Method for eliminating spurious peaks of silver-based surface-enhanced Raman substrate and trace detection method

Abstract

The present disclosure provides a method for eliminating spurious peaks of a silver-based surface-enhanced Raman substrate, including: preparing a palladium ion-containing solution; using the palladium ion-containing solution to modify the surface of the silver-based surface-enhanced Raman substrate so that the palladium ions combine with the surface to form a thin layer of palladium atoms covering the surface; wherein the thin layer of palladium atoms is used to remove adsorbed impurities and oxidation substances on the surface. Without damaging the sensitivity of the silver-based SERS substrate, this method eliminates the interference of impurity peaks adsorbed on the silver-based substrate, solves problems such as easy oxidation of nano silver, and moreover, this method has a simple operation process, extremely low cost, and is easy to promote and mass-produce.

Description

Technical Field

[0001] The present disclosure relates to the technical field of Raman spectroscopy analysis, and particularly to a method for eliminating spurious peaks of a silver-based surface-enhanced Raman substrate and a trace detection method. Background Art

[0002] As a trace substance detection method, the surface-enhanced Raman effect has shown strong application prospects in many fields due to its advantages such as ultrasensitive detection and the ability to perform structural analysis on analytes, including chemical sensing, forensic identification analysis, food safety, and medical drug diagnosis.

[0003] Traditional surface-enhanced Raman scattering (SERS) substrates include silver, gold, and copper. Among them, silver has become the most commonly used material for preparing SERS substrates because of its best Raman enhancement ability. However, the micro-nano structure of silver has poor chemical stability in air. At the same time, the nano-structured silver atoms have unsaturated coordination and high surface energy, making it easy to adsorb impurity molecules in the environment, which results in many difficult-to-calibrate impurity peaks on the blank SERS substrate. The presence of these adsorbed impurities reduces the sensitivity of the SERS substrate. More seriously, the presence of impurity peaks increases the difficulty of identifying and recognizing the fingerprint peaks of the target analyte, causing serious interference to the qualitative and quantitative detection of unknown analytes. Summary of the Invention

[0004] Aiming at the problems of the prior art, the present disclosure provides a method for eliminating spurious peaks of a silver-based surface-enhanced Raman substrate and a trace detection method, which are used to solve the technical problems that the impurity peaks on the SERS substrate in the prior art reduce the sensitivity of the SERS substrate, increase the difficulty of identifying and recognizing the fingerprint peaks of the target analyte, and cause serious interference to the qualitative and quantitative detection of unknown analytes.

[0005] The first aspect of the present disclosure provides a method for eliminating spurious peaks of a silver-based surface-enhanced Raman substrate, including: preparing a palladium ion solution; modifying the surface of the silver-based surface-enhanced Raman substrate with the palladium ion solution so that palladium ions combine with the surface to form a palladium atom thin layer covering the surface; wherein, the palladium atom thin layer is used to remove adsorbed impurities and oxidation substances on the surface.

[0006] According to an embodiment of the present disclosure, the palladium ion solution includes one of palladium chloride solution, palladium sulfate solution, palladium nitrate solution, palladium phosphate solution, palladium carbonate solution, and palladium acetate solution.

[0007] According to an embodiment of the present disclosure, the solvent of the palladium ion solution includes palladium water or an organic solvent.

[0008] According to an embodiment of the present disclosure, the organic solvent includes one of ethanol, acetonitrile, and n-hexane.

[0009] According to an embodiment of the present disclosure, preparing a palladium ion-containing solution includes: preparing a palladium ion solution with a palladium ion concentration range of 0.1 mM - 10 mM.

[0010] According to an embodiment of the present disclosure, modifying the surface of a silver-based surface-enhanced Raman substrate with a palladium ion-containing solution includes: immersing the silver-based surface-enhanced Raman substrate in the palladium ion-containing solution for a preset period of time; or dropping the palladium ion-containing solution onto the surface of the silver-based surface-enhanced Raman substrate and maintaining it for a preset period of time.

[0011] According to an embodiment of the present disclosure, the range of the preset period of time is 10 min - 360 min.

[0012] According to an embodiment of the present disclosure, the thickness range of the palladium atom thin layer is 1 nm - 10 nm.

[0013] A second aspect of the present disclosure provides a trace detection method. The trace detection method is based on the method for eliminating spurious peaks of the above silver-based surface-enhanced Raman substrate for detection, and includes: modifying the surface of the silver-based surface-enhanced Raman substrate with a palladium ion-containing solution; performing Raman detection on a substance to be detected using the modified silver-based surface-enhanced Raman substrate to obtain a Raman spectrum of the substance to be detected; and performing trace analysis on the substance to be detected according to the Raman spectrum.

[0014] According to an embodiment of the present disclosure, performing Raman detection on a solution of a substance to be detected using the modified silver-based surface-enhanced Raman substrate includes: dropping a solution containing the substance to be detected onto the surface of the modified silver-based surface-enhanced Raman substrate or immersing the surface of the modified silver-based surface-enhanced Raman substrate in a solution containing the substance to be detected; and after an interval of a preset period of time, detecting the Raman spectrum of the substance to be detected using a bench-top Raman spectrometer.

[0015] According to an embodiment of the present disclosure, the laser wavelength used for Raman detection includes one of 532 nm, 633 nm, 785 nm, and 1064 nm.

[0016] The method for eliminating spurious peaks of the silver-based surface-enhanced Raman substrate and the trace detection method provided according to an embodiment of the present disclosure at least include the following beneficial effects:

[0017] By using a palladium ion solution to modify the surface of a silver-based SERS substrate, a stable and coated thin layer of palladium atoms is formed by combining the surface of the silver-based SERS substrate with palladium ions, which changes the surface adsorption state and oxidation situation, thereby eliminating the interference of impurity peaks adsorbed on the surface of the silver-based SERS substrate, making it easier to identify and determine the fingerprint peaks of the substance to be measured, and laying a material foundation for the trace detection of the substance to be measured. Moreover, since palladium atoms have Raman activity, the formed thin layer of palladium atoms sacrifices very little sensitivity to the silver-based SERS substrate, thus achieving the effect of removing miscellaneous peaks without damaging the sensitivity of the silver-based SERS substrate.

[0018] Furthermore, since the formed thin layer of palladium atoms is coated on the surface of the silver-based SERS substrate, it can improve the antioxidant ability of the silver-based SERS substrate, solve problems such as the easy oxidation of nano-silver, thereby improving the stability during the application of the silver-based SERS substrate and extending the shelf life.

[0019] In addition, this method only needs to be modified with a palladium ion solution, has a simple operation process, extremely low cost, and is easy to promote and mass-produce. Description of the Drawings

[0020] Figure 1 Schematically shows the flowchart of the method for eliminating miscellaneous peaks of the silver-based SERS substrate provided by the embodiments of the present disclosure.

[0021] Figure 2 Schematically shows the flowchart of the trace detection method provided by the embodiments of the present disclosure.

[0022] Figure 3 Schematically shows the Raman spectrum of a typical bare silver-based substrate adsorbed with impurities.

[0023] Figure 4 Schematically shows the Raman spectra of the substrate modified with palladium ions and the bare silver-based substrate provided by the embodiments of the present disclosure.

[0024] Figure 5 Schematically shows the EDS surface scan image of the modified substrate provided by the embodiments of the present disclosure.

[0025] Figure 6 Schematically shows the transmission electron microscope morphology images of the substrate before and after modification and the bare silver-based substrate provided by the embodiments of the present disclosure.

[0026] Figure 7 Schematically shows the Raman spectrum of methylene blue detected by a silver-based substrate modified with an aqueous solution of palladium nitrate provided by the embodiments of the present disclosure.

[0027] Figure 8 Schematically shows the Raman spectrum of methylene blue detected by a silver-based substrate modified with an acetonitrile solution of palladium acetate provided by the embodiments of the present disclosure.

[0028] Figure 9 Schematically shows the Raman spectrum of methylene blue detected by a silver substrate modified with a palladium chloride ethanol solution provided by an embodiment of the present disclosure.

[0029] Figure 10 Schematically shows the comparative Raman spectrum of methylene blue detected by a substrate with impurity peaks and a modified substrate provided by an embodiment of the present disclosure. Specific embodiments

[0030] To make the objectives, technical solutions, and advantages of the present disclosure clearer and more understandable, the following further elaborates on the present disclosure in detail with reference to specific embodiments and the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0031] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0032] In the present disclosure, unless otherwise clearly defined and limited, terms such as "installed", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or indirectly connected through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0033] In the description of the present disclosure, it should be understood that the orientation or positional relationships indicated by terms such as "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the subsystems or components referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present disclosure.

[0034] Throughout the accompanying drawings, the same elements are denoted by the same or similar reference numerals. When it may cause confusion in the understanding of the present disclosure, conventional structures or configurations will be omitted. Moreover, the shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual sizes, proportions, and actual positional relationships. Additionally, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0035] Similarly, in order to streamline the present disclosure and assist in understanding one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together in a single embodiment, figure, or description thereof. Descriptions with reference terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present disclosure, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0037] The embodiments of the present disclosure provide a method for eliminating the spurious peaks of a silver-based SERS substrate, aiming to improve the serious drawback that the silver-based SERS substrate is prone to adsorb impurities, thereby introducing impurity Raman peaks that interfere with the detection of the target substance. The technical principle of this elimination method is as follows: a palladium atom protective layer with a thickness of several nanometers is obtained through a chemical displacement reaction in a palladium ion solution. During the diffusion process of the palladium atoms, the oxidation species and other adsorbed impurities adsorbed on the silver-based SERS substrate are removed, thereby removing the impurity peaks and enhancing the stability of the substrate. At the same time, since the palladium atoms have Raman activity, the formed palladium atom protective layer sacrifices very little sensitivity for the SERS substrate.

[0038] The following will specifically describe in detail the method for eliminating the spurious peaks of the silver-based SERS substrate provided by the embodiments of the present disclosure with reference to the specific drawings.

[0039] Figure 1 Schematically shows the flowchart of the method for eliminating the spurious peaks of the silver-based SERS substrate provided by the embodiments of the present disclosure.

[0040] As Figure 1As shown, the method may include, for example, operation S101 to operation S102.

[0041] In operation S101, a palladium ion solution is prepared.

[0042] In an embodiment of the present disclosure, the palladium ion solution includes, but is not limited to, one of palladium chloride solution, palladium sulfate solution, palladium nitrate solution, palladium phosphate solution, palladium carbonate solution, and palladium acetate solution. The solvent of the palladium ion solution includes, but is not limited to, water or an organic solvent. In the embodiment of the present disclosure, an organic solvent is preferably used, and the organic solvent includes, but is not limited to, one of ethanol, acetonitrile, and n-hexane.

[0043] In an embodiment of the present disclosure, a palladium ion solution with a palladium ion concentration range of 0.1 mM - 10 mM can be prepared.

[0044] In operation S102, the surface of the silver-based surface-enhanced Raman substrate is modified with the palladium ion solution, so that the palladium ions bind to the surface to form a thin layer of palladium atoms covering the surface.

[0045] In an embodiment of the present disclosure, the method for modifying the surface of the silver-based surface-enhanced Raman substrate may include the following two methods:

[0046] The first method is: placing the silver-based surface-enhanced Raman substrate in the palladium ion solution and soaking for a preset period of time.

[0047] The second method is: dropping the palladium ion solution onto the surface of the silver-based surface-enhanced Raman substrate and maintaining for a preset period of time.

[0048] As a preferred embodiment, the modification time of the surface of the silver-based surface-enhanced Raman substrate, that is, the range of the preset period of time, can be 10 min - 360 min. The thickness of the thin layer of palladium atoms formed on the surface of the silver-based surface-enhanced Raman substrate after modification is extremely thin. Preferably, the thickness range of the palladium atom thin layer is 1 nm - 10 nm.

[0049] After the modification is completed, the modified silver-based surface-enhanced Raman substrate needs to be dried and stored in the dark after air-drying.

[0050] It should be noted that the silver-based surface-enhanced Raman substrate is a metal silver nanostructure of various shapes, including but not limited to a silver self-supporting or a surface silver-containing nanocomposite structure formed on different substrates. For example, nanorods, nanotubes, nanowires, nanoparticles, and various complex morphologies prepared by physical or chemical methods. Any silver-based substrate that is prone to impurity peak interference can be applicable.

[0051] Based on the same inventive concept, the embodiment of the present disclosure also provides a trace detection method, which is based on Figure 1The elimination method shown is used for detection.

[0052] Figure 2 The flowchart of the trace detection method provided by the embodiment of the present disclosure is schematically shown.

[0053] like Figure 2 As shown, the method may include, for example, operations S201 to S203.

[0054] In operation S201, a solution containing palladium ions is used to modify the surface of a silver-based surface enhanced Raman substrate.

[0055] In the embodiments of the present disclosure, Figure 1 The modification method shown is used to modify the surface of the silver-based surface enhanced Raman substrate, which will not be described in detail here.

[0056] In operation S202, Raman detection is performed on the substance to be detected using the modified silver-based surface enhanced Raman substrate to obtain a Raman spectrum of the substance to be detected.

[0057] In the embodiments of the present disclosure, a solution containing the substance to be detected can be dropped onto the surface of the modified silver-based surface-enhanced Raman substrate, or the surface of the modified silver-based surface-enhanced Raman substrate can be immersed in a solution containing the substance to be detected.

[0058] In the embodiments of the present disclosure, the laser wavelength used in Raman detection includes but is not limited to one of 532 nm, 633 nm, 785 nm and 1064 nm.

[0059] In operation S203, trace analysis is performed on the substance to be detected according to Raman spectroscopy.

[0060] In order to further verify the advantages of the method for eliminating impurity peaks of a silver-based surface enhanced Raman substrate provided by the embodiments of the present disclosure, some specific examples are listed below for illustration.

[0061] Example 1:

[0062] If no special protective measures are taken after the ordinary silver-based SERS substrate is prepared, it will have obvious stray peaks during placement and storage in the air (usually after 3 hours), which will seriously affect the Raman test of subsequent samples. Therefore, the present invention adopts a modification method to remove the stray peaks.

[0063] The blank sample of the bare Ag substrate before modification was subjected to Raman testing using a Zhuoli Hanguang micro-Raman spectrometer with the following test parameters: integration time 15s, laser power 40mW, laser wavelength 638nm.

[0064] Figure 3 The Raman spectrum of a typical bare silver substrate adsorbed with impurities is schematically shown.

[0065] As Figure 3 shown, obvious impurity peaks exist near 382 cm -1 , 857 cm -1 , 1131 cm -1 , 1404 cm -1 and 1606 cm -1 , and there are multiple impurity peaks with weaker intensities accompanying them (such as 2139 cm -1 ). It is difficult to accurately determine the attribution of these impurity peaks, which may be related to different forms of oxygen adsorbed on the silver surface. For the testing of some substances with low concentrations, the existence of impurity peaks will interfere with the characteristic peaks of some substances to be measured, bringing certain difficulties to the identification of substances.

[0066] The Ag substrate with impurity peaks is modified according to the following operations:

[0067] To compare the effects of different salt solutions and forms on the modification effect, 1 mM aqueous palladium nitrate solution, palladium acetate acetonitrile solution, and palladium chloride ethanol solution are prepared.

[0068] The SERS substrate of silver with impurity peaks is immersed in the solution of the above-mentioned ions with a concentration of 1 mM. After being immersed for 10 minutes, it is taken out, and the surface solution is gently blown away with an ear bulb, and then naturally dried and stored away from light under air conditions.

[0069] The substrate is taken out for Raman testing. The testing parameters are: integration time is 15 s, laser power is 40 mW, and laser wavelength is 638 nm.

[0070] Figure 4 Schematically shows the Raman spectra of the substrate modified with palladium ions and the bare silver substrate provided by the embodiments of the present disclosure.

[0071] As Figure 4 shown, compared with the impurity peaks presented in the Raman spectrum shown in Figure 3 , no obvious Raman peaks appear on the modified substrate, indicating that this modification method can achieve the effect of eliminating impurity peaks.

[0072] Figure 5 Schematically shows the EDS surface scanning image of the modified substrate provided by the embodiments of the present disclosure.

[0073] As Figure 5 shown, the distribution of palladium elements on the surface of the silver rod is uniform.

[0074] Figure 6 Schematically shows the transmission electron microscope morphology images of the substrate before and after modification and the bare silver substrate provided by the embodiments of the present disclosure.

[0075] As Figure 6As shown, there is an adsorption layer of 1-2 nm on the silver surface before modification, with poor crystallinity and difficult to calibrate its phase. After modification, a coating layer of about 2 nm is formed, with good crystallinity and obvious ordered lattice fringes can be seen.

[0076] Example 2:

[0077] To verify the Raman enhancement effect of the silver substrate after modification with palladium nitrate to remove impurity peaks, methylene blue (MB) was used as the probe molecule for detection and evaluation. The process is as follows:

[0078] The Ag substrate with impurity peaks was immersed in an aqueous solution of 10 mM palladium nitrate, and the liquid level covered the Ag surface. After soaking for 10 min, it was taken out, and the modification solution on the silver substrate surface was gently blown dry with an ear bulb.

[0079] The modified SERS substrate was immersed in the MB standard solution with a concentration ranging from 0.1 ppb (μg / L) to 1 ppm (mg / L). After soaking for 5 minutes, it was taken out, and the surface was gently blown dry with an ear bulb, and the residual solution around was sucked away with filter paper.

[0080] A Zolix desktop Raman spectrometer was used for detection. Test parameters: integration time was 15 s, integration times was 1 time, laser power was 40 mW, and laser wavelength was 785 nm.

[0081] Figure 7 Schematically shows the Raman spectrum of methylene blue detected by the silver substrate modified with an aqueous solution of palladium nitrate provided by the embodiment of the present disclosure.

[0082] As Figure 7 shown, when the substrate modified with palladium nitrate was used to detect MB, all the peak positions of the Raman spectrum (curve 1) appeared as characteristic peaks of the detected substance. As the detection concentration decreased, the intensities of different characteristic peaks decreased (curve 2), and there was a good linear relationship between the intensity change and the concentration. Under the conditions of this embodiment, the modified substrate could clearly detect MB molecules with a concentration lower than 0.01 ppm (curve 3), demonstrating the characteristics of ultra-trace analysis, and no interference caused by the modified background was seen (curve 4).

[0083] Example 3:

[0084] To verify the Raman enhancement effect of the silver substrate after modification with palladium acetate to remove impurity peaks, methylene blue (MB) was used as the probe molecule for detection and evaluation. The process is as follows:

[0085] The prepared Ag-based SERS substrate stored in air for half a month was immersed in a 1 mM acetonitrile solution of palladium acetate, and the liquid level covered the Ag surface. After soaking for 60 min, it was taken out, and the silver substrate surface was naturally dried and stored in the dark for one month and then taken out after one month.

[0086] 30 μL of MB standard solutions with different concentrations were dropped onto the surface of a substrate with a specification of 5 mm * 5 mm, waited for 30 s, and the surface test solution was blown away with an ear bulb.

[0087] It was detected by a HORIBA bench-top Raman spectrometer. Test parameters: integration time was 15 s, integration times was 1 time, laser power was 40 mW, and laser wavelength was 532 nm.

[0088] Figure 8 Schematically shows the Raman spectrum of methylene blue detected by a silver substrate modified with a palladium acetate acetonitrile solution provided by an embodiment of the present disclosure.

[0089] As Figure 8 shown, when the substrate modified with palladium acetate was used to detect MB, all the peak positions of the Raman spectrum (curve 1) were characteristic peaks of the detected substance. As the detection concentration decreased, the intensities of different characteristic peaks decreased (curve 2). Under the conditions of this embodiment, the substrate modified and stored for one month could significantly detect MB molecules with a concentration lower than 10 ppb (curve 3), demonstrating the characteristics of ultra-trace analysis, and no interference from the modified background was seen (curve 4).

[0090] Example 4:

[0091] In order to verify the Raman enhancement effect of the substrate modified with palladium chloride after removing the miscellaneous peaks, methylene blue (MB) was used as the detection molecule for detection and evaluation. At the same time, in order to verify the stability of the substrate, the modified substrate was placed in the dark for 6 months and then detected. The process is as follows:

[0092] The Ag-based SERS substrate prepared and stored in air for 3 months was put into a 1 mM palladium chloride ethanol solution, and the liquid level covered the Ag-based surface. After soaking for 30 min, it was taken out, and the surface of the silver-based substrate was naturally dried and stored in the dark. It was taken out after 6 months.

[0093] 30 μL of MB standard solutions with different concentrations were dropped onto the surface of a substrate with a specification of 5 mm * 5 mm. After dropping onto the substrate, waited for 60 s, and the unevaporated solution was dried with an ear bulb.

[0094] It was detected by a B&W Tek bench-top Raman spectrometer. Test parameters: integration time was 10 s, integration times was 1 time, laser power was 20 mW, and laser wavelength was 785 nm.

[0095] Figure 9 Schematically shows the Raman spectrum of methylene blue detected by a silver substrate modified with a palladium chloride ethanol solution provided by an embodiment of the present disclosure.

[0096] As Figure 9As shown, when detecting MB with a palladium nitrate-modified silver substrate, all the peak positions of the Raman spectrum (curve 1) are characteristic peaks of the detected substance. As the detection concentration decreases, the intensities of different characteristic peaks decrease, and there is a good linear relationship between the intensity change and the concentration. Under the conditions of this example, the substrate that has been modified and stored for 6 months can clearly detect MB molecules with a concentration lower than 0.01 ppm (curve 4), demonstrating the characteristics of ultra-trace analysis, and no interference from the modified background is seen (curve 5).

[0097] Example Five:

[0098] After a common silver-based SERS substrate is prepared, obvious miscellaneous peaks will appear after being placed in the air for a period of time. Take out 2 substrates with the same preparation conditions and stored for one week. One of them is chemically modified, and the other is untreated. Detect methylene blue dye molecules on the two substrates respectively, and compare and analyze the changes in the peak positions and peak shapes of their Raman spectra. The process is as follows.

[0099] Put the prepared Ag-based SERS substrate into a 1 mM palladium acetate acetonitrile solution, soak it for 1 h and then take it out, and let the surface of the silver-based substrate dry naturally to obtain a substrate modified with palladium ions.

[0100] Drop 30 μL of a standard aqueous solution of methylene blue onto the surfaces of the substrates modified and unmodified with palladium ions with a specification of 5 mm * 5 mm. The concentration of methylene blue is 1 ppm. After dropping it onto the substrate, let it stand for 5 min, blow dry the surface with an ear bulb, and suck away the remaining solution around the substrate with filter paper.

[0101] Detect with a Zhuoli Hanguang bench-top Raman spectrometer. Test parameters: integration time is 15 s, integration times is 1 time, laser power is 40 mW, and laser wavelength is 638 nm.

[0102] Figure 10 Schematically shows a Raman spectrum comparison diagram of a substrate with miscellaneous peaks and a modified substrate for detecting methylene blue provided by an embodiment of the present disclosure.

[0103] As Figure 10 shown, the Raman peaks of methylene blue measured at 1 ppm are the most obvious, and obvious signals are measured at multiple places such as 450 cm -1 , 499 cm -1 , 768 cm -1 , 1182 cm -1 , 1393 cm -1 and 1622 cm -1 etc. The substrate modified with palladium ions has completely removed the impurity peaks (curve 4), and all the peak positions generated after soaking in MB are vibration peaks of different groups of MB (curve 1). In contrast, after the unmodified substrate is soaked in MB, its peak shape still exists (curves 2 and 3). Among them, the one located at 1606 cm-1 The impurity peak of -1 is very close to the side peak 1622 cm of MB and difficult to distinguish (curve 2). The peak intensity and sharpness of the MB peak on the substrate containing the impurity peak are significantly lower than those of the modified substrate. It can be predicted that the impurity peak of the SERS substrate will seriously affect the detection of target molecules, especially for the detection of unknown molecules in complex systems. The presence of the miscellaneous peak seriously interferes with the identification of substances, and the decrease in its sensitivity makes it difficult to achieve trace and ultra-trace quantitative analysis.

[0104] Based on the test data of the above examples, it can be seen that the method for eliminating the miscellaneous peak of the silver-based surface-enhanced Raman substrate provided by the present disclosure is simple to operate, has obvious effects in eliminating miscellaneous peaks, high sensitivity, and significant surface-enhanced effects of the silver-based surface-enhanced Raman substrate, and can perform quantitative analysis of trace substances. In addition, this method greatly improves the stability and durability of the SERS substrate and has high practicability. Therefore, the method for eliminating the miscellaneous peak of the silver-based surface-enhanced Raman substrate enables the SERS substrate to have broad application prospects in biological medicine, forensic identification, food safety, and environmental monitoring, etc.

[0105] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not used to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A method for eliminating miscellaneous peaks of a silver-based surface-enhanced Raman substrate, comprising: Preparing a palladium ion-containing solution; Modifying the surface of the silver-based surface-enhanced Raman substrate with the palladium ion-containing solution so that the palladium ions combine with the surface to form a thin layer of palladium atoms covering the surface, and the thickness range of the thin layer of palladium atoms is 1 nm - 10 nm; Wherein, the thin layer of palladium atoms is used to remove adsorbed impurities and oxidized substances on the surface.

2. The elimination method according to claim 1, wherein, The palladium ion-containing solution includes one of palladium chloride solution, palladium sulfate solution, palladium nitrate solution, palladium phosphate solution, palladium carbonate solution, and palladium acetate solution.

3. The elimination method according to claim 1 or 2, wherein, The solvent of the palladium ion-containing solution includes palladium water or an organic solvent.

4. The elimination method according to claim 3, wherein, The organic solvent includes one of ethanol, acetonitrile, and n-hexane.

5. The elimination method according to claim 1 or 2, wherein The preparing of the palladium ion-containing solution includes: Preparing the palladium ion-containing solution with a palladium ion concentration range of 0.1 mM - 10 mM.

6. The elimination method according to claim 1, wherein The modifying of the surface of the silver-based surface-enhanced Raman substrate with the palladium ion-containing solution includes: Placing the silver-based surface-enhanced Raman substrate in the palladium ion-containing solution and soaking for a preset period of time; or Dropping the palladium ion-containing solution onto the surface of the silver-based surface-enhanced Raman substrate and maintaining for a preset period of time.

7. The elimination method according to claim 6, wherein, The range of the preset period of time is 10 min - 360 min.

8. A trace detection method, the trace detection method is based on the elimination method according to any one of claims 1 - 7 for detection, comprising: Modifying the surface of a silver-based surface-enhanced Raman substrate with a palladium ion-containing solution; Performing Raman detection on a substance to be detected using the modified silver-based surface-enhanced Raman substrate to obtain a Raman spectrum of the substance to be detected; Performing trace analysis on the substance to be detected according to the Raman spectrum.

9. The trace detection method according to claim 8, wherein, The performing of Raman detection on a solution of a substance to be detected using the modified silver-based surface-enhanced Raman substrate includes: Dropping a solution containing the substance to be detected onto the surface of the modified silver-based surface-enhanced Raman substrate or soaking the surface of the modified silver-based surface-enhanced Raman substrate in a solution containing the substance to be detected; After an interval of a preset period of time, detecting the Raman spectrum of the substance to be detected using a bench-top Raman spectrometer.

10. The trace detection method according to claim 8 or 9, wherein, The laser wavelength used for the Raman detection includes one of 532 nm, 633 nm, 785 nm, and 1064 nm.

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