A method for high-sensitivity detection of se (iv) based on au-mno2-pd np composite material

Abstract

The application relates to a method for high-sensitivity detection of Se(IV) based on an Au-MnO2-Pd NPs composite material, and belongs to the technical field of selenium detection. The detection method comprises the following steps: placing a to-be-detected solution containing Se(IV) and hydrochloric acid in a headspace bottle, placing a dispersion of the Au-MnO2-Pd NPs composite material on a headspace bottle cap, and injecting a reducing agent solution into the headspace bottle, and after reaction, liquid on the headspace bottle cap forms a to-be-detected mixed solution; the to-be-detected mixed solution is dropped and coated on the surface of a GCE electrode, then DPV is scanned in a test base solution, and qualitative and quantitative detection of Se(IV) is realized. In the application, Se(IV) in a sodium borohydride reducing solution is reduced to generate H2Se gas, the H2Se gas reacts with the Au-MnO2-Pd NPs composite material with electrochemical activity, a DPV signal is combined to drop, and high-sensitivity detection of Se(IV) in a solution is realized.

Description

Technical Field

[0001] This invention relates to the technical field of selenium detection, and in particular to a highly sensitive method for the detection of Se(Ⅳ) based on Au-MnO2-Pd NPs composite material. Background Technology

[0002] Selenium is an essential trace element for the human body, with an recommended daily intake of 40-400 μg. Both excess and deficiency can lead to health risks (such as neurological damage and cardiovascular disease). In aquatic environments, selenium exists primarily as selenate (Se(VI)) and selenite (Se(IV)), with Se(IV) exhibiting higher toxicity, greater solubility, and stronger bioaccumulation. Furthermore, Se(IV) can accumulate through the food chain, threatening ecosystems and human health. Therefore, there is a need to develop a rapid and sensitive detection method for the quantitative analysis of selenium in food, soil, and water.

[0003] Electrochemical sensors offer advantages such as simple equipment, high sensitivity, and ease of operation. Currently, commonly used electroactive probes are primarily electrochemical reduction tags, which utilize the inherent electrochemical oxidation peaks resulting from electron transfer during the electrochemical oxidation of metals from high to low valence. Metals and metal oxides not only exhibit good electrochemical oxidation signals under mild and neutral conditions but also display tunable signals by controlling their composition, size, and structure.

[0004] Currently, among the commonly used traditional detection methods for Se(Ⅳ), spectroscopic technology has high accuracy but expensive equipment; chromatography-spectroscopy coupling technology is complex to operate; therefore, there is an urgent need to provide a more sensitive method for detecting Se(Ⅳ) in food, soil and water. Summary of the Invention

[0005] To address the above technical problems, this invention provides a highly sensitive method for the detection of Se(Ⅳ) based on Au-MnO2-Pd NPs composite materials. This invention utilizes sodium borohydride to reduce Se(Ⅳ) in solution, generating H2Se gas, which reacts with the electrochemically active Au-MnO2-Pd NPs composite material. Combined with a decrease in the DPV signal, this achieves highly sensitive detection of Se(Ⅳ) in solution.

[0006] The purpose of this invention is to provide a highly sensitive method for the detection of Se(Ⅳ) based on Au-MnO2-Pd NPs composite materials, comprising the following steps:

[0007] The test solution containing Se(Ⅳ) and acid were placed in a headspace vial, the dispersion of Au-MnO2-Pd NPs composite material was placed in the headspace vial cap, and the reducing agent solution was injected into the headspace vial. After the reaction, the liquid in the headspace vial cap formed the test mixture.

[0008] The test mixture was drop-coated onto the surface of the GCE electrode, and then the DPV was scanned in the test base solution (phosphate buffer with pH = 7.4~8.04) with a scanning range of 0.8~-0.8 V to achieve qualitative and quantitative detection of Se(Ⅳ).

[0009] In some embodiments of the present invention, the concentration of the test solution containing Se(Ⅳ) is 0.001~1 mg / mL.

[0010] In some embodiments of the present invention, the volume concentration of the acid is 0.1%-15%;

[0011] The acid is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid; the present invention provides an acidic environment by adding an acid, which promotes the reduction of Se(IV) to H2Se gas by a reducing agent (such as NaBH4) (reaction formula: Se(IV) + BH4). - +H + →H3BO3+H2Se+H2), ensuring the smooth progress of the reduction reaction. Maintaining the reducing activity of the reducing agent (such as NaBH4), which is more likely to release hydride ions under acidic conditions, enhancing its ability to reduce Se(Ⅳ). Suppressing the generation of other interfering gases, reducing the influence of reducing substances in the matrix, and improving the specificity of detection.

[0012] Furthermore, when the acid is hydrochloric acid, the volume concentration is 0.1–0.5% (0.012–0.06 mol / L); when the acid is sulfuric acid, the concentration is 5%–15% (v / v). Too high a concentration may cause sodium borohydride to decompose too quickly, while too low a concentration will result in insufficient acidity, affecting H₂Se formation. When the acid is nitric acid, the concentration is 5%–10% (v / v). Because nitric acid has oxidizing properties, too high a concentration may oxidize H₂Se, interfering with detection. When the acid is an organic acid (such as acetic acid), due to its weak acidity, it cannot provide sufficient H₂. + It is not recommended for efficient H2Se generation.

[0013] The concentration of the dispersion of Au-MnO2-Pd NPs composite material is 0.02~0.1 g / mL;

[0014] The mass ratio of Se(Ⅳ), Au-MnO2-Pd NPs composite material to reducing agent is (10) -6 ~10 -4 : (0.05~0.1): (0.02~0.06).

[0015] In some embodiments of the present invention, the reducing agent in the reducing agent solution is selected from one or more of sodium borohydride, ascorbic acid, and sodium hypophosphite;

[0016] The concentration of the reducing agent solution is 0.02-0.05 g / mL;

[0017] The solvent for the reducing agent solution is phosphate buffer.

[0018] In this invention, the "bottle body + top space" structure of the headspace bottle can strictly separate the liquid-phase reaction from the gas-phase reaction. Specifically: the liquid phase Se(IV) at the bottom of the bottle reacts with a reducing agent (such as NaBH4) under acidic conditions to generate H2Se gas, which diffuses into the top and reacts with pre-placed Au-MnO2-Pd NPs composite material droplets, ensuring that only the target gas participates in the subsequent reaction. The closed environment of the headspace bottle allows H2Se gas to accumulate in the top space, improving the reaction efficiency with the Au-MnO2-Pd NPs composite material droplets. Actual samples (such as food and water) contain -SH and S. 2- Substances (such as Na2S), if directly mixed, will react with the beacon Pd of the Au-MnO2-Pd NPs composite material, simulating a false positive signal of "Se(IV) presence". Headspace vials allow only H2Se to enter the top reaction, significantly reducing matrix interference.

[0019] In some embodiments of the present invention, the Au-MnO2-Pd NPs composite material is prepared by the following method:

[0020] S1: Mix the gold nanoparticle dispersion with potassium permanganate solution evenly, add the first reducing agent solution to carry out the reduction reaction, stir the reaction and resuspend in water to obtain Au-MnO2NPs dispersion;

[0021] S2: Take the Au-MnO2NPs dispersion obtained in step S1, add the second reducing agent solution and palladium source solution, mix them evenly, and react to obtain the Au-MnO2-Pd NPs composite material.

[0022] In some embodiments of the present invention, in step S1, the molar ratio of gold nanoparticle dispersion, potassium permanganate and polyacrylic acid is (1~2):(1~3):(0.2~1).

[0023] The concentration of potassium permanganate is 0.01~0.04 g / mL. In this invention, potassium permanganate is used as the manganese source and precursor for the MnO2 shell. In the preparation of Au-MnO2 nanoparticles, KMnO4 provides manganese, which is converted into MnO2 under the reduction action of a structure directing agent (such as polyacrylic acid) and uniformly coated on the surface of gold nanoparticles to form a core-shell structure.

[0024] The concentration of the first reducing agent solution is 2~4 mg / mL;

[0025] The first reducing agent in the first reducing agent solution is selected from polyacrylic acid and / or polyallylamine hydrochloride (PAH). This invention utilizes polyacrylic acid (PAA) and / or polyallylamine hydrochloride (PAH) as both reducing agents and structure directing agents to participate in the reduction reaction of potassium permanganate (KMnO4), thereby promoting the deposition of MnO2 on the surface of gold nanoparticles to form a shell.

[0026] The reduction reaction is carried out at a temperature of 25-30 ℃ for 30-60 min.

[0027] In some embodiments of the present invention, in step S2, the concentration of the second reducing agent solution is 0.03~0.05 g / mL.

[0028] In some embodiments of the present invention, in step S2, the concentration of the palladium source solution is 2~5 mg / mL.

[0029] In some embodiments of the present invention, in step S2, the palladium source in the palladium source solution is selected from one or more of sodium palladium chlorate, tetrachloropalladium acid, palladium chloride, and palladium nitrate.

[0030] In some embodiments of the present invention, the standard curve for quantitative detection is prepared by the following method:

[0031] The test solution and hydrochloric acid were placed in a headspace vial, and the Au-MnO2-Pd NPs composite material dispersion was placed in the headspace vial cap. Sodium borohydride was injected into the vial. After the reaction was complete, the liquid in the headspace vial cap formed the test mixture. 8 μL of the test mixture was drop-coated onto the surface of the GCE electrode, and the DPV was scanned in phosphate buffer at pH 7.4. The electrochemical parameters were: scan range 0.8 to -0.8 V.

[0032] In some embodiments of the present invention, the concentration of the test solution is 0.001~1 mg / mL.

[0033] The experimental principle of this invention:

[0034] The core mechanism of this invention for achieving sensitive detection of Se(IV) is based on the conversion of Se(IV) to H2Se, the reaction of H2Se with Pd, and the resulting changes in electrochemical signals. The specific process is as follows:

[0035] The conversion of Se(IV) to volatile H₂Se: In the sample detection system, Se(IV) first undergoes a chemical reduction reaction. Under acidic conditions (in the presence of H₂Se), + Sodium borohydride provides BH4 - As a reducing agent, it converts non-volatile Se(IV) into volatile hydrogen selenide (H₂Se) gas. The reaction equation is: Se(IV) + BH₄ −+H + →H3BO3 + H2Se. This step converts the non-reactive Se(IV) into the easily diffused and reactant H2Se gas through chemical reduction, laying the foundation for its subsequent interaction with the detection material.

[0036] The reaction of H₂Se with Pd: The generated H₂Se gas rapidly reacts with the Pd component (including tetravalent Pd, divalent Pd, and Pd nanoparticles) in the Au-MnO₂-Pd NPs composite material in a headspace single drop. In this process, H₂Se is oxidized to elemental selenium (Se₂Se) as a reducing agent. 0 The higher valence states of Pd (tetravalent and divalent) are reduced to lower valence states, and the two further combine to form Se-Pd complexes. The resulting Se... 0 It binds to the electrochemical beacon pd in the composite material Au-MnO2-Pd NPs to form Au-MnO2-Pd-Se aggregates.

[0037] DPV signal changes and quantitative analysis of Se(IV): High-valence Pd is reduced to a low-valence state, altering its electrochemical activity; the generated Se... 0 The coating on the active sites of Pd hinders electron transfer between Pd and the electrode surface. These two effects work together to significantly reduce the differential pulse voltammetry (DPV) signal of Pd.

[0038] Since the amount of H2Se generated is positively correlated with the initial Se(IV) concentration, its reaction degree with Pd and Se... 0 The coverage also increases with the increase of Se(IV) concentration, resulting in a quantitative relationship between the decrease in DPV signal and Se(IV) concentration, enabling multicolor quantitative analysis of Se(IV) in solution and achieving highly sensitive detection.

[0039] In summary, this experiment achieved sensitive detection of Se(IV) by utilizing the targeting effect of H2Se and Pd and the quantitative change of electrochemical signal through a series mechanism of "chemical transformation-specific reaction-signal response".

[0040] The technical solution of the present invention has the following advantages compared with the prior art:

[0041] (1) High specificity: By utilizing the targeting reaction between H2Se and Pd, the influence of other components can be reduced, thereby improving the specificity of detection.

[0042] (2) High sensitivity: Through the series mechanism of "chemical transformation-specific reaction-signal response", the amount of H2Se generated is positively correlated with the concentration of Se(IV), and the degree of reaction and signal change are quantitatively related to the concentration of Se(IV), which can achieve high sensitivity detection.

[0043] (3) Good quantitative relationship: There is a clear quantitative relationship between the DPV signal reduction magnitude and the Se (IV) concentration, which can ensure the accuracy of the detection results. Attached Figure Description

[0044] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0045] Figure 1 These are characterization diagrams of Au NPs, Au-MnO2 NPs, and Au-MnO2-Pd NPs obtained in Example 1 of this invention.

[0046] Figure 2 In Example 1 of this invention, the chemical composition and valence state of Au, MnO2 and Pd in ​​Au-MnO2NPs and Au-MnO2-Pd NPs were analyzed by XPS.

[0047] Figure 3 Au-MnO2NPs ( Figure 3 a) and Au-MnO2-Pd NPs ( Figure 3 b) Electroreduction curves obtained by multiple cycles on the same electrode.

[0048] Figure 4 This illustrates the effect of different ions on the detection signal in this embodiment of the invention.

[0049] Figure 5 The electrochemical DPV response and standard curves of solutions containing different concentrations of Se(Ⅳ) in this invention are shown.

[0050] Figure 6 The results are actual sample test results in the embodiments of the present invention. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0052] Example 1

[0053] This embodiment provides a highly sensitive method for detecting Se(Ⅳ) based on Au-MnO2-Pd NPs composite materials, as detailed below:

[0054] (1) Preparation steps of Au-MnO2-Pd NPs composite material:

[0055] S1: Preparation of 18 nm Au NPs: Take 500 μL of 1wt% chloroauric acid solution, dilute to 50 mL with ultrapure water, heat to boiling, quickly add 1 mL of 0.01 g / mL sodium citrate solution, stir for 15 min and the solution turns wine red to obtain Au NPs gold nanoparticle solution;

[0056] S2: Preparation of Au-MnO2NPs solution: Take 10 mL of Au NPs gold nanoparticle solution obtained in step S1, centrifuge at 8000 r for 5 min and redisperse in 10 mL of water to obtain a dispersion. Mix the dispersion with 300 μL of 0.01 g / mL potassium permanganate, add 1 mL of 4 mg / mL polyacrylic acid to carry out a reduction reaction, stir for 30 min and the solution turns brown. Centrifuge at 8000 r for 5 min and wash, disperse in 1 mL of water to obtain Au-MnO2NPs solution;

[0057] S3: Preparation of Au-MnO2-Pd NPs: 200 μL of Au-MnO2NPs solution obtained in step S2 was dispersed in 4 mL of water. 600 μL of sodium hypophosphite solution (0.0375 g / mL) and 200 μL of sodium palladium chlorate solution (2.9 mg / mL) were added sequentially and mixed at 35 °C for 10 minutes. The solution turned black. After centrifugation and washing, the solution was re-diluted to 200 μL of ultrapure water to obtain the Au-MnO2-Pd NPs composite material dispersion.

[0058] The obtained Au NPs, Au-MnO2 NPs, and Au-MnO2-Pd NPs were structurally characterized and subjected to UV-Vis absorption spectroscopy. The experimental results are shown in [Figure number missing]. Figure 1 and Figure 2 ;in, Figure 1 Image a shows the TEM image of Au NPs, with an average size of 18.0 ± 0.2 nm; image b shows the TEM image of Au-MnO2 NPs, with an average size of 81.5 ± 0.4 nm; image c shows the TEM image of Au-MnO2-Pd NPs, with an average size of 6.27 ± 0.35 nm; image d shows the UV-Vis absorption spectra of Au NPs, Au-MnO2 NPs, and Au-MnO2-Pd NPs. The insets show a wine-red Au NPs solution, a brown Au-MnO2 NPs solution, and a black Au-MnO2-Pd NPs solution. Au NPs exhibit a UV absorption peak at 520 nm; after loading MnO2 onto Au NPs, the absorption peak red-shifts.

[0059] Figure 2 The valence states of Au, Mn, and Pd in ​​Au-MnO2 NPs and Au-MnO2-Pd NPs were analyzed using XPS. Figure 2 Figure a: The Au XPS spectrum of Au-MnO2NPs shows peaks at 80.50 eV and 85.5 eV, corresponding to Au(0)4f7 / 2 and Au(0)4f5 / 2, respectively. Figure b: The Mn XPS spectrum of Au-MnO2NPs shows peaks at 639.05 eV and 650.5 eV, which can be attributed to Mn. 4+ Figure c: The Au XPS spectrum of Au-MnO2-PdNPs shows peaks at 83.50 eV and 87.2 eV corresponding to Au(0)4f7 / 2 and Au(0)4f5 / 2, respectively. Figure d: The Pd XPS spectrum of Au-MnO2-PdNPs shows two Pd 3d peaks at 334.6 eV and 339.9 eV, indicating the presence of Pd. 0 The peaks at 335.9 eV and 340.8 eV are attributed to Pd. 2+ The peaks at 337.5 eV and 342.6 eV are attributed to Pd. 4+ .

[0060] The Au NPs, Au-MnO2 NPs, and Au-MnO2-Pd NPs obtained above were subjected to multiple cycles of electroreduction experiments, and the results are shown in [Figure number missing]. Figure 3 ;Depend on Figure 3 As shown in Figure a, the electrochemical signal of the Au-MnO2 NPs-modified glassy carbon electrode decreased significantly after three cycles, while the electrochemical signal of the Au-MnO2-Pd NPs-modified glassy carbon electrode remained almost unchanged after three cycles. Figure 3 As shown in Figure b, by comparing the DPV signals of various materials Au-MnO2NPs, Au-MnO2-Pd NPs, and Au-Pd NPs, it can be seen that the DPV peak of Au-MnO2NPs is around 0.5 V, while the DPV peaks of Au-Pd NPs and Au-MnO2-Pd NPs are around 0 and -0.5 V, respectively. Compared with Au-Pd NPs, Au-MnO2NPs, with MnO2 as a support surface, can grow more Pd, expose more DPV sites, and have a stronger DPV signal.

[0061] (2) Se(Ⅳ) detection: 1-100 ppm of the test solution and 1 mL of 0.12 mol / L hydrochloric acid were placed in a headspace vial, and 20 μL of the Au-MnO2-Pd NPs composite material dispersion was placed in the headspace vial cap. 1 mL of 0.04 g / mL sodium borohydride was injected into the vial. After reacting at room temperature for 15 minutes, the liquid in the headspace vial cap formed the test mixture. 8 μL of the test mixture was drop-coated onto the surface of the GCE electrode, using a saturated calomel electrode as the reference electrode and a platinum sheet electrode as the counter electrode. The DPV was scanned in phosphate buffer at pH 7.4. The electrochemical parameters were: scan range 0.8 to -0.8 V. Experimental results are shown in […]. Figure 5 As shown in the figure, the peak intensity of DPV decreases with increasing Se(Ⅳ) concentration within the concentration range of 1 ppm to 100 ppm. The detection limit of Se(Ⅳ) by the above method is 0.335 ppm. Within the concentration range of 1 to 100 ppm, a good linear relationship (standard curve) is established between the sum of DPV peak values ​​at 0 V and -0.5 V and the Se(Ⅳ) concentration, with the linear relationship being: y = 60.91746 - 0.4103x, where x is the Se(Ⅳ) concentration in ppm; y is the DPV signal, and the correlation coefficient R is 0. 2 =0.91.

[0062] (3) Actual sample detection: A known amount of Se(Ⅳ) standard solution was added to the treated rice mixture (treatment steps: 0.5 g rice added to 5 mL of 5wt% nitric acid, extraction temperature of 100 ℃, water bath extraction for 10 min, shaking every two minutes to ensure uniform heating of the sample, cooling to room temperature after the reaction, adjusting the pH to neutral with 0.5% sodium hydroxide, and finally adjusting the volume to 10 mL, at which point the content of Se element in the rice mixture was detected to be 0.00165 ppm). Sample 1 with a Se(Ⅳ) concentration of 60 ppm and Sample 2 with a Se(Ⅳ) concentration of 90 ppm were obtained respectively. According to the detection method of Se(Ⅳ) detection in (2), the Se(Ⅳ) spiked recovery experiment was carried out. The same sample was tested three times (sample 1, sample 2, sample 3; sample 2-1, sample 2-2, sample 2-3 respectively). The DPV signals corresponding to the detection of sample 1 were 38.5 V, 37.06 V, and 34.09 V respectively. V, substituting into the standard curve equation y = 60.91746 - 0.4103x, R 2=0.91, the detected concentrations were 54.64 ppm, 58.15 ppm, and 65.38 ppm, the average detected concentration was 59.39 ppm, the standard deviation was 5.48, the RSD was 9.23%, and the recovery rate was 98.98%. The corresponding DPV signals for sample 2 were 22.89 V, 26.50 V, and 20.61 V, respectively. Substituting these values ​​into the standard curve equation y = 60.91746 - 0.4103x, R0... 2 =0.91, the detected concentrations were 92.68 ppm, 83.88 ppm, and 98.24 ppm, respectively, the average detected concentration was 91.60 ppm, the standard deviation was 7.24, the RSD was 7.90%, and the recovery rate was 102%; the experimental results are shown in the figure. Figure 6 See Table 1.

[0063] Depend on Figure 6 The results show that the detection method exhibits good accuracy and repeatability in the detection of Se(Ⅳ) in treated rice. The average recovery rate of sample 1 (60 ppm spiked) was 98.98%, and the average recovery rate of sample 2 (90 ppm spiked) was 102%, both within a reasonable range (the acceptable range of recovery rate is usually 80%~120%). This indicates that the spiked recovery results of this method for Se(Ⅳ) in rice are reliable, and the accuracy and repeatability meet the detection requirements, making it suitable for the quantitative analysis of Se(Ⅳ) in actual samples.

[0064] Table 1

[0065]

[0066] Note: The Se content in the treated rice was 0.00165 ppm, which is a trace level and its impact on the spiked recovery experiment data is negligible.

[0067] Among them, Sample 1 is the average value of Sample 1, Sample 2 and Sample 3, and Sample 2 is the average value of Sample 2-1, Sample 2-2 and Sample 2-3.

[0068] Comparative Example 1

[0069] Preparation of Au-Pd NPs: After centrifuging 4 mL of the gold nanoparticle solution, it was redispersed in 4 mL of water to obtain a dispersion. 600 μL of 0.0375 g / mL sodium hypophosphite solution and 200 μL of 2.9 mg / mL sodium palladium chlorate solution were added to the dispersion and mixed thoroughly until the solution turned black. After centrifugation and washing, the solution was reconstituted to 200 μL to obtain Au-Pd NPs.

[0070] Comparative Example 2

[0071] Preparation of Au-MnO2NPs: 10 mL of 50 μg / mL gold nanoparticle dispersion was mixed evenly with 300 μL of 0.01 g / mL potassium permanganate solution, and a first reducing agent of 4 mg / mL 1 mL (polyacrylic acid, i.e. PAA) solution was added to carry out a reduction reaction. The reaction was stirred and then resuspended in water to obtain Au-MnO2NPs dispersion.

[0072] Feasibility verification

[0073] Eight microliters of 0.00165 g / mL Au-MnO2 NPs composite material dispersion and 0.059 g / mL Au-MnO2-Pd NPs composite material dispersion were respectively drop-coated onto a GCE electrode, and electroreduction curves were obtained after multiple cycles. The experimental results are shown in [Figure number missing]. Figure 3 .

[0074] Figure 3 As shown in Figure a, the electroreduction signal of Au-MnO2-PdNPs hardly changes. Compared with Au-MnO2NPs, Au-MnO2-PdNPs materials have good electrochemical stability and reversibility.

[0075] Figure 3 As shown in Figure b, the DPV peak of Au-MnO2NPs is around 0.5 V, while the DPV peaks of Au-PdNPs and Au-MnO2NPs are around 0 and -0.5 V, respectively. Compared with Au-PdNPs, Au-MnO2NPs have MnO2 as a carrier surface, which allows more Pd to grow, exposes more DPV sites, and has a stronger DPV signal.

[0076] Specificity verification

[0077] 1 mL of 0.01 mol / L As(III), Cd(II), Hg(II), Zn(II), Se(IV) and 1 mL of 0.12 mol / L hydrochloric acid were placed in a headspace vial. 20 μL of the Au-MnO2-Pd composite material dispersion was placed in the headspace vial cap. 1 mL of 0.04 g / mL sodium borohydride was injected into the vial. After sufficient reaction, the liquid in the headspace vial cap formed the test mixture. 8 μL of the test mixture was drop-coated onto the surface of the GCE electrode. The DPV was scanned in a test substrate at pH 7.4. The electrochemical parameters were: scan range 0.8 to -0.8 V. Experimental results are shown in […]. Figure 4 As shown in the figure, Au-MnO2-Pd NPs in the headspace experimental setup are specific for Se(Ⅳ).

[0078] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A highly sensitive method for detecting Se(Ⅳ) based on Au-MnO2-Pd NPs composite materials, characterized in that, Includes the following steps: The test solution containing Se(Ⅳ) and acid were placed in a headspace vial, the dispersion of Au-MnO2-Pd NPs composite material was placed in the headspace vial cap, and the reducing agent solution was injected into the headspace vial. After the reaction, the liquid in the headspace vial cap formed the test mixture. The test mixture was drop-coated onto the surface of the GCE electrode, and then the DPV was scanned in phosphate buffer with a scanning range of 0.8 to -0.8 V to achieve qualitative and quantitative detection of Se(Ⅳ). The Au-MnO2-Pd NPs composite material was prepared by the following method: S1: Mix the gold nanoparticle dispersion with potassium permanganate solution evenly, add the first reducing agent solution to carry out the reduction reaction, stir the reaction and resuspend in water to obtain Au-MnO2 NPs dispersion; S2: Take the Au-MnO2 NPs dispersion obtained in step S1, add the second reducing agent and palladium source solution, mix evenly, and react to obtain the Au-MnO2-Pd NPs composite material; The concentration of the test solution containing Se(Ⅳ) is 0.001~1 mg / mL; The first reducing agent in the first reducing agent solution is selected from polyacrylic acid and / or polyallylamine hydrochloride; The acid is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid.

2. The highly sensitive detection method for Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, The volume concentration of the acid is 0.1%-15%; The concentration of the dispersion of Au-MnO2-Pd NPs composite material is 0.02~0.1 g / mL; The mass ratio of Se(Ⅳ), Au-MnO2-Pd NPs composite material to reducing agent is (10) -6 ~10 -4 : (0.05~0.1): (0.02~0.06).

3. The highly sensitive detection method for Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, The reducing agent in the reducing agent solution is selected from one or more of sodium borohydride, ascorbic acid, and sodium hypophosphite; The concentration of the reducing agent solution is 0.02-0.05 g / mL.

4. The highly sensitive detection method for Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, In step S1, the concentration of the first reducing agent solution is 2~4 mg / mL.

5. The highly sensitive detection method for Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, In step S1, the molar ratio of gold nanoparticles, potassium permanganate, and the first reducing agent is (1~2):(1~3):(0.2~1).

6. The highly sensitive method for detecting Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, In step S1, the concentration of potassium permanganate is 0.01~0.04 g / mL.

7. The highly sensitive detection method for Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, In step S2, the concentration of the second reducing agent solution is 0.03~0.05 g / mL; The second reducing agent in the second reducing agent solution is selected from one or more of sodium hypophosphite, ascorbic acid, and sodium borohydride.

8. The highly sensitive detection method for Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, In step S2, the concentration of the palladium source solution is 2~5 mg / mL.

9. The highly sensitive detection method for Se(Ⅳ) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that, In step S2, the palladium source in the palladium source solution is selected from one or more of sodium palladium chlorate, tetrachloropalladium acid, palladium chloride, and palladium nitrate.

Images