Petroleum substance detection method based on SERS (Surface Enhanced Raman Scattering) technology and application

Abstract

The invention relates to the field of surface enhanced Raman detection, and discloses a petroleum substance detection method based on an SERS (Surface Enhanced Raman Scattering) technology and application. The detection method comprises the following steps: dropwise adding a solution to be detected onto a composite SERS detection chip, detecting by adopting a Raman spectrometer, and calculating the content of petroleum substances in the solution to be detected according to a formula c = 3.695 * 10 <-5 > a + 6.266 * 10 <-3 > b, wherein c is the concentration of the petroleum substances in the solution to be detected, the unit is mg / L, a is the Raman intensity at the wavelength of 1452 cm <-1 >, and b is the Raman intensity at the wavelength of 3062 cm <-1 >; the composite SERS detection chip comprises: a substrate having a groove; the silver nanowires and the metal nanoparticles are located in the grooves, the silver nanowires form a net structure, and the metal nanoparticles are loaded on the silver nanowires. By utilizing the surface enhanced Raman technology and combining with the composite SERS detection chip provided by the invention, quantitative detection of petroleum substances can be realized, and the precision is high.

Description

Technical Field

[0001] The present invention relates to the field of surface-enhanced Raman detection, and in particular to a detection method and application of petroleum substances based on SERS technology. Background Art

[0002] At present, methods for detecting trace petroleum in water all involve an extraction step, which requires corresponding manual operations or the provision of corresponding extraction equipment, and toxic organic solvents such as tetrachloroethylene and n-hexane. The detection limit of the gravimetric method is relatively high (10 mg / L). The infrared spectrophotometer method requires extraction and cannot directly detect aqueous solutions. The ultraviolet and fluorescence spectrophotometer methods can only detect petroleum substances with benzene rings and cannot detect alkanes, alkenes, etc., resulting in certain method errors. Due to problems such as complicated extraction operations, the involvement of more toxic organic reagents, and low detection sensitivity, it is of great significance to establish a set of rapid, real-time, and convenient analysis and detection technologies for petroleum substances to meet the severe safety and environmental protection situation in the chemical industry.

[0003] Surface Enhanced Raman Spectroscopy (SERS) technology refers to the phenomenon that when the laser of a Raman spectrometer is incident on some specially prepared nano-substrates or sols, the Raman scattering signal of the adsorbed molecules is greatly enhanced compared with the ordinary Raman signal due to the enhancement of the electromagnetic field on the surface of the nano-structure. This technology can overcome the characteristics of low intensity and sensitivity of ordinary Raman spectroscopy, and has the advantages of high sensitivity, rich chemical fingerprint information, direct detection of aqueous solutions, simplicity and convenience, etc., and is widely used in detection and identification fields such as material preparation, chemical analysis, biological detection, and medical health. To achieve the detection of trace petroleum substances through SERS technology, it is necessary to construct a suitable SERS enhancement substrate to enhance the Raman signal of petroleum substances, and then further realize its qualitative and quantitative detection through the mathematical relationship between the concentration of petroleum substances and the intensity of Raman signals.

[0004] Patent application CN 107490559 A discloses a method for determining the petroleum content in solid waste in oil fields, and the steps are as follows: (1) Accurately weigh 10 g of solid waste sample, transfer it to a conical flask, add 40 mL of carbon tetrachloride, tighten the tube plug, place it in an ultrasonic cleaner, and perform ultrasonic extraction in a 40 °C water bath for 30 min; (2) After the oscillation is completed, take out the conical flask, let it stand still for 15 min, and then pour all the solutions and samples in the conical flask into a sintered glass funnel; (3) Place the conical flask containing magnesium silicate on a reciprocating speed control oscillator and oscillate for 30 min. After the oscillation is completed, transfer all the solutions in the conical flask to a colorimetric tube through a sintered glass funnel, and detect with an infrared spectrometer, and calculate the petroleum content in the solid waste in the oil field through calculation. Patent application CN113984668 A provides a portable detector and rapid detection method for petroleum pollutants in soil and groundwater based on Raman spectroscopy. Detection method: Sampling soil or groundwater for detection, and the detection includes: detecting Raman signals in the long-wavelength mode, and qualitatively identifying pollutants through comparison with a spectral database; detecting fluorescence signals in the short-wavelength mode, and obtaining the pollutant concentration based on the fluorescence intensity corresponding to the wavenumber at the maximum spectral intensity The relationship between the petroleum pollutant concentration. Patent application CN115078296 A relates to a detection method for petroleum pollutants in soil. It includes the following steps: 1) Load the collected soil sample into an accelerated solvent extractor, quickly rinse and extract with a solvent, and perform a cyclic extraction process, and then concentrate by nitrogen purging, purify with a small column, and elute and make up the volume to obtain the sample; 2) Use an infrared spectrophotometer for detection and calculate the mass concentration of petroleum. Summary of the Invention

[0005] The object of the present invention is to overcome the problem that the concentration of trace petroleum mixtures cannot be quantitatively detected by SERS technology, and provide a detection method and application of petroleum substances based on SERS technology. This detection method uses surface-enhanced Raman technology to obtain a standard curve of concentration and Raman intensity by measuring the Raman signal intensity of the characteristic peaks of petroleum substances under the conditions of not involving extraction and toxic organic substances, and realizes the quantitative detection of petroleum substances.

[0006] To achieve the above object, on the one hand, the present invention provides a detection method of petroleum substances based on SERS technology. This detection method includes the following steps: Drop the solution to be measured onto a composite SERS detection chip, detect it with a Raman spectrometer, and calculate the content of petroleum substances in the solution to be measured according to the formula c = 3.695×10 -5 a + 6.266×10 -3 b.

[0007] Wherein, c is the concentration of petroleum substances in the solution to be measured, with the unit of mg / L, a is 1452 cm -1Raman intensity at the wavelength, b is 3062 cm -1 Raman intensity at the wavelength;

[0008] The composite SERS detection chip includes:

[0009] A bottom plate with grooves; and

[0010] Silver nanowires and metal nanoparticles located in the grooves, and the silver nanowires form a network structure, and the metal nanoparticles are loaded on the silver nanowires.

[0011] Preferably, the dosage of the solution to be measured is 2 - 12 μL.

[0012] Preferably, the detection conditions for detection using a Raman spectrometer include: a power of 0.2 - 1.5 mW, an integration time of 10 - 80 s, and an integration number of 1 - 4 times.

[0013] Preferably, the diameter of the silver nanowires is 10 - 50 nm, and the length is 12 - 60 μm.

[0014] Preferably, the metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0015] Preferably, the size of the metal nanoparticles is 10 - 80 nm.

[0016] Preferably, the bottom area of the groove is 2 - 20 mm 2 , and the height is 4 - 10 mm.

[0017] Preferably, the preparation method of the composite SERS detection chip includes the following steps:

[0018] (1) Provide a bottom plate with grooves;

[0019] (2) Inject a mixed solution containing silver nanowires and metal nanoparticles into the grooves, then place the bottom plate in liquid nitrogen, and then perform freeze-drying;

[0020] Wherein, in the mixed solution containing silver nanowires and metal nanoparticles, the concentration of silver nanowires is 15 - 80 mg / mL, and the concentration of metal nanoparticles is 20 - 70 mg / mL.

[0021] Preferably, in the solution containing silver nanowires and metal nanoparticles, the weight ratio of silver nanowires to metal nanoparticles is 1:0.5 - 1.5.

[0022] Preferably, the material of the bottom plate is a polymer material, silicon nitride, glass, silicon wafer or metal.

[0023] Preferably, the polymer material is selected from PMMA, PC, PVC or PET.

[0024] Preferably, the injection volume of the mixed solution containing silver nanowires and metal nanoparticles and the volume of the groove are in a ratio of 0.4 - 0.9:1.

[0025] Preferably, the conditions for freeze-drying include: a pressure of 1 - 50 Pa and a time of 6 - 30 h.

[0026] The second aspect of the present invention provides an application of the above detection method in the detection of trace petroleum molecules.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. For the composite SERS detection chip used in the present invention, the detection of petroleum substances can be achieved without introducing modification molecules. Specifically, the silver nanowires located in the grooves of the bottom plate form a network structure, and at the same time, metal nanoparticles are loaded on the silver nanowires. After the test solution is injected into the grooves, it can be quickly absorbed by the composite structure of the silver nanowires and metal nanoparticles, and then collapse, fixing the target molecules in the nanogaps formed by the silver nanowires and metal nanoparticles.

[0029] 2. The preparation method of the composite SERS detection chip of the present invention has the characteristics of simple steps, controllable size, and does not require the use of large and expensive instruments. Combining with the freeze-drying technology, the silver nanowires self-assemble into a network structure, and at the same time, metal nanoparticles adhere to the silver nanowires, facilitating the adsorption of the test molecules in the solution.

[0030] 3. The present invention uses surface-enhanced Raman technology, combined with the composite SERS detection chip of the present invention, to obtain a standard curve of concentration and Raman intensity by measuring the Raman signal intensity of the characteristic peaks of petroleum substances, realizing the quantitative detection of petroleum substances. This method does not involve extraction operations and toxic organic reagents, and is green and environmentally friendly. At the same time, the operation steps are simple, the detection time is shortened, the overall detection time is 10 min, the detection efficiency can be effectively improved, and it is conducive to further promotion and application. Description of the Drawings

[0031] Figure 1 is a schematic diagram of the detection process of the present invention;

[0032] Figure 2 is a top view of the optical photograph of the composite SERS detection chip obtained in Example 1;

[0033] Figure 3 is a scanning photograph of the composite SERS detection chip obtained in Example 1;

[0034] Figure 4 is a Raman spectrogram of the detection of petroleum substances in Example 1;

[0035] Figure 5 is the Raman spectrum of the detection of petroleum substances in Example 2;

[0036] Figure 6 is the Raman spectrum of the detection of petroleum substances in Example 3. Detailed implementation manners

[0037] The following will describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention.

[0038] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0039] On the one hand, the present invention provides a method for detecting petroleum substances based on SERS technology. The detection method includes the following steps: dropping a solution to be detected onto a composite SERS detection chip, detecting with a Raman spectrometer, and calculating the content of petroleum substances in the solution to be detected according to the formula c = 3.695×10 -5 a + 6.266×10 -3 b;

[0040] where c is the concentration of petroleum substances in the solution to be detected, with the unit of mg / L, a is the Raman intensity at the wavelength of 1452 cm -1 and b is the Raman intensity at the wavelength of 3062 cm -1 ;

[0041] The composite SERS detection chip includes:

[0042] a bottom film with grooves; and

[0043] silver nanowires and metal nanoparticles located in the grooves, and the silver nanowires form a network structure, and the metal nanoparticles are loaded on the silver nanowires.

[0044] In the present invention, petroleum substances generally include substances such as alkanes, alkenes, and polycyclic aromatic hydrocarbons. The solution to be detected can be from river water, domestic sewage, and industrial effluent sewage, etc. The content of petroleum substances detected by the method of the present invention is the total content of various petroleum substances in the solution to be detected.

[0045] In a preferred embodiment, to obtain a better detection effect, the dosage of the solution to be tested is preferably controlled to be 2-12 μL, specifically it can be 2 μL, 4 μL, 6 μL, 8 μL, 10 μL or 12 μL.

[0046] In a preferred case, the detection conditions for detection using a Raman spectrometer include: the power is 0.2-1.5 mW, the integration time is 10-80 s, and the integration times is 1-4 times.

[0047] In a specific embodiment, when using a Raman spectrometer for detection, the laser wavelength is 633 nm.

[0048] In the detection method of the present invention, the signal at 1452 cm -1 wavelength represents the characteristic peak of aliphatic hydrocarbon (-CH2), and the signal at 3062 cm -1 wavelength represents the characteristic peak of benzene ring substances. By detecting the Raman intensities at these two wavelengths and substituting them into the formula of the present invention, the concentration of petroleum substances in the solution to be tested can be calculated.

[0049] In the detection method of the present invention, to obtain better detection results, a specific composite SERS detection chip is used for detection. In this composite SERS detection chip, the silver nanowires located in the groove form a network structure through self-assembly and can also serve as a carrier for metal nanoparticles. Based on the cooperation of silver nanowires and metal nanoparticles, more nano-gaps can be formed, providing an electromagnetic field enhancement region with stronger intensity and higher density, thereby improving the detection sensitivity.

[0050] In a preferred embodiment, the diameter of the silver nanowires is 10-50 nm, preferably 20-40 nm, and the length is 12-60 μm, preferably 20-45 μm.

[0051] In a preferred embodiment, the metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0052] In a specific embodiment, the metal nanoparticles can be gold nanospheres, silver nanospheres, gold nanorods, silver nanocubes, gold nanotriangles, etc.

[0053] Further preferably, the size of the metal nanoparticles is 10-80 nm.

[0054] Further preferably, the metal nanoparticles are gold nanorods with a diameter of 10-20 nm and a length of 30-70 nm.

[0055] Preferably, the bottom area of the groove is 2-20 mm 2 , and the height is 4-10 mm.

[0056] In a specific embodiment, the bottom area of the groove can be 2 mm 2 , 5 mm 2 , 10 mm 2 , 15 mm 2 or 20 mm 2 , and the height of the groove can be 4 mm, 5 mm, 6 mm, 8 mm or 10 mm.

[0057] In a preferred embodiment, to obtain the above-mentioned composite SERS detection chip, the preparation method of the composite SERS detection chip includes the following steps:

[0058] (1) Provide a negative film with a groove;

[0059] (2) Inject a mixed solution containing silver nanowires and metal nanoparticles into the groove, then place the negative film in liquid nitrogen, and then perform freeze-drying;

[0060] Among them, in the mixed solution containing silver nanowires and metal nanoparticles, the concentration of silver nanowires is 15 - 80 mg / mL, and the concentration of metal nanoparticles is 20 - 70 mg / mL.

[0061] In the method of the present invention, a solution containing silver nanowires and metal nanoparticles is injected into the groove of the negative film. The ultra-low temperature of liquid nitrogen can quickly turn the solution into a solid state, and then through the freeze-drying technology, the solvent can be sublimated without destroying the structure formed by silver nanowires and metal nanoparticles. The present invention combines the freeze-drying technology to obtain a composite SERS detection chip, which does not involve large and expensive instruments such as vacuum coating machines and electron beam etching machines, and is convenient for further popularization and application.

[0062] In the present invention, the concentration of silver nanowires in the solution containing silver nanowires and metal nanoparticles is reasonably controlled. If the concentration is too low, the network structure is prone to collapse during freeze-drying. If the concentration is too high, the cost will increase. Therefore, the present invention limits the concentration of the silver nanowire solution to 15 - 80 mg / mL, and the concentration of the metal nanoparticle solution to 20 - 70 mg / mL. It can not only form a stable network structure, but also ensure the economic practicality of the method, and effectively improve the detection sensitivity.

[0063] In the present invention, the silver nanowires can be commercially available products or self-made in the laboratory.

[0064] In a specific embodiment, when the silver nanowires are self-made in the laboratory, the silver nanowires can be prepared according to the following process:

[0065] A1: Mix polyvinylpyrrolidone and water, and then add AgNO3 for mixing to obtain a mixture;

[0066] A2: Hydrothermally react the mixture and then perform solid-liquid separation.

[0067] Preferably, the weight ratio of the dosage of polyvinylpyrrolidone to AgNO3 is 1:0.04 - 0.15, specifically it can be 1:0.04, 1:0.07, 1:0.1 or 1:0.15.

[0068] Preferably, in step A2, the conditions of the hydrothermal reaction include: the temperature is 120 - 180 °C and the time is 5 - 12 h.

[0069] Preferably, the solid-liquid separation can be carried out by centrifugation.

[0070] In the present invention, the metal nanoparticles can be commercially available products or self-made in the laboratory.

[0071] According to some specific embodiments of the present invention, when the gold nanorods are obtained by self-making in the laboratory, the gold nanorods can be prepared according to the following procedures:

[0072] B1: Mix cetyltrimethylammonium bromide (CTAB), HAuCl4 and water, and then add NaBH4 for mixing to obtain a first mixed solution;

[0073] B2: Mix CTAB, HAuCl4 and water, and then add ascorbic acid for mixing to obtain a second mixed solution;

[0074] B3: Mix the first mixed solution and the second mixed solution for reaction, then add NaCl and continue the reaction, perform solid-liquid separation, and wash.

[0075] Preferably, in step B1, the molar ratio of the dosages of CTAB, HAuCl4 and NaBH4 is 1:2 - 3:0.003 - 0.01, specifically it can be 1:2:0.003, 1:2:0.005, 1:2:0.007, 1:2:0.01, 1:2.5:0.003, 1:2.5:0.005, 1:2.5:0.007, 1:2.5:0.01, 1:3:0.003, 1:3:0.005, 1:3:0.007 or 1:3:0.01.

[0076] Preferably, in step B2, the molar ratio of the amounts of CTAB, HAuCl4, and ascorbic acid used is 1:0.01 to 0.04:0.01 to 0.07, specifically, it can be 1:0.01:0.01, 1:0.01:0.03, 1:0.01:0.05, 1:0.01:0.07, 1:0.03:0.01, 1:0.03:0.03, 1:0.03:0.05, 1:0.03:0.07, 1:0.04:0.01, 1:0.04:0.03, 1:0.04:0.05, or 1:0.04:0.07.

[0077] In a preferred embodiment, in step B3, when the first mixed solution and the second mixed solution are mixed, the volume ratio of the first mixed solution to the second mixed solution is 1:350 to 450, where the amount of the first mixed solution is based on the molar amount of CTAB introduced when preparing the first mixed solution, and the amount of the second mixed solution is based on the molar amount of CTAB introduced when preparing the second mixed solution.

[0078] Preferably, in the solution containing silver nanowires and metal nanoparticles, the weight ratio of silver nanowires to metal nanoparticles is 1:0.5 - 1.5, specifically, it can be 1:0.5, 1:0.7, 1:1, 1:1.2, or 1:1.5.

[0079] Preferably, the material of the negative film is a polymer material, silicon nitride, glass, silicon wafer, or metal.

[0080] Preferably, the polymer material is selected from PMMA, PC, PVC, or PET.

[0081] In a preferred case, the volume ratio of the injection volume of the mixed solution containing silver nanowires and metal nanoparticles to the volume of the groove is 0.4 - 0.9:1, specifically, it can be 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, or 0.9:1.

[0082] Preferably, the conditions for freeze-drying include: a pressure of 1 - 50 Pa and a time of 6 - 30 h.

[0083] In a specific embodiment, the pressure for freeze-drying can be 1 Pa, 10 Pa, 20 Pa, 30 Pa, 40 Pa, or 50 Pa, and the time for freeze-drying can be 6 h, 10 h, 15 h, 20 h, 25 h, or 30 h.

[0084] In a specific embodiment, the combination participates Figure 1During the Raman detection process, the process of treating the solution to be detected using the composite SERS detection chip of the present invention includes: dropping the solution to be detected into the groove, and the solution to be detected quickly fills the entire groove. As the liquid evaporates, the silver nanowire network structure in the groove will collapse, and the target molecules will be wrapped in the nano-gaps between the silver nanowires and the metal nanoparticles.

[0085] The present invention discloses a detection method for petroleum substances based on SERS technology. A SERS detection chip of silver nanowires - metal nanoparticles is prepared by freeze-drying technology. Then, through this chip, the Raman signal intensity of petroleum substances is detected, and thus the concentration of petroleum substances is obtained. This method does not involve an extraction process and toxic organic reagents, and does not involve fluorescence detection, and can better reflect the content of various parameters in petroleum substances, and the detection steps are simple and fast.

[0086] The second aspect of the present invention provides an application of the above detection method in the detection of trace petroleum molecules.

[0087] The detection method of the present invention has the following characteristics:

[0088] 1. Detecting trace petroleum substances in water by SERS technology, without involving extraction operations and toxic organic reagents, which is green and environmentally friendly and has high economic efficiency.

[0089] 2. Compared with the current detection time of 30 - 60 minutes, this detection method is simple and fast to operate, and the overall measurement time ≤ 10 minutes, which can effectively improve the detection efficiency.

[0090] 3. This method can be applied to on-site rapid detection, not only limited to laboratory detection, with a wide application range, suitable for detecting petroleum substances in various water quality detection fields such as petrochemical enterprise sewage, domestic wastewater, and environmental sewage, which is conducive to further promotion and application.

[0091] The present invention will be described in detail below through embodiments, but the protection scope of the present invention is not limited thereto.

[0092] Example 1

[0093] Preparing a composite SERS detection chip:

[0094] (1) Providing a negative film with a groove, the material of the negative film is PET, the shape of the negative film is rectangular, the thickness of the negative film is 10 mm, and the bottom area of the groove is 3.5 mm 2 , and the height of the groove is 5 mm;

[0095] (2) Mix commercially available silver nanowires (with a diameter of 25 nm and a length of 23 μm), commercially available gold nanorods (with a diameter of 18 nm and a length of 40 nm) and water to obtain a mixed solution, and control the concentration of silver nanowires in the mixed solution to be 50 mg / mL and the concentration of gold nanorods to be 45 mg / mL;

[0096] Take 13 μL of the mixed solution and drop it into the groove of the substrate, and then put the substrate into liquid nitrogen together. Further, place it in a freeze dryer and place it for 23 h under a vacuum of 8 Pa to obtain a composite SERS detection chip;

[0097] Use an Olympus CX31 microscope to take pictures of the prepared chip, and the results are as Figure 2 shown; use SEM to characterize the prepared chip, and the results are as Figure 3 shown;

[0098] It can be observed from Figure 2 that the silver nanowire-gold nanorod composite structure is distributed in the groove of the substrate.

[0099] It can be observed from Figure 3 that the silver nanowires cross each other to form a loose network structure, and the gold nanorods are attached to the network structure.

[0100] Detection of petroleum substances:

[0101] Drop 5 μL of a self-prepared aqueous solution of n-hexadecane with a concentration of 0.1 mg / L into the groove of the composite SERS detection chip. After the solvent has evaporated completely, use a Horiba Xplus microscopic confocal Raman spectrometer to test the substrate. Select a laser with a wavelength of 633 nm, a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. The Raman spectrum is as Figure 4 shown. The Raman signal intensity at 1452 cm -1 is 2654; that is, a is 2654. Since there is no benzene ring structure in n-hexadecane, there is no characteristic peak at the wavelength of 3062 cm -1 . b is 0; Substitute into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, and calculate the concentration c of petroleum substances (n-hexadecane) in the aqueous solution of n-hexadecane to be 0.098 mg / L, and the calculated error is 2%.

[0102] Example 2

[0103] 5 μL of a self-prepared aqueous solution of benzene with a concentration of 10 mg / L was dropped into the groove of the composite SERS detection chip in Example 1. After the solvent had evaporated completely, the substrate was tested using a Horiba Xplus micro confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, with a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. The Raman spectrum is as shown in Figure 5 and the Raman signal intensity at 3062 cm -1 is 1698; that is, b is 1698. Since benzene does not have an aliphatic hydrocarbon structure, there is no characteristic peak at the wavelength of 1452 cm -1 , so a is 0. Substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the concentration c of petroleum substances (benzene) in the aqueous solution of benzene is calculated to be 10.6 mg / L, and the calculated error is 6%.

[0104] Example 3

[0105] 5 μL of a self-prepared aqueous solution of petroleum substances (benzene and n-hexadecane, with a total concentration of benzene and n-hexadecane of 5.9 mg / L) with a concentration of 5.9 mg / L was dropped into the groove of the composite SERS detection chip in Example 1. After the solvent had evaporated completely, the substrate was tested using a Horiba Xplus micro confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, with a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. The Raman spectrum is as shown in Figure 6 and the Raman signal intensity at 1452 cm -1 is 2279, and the Raman signal intensity at 3062 cm -1 is 905; that is, a is 2279 and b is 905. Substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the total concentration c of petroleum substances (benzene and n-hexadecane) in the aqueous solution of petroleum substances is calculated to be 5.75 mg / L, with an error of 2.5%.

[0106] Example 4

[0107] 5 μL of a self-prepared aqueous solution of petroleum substances (benzene and n-hexadecane, with a total concentration of benzene and n-hexadecane of 0.5 mg / L) with a concentration of 0.5 mg / L was dropped into the groove of the composite SERS detection chip in Example 1. After the solvent had evaporated completely, the substrate was tested using a Horiba Xplus micro confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, with a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. At 1452 cm -1The Raman signal intensity at [location] is 1258, at 3062 cm -1 The Raman signal intensity at [location] is 67; that is, a is 1258 and b is 67; substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the total concentration c of petroleum substances (benzene and n-hexadecane) in the aqueous solution of petroleum substances is calculated to be 0.47 mg / L, and the calculated error is 6%.

[0108] Example 5

[0109] 5 μL of an aqueous solution of petroleum substances (benzene and n-hexadecane, with a total concentration of benzene and n-hexadecane of 0.25 mg / L) prepared by oneself was dropped into the groove of the composite SERS detection chip in Example 1. After the solvent evaporated completely, the substrate was tested with a Horiba Xplus micro confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, the power was 0.6 mW, the integration time was 35 s, and the integration times was 2 times. The Raman signal intensity at 1452 cm -1 was 125, and the Raman signal intensity at 3062 cm -1 was 36; that is, a was 125 and b was 36; substituting into the formula c = 3.695×10 -5 a + 6.266×10 - 3 b, the total concentration c of petroleum substances (benzene and n-hexadecane) in the aqueous solution of petroleum substances was calculated to be 0.23 mg / L, and the calculated error was 8%.

[0110] Example 6

[0111] 5 μL of an aqueous solution of petroleum substances (benzene and n-hexadecane, with a total concentration of benzene and n-hexadecane of 3.2 mg / L) prepared by oneself was dropped into the groove of the composite SERS detection chip in Example 1. After the solvent evaporated completely, the substrate was tested with a Horiba Xplus micro confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, the power was 0.6 mW, the integration time was 35 s, and the integration times was 2 times. The Raman signal intensity at 1452 cm -1 was 2475, and the Raman signal intensity at 3062 cm -1 was 486; that is, a was 2475 and b was 486; substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the total concentration c of petroleum substances (benzene and n-hexadecane) in the aqueous solution of petroleum substances was calculated to be 3.14 mg / L, and the calculated error was 1.9%.

[0112] Example 7

[0113] 5 μL of an aqueous solution of self-prepared petroleum substances (benzene and n-hexadecane, with a total concentration of benzene and n-hexadecane of 10 mg / L) was dropped into the groove of the composite SERS detection chip in Example 1. After the solvent had evaporated completely, the substrate was tested using a Horiba Xplus micro confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, with a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. The Raman signal intensity at 1452 cm -1 was 7019, and the Raman signal intensity at 3062 cm -1 was 1678; that is, a was 7019 and b was 1678. Substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the total concentration c of petroleum substances (benzene and n-hexadecane) in the aqueous solution of petroleum substances was calculated to be 10.8 mg / L, and the calculated error was 8%.

[0114] Example 8

[0115] Preparing a composite SERS detection chip:

[0116] (1) Providing a negative film with a groove. The material of the negative film is PET, the shape of the negative film is rectangular, the thickness of the negative film is 10 mm, the bottom area of the groove is 3.5 mm 2 , and the height of the groove is 5 mm;

[0117] (2) Mixing commercially available silver nanowires (with a diameter of 25 nm and a length of 23 μm), commercially available gold nanorods (with a diameter of 18 nm and a length of 40 nm), and water to obtain a mixed solution, and controlling the concentration of silver nanowires in the mixed solution to be 45 mg / mL and the concentration of gold nanorods to be 40 mg / mL;

[0118] 13 μL of the mixed solution was taken and dropped into the groove of the negative film, and then the negative film was placed into liquid nitrogen together. Further, it was placed in a freeze dryer and left for 23 h under a vacuum of 8 Pa to obtain a composite SERS detection chip;

[0119] 5 μL of an aqueous solution of self-prepared n-hexadecane with a concentration of 0.1 mg / L was dropped into the groove of the composite SERS detection chip. After the solvent had evaporated completely, the substrate was tested using a Horiba Xplus micro confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, with a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. The Raman signal intensity at 1452 cm -1The Raman signal intensity at [the specific position] is 2596; that is, a is 2596. Since there is no benzene ring structure in n - hexadecane, there is no characteristic peak at 3062 cm -1 wavelength, and b is 0; substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the concentration c of petroleum substances (n - hexadecane) in the aqueous solution of n - hexadecane is calculated to be 0.096 mg / L, and the calculated error is 4%.

[0120] Example 9

[0121] Prepare a composite SERS detection chip:

[0122] (1) Provide a bottom plate with grooves. The material of the bottom plate is PET, the shape of the bottom plate is rectangular, the thickness of the bottom plate is 10 mm, the bottom area of the groove is 3.5 mm 2 , and the height of the groove is 5 mm;

[0123] (2) Mix commercially available silver nanowires (diameter 25 nm, length 23 μm), commercially available gold nanorods (diameter 18 nm, length 40 nm) and water to obtain a mixed solution, and control the concentration of silver nanowires in the mixed solution to be 50 mg / mL and the concentration of gold nanorods to be 45 mg / mL;

[0124] Take 15.5 μL of the mixed solution and drop it into the groove of the bottom plate, then put the bottom plate into liquid nitrogen together. Further, place it in a freeze - dryer, and place it for 23 h under a vacuum of 8 Pa to obtain a composite SERS detection chip;

[0125] Drop 5 μL of the self - prepared aqueous solution of n - hexadecane with a concentration of 0.1 mg / L onto the groove of the composite SERS detection chip. After the solvent has evaporated, use a Horiba Xplus micro - confocal Raman spectrometer to test the substrate. Select a laser with a wavelength of 633 nm, a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. The Raman signal intensity at 1452 cm -1 is 2753; that is, a is 2753. Since there is no benzene ring structure in n - hexadecane, there is no characteristic peak at 3062 cm -1 wavelength, and b is 0; substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the concentration c of petroleum substances (n - hexadecane) in the aqueous solution of n - hexadecane is calculated to be 0.102 mg / L, and the calculated error is 2%.

[0126] Example 10

[0127] Prepare a composite SERS detection chip:

[0128] (1) Provide a negative film with grooves. The material of the negative film is PET, the shape of the negative film is rectangular, the thickness of the negative film is 10 mm, the bottom area of the groove is 3.5 mm 2 , and the height of the groove is 5 mm;

[0129] (2) Mix commercially available silver nanowires (diameter: 25 nm, length: 23 μm), commercially available gold nanorods (diameter: 18 nm, length: 40 nm) and water to obtain a mixed solution. Control the concentration of silver nanowires in the mixed solution to be 50 mg / mL and the concentration of gold nanorods to be 45 mg / mL;

[0130] Take 13 μL of the mixed solution and drop it into the groove of the negative film. After the solvent has completely evaporated, a composite SERS detection chip is obtained;

[0131] Drop 5 μL of a self-prepared aqueous solution of n-hexadecane with a concentration of 0.1 mg / L into the groove of the composite SERS detection chip. After the solvent has evaporated completely, use a Horiba Xplus micro confocal Raman spectrometer to test the substrate. Select a laser with a wavelength of 633 nm, a power of 0.6 mW, an integration time of 35 s, and an integration number of 2 times. At 1452 cm -1 , the Raman signal intensity is 2317; that is, a is 2317. Since there is no benzene ring structure in n-hexadecane, there is no characteristic peak at the wavelength of 3062 cm -1 . b is 0. Substitute into the formula c = 3.695×10 -5 a + 6.266×10 -3 b. Calculate the concentration c of petroleum substances (n-hexadecane) in the aqueous solution of n-hexadecane to be 0.086 mg / L, and the calculated error is 14%.

[0132] In this example, the SERS substrate is obtained by evaporating the solvent in the mixed solution, and the freeze-drying technology is not used for preparation, resulting in a reduction in the number of target molecules entering the nanogap, thereby resulting in lower Raman intensity and larger detection error.

[0133] Comparative Example 1

[0134] Prepare a composite SERS detection chip:

[0135] (1) Provide a negative film with grooves. The material of the negative film is PET, the shape of the negative film is rectangular, the thickness of the negative film is 10 mm, the bottom area of the groove is 3.5 mm 2 , and the height of the groove is 5 mm;

[0136] (2) Commercially available silver nanowires (with a diameter of 25 nm and a length of 23 μm) and water were selected and mixed to obtain a mixed solution, and the concentration of silver nanowires in the mixed solution was controlled to be 50 mg / mL;

[0137] 13 μL of the mixed solution was taken and dropped into the groove of the substrate, and then the substrate was placed in liquid nitrogen together. Further, it was placed in a freeze dryer and left for 23 h under a vacuum degree of 8 Pa to obtain a composite SERS detection chip;

[0138] 5 μL of an aqueous solution of n - hexadecane with a concentration of 0.1 mg / L was dropped into the groove of the composite SERS detection chip. After the solvent had evaporated completely, the substrate was tested with a Horiba Xplus micro - confocal Raman spectrometer. A laser with a wavelength of 633 nm was selected, the power was 0.6 mW, the integration time was 35 s, and the number of integrations was 2 times. The Raman signal intensity at 1452 cm -1 was 2176; that is, a was 2176. Since there is no benzene ring structure in n - hexadecane, there was no characteristic peak at 3062 cm -1 wavelength, and b was 0; substituting into the formula c = 3.695×10 -5 a + 6.266×10 -3 b, the concentration c of petroleum substances (n - hexadecane) in the aqueous solution of n - hexadecane was calculated to be 0.08 mg / L, and the calculated error was 20%.

[0139] In this comparative example, there are only silver nanowires in the composite SERS detection chip and no metal particles, resulting in a decrease in the intensity and density of the electromagnetic field enhancement region of the substrate, thus leading to a low Raman intensity and a large error.

[0140] According to the above results, the present invention uses surface - enhanced Raman technology, combined with the composite SERS detection chip of the present invention, to obtain a standard curve of concentration versus Raman intensity by measuring the Raman signal intensity of the characteristic peaks of petroleum substances, realizing the quantitative detection of petroleum substances with an error of less than 15% and high precision.

[0141] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A detection method for petroleum substances based on SERS technology, characterized in that, The detection method includes the following steps: dropping the solution to be measured onto the composite SERS detection chip, detecting it with a Raman spectrometer, and calculating the content of petroleum substances in the solution to be measured according to the formula c = 3.695×10 -5 a + 6.266×10 -3 b; Among them, c is the concentration of petroleum substances in the solution to be measured, with the unit of mg / L, a is the Raman intensity at a wavelength of 1452 cm -1 and b is the Raman intensity at a wavelength of 3062 cm -1 . The composite SERS detection chip includes: a bottom plate with grooves; and silver nanowires and metal nanoparticles located in the grooves, wherein the silver nanowires form a network structure and the metal nanoparticles are loaded on the silver nanowires.

2. The detection method according to claim 1, wherein The dosage of the solution to be measured is 2 - 12 μL.

3. The detection method according to claim 1 or 2, characterized in that The detection conditions for detection using a Raman spectrometer include: a power of 0.2 - 1.5 mW, an integration time of 10 - 80 s, and an integration number of 1 - 4 times.

4. The detection method according to claim 1, wherein The diameter of the silver nanowires is 10 - 50 nm, and the length is 12 - 60 μm.

5. The detection method according to claim 1, wherein The metal nanoparticles are gold nanoparticles or silver nanoparticles.

6. The detection method according to claim 1 or 5, characterized in that The size of the metal nanoparticles is 10 - 80 nm.

7. The detection method according to any one of claims 1, 4 or 5, characterized in that The bottom area of the groove is 2 - 20 mm 2 , and the height is 4 - 10 mm.

8. The detection method according to claim 1, characterized in that The preparation method of the composite SERS detection chip includes the following steps: (1) Provide a bottom plate with grooves; (2) Inject a mixed solution containing silver nanowires and metal nanoparticles into the grooves, then place the bottom plate in liquid nitrogen, and then perform freeze-drying; Among them, in the mixed solution containing silver nanowires and metal nanoparticles, the concentration of silver nanowires is 15 - 80 mg / mL, and the concentration of metal nanoparticles is 20 - 70 mg / mL.

9. The detection method according to claim 8, wherein In the solution containing silver nanowires and metal nanoparticles, the weight ratio of silver nanowires to metal nanoparticles is 1:0.5 - 1.

5.

10. The detection method according to claim 7 or 8, characterized in that, The material of the bottom plate is a polymer material, silicon nitride, glass, silicon wafer or metal.

11. The detection method according to claim 10, characterized in that, The polymer material is selected from PMMA, PC, PVC or PET.

12. The detection method according to claim 7, wherein The volume ratio of the injection volume of the mixed solution containing silver nanowires and metal nanoparticles to the volume of the grooves is 0.4 - 0.9:

1.

13. The detection method according to claim 7, characterized in that The conditions for freeze-drying include: a pressure of 1 - 50 Pa and a time of 6 - 30 h.

14. Application of the detection method according to any one of claims 1 - 13 in the detection of trace petroleum molecules.

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