A method for analyzing multi-target surface-enhanced raman spectroscopy of pesticides and antibiotics in water body

Abstract

The application discloses a kind of pesticide and antibiotic multi-target surface enhanced Raman spectrum analysis methods in water body, first, the enhancement substrate for surface enhanced Raman spectrum analysis is prepared;The prepared enhancement substrate is evenly spread on the silicon chip of 5 × 5mm by vacuum suction filtration method, and the silicon chip is pasted on the glass sheet of 25 × 75mm;100mL of water sample to be analyzed is taken, and is divided into 5 parts, and the glass sheet pasted with silicon chip is immersed in 5 water samples in turn, and is taken out after standing for 5min each time;Again, the glass sheet after immersion is placed under Raman spectrum optical fiber probe, and laser is focused on the surface of silicon chip to collect Raman signal, and then the collected Raman signal is qualitatively determined by Raman shift.The above-mentioned method can realize the SERS analysis of multiple pesticides and antibiotics in flowing water body simultaneously, and meet the needs of high-sensitivity, multi-target, rapid analysis of multiple target pollutants in actual samples.

Description

Technical Field

[0001] This invention relates to the field of pesticide and antibiotic monitoring technology, and in particular to an analytical method for multi-target surface-enhanced Raman spectroscopy of pesticides and antibiotics in water. Background Technology

[0002] Currently, the monitoring of pesticides and antibiotics, as emerging agricultural non-point source pollutants, still relies on a combination of manual sampling and laboratory analysis. This method has a long detection cycle and delayed analysis results, which is not conducive to real-time monitoring of surface water pollution in watersheds. Due to the structural limitations of the sensing substrate, existing research reports using surface-enhanced Raman spectroscopy (SERS) still face three major bottlenecks:

[0003] First, the targets are limited to one type or multiple types of analytes, making it impossible to detect multiple types of analytes. Second, the detection sensitivity is insufficient, only reaching the ppm level. Third, the analysis cycle is long. These problems make it difficult to meet the needs of high-sensitivity, multi-target, and rapid analysis of multiple types of pollutants in real-world samples. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-target surface-enhanced Raman spectroscopy (SERS) analysis method for pesticides and antibiotics in water. This method can achieve simultaneous multi-target, highly sensitive SERS analysis of multiple pesticides and antibiotics in flowing water, meeting the needs of high-sensitivity, multi-target, and rapid analysis of multiple target pollutants in actual samples.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for analyzing pesticides and antibiotics in water using multi-target surface-enhanced Raman spectroscopy, the method comprising:

[0007] Step 1: First, prepare an enhanced substrate for surface-enhanced Raman spectroscopy analysis;

[0008] Step 2: The prepared reinforced substrate is uniformly coated onto a 5×5mm silicon wafer using a vacuum filtration method, and the silicon wafer is then attached to a 25×75mm glass plate.

[0009] Step 3: Take 100mL of the water sample to be analyzed and divide it into 5 portions. Immerse the glass slide with the silicon wafer attached into the 5 portions of water sample in turn, and take it out after standing for 5 minutes each time.

[0010] Step 4: Place the soaked glass slide under the Raman spectroscopy fiber optic probe, use a laser to focus on the surface of the silicon wafer to collect Raman signals, and then perform Raman shift qualitative determination on the collected Raman signals.

[0011] As can be seen from the technical solution provided by the present invention, the above method can realize the simultaneous multi-target and highly sensitive SERS analysis of multiple pesticides and antibiotics in flowing water, meeting the needs of highly sensitive, multi-target, and rapid analysis of multiple target pollutants in actual samples. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A schematic diagram of the analytical method for multi-target surface-enhanced Raman spectroscopy of pesticides and antibiotics in water provided in this embodiment of the invention. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments, and do not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0015] like Figure 1 This is a schematic flowchart of a method for analyzing pesticides and antibiotics in water using multi-target surface-enhanced Raman spectroscopy, provided in an embodiment of the present invention. The method includes:

[0016] Step 1: First, prepare an enhanced substrate for surface-enhanced Raman spectroscopy analysis;

[0017] In this step, 0.6 g to 1.0 g of polyvinylpyrrolidone-K30 is first dissolved in 35 mL of a mixed solution of ethylene glycol and anhydrous ethanol (v / v = 6:1) and stirred at room temperature for 45 minutes.

[0018] Add 20 mL of 5.5 mM silver chloride and mix and stir for 60 minutes in the dark.

[0019] Then add 2 mL of 6 mM sodium chloride ethylene glycol solution and 1 mL of 3.2 mM potassium nitrate, and mix and stir for 10 minutes. In practice, 2 mL of 6 mM sodium chloride ethylene glycol solution and 1 mL of 3.2 mM potassium nitrate must be added to prepare the reinforced substrate.

[0020] Next, add 20 mL of 5.5 mM silver chloride ethylene glycol solution and 30 mL of polyvinylpyrrolidone-K30 ethylene glycol solution, mix well, and then transfer to a reaction vessel to react at 140℃~180℃ for 1.5~2.5 h. After the reaction is completed, allow it to cool naturally to room temperature and remove it.

[0021] Then add 3 times the volume of ultrapure water and transfer to a clean beaker. Let it stand at room temperature for more than 48 hours, discard the supernatant, and wash the lower product three times with ultrapure water and methanol in turn, and then disperse it in methanol for later use. In practice, it is necessary to let it stand at room temperature for more than 48 hours, otherwise the yield will be less than 30%.

[0022] Take 20 mL of the prepared solution dispersed in methanol, centrifuge and discard the supernatant, then add 3 mg to 10 mg of 1,3,6,8-tetra(p-benzoic acid)pyrene and 10 mL of deionized water and stir for 1 min. In specific implementation, the added 1,3,6,8-tetra(p-benzoic acid)pyrene ligand is the core of the scheme of this application and is the key to achieving multi-target SERS analysis of various pesticides and antibiotics. The added 1,3,6,8-tetra(p-benzoic acid)pyrene ligand can be linked into an ordered porous crystal structure to capture various pesticides and antibiotics, thereby increasing the analytical concentration of the target analytes in subsequent SERS detection. Other ligand structures cannot achieve this function.

[0023] Add 8.3 mL of anhydrous ethanol and stir overnight. Wash the resulting product, which is the enhanced substrate for SERS analysis, three times with anhydrous ethanol and acetone, and then disperse it in methanol for later use.

[0024] Step 2: The prepared reinforced substrate is uniformly coated onto a 5×5mm silicon wafer using a vacuum filtration method, and the silicon wafer is then attached to a 25×75mm glass plate.

[0025] In this step, the vacuum filtration process is as follows:

[0026] Slowly pour the SERS-enhanced substrate solution, which is dispersed in methanol, into the filtration flask in three separate pours, with each pour lasting more than 30 seconds. Otherwise, the prepared substrate will be uneven. After filtration, let it stand and dry. Repeat the above operation three times.

[0027] Step 3: Take 100mL of the water sample to be analyzed and divide it into 5 portions. Immerse the glass slide with the silicon wafer attached into the 5 portions of water sample in turn, and take it out after standing for 5 minutes each time.

[0028] In this step, the 100mL water sample is divided into 5 portions, i.e., 20mL × 5. This operation is to maximize the adsorption of pollutants in the water. This method has higher analytical sensitivity compared to testing the 100mL water sample at once.

[0029] Each sample was allowed to stand for 10 minutes before being pretreated through a 0.22 μm filter membrane.

[0030] Step 4: Place the soaked glass slide under the Raman spectroscopy fiber optic probe, use a laser to focus on the surface of the silicon wafer to collect Raman signals, and then perform Raman shift qualitative determination on the collected Raman signals.

[0031] In this step, during the Raman signal collection process by focusing a laser on the silicon wafer surface, different points are randomly scanned 6 times and the average value is taken.

[0032] In practice, the Raman characteristic absorption shifts of pesticides and antibiotics (a total of 13 types) are determined by the enhancement effect of the substrate described in this invention. Specifically, under the enhancement effect of the substrate described in this embodiment, the vibrational and rotational absorption of the main functional groups of pesticides and antibiotics (a total of 13 types) can be effectively enhanced, thus their characteristic Raman absorption can be used as a basis for qualitative judgment. This method can simultaneously identify more than 10 pesticides and antibiotics, with an analytical sensitivity of 0.18–12.3 ng / mL, and detection can be completed within 30 minutes.

[0033] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0034] The method described in the embodiments of the present invention will be explained in detail below with specific examples:

[0035] Example 1

[0036] 1. First, an enhanced substrate for surface-enhanced Raman spectroscopy analysis is prepared.

[0037] 0.6 g of polyvinylpyrrolidone-K30 was dissolved in 35 mL of a mixture of ethylene glycol and anhydrous ethanol (v / v = 6:1) and stirred at room temperature for 45 minutes. 20 mL of 5.5 mM silver chloride was added, and the mixture was stirred for 60 minutes in the dark. Then, 2 mL of sodium chloride ethylene glycol solution (6 mM) and 1 mL of potassium nitrate (3.2 mM) were added, and the mixture was stirred for 10 minutes. Next, 20 mL of silver chloride ethylene glycol solution (5.5 mM) and 30 mL of polyvinylpyrrolidone-K30 ethylene glycol solution were added, and the mixture was thoroughly mixed. The mixture was then transferred to a reaction vessel and reacted at 140 °C for 1.5 h. After the reaction was complete, the mixture was allowed to cool naturally to room temperature. Three times the volume of ultrapure water was then added and transferred to a clean beaker. The mixture was allowed to stand at room temperature for at least 48 hours. The supernatant was discarded, and the lower layer product was washed three times with ultrapure water and methanol, and then dispersed in methanol for later use.

[0038] Take 20 mL of the above solution, centrifuge and discard the supernatant, then add 8 mg of 1,3,6,8-tetra(parabenzoic acid)pyrene, add 10 mL of deionized water and stir for 1 min, then pour in 8.3 mL of anhydrous ethanol and stir overnight. The product is washed three times with anhydrous ethanol and acetone, and finally dispersed in methanol for later use.

[0039] 2. The prepared reinforced substrate is uniformly coated onto the silicon wafer (5×5mm) by vacuum filtration. During the vacuum filtration process, the solution is slowly poured into the filtration flask in three batches (each batch is controlled to be more than 30 seconds). After filtration, the substrate is allowed to stand and dry. This step is repeated three times. The silicon wafer is then attached to the glass slide (25×75mm).

[0040] 3. The water sample to be analyzed is 100 mL, divided into 5 portions (20 mL × 5; the sample is allowed to stand for 10 min before being pretreated by a 0.22 μm filter membrane). The glass slides are then immersed in the 5 portions of surface water sample in sequence, and removed after standing for 5 min each time.

[0041] Finally, the glass slide was placed under the Raman spectroscopy fiber optic probe, and the laser was focused on the surface of the silicon wafer to collect Raman signals. Different points were randomly scanned 6 times, and the average value was taken.

[0042] 4. Qualitative determination of Raman shift was performed on the collected Raman signals, as detailed in Table 1 below:

[0043] Table 1

[0044]

[0045]

[0046] Example 2

[0047] 1. First, an enhanced substrate for surface-enhanced Raman spectroscopy analysis is prepared.

[0048] 0.8 g of polyvinylpyrrolidone-K30 was dissolved in 35 mL of a mixture of ethylene glycol and anhydrous ethanol (v / v = 6:1) and stirred at room temperature for 45 minutes. 20 mL of 5.5 mM silver chloride was added, and the mixture was stirred for 60 minutes in the dark. Then, 2 mL of 6 mM sodium chloride ethylene glycol solution and 1 mL of 3.2 mM potassium nitrate solution were added, and the mixture was stirred for 10 minutes. Next, 20 mL of 5.5 mM silver chloride ethylene glycol solution and 30 mL of polyvinylpyrrolidone-K30 ethylene glycol solution were added, and the mixture was thoroughly mixed. The mixture was then transferred to a reaction vessel and reacted at 160 °C for 2.5 h. After the reaction was complete, the mixture was allowed to cool naturally to room temperature. Three times the volume of ultrapure water was then added and transferred to a clean beaker. The mixture was allowed to stand at room temperature for at least 48 hours. The supernatant was discarded, and the lower layer product was washed three times successively with ultrapure water and methanol, and then dispersed in methanol for later use.

[0049] Take 20 mL of the above solution, centrifuge and discard the supernatant. Then add 3 mg of 1,3,6,8-tetra(p-benzoic acid)pyrene, add 10 mL of deionized water and stir for 1 min. Then add 8.3 mL of anhydrous ethanol and stir overnight. Wash the obtained product three times with anhydrous ethanol and acetone, and finally disperse it in methanol for later use.

[0050] 2. The prepared reinforced substrate is uniformly coated onto a silicon wafer (5×5mm) using a vacuum filtration method. During the vacuum filtration process, the solution is slowly poured into the filtration flask in three batches (each batch lasting more than 30 seconds). After filtration, the substrate is allowed to stand and dry. This step is repeated four times, and the silicon wafer is then attached to a glass slide (25×75mm).

[0051] 3. The water sample to be analyzed is 100 mL, divided into 5 portions (20 mL × 5; the sample is allowed to stand for 10 min before being pretreated by a 0.22 μm filter membrane). The glass slides are then immersed in the 5 portions of surface water sample in sequence, and removed after standing for 5 min each time.

[0052] Finally, the glass slide was placed under the Raman spectroscopy fiber optic probe, and the laser was focused on the surface of the silicon wafer to collect Raman signals. Different points were randomly scanned 6 times, and the average value was taken.

[0053] 4. Qualitative determination of Raman shift was performed on the collected Raman signals, as detailed in Table 2 below:

[0054] Table 2

[0055]

[0056] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for analyzing pesticides and antibiotics in water using multi-target surface-enhanced Raman spectroscopy, characterized in that, The method includes: Step 1: First, prepare an enhanced substrate for surface-enhanced Raman spectroscopy analysis; The process of step 1 is as follows: Dissolve 0.6g~1.0g of polyvinylpyrrolidone-K30 in 35mL of a mixed solution of ethylene glycol and anhydrous ethanol, and stir at room temperature for 45 minutes. Add 20 mL of 5.5 mM silver chloride and mix and stir for 60 minutes in the dark. Then add 2 mL of 6 mM sodium chloride ethylene glycol solution and 1 mL of 3.2 mM potassium nitrate, and mix and stir for 10 minutes; Next, add 20 mL of 5.5 mM silver chloride ethylene glycol solution and 30 mL of polyvinylpyrrolidone-K30 ethylene glycol solution, mix well, and then transfer to a reaction vessel to react at 140℃~180℃ for 1.5~2.5 h. After the reaction is completed, allow it to cool naturally to room temperature and remove it. Then add 3 times the volume of ultrapure water and transfer to a clean beaker. Let it stand at room temperature for more than 48 hours, discard the supernatant, and wash the lower layer product three times with ultrapure water and methanol in turn, and then disperse it in methanol for later use. Take 20 mL of the prepared solution dispersed in methanol, centrifuge and discard the supernatant, then add 3 mg to 10 mg of 1,3,6,8-tetra(p-benzoic acid)pyrene and 10 mL of deionized water and stir for 1 min; the added 1,3,6,8-tetra(p-benzoic acid)pyrene ligands can be linked into an ordered porous crystal structure to capture a variety of pesticides and antibiotics; Add 8.3 mL of anhydrous ethanol and stir overnight. Wash the resulting product, which is the enhanced substrate for SERS analysis, three times with anhydrous ethanol and acetone, and then disperse it in methanol for later use. Step 2: The prepared reinforced substrate is uniformly coated onto a 5×5mm silicon wafer using a vacuum filtration method, and the silicon wafer is then attached to a 25×75mm glass plate. Step 3: Take 100mL of the water sample to be analyzed and divide it into 5 portions. Immerse the glass slide with the silicon wafer attached into the 5 portions of water sample in turn, and take it out after standing for 5 minutes each time. Step 4: Place the soaked glass slide under the Raman spectroscopy fiber optic probe, use a laser to focus on the surface of the silicon wafer to collect Raman signals, and then perform Raman shift qualitative determination on the collected Raman signals.

2. The analytical method for multi-target surface-enhanced Raman spectroscopy of pesticides and antibiotics in water as described in claim 1, characterized in that, In step 2, the vacuum filtration process is as follows: Slowly pour the SERS-enhanced substrate solution, which is dispersed in methanol, into the filtration flask in three separate pours, with each pour lasting more than 30 seconds. Otherwise, the prepared substrate will be uneven. After filtration, let it stand and dry. Repeat the above operation three times.

3. The analytical method for multi-target surface-enhanced Raman spectroscopy of pesticides and antibiotics in water according to claim 1, characterized in that, In step 3, the 100 mL water sample is divided into 5 portions, i.e., 20 mL × 5; Each sample was allowed to stand for 10 minutes before being pretreated through a 0.22 μm filter membrane.

4. The analytical method for multi-target surface-enhanced Raman spectroscopy of pesticides and antibiotics in water as described in claim 1, characterized in that, In step 4, during the Raman signal collection process by focusing a laser on the silicon wafer surface, different points are randomly scanned 6 times and the average value is taken. Because the vibrational and rotational absorption of the main functional groups of pesticides and antibiotics is effectively enhanced under the reinforcement of the substrate, their characteristic Raman absorption energy can be used as a basis for qualitative judgment.

Images