a double-quantum-dot paper chip substrate, wherein the double-quantum-dot paper chip substrate responds to the sample in color, and obtaining the concentration of the organophosphorus pesticide in the sample by contrasting with an organophosphorus pesticide standard colorimetric card;
the concentration of the CdTe quantum dots is 143-146 nmol/L, the concentration of the ZnCdSe quantum dots is 318-422 nmol/L, and the volume ratio of the CdTe quantum dots to the ZnCdSe quantum dots is 1-2: 1-2;
in the step (5), the concentration of the tetra- (4-pyridyl) zinc porphyrin self-assembly solution is 0.46-0.48 mu mol/L, and the concentration of the organophosphorus pesticide is 0-50 mu g/L.
2. The method for detecting the organophosphorus pesticide based on the CdTe-ZnCdSe double-quantum-dot paper chip substrate as claimed in claim 1, wherein in the step (1), the CdTe quantum dots emit purple red fluorescence and the emission wavelength is 630-640 nm; and (2) the ZnCdSe quantum dots emit light yellow green fluorescence with the emission wavelength of 480-500 nm.
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