Method for visualized detection of organophosphorus pesticide residue by doped quantum dot ratio fluorescence technique

An organophosphorus pesticide and ratio fluorescence technology, applied in the field of agrochemical analysis, can solve the problems of inability to distinguish between organophosphorus and carbamate pesticides, expensive instruments, difficult on-site detection, etc. Simple operation, avoid interference effect

Inactive Publication Date: 2013-11-27
HEFEI INSTITUTES OF PHYSICAL SCIENCE - CHINESE ACAD OF SCI
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AI-Extracted Technical Summary

Problems solved by technology

The detection results of these large-scale instruments are accurate and reliable, but they are difficult to use for on-site detection due to the shortcomings of expensive instruments, high detection costs, complex sample pretreatment, and professional training for operators.
In addition, although the "enzyme inhibition rate method + spectrophotometry" has been listed as a national recommended standard (GB/T5009.199-2003), it has become a rapid on-site preliminary scre...
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Abstract

The invention relates to a method for visualized detection of organophosphorus pesticide residue by a doped quantum dot ratio fluorescence technique. Being a standard curve method, the method includes preparation and quenching of a double-fluorescence emission quantum dot, establishment of a standard curve and detection of organophosphorus pesticide residue. The method is characterized in that: the standard curve is determined under ultraviolet irradiation and is a curve about the corresponding relationship of a fluorescence ratio and a sample concentration, i.e. the standard curve is established by adding sample solutions with gradient concentrations into a quenched doped quantum dot probe dispersion fluid with a concentration of 30-40mcg/ml in order under ultraviolet irradiation, and determining fluorescence ratios successively. For the quenched doped quantum dot, a quenching agent is employed to quench the double-fluorescence of the doped quantum dot probe dispersion fluid to fluorescence intensity that no longer reduces. The method provided in the invention realizes sensitive and high selectivity detection of organophosphorus pesticide residue.

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Technology Topic

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  • Method for visualized detection of organophosphorus pesticide residue by doped quantum dot ratio fluorescence technique
  • Method for visualized detection of organophosphorus pesticide residue by doped quantum dot ratio fluorescence technique
  • Method for visualized detection of organophosphorus pesticide residue by doped quantum dot ratio fluorescence technique

Examples

  • Experimental program(2)

Example Embodiment

[0034] Example 1: Detection of chlorpyrifos and its degradation products
[0035] 1. Preparation of manganese-doped zinc sulfide quantum dots
[0036] First dissolve 50 mmol of zinc nitrate in 40 mL of deionized water, then take 0.5-7.5 mmol of manganese acetate and dissolve it in the above solution to do a series of manganese doping experiments to determine which amount has the highest luminescence yield. The above mixture was sonicated for 10 min to Completely dissolve, then reflux and pass dry nitrogen for more than 30min to remove oxygen in the solution. Dissolve 50 mmol of sodium sulfide in 10 mL of deionized water, add dropwise to the above boiling mixture, reflux and stir vigorously for 5 h. After cooling it was centrifuged, sonicated and washed three times with deionized water before redispersing in water. Fluorescence spectra see figure 1.
[0037] 2. Quenching of double emission band fluorescence of doped quantum dots
[0038] Add 5 mL of manganese-doped zinc sulfide quantum dots aqueous dispersion to a mixed solution containing a certain amount of triethylamine (20 μl), carbon disulfide (20 μl) and dopamine (50 mg), react for 24 hours, centrifuge and wash again. Disperse into water, the concentration of dispersion liquid is 30 micrograms per milliliter. Dopamine apparently minimizes the intensity of both emission peaks. The fluorescence spectra before and after quenching are shown in figure 2.
[0039] 3. Establishment of standard curve of chlorpyrifos and fluorescence ratio
[0040] Under ultraviolet light irradiation, a series of 20 μM to 260 μM solutions of degradation products of the organophosphorus pesticide chlorpyrifos were added to the quenched manganese-doped zinc sulfide quantum dot probe (30 μg/ml) dispersion. There is a response at 20μM content, and the detection is relatively sensitive. As the amount of organophosphorus pesticides gradually increased, the fluorescence color gradually changed from yellow to red. Fluorescence ratio changes see image 3. Visualization photos see Figure 4. Draw a standard curve with the concentration as the abscissa and the fluorescence ratio as the ordinate. The linear relationship between the concentration of chlorpyrifos degradation products and the fluorescence ratio is shown in Figure 5.
[0041] 4. Visual detection of chlorpyrifos and its degradation products
[0042] The solution of the degradation product of the organophosphorus pesticide chlorpyrifos to be detected was added to the quenched manganese-doped zinc sulfide (30 micrograms per milliliter) dispersion, and the fluorescence ratio was detected under ultraviolet light irradiation, and its concentration was obtained according to the standard curve.

Example Embodiment

[0043] The detection of embodiment 2 methyl parathion
[0044] 1. Preparation of copper and manganese co-doped zinc sulfide quantum dots
[0045] First dissolve 50 mmol of zinc chloride in 40 mL of deionized water, and then take 0.5-7.5 mmol of manganese chloride and copper chloride to dissolve in the above solution to do a series of manganese parameter experiments to determine which amount has the highest luminescence yield. The above mixture was sonicated for 10 min to dissolve completely, then refluxed and passed through dry nitrogen for more than 30 min to remove oxygen from the solution. Dissolve 50 mmol of sodium sulfide in 10 mL of deionized water, add dropwise to the above boiling mixture, reflux and stir vigorously for 5 h. After cooling, centrifuge, ultrasonically disperse and wash three times with deionized water, and then re-disperse in water (concentration micrograms per milliliter) for use.
[0046] 2. Quenching of double emission band fluorescence of doped quantum dots
[0047] Take 3 mL of copper and manganese co-doped zinc sulfide quantum dot aqueous dispersion and add it to a mixed solution containing a certain amount of triethylamine (20 μl), carbon disulfide (20 μl) and dopamine (50 mg), and react for 36 hours. Centrifugal washing and redispersion in water, the concentration of the dispersion is 40 μg per ml. Dopamine apparently minimizes the intensity of both emission peaks.
[0048] 3. Establishment of standard curve of methyl parathion and fluorescence ratio
[0049] Under UV light irradiation, a series of solutions of degradation products of the organophosphorus pesticide methyl parathion with a concentration of 20 μM to 180 μM were added to the quenched dispersion of the co-doped zinc sulfide quantum dot probe (40 μg/ml). There is a response at 20μM content, and the detection is relatively sensitive. As the amount of organophosphorus pesticides gradually increased, the fluorescence color gradually changed from blue to yellow. Fluorescence ratio changes see Image 6. Visualization photos see Figure 7. A standard curve was drawn with the concentration as the abscissa and the fluorescence ratio as the ordinate to determine the linear relationship between the concentration of methyl parathion degradation products and the fluorescence ratio.
[0050] 4. Visual detection of methyl parathion and its degradation products
[0051] The solution of the degradation product of the organophosphorus pesticide methyl parathion to be detected was added to the quenched dispersion of co-doped zinc sulfide (40 μg/ml), and the fluorescence ratio was detected under ultraviolet light irradiation, and calculated according to the standard curve. get its concentration.
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