Method for rapidly detecting azoxystrobin by utilizing illumination and surface enhanced Raman spectroscopy
阅读说明：本技术 一种利用光照和表面增强拉曼快速检测嘧菌酯的方法 (Method for rapidly detecting azoxystrobin by utilizing illumination and surface enhanced Raman spectroscopy ) 是由 纪丽君 李培 丁洪流 于 2021-08-20 设计创作，主要内容包括：本发明提供了一种利用光照和表面增强拉曼快速检测嘧菌酯的方法,属于物质的分析检测领域。该方法将含有目标物的溶液经过一定时间的紫外照射,与表面增强试剂混合,采用表面增强拉曼技术进行测试。本发明通过检测嘧菌酯的光解产物新增特征峰来确证嘧菌酯的存在,该特征峰出现在一般拉曼图谱的静默区,创新地将2230cm～(-1)处的拉曼峰作为定性定量特征峰。该方法具有灵敏、简便、成本低的优点。(The invention provides a method for rapidly detecting azoxystrobin by utilizing illumination and surface enhanced Raman spectroscopy, belonging to the field of substance analysis and detection. The method comprises the steps of carrying out ultraviolet irradiation on a solution containing a target object for a certain time, mixing the solution with a surface enhanced reagent, and testing by adopting a surface enhanced Raman technology. The invention confirms the existence of the azoxystrobin by detecting a newly added characteristic peak of a photolysis product of the azoxystrobin, the characteristic peak appears in a silent zone of a general Raman spectrum, and 2230cm is innovatively detected ‑1 The Raman peak at (A) is taken as a qualitative and quantitative characteristic peak. The method has the advantages of sensitivity, simplicity and low cost.)
1. A method for rapidly detecting azoxystrobin by utilizing illumination and surface enhanced Raman is characterized by comprising the following steps:
(1) preparing gold sol by adopting a method of reducing potassium chloroaurate with trisodium citrate: stirring and heating the potassium chloroaurate solution to boiling, quickly adding trisodium citrate solution, continuously stirring and heating until the color is stable, and stopping to obtain gold sol;
(2) preparation of two solutions to be tested: dissolving the azoxystrobin standard product in an organic solvent to obtain a to-be-detected solution of the azoxystrobin standard product; pretreating the actual sample to obtain a solution to be detected of the actual sample;
(3) illumination: placing the two solutions to be detected under an ultraviolet light source for irradiation;
(4) raman measurement: setting working parameters of the laser Raman spectrometer: wavelength of laser, laser power and scanning time: respectively mixing the gold sol and the two photolyzed solutions to be detected according to the proportion of 10: 1 or 3: 2, and then detecting;
(5) and (3) characterization: scanning using a laser Raman spectrometer at 2230cm-1The Raman peak at (A) is taken as a qualitative characteristic peak.
2. The method according to claim 1, wherein the mass percent concentration of the potassium chloroaurate solution is 0.6-1%, the mass percent concentration of the trisodium citrate solution is 0.5-4.0%, and the volume ratio of the potassium chloroaurate solution to the trisodium citrate solution is 100: 3-12; the heating temperature is 100-150 ℃; stirring at a speed of 300-900 r/min; the heating time is 10-40 min.
3. The method according to claim 1 or 2, wherein the organic solvent is methanol or methanol water.
4. The method according to claim 1 or 2, wherein the actual sample is fruit or vegetable.
5. The method of claim 3, wherein the physical sample is fruit or vegetable.
6. The method according to claim 4, wherein 1-10 g of vegetable leaves or fruit skins are taken in the pretreatment process of the actual sample, the vegetable leaves or fruit skins are cut into pieces, an extracting agent is added, the vibration extraction is carried out for 10min, then the ultrasonic extraction is carried out for 3min, the extract is transferred to a volumetric flask, and the volume is fixed.
7. The method according to claim 5, wherein 1-10 g of vegetable leaves or fruit skins are taken in the pretreatment process of the actual sample, the vegetable leaves or fruit skins are cut into pieces, an extracting agent is added, the vibration extraction is carried out for 10min, then the ultrasonic extraction is carried out for 3min, the extract is transferred to a volumetric flask, and the volume is fixed.
8. The method according to claim 1, 2, 5, 6 or 7, wherein the wavelength of the ultraviolet light source in the step (3) is 302nm or 254nm, and the irradiation time is 10-60 min.
9. The method according to claim 1, 2, 5, 6 or 7, wherein the wavelength of the laser is set to 785nm, the laser power is set to 50-300 mW, and the scanning time is set to 5-30 s.
10. The method according to claim 8, wherein the wavelength of the laser is set to 785nm, the laser power is set to 50-300 mW, and the scanning time is set to 5-30 s.
Technical Field
The invention belongs to the field of substance analysis and detection, and particularly relates to the technical field of rapid detection of environmental and food safety. In particular to a method for rapidly detecting azoxystrobin by utilizing illumination and surface enhanced Raman spectroscopy.
Background
Azoxystrobin (azoxystrobin, (E) - [2- [6- (2-cyanophenoxy) pyrimidin-4-yloxy ] phenyl ] -3-methoxy methyl acrylate) is a methoxy acrylate fungicide synthesized by Junda corporation of Switzerland at the end of the 20 th century. The composition has effect in inhibiting fungi respiration, and can destroy energy synthesis of thallus. The azoxystrobin has the advantages of high targeting property, long effective period of action, high activity and the like, so that the azoxystrobin is widely applied to the control of diseases of crops such as cucumbers, grapes, rice, tomatoes, potatoes and the like in agricultural production in China. The bactericidal composition has broad-spectrum bactericidal activity and can achieve good control effects on most fungal diseases such as rice blast, downy mildew, stinking smut, net blotch, rust disease, powdery mildew and the like. Azoxystrobin has low acute and chronic toxicity to humans, birds, mammals and bees, but it is extremely toxic to aquatic invertebrates.
The current detection of azoxystrobin is mainly focused on liquid chromatography. Liquid chromatography has many drawbacks such as susceptibility to solvents, high cost, and long analysis time. The surface enhanced raman spectroscopy is increasingly applied to food detection because of the capability of amplifying fingerprint information, and has the characteristics of higher sensitivity, high result output speed and the like.
Disclosure of Invention
The invention aims to provide a method for rapidly detecting azoxystrobin by utilizing illumination and surface enhanced Raman spectroscopy. The invention confirms the existence of the azoxystrobin by detecting the photolysis product of the azoxystrobin, and the azoxystrobin solution which is not subjected to photolysis is 2230cm-1No raman signal; the photolyzed azoxystrobin solution, whether it is a photoisomerization reaction or a double bond cleavage, changes the state of the cyano function with the formation of photolysis product, and the changed cyano group is in the silent zone 2230cm-1To generate a stable raman signal. Therefore 2230cm-1Becomes the qualitative characteristic peak of azoxystrobin, thereby realizing rapid detection.
The technical scheme of the invention is as follows:
a method for rapidly detecting azoxystrobin by utilizing illumination and surface enhanced Raman comprises the following steps:
(1) preparing gold sol by adopting a method of reducing potassium chloroaurate with trisodium citrate: stirring and heating the potassium chloroaurate solution to boiling, quickly adding trisodium citrate solution, continuously stirring and heating until the color is stable, and stopping to obtain gold sol;
(2) preparation of two solutions to be tested: dissolving the azoxystrobin standard product in an organic solvent to obtain a to-be-detected solution of the azoxystrobin standard product; pretreating the actual sample to obtain a solution to be detected of the actual sample;
(3) photolysis: placing the two solutions to be detected under an ultraviolet light source for irradiation;
(4) raman measurement: setting working parameters of the laser Raman spectrometer: wavelength of laser, laser power and scanning time: respectively mixing the gold sol and the two photolyzed solutions to be detected according to the proportion of 10: 1 or 3: 2, and then detecting;
(5) and (3) characterization: scanning using a laser Raman spectrometer at 2230cm-1The Raman peak at (A) is taken as a qualitative characteristic peak.
The mass percentage concentration of the potassium chloroaurate solution is 0.6%, the mass percentage concentration of the trisodium citrate solution is 0.5% -2.0%, and the volume ratio of the potassium chloroaurate solution to the trisodium citrate solution is 100: 3-8; the heating temperature is 100-150 ℃; stirring at a speed of 300-900 r/min; the heating time is 10-40 min.
The organic solvent is methanol or methanol water.
The actual sample is fruit and vegetable.
The pretreatment process of the actual sample comprises the following steps: cutting 1-10 g of vegetable leaves or fruit skins into pieces, adding an extracting agent, performing oscillation extraction for 10min, performing ultrasonic extraction for 3min, transferring the extract into a volumetric flask, and performing constant volume.
The wavelength of the ultraviolet light source is 302nm or 254nm, and the irradiation time is 10-60 min.
The wavelength of the laser is set to be 785nm, the laser power is set to be 50-300 mW, and the scanning time is set to be 5-30 s.
The invention has the beneficial effects that: the Raman spectrum is divided into fingerprint regions (wave number less than 1800 cm)-1) And a silence region (wave number) 1800cm-1) The most common of them is the information of the fingerprint area, while the silence area is less applied. In the invention, the characteristic peak is analyzed to generate a silent area, and the rich information of the Raman spectrum is utilized more deeply, thereby providing favorable evidence for the theoretical research of the functional group vibration and providing possibility for the subsequent research.
Drawings
FIG. 1 is a surface enhanced Raman spectrum of a 10ppm azoxystrobin methanol solution before and after illumination.
FIG. 2 is a surface enhanced Raman spectrum of azoxystrobin methanol solutions with different concentrations after being irradiated for 20min by a 302nm light source.
FIG. 3 is 2230cm in FIG. 1-1At wave number, different concentrationsPlot of linear relationship between the standard solution of azoxystrobin and peak intensity.
FIG. 4 is a surface enhanced Raman spectrum of a grape extract sprayed with azoxystrobin standard solution before and after illumination.
Detailed Description
The following detailed description of specific embodiments of the present invention is provided in connection with the accompanying drawings.
A novel detection method of azoxystrobin comprises the following steps: firstly, carrying out illumination treatment on a target object containing an object to be detected: thereafter, surface enhanced raman spectroscopy scans were performed: finally, at 2230cm-1The Raman peak at (A) is taken as a qualitative characteristic peak. The method comprises the following steps:
(1) preparing gold sol: a method for reducing potassium chloroaurate by trisodium citrate is adopted, 47mL of ultrapure water and 3mL of potassium chloroaurate (6-10 mg/mL) solution are mixed uniformly, stirred, heated and boiled, and 2mL of trisodium citrate solution (0.5-2.0%) is added rapidly. And continuously keeping the boiling state for 10-40 min until the color is stable, and obtaining the gold sol with a proper particle size.
(2) Setting scanning parameters of the laser Raman spectrometer: an excitation light source is 785nm, the laser power of the instrument is 50-300 mW, and the scanning time is 5-30 s.
Example 1
The azoxystrobin solid powder is prepared into a solution with the concentration of 1000mg/L by methanol, and then is diluted into 0.1, 0.5, 1, 2, 5, 10, 25, 50 and 100mg/L by methanol, and is subpackaged into 2mL centrifuge tubes. Placing the azoxystrobin in the sample under an ultraviolet light source of 302nm for 20in, taking out, mixing with gold sol according to the ratio of 1: 2, and performing Raman spectrum scanning to obtain surface enhanced Raman spectrograms of azoxystrobin with various concentrations, wherein the lowest detection concentration can be as low as 0.5 mg/L. In the range of 0.5-25mg/L, the silent zone is 2230cm-1There is a good linear relationship between the peak intensity and the logarithm of the concentration, and r can reach 0.9880.
Example 2
Cleaning the surface of grape, drying, weighing a proper amount of sample, placing the sample in a beaker, quantitatively dripping 0.5, 1.0 and 5.0mg/kg cymoxanil methanol standard solution on the surface of fruit and vegetable, and placing the fruit and vegetable in a dark environment until the solvent is completely volatilized. Towards the interior of the beakerAdding methanol for extraction, extracting for 10min under oscillation, performing ultrasonic extraction for 3min, transferring the extractive solution into volumetric flask, washing the beaker with small amount of methanol for several times, transferring all the washing solution into volumetric flask, and diluting to desired volume with methanol. Absorbing 2mL of extract liquid, irradiating for 20min under a 302nm ultraviolet light source, taking out, mixing with the gold sol according to the proportion of 1: 2 respectively, and using for Raman detection. The results are shown in FIG. 3. The grape extract after illumination is 2230cm-1There is a clear raman signal, whereas the grape extract without illumination is absent.