High-sensitivity Se (IV) detection method based on Au-MnO2-Pd NPs composite material

Abstract

The invention relates to a Se (IV) high-sensitivity detection method 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 liquid of an Au-MnO2-Pd NPs composite material in a headspace bottle cap, injecting a reducing agent solution into the headspace bottle, and forming a to-be-detected mixed solution from the liquid of the headspace bottle cap after reaction; and dispensing the mixed solution to be detected on the surface of the GCE electrode, and scanning DPV in the test base solution to realize qualitative and quantitative detection of Se (IV). According to the invention, Se (IV) in the solution is reduced by sodium borohydride to generate H2Se gas, the H2Se gas reacts with the Au-MnO2-Pd NPs composite material with electrochemical activity, and high-sensitivity detection of Se (IV) in the solution is realized in combination with DPV signal decline.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of selenium detection, in particular to a method for high-sensitivity detection of Se (IV) based on an Au-MnO2-Pd NPs composite material. BACKGROUND

[0002] Selenium is an essential trace element for human body, and the intake amount needs to be maintained at 40-400 mu g / day, and excessive or insufficient intake will cause health risks (such as damage to the nervous system, cardiovascular diseases, etc.). In the water environment, selenium mainly exists in the form of selenate (Se (VI)) and selenite (Se (IV)), and Se (IV) is more toxic, has greater solubility and stronger biological accumulation. In addition, Se (IV) threatens the ecosystem and human health after enrichment through the food chain. Therefore, it is necessary to develop a rapid and sensitive detection method for the quantitative analysis of selenium in food, soil and water.

[0003] Electrochemical sensors have the advantages of simple equipment, high sensitivity and easy operation. Currently, the commonly used electroactive probes are mainly electrochemical reduction labels, and the electron transfer inherent in the electrochemical oxidation process of metals from high valence to low valence produces an electrochemical oxidation peak. Metals and metal oxides not only exhibit good electrochemical oxidation signals under mild neutral conditions, but also show adjustable signals by controlling the composition, size and structure.

[0004] In the conventional detection method for detecting Se (IV) at present, although the spectral technology has high precision, the equipment cost is high; the chromatography-spectroscopy combined technology is complex to operate; therefore, it is urgent to provide a more sensitive method for detecting Se (IV) in food, soil and water. SUMMARY

[0005] To solve the above technical problems, the application provides a method for high-sensitivity detection of Se (IV) based on an Au-MnO2-Pd NPs composite material. In the application, sodium borohydride is used to reduce Se (IV) in the solution to generate H2Se gas, which reacts with the electrochemically active Au-MnO2-Pd NPs composite material, and the DPV signal decreases, thereby realizing high-sensitivity detection of Se (IV) in the solution.

[0006] The purpose of the application is to provide a method for high-sensitivity detection of Se (IV) based on an Au-MnO2-Pd NPs composite material, which comprises the following steps: The solution to be measured containing Se (IV) and acid are placed in a headspace bottle, a dispersion of the Au-MnO2-Pd NPs composite material is placed in the headspace bottle cap, and a reducing agent solution is injected into the headspace bottle, and the liquid in the headspace bottle cap forms a mixed solution to be measured after reaction; Dropping the mixed solution to be tested on the surface of the GCE electrode, and then scanning DPV in the test base solution (phosphoric acid buffer solution with pH=7.4~8.04), the scanning range is 0.8~-0.8 V, so as to realize qualitative and quantitative detection of Se(Ⅳ).

[0007] In some embodiments of the present application, the concentration of the Se(Ⅳ)-containing solution to be tested is 0.001~1 mg / mL.

[0008] In some embodiments of the present application, the volume concentration of the acid is 0.1%-15%; The acid is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid; the present application can provide an acidic environment by adding an acid, promote Se (Ⅳ) to be reduced to H2Se gas by a reducing agent (such as NaBH4) (reaction formula: Se(IV)+BH4 - +H + →H3BO3+H2Se+H2), ensure the smooth progress of the reduction reaction. Maintain the reduction activity of the reducing agent (such as NaBH4), which is more prone to release hydrogen anions under acidic conditions, enhance the reduction ability to Se (Ⅳ). Inhibit the generation of other interfering gases, reduce the influence of reducing substances in the matrix, and improve the specificity of detection.

[0009] Further, when the acid is hydrochloric acid, the volume concentration of the acid is 0.1~0.5% (0.012-0.06 mol / L); when the acid is sulfuric acid, the acid concentration is 5%-15% (v / v), too high may lead to sodium borohydride decomposition too fast, too low the acidity is insufficient to affect H2Se generation. When the acid is nitric acid, the acid concentration is 5%-10% (v / v), because nitric acid has oxidizing property, too high concentration may oxidize H2Se, interfere with detection. When the acid is organic acid (such as acetic acid), because the acidity is weak, it cannot provide enough H + To generate H2Se efficiently, it is not recommended to use.

[0010] The concentration of the dispersion of the 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 and reducing agent is (10 -6 ~10 -4 ): (0.05~0.1): (0.02~0.06).

[0011] In some embodiments of the present application, 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; The solvent of the reducing agent solution is phosphoric acid buffer solution.

[0012] In the present application, the structure of "bottle body + headspace" of the headspace bottle can strictly separate the liquid phase reaction and the gas phase reaction. Specifically, the bottom liquid phase Se (IV) and the reducing agent (such as NaBH4, etc.) generate H2Se gas under acidic conditions, which diffuses into the top and reacts with the pre-placed Au-MnO2-Pd NPs composite material to ensure that only the target gas participates in the subsequent reaction. The closed environment of the headspace bottle can make H2Se gas enrich in the top space, thereby improving the reaction efficiency with the Au-MnO2-Pd NPs composite material droplets. The actual sample (such as food, water) contains -SH, S 2- substances (such as Na2S, etc.), if directly mixed, these substances will react with the beacon Pd of the composite material Au-MnO2-Pd NPs, simulating the false positive signal of "Se (IV) present". The headspace bottle only allows H2Se to enter the top reaction, which significantly reduces the matrix interference.

[0013] In some embodiments of the present application, the Au-MnO2-Pd NPs composite material is prepared by the following method: S1: uniformly mix the gold nanoparticle dispersion liquid with the potassium permanganate solution, add the first reducing agent solution to undergo a reduction reaction, stir the reaction and resuspend in water to obtain an Au-MnO2 NPs dispersion liquid; S2: take the Au-MnO2 NPs dispersion liquid obtained in step S1, uniformly mix the second reducing agent solution and the palladium source solution, and react to obtain the Au-MnO2-Pd NPs composite material.

[0014] In some embodiments of the present application, in step S1, the molar ratio of the gold nanoparticle dispersion liquid, potassium permanganate and polyacrylic acid is (1-2): (1-3): (0.2-1); The concentration of the potassium permanganate is 0.01-0.04 g / mL; the present application uses potassium permanganate as the manganese source of the MnO2 shell layer and the precursor, and in the preparation of Au-MnO2 nanoparticles, KMnO4 provides manganese elements, which are converted to MnO2 and uniformly coated on the surface of the gold nanoparticles under the reduction of the structure directing agent (such as polyacrylic acid), forming a core-shell structure.

[0015] The concentration of the first reducing agent solution is 2-4 mg / mL; The first reducing agent in the first reducing agent solution is selected from polyacrylic acid and / or polyallylamine hydrochloride (PAH). The present application uses polyacrylic acid (PAA) and / or polyallylamine hydrochloride (PAH) as a reducing agent and a structure directing agent, which participates in the reduction reaction of potassium permanganate (KMnO4) to promote the deposition of MnO2 on the surface of the gold nanoparticles to form a shell layer.

[0016] The reaction temperature of the reduction reaction is 25-30°C, and the reaction time is 30-60 min.

[0017] 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.

[0018] In some embodiments of the present invention, in step S2, the concentration of the palladium source solution is 2-5 mg / mL.

[0019] 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, tetrachloropalladic acid, palladium chloride and palladium nitrate.

[0020] In some embodiments of the present invention, the standard curve for quantitative detection is prepared by the following method: The test solution and hydrochloric acid were placed in a headspace bottle, the Au-MnO2-Pd NPs composite material dispersion was placed in the headspace bottle cap, sodium borohydride was injected into the bottle, and after sufficient reaction, the liquid in the headspace bottle cap formed a test mixture; 8 μL of the test mixture was dropwise applied to the surface of the GCE electrode, and DPV was scanned in a phosphate buffer solution with a pH of 7.4. The electrochemical parameters were: scanning range 0.8~-0.8 V.

[0021] In some embodiments of the present invention, the concentration of the test solution is 0.001-1 mg / mL.

[0022] Experimental principle of the present invention: The core mechanism of the present 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 electrochemical signal changes. The specific process is as follows: Conversion of Se(IV) to volatile H2Se: In the sample detection system, Se(IV) first undergoes chemical reduction reaction. + ), BH4 provided by sodium borohydride - 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 Se(IV), which is not easily reacted directly, into H2Se gas, which is easy to diffuse and react, through chemical reduction, laying the foundation for subsequent interaction with the detection material.

[0023] Reaction of H2Se with Pd: The generated H2Se gas reacts rapidly with the Pd component (including tetravalent Pd, divalent Pd and Pd nanoparticles) in the Au-MnO2-Pd NPs composite material in the headspace single drop. In this process, H2Se is oxidized to elemental selenium (Se 0 ) as a reducing agent, while the high-valence Pd (tetravalent, divalent) is reduced to low-valence Pd, which further combines to form Se-Pd composite. The generated Se 0 binds with the electrochemical beacon pd in the Au-MnO2-Pd NPs composite material to form Au-MnO2-Pd-Se aggregates.

[0024] DPV signal change and quantitative analysis of Se(IV): The high-valence Pd is reduced to low-valence Pd, and its electrochemical activity changes; the generated Se 0 covers the active sites of Pd, hindering the electron transfer between Pd and the electrode surface. These two effects work together to significantly reduce the differential pulse voltammetry (DPV) signal of Pd.

[0025] Since the amount of H2Se generated is positively correlated with the initial Se(IV) concentration, the degree of reaction with Pd and the coverage of Se 0 also increase with the increase of Se(IV) concentration, resulting in a quantitative relationship between the reduction amplitude of DPV signal and Se(IV) concentration, realizing multi-color quantitative analysis of Se(IV) in solution and achieving high-sensitivity detection.

[0026] In summary, through the tandem mechanism of "chemical conversion-specific reaction-signal response", the target reaction of H2Se with Pd and the quantitative change of electrochemical signal are used to realize sensitive detection of Se(IV).

[0027] The above technical solutions of the present application have the following advantages compared with the prior art: (1) High specificity: the target reaction between H2Se and Pd can reduce the influence of other components and improve the specificity of detection.

[0028] (2) High sensitivity: through the tandem mechanism of "chemical conversion-specific reaction-signal response", the amount of H2Se generated is positively correlated with the Se(IV) concentration, and the degree of reaction and the change of signal are quantitatively related to the Se(IV) concentration, which can realize high-sensitivity detection.

[0029] (3) Good quantitative relationship: the reduction amplitude of DPV signal is positively related to the Se(IV) concentration, which can ensure the accuracy of the detection results. BRIEF DESCRIPTION OF DRAWINGS

[0030] For the purpose of making the content of the present application more easily understood, the present application is further described in detail below according to the specific embodiments of the present application and in conjunction with the drawings, in which, Figure 1 are the characterization figures of Au NPs, Au-MnO2 NPs and Au-MnO2-Pd NPs obtained in Example 1 of the present application.

[0031] Figure 2 are the chemical compositions and valence states of Au, MnO2 and Pd in Au-MnO2 NPs and Au-MnO2-Pd NPs analyzed by XPS in Example 1 of the present application.

[0032] Figure 3 are the electrochemical reduction curves of Au-MnO2 NPs (a) and Au-MnO2-Pd NPs (b) in Example 1 of the present application. Figure 3 Figure 3

[0033] Figure 4 are the influences of different ions on the detection signal in Example of the present application.

[0034] Figure 5 are the electrochemical DPV responses of solutions containing different concentrations of Se(IV) and the standard curve in the present application.

[0035] Figure 6 are the actual sample detection results in Example of the present application. DETAILED DESCRIPTION

[0036] The present application is further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present application and implement it, but the embodiments are not limiting to the present application.

[0037] Example 1 This embodiment provides a high-sensitivity Se(IV) detection method based on Au-MnO2-Pd NPs composite material, which is specifically as follows: (1) Preparation steps of Au-MnO2-Pd NPs composite material: S1: Preparation of 18 nm Au NPs: take 500 μL of 1 wt% chloroauric acid solution, dilute to 50 mL with ultrapure water, heat and boil, 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; ​​S2: Au-MnO2NPs solution preparation: 10 mL of Au NPs solution obtained in step S1 was centrifuged at 8000 r for 5 min, and then redispersed in 10 mL of water to obtain a dispersion liquid. The dispersion liquid was mixed with 300 μL of 0.01 g / mL potassium permanganate, and 1 mL of 4 mg / mL polyacrylic acid was added to perform a reduction reaction. After stirring for 30 min, the solution turned brown. The solution was centrifuged at 8000 r for 5 min, and then dispersed in 1 mL of water to obtain an Au-MnO2NPs solution. S3: Au-MnO2-Pd NPs preparation: 200 μL of Au-MnO2NPs solution obtained in step S2 was dispersed in 4 mL of water, and 600 μL of 0.0375 g / mL sodium hypophosphite solution and 200 μL of 2.9 mg / mL sodium palladium chlorate solution were sequentially added and mixed at 35°C for 10 min. The solution turned black. The solution was centrifuged and redispersed in 200 μL of ultrapure water to obtain an Au-MnO2-Pd NPs composite dispersion liquid.

[0038] The Au NPs, Au-MnO2NPs, and Au-MnO2-Pd NPs obtained above were subjected to structural characterization and ultraviolet-visible absorption spectrum detection. The experimental results are shown in Figure 1 and Figure 2 ; wherein, Figure 1 Fig. a is a TEM image of Au NPs, and the average size is 18.0 ± 0.2 nm; Fig. b is a TEM image of Au-MnO2NPs, and the average size is 81.5 ± 0.4 nm; Fig. c is a TEM image of Au-MnO2-Pd NPs, and the average size is 6.27 ± 0.35 nm; Fig. d is an ultraviolet-visible absorption spectrum of Au NPs, Au-MnO2NPs, and Au-MnO2-Pd NPs. The inset is a wine-red Au NPs solution, a brown Au-MnO2NPs solution, and a black Au-MnO2-Pd NPs solution. Au NPs exhibit an ultraviolet absorption peak at 520 nm, and the absorption peak is red-shifted after MnO2 is loaded on Au NPs.

[0039] Figure 2 The valence states of Au, Mn, and Pd in Au-MnO2NPs and Au-MnO2-Pd NPs were analyzed by XPS. Figure 2 Fig. a: Au XPS spectrum of Au-MnO2NPs shows peaks at 80.50 eV and 85.5 eV, which correspond to Au (0) 4f 7 / 2 and Au (0) 4f 5 / 2. Fig. b: 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: Au XPS spectrum of Au-MnO2-PdNPs shows peaks at 83.50 eV and 87.2 eV corresponding to Au (0) 4f 7 / 2 and Au (0) 4f 5 / 2. Figure d: Two Pd 3d peaks at 334.6 eV and 339.9 eV can be observed in the Pd XPS spectrum of Au-MnO2-PdNPs, 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+ .

[0040] The Au NPs, Au-MnO2NPs, and Au-MnO2-Pd NPs obtained above were subjected to multiple cycles of electroreduction experiments. Figure 3 ;Depend on Figure 3 As shown in Figure a, the electrochemical signal of the Au-MnO2NPs modified glassy carbon electrode decreased significantly after three cycles, while the electrochemical signal of the Au-MnO2-PdNPs modified glassy carbon electrode remained almost unchanged after three cycles. Figure 3 As can be seen from Figure b, by comparing the DPV signals of Au-MnO2NPs, Au-MnO2-Pd NPs, and Au-Pd NPs in the figure, it can be seen that the DPV peak of Au-MnO2NPs is near 0.5 v, and the DPV peaks of Au-Pd NPs and Au-MnO2-Pd NPs are both near 0 and -0.5 v. Compared with Au-PdNPs, Au-MnO2NPs have MnO2 as the carrier surface, which can grow more Pd, expose more DPV sites, and have a stronger DPV signal.

[0041] (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 bottle, 20 μL of the Au-MnO2-Pd NPs composite material dispersion was placed in the headspace bottle cap, 1 mL of 0.04 g / mL sodium borohydride was injected into the bottle, and after reacting at room temperature for 15 minutes, the liquid in the headspace bottle cap formed the test mixture; 8 μL of the test mixture was dropped on the surface of the GCE electrode, and a saturated calomel electrode was used as the reference electrode and a platinum electrode was used as the counter electrode. DPV was scanned in a phosphate buffer solution of pH=7.4. The electrochemical parameters were: scanning range 0.8~-0.8V. The experimental results are shown in Figure 5From the figure: DPV peak intensity in the concentration range of 1 ppm to 100 ppm decreases with the increase of Se(IV) concentration. The detection limit of Se(IV) detected by the above method is 0.335 ppm. In 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 Se(IV) concentration, and the linear relationship is: y = 60.91746-0.4103x, wherein x is the concentration of Se(IV), unit, ppm; y is the DPV signal, and the correlation coefficient R 2 =0.91.

[0042] (3) Actual sample detection: In the treated rice mixed solution (treatment steps: 0.5 g of rice is added with 5 mL of 5wt% nitric acid, the extraction temperature is 100°C, the water bath extraction is 10 min, and it needs to be shaken every two minutes to ensure that the sample is uniformly heated. After the reaction is completed and cooled to room temperature, the pH is adjusted to neutral with 0.5wt% sodium hydroxide, and finally the volume is adjusted to 10 mL. At this time, the content of Se element in the rice mixed solution is 0.00165 ppm), a known amount of Se(IV) standard solution is added to obtain sample one with a Se(IV) concentration of 60 ppm and sample two with a concentration of 90 ppm. According to the detection method of Se(IV) in (2), the Se(IV) standard recovery experiment is carried out, and the same sample is repeatedly detected three times (sample 1, sample 2, sample 3; sample 2-1, sample 2-2, sample 2-3). The corresponding DPV signals of sample one are 38.5 V, 37.06 V and 34.09 V, respectively. Substitute the standard curve equation y = 60.91746-0.4103x, R 2 =0.91, the detection concentrations are 54.64 ppm, 58.15 ppm and 65.38 ppm, respectively, the average detection concentration is 59.39 ppm, the standard deviation is 5.48, the RSD is 9.23%, and the recovery rate is 98.98%; the corresponding DPV signals of sample two are 22.89 V, 26.50 V and 20.61 V, respectively. Substitute the standard curve equation y = 60.91746-0.4103x, R 2 =0.91, the detection concentrations are 92.68 ppm, 83.88 ppm and 98.24 ppm, respectively, the average detection concentration is 91.60 ppm, the standard deviation is 7.24, the RSD is 7.90%, and the recovery rate is 102%; the experimental results are shown in Figure 6 and Table 1.

[0043] From Figure 6It can be seen that the detection method shows good accuracy and repeatability for the detection of Se (IV) in treated rice. The average recovery rate of sample one (spiked with 60 ppm) is 98.98%, and the average recovery rate of sample two (spiked with 90 ppm) is 102%, both of which are within the reasonable range (usually the acceptable range of recovery rate is 80%~120%), indicating that the method is reliable for the recovery experiment of Se (IV) in rice, and the accuracy and repeatability can meet the detection requirements, and is suitable for quantitative analysis of Se (IV) in actual samples.

[0044] Table 1

[0045] Note: The content of Se element in treated rice is 0.00165 ppm, which belongs to trace level, and the influence on the data of the spiked recovery experiment can be ignored.

[0046] Among them, sample one is the average value of sample 1, sample 2 and sample 3, and sample two is the average value of sample 2-1, sample 2-2 and sample 2-3.

[0047] Comparative example 1 Au-Pd NPs preparation: 4 mL of the gold nanoparticle solution was centrifuged and then redispersed in 4 mL of water to obtain a dispersion liquid. 600 μL of 0.0375 g / mL sodium hypophosphite solution and 200 μL of 2.9 mg / mL palladium sodium chloroplatinite solution were added to the dispersion liquid in sequence and mixed uniformly. The solution turned black, and the Au-Pd NPs were obtained by centrifugal washing and redispersion in 200 μL.

[0048] Comparative example 2 Au-MnO2NPs preparation: 10 mL of 50 μg / mL gold nanoparticle dispersion liquid was mixed uniformly with 300 μL of 0.01 g / mL potassium permanganate solution. The first reducing agent 4 mg / mL 1 mL (polyacrylic acid, PAA) solution was added to generate a reduction reaction. The reaction was stirred and resuspended in water to obtain Au-MnO2NPs dispersion liquid.

[0049] Feasibility verification 8 microliters of 0.00165 g / mL Au-MnO2NPs composite material dispersion liquid and 0.059 g / mL Au-MnO2-PdNPs composite material dispersion liquid were respectively dropped on the GCE electrode for multiple cycle reduction curves. The experimental results are shown in Figure 3 .

[0050] Figure 3As can be seen from Fig. 2, the Au-MnO2-Pd NPs have almost no change in the electro-reduction signal, and compared with the Au-MnO2 NPs, the Au-MnO2-Pd NPs material has good electrochemical stability and reversibility.

[0051] Figure 3 As can be seen from Fig. 2, the Au-MnO2-Pd NPs have almost no change in the electro-reduction signal, and compared with the Au-MnO2 NPs, the Au-MnO2-Pd NPs material has good electrochemical stability and reversibility.

[0052] Specificity verification 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 bottle, 20 μL of the Au-MnO2-Pd composite material dispersion liquid was placed in the headspace bottle cap, 1 mL of 0.04 g / ml sodium borohydride was injected into the bottle, and after sufficient reaction, the liquid in the headspace bottle cap formed a mixed solution to be tested; 8 μL of the mixed solution to be tested was dropped and coated on the surface of the GCE electrode, and DPV was scanned in a test base solution with pH=7.4, and the electrochemical parameters were: scanning range 0.8~ -0.8V. The experimental results are shown in Fig. 6. Figure 4 As can be seen from Fig. 6, the Au-MnO2-Pd NPs have specificity for Se(IV) in the headspace experimental device.

[0053] Obviously, the above examples are only examples for clearly illustrating, and are not limited to the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A highly sensitive detection method for Se(IV) based on Au-MnO2-Pd NPs composite material, characterized in that: The following steps are involved: The Se(Ⅳ)-containing test solution and acid are placed in a headspace bottle, the dispersion of the Au-MnO2-Pd NPs composite material is placed in the headspace bottle cap, and the reducing agent solution is injected into the headspace bottle. After the reaction, the liquid in the headspace bottle cap forms the test mixture; The mixed solution to be tested was dropped onto the surface of the GCE electrode, and then DPV was scanned in phosphate buffer over a range of 0.8 to -0.8 V to achieve qualitative and quantitative detection of Se(Ⅳ). The Au-MnO2-Pd NPs composite material is prepared by the following method: S1: Mix the gold nanoparticle dispersion and potassium permanganate solution evenly, add the first reducing agent solution to cause a reduction reaction, stir the reaction and resuspend in water to obtain an Au-MnO2 NPs dispersion; S2: taking the Au-MnO2 NPs dispersion obtained in step S1, adding a second reducing agent and a palladium source solution, mixing them evenly, and reacting to obtain the Au-MnO2-Pd NPs composite material.

2. The method for highly sensitive detection of Se(IV) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that: The concentration of the test solution containing Se(Ⅳ) is 0.001~1 mg / mL.

3. The method for highly sensitive detection of 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 composites was 0.02~0.1 g / mL; The mass ratio of Se(Ⅳ), Au-MnO2-Pd NPs composite material and reducing agent is (10 -6 ~10 -4 ):(0.05~0.1):(0.02~0.06).

4. The method for highly sensitive detection of 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.

5. The method for highly sensitive detection of Se(IV) based on Au-MnO2-Pd NPs composite material according to claim 1, characterized in that: In step S1, the first reducing agent in the first reducing agent solution is selected from polyacrylic acid and / or polyallylamine hydrochloride; The concentration of the first reducing agent solution is 2-4 mg / mL.

6. The method for highly sensitive detection of 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).

7. The method for highly sensitive detection of 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.

8. The method for highly sensitive detection of 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.

9. The method for highly sensitive detection of 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.

10. The method for highly sensitive detection of 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, tetrachloropalladic acid, palladium chloride and palladium nitrate.

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