Electrochemical detection method for trace iodide ions in high-chlorine sample based on double-signal strategy

Abstract

The invention provides an electrochemical detection method for trace iodide ions in a high-chlorine sample based on a double-signal strategy, which utilizes a double-response phenomenon that the oxidation peak current and the oxidation peak potential change along with the concentration when a ligand-free silver nanoparticle modified electrode responds to iodide ions. A synchronous calibration relation between current-concentration and potential-concentration logarithm is constructed, and a unique dual-signal detection mode is formed. The mode provides a wider linear range and a lower detection limit, and more importantly, the two independent signals can be mutually verified and supplemented, so that the reliability and the accuracy of a detection result are greatly enhanced, and the inherent defect that a single-signal sensor is easily interfered in a complex matrix is effectively overcome. The method has excellent anti-interference capability, can realize specific and high-selectivity detection of iodide ions in a complex environment containing extremely high-concentration chloride ions, and solves the problem that the performance of an existing sensor in a high-chlorine matrix is severely reduced.

Description

Technical Field

[0001] This invention relates to the field of detection technology, and in particular to an electrochemical detection method for trace iodide ions in high-chlorine samples based on a dual-signal strategy. Background Technology

[0002] Iodine is an essential trace element for maintaining normal thyroid function. Insufficient or excessive intake can lead to serious health problems such as goiter, intellectual disability, hyperthyroidism, and an increased risk of cancer. Therefore, accurate monitoring of iodine ion concentrations in body fluids, especially urine, is crucial for assessing iodine nutritional status and guiding public health policies. On the other hand, with the expansion of nuclear energy applications, nuclear accidents or improper disposal of nuclear waste could release radioactive iodine isotopes into the environment, posing a long-term radioactive and chemical toxicity threat to ecosystems and human health. Developing a rapid, sensitive, accurate, and complex-matrix-compatible iodine ion detection technology is of great practical significance, both in clinical diagnostics and environmental safety monitoring.

[0003] Currently, the main detection techniques for iodide ions include ion chromatography, inductively coupled plasma mass spectrometry, spectrometry, and electrochemical methods. While chromatographic and mass spectrometric methods offer high sensitivity, they typically rely on large, expensive instruments and complex sample pretreatment processes, making them unsuitable for on-site, rapid, and low-cost detection. Electrochemical methods, with their advantages of simple instrumentation, convenient operation, and ease of miniaturization and integration, have demonstrated significant advantages in the field of point-of-care testing. Among these, electrochemical sensors constructed using silver-based materials, based on the specific reaction between silver and iodide ions to form silver iodide precipitate, have received extensive research attention. In recent years, nanomaterials, especially silver nanoparticles, have been used to modify electrodes to improve sensor sensitivity due to their high specific surface area and excellent electrocatalytic properties.

[0004] However, existing electrochemical iodine sensors based on silver nanoparticles still face multiple challenges. First, to obtain uniformly sized and stably dispersed silver nanoparticles during synthesis, surfactants or organic ligands are typically introduced as stabilizers. These residual ligands severely cover the active sites on the nanoparticle surface, hindering electron transfer and significantly weakening their electrocatalytic activity, leading to reduced sensor sensitivity. Although studies have attempted to remove ligands through physical or chemical methods, these processes are often cumbersome and may cause nanoparticle aggregation or structural damage. Second, most electrochemical sensors rely on a single current response signal. In complex real-world samples (such as urine rich in urea and creatinine, and seawater containing high concentrations of chloride and bromide ions), interference from coexisting substances can easily affect the stability and specificity of the current response, resulting in unreliable detection results and a lack of effective built-in correction mechanisms. In particular, in high-chloride matrices (such as seawater and brine), the competitive adsorption and reaction of chloride ions can severely interfere with silver-based iodine sensors, greatly limiting their practical application in key areas such as environmental monitoring and marine chemistry. Therefore, developing a novel electrochemical iodine sensing strategy that can effectively remove ligands to expose active sites, resist interference from complex matrices, and especially operate stably and accurately in high-chlorine environments has become an urgent and challenging task in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an electrochemical detection method for trace iodide ions in high-chlorine samples based on a dual-signal strategy, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides an electrochemical detection method for trace iodide ions in high-chlorine samples based on a dual-signal strategy, the method comprising: S1. Preparation of ligand-free silver nanoparticle modified electrode: alkyl pyridine salt and silver salt are reacted in an alkaline aqueous solution to generate a silver nanoparticle composite material loaded with carbon dots; the composite material is extracted and separated with an organic solvent, and then washed with ethanol to remove the carbon dots to obtain ligand-free silver nanoparticles; the ligand-free silver nanoparticles are loaded onto the electrode surface to prepare a ligand-free silver nanoparticle modified electrode. S2. Construct a dual-signal detection platform: Use a ligandless silver nanoparticle modified electrode as the working electrode, and place it together with the reference electrode and the counter electrode in an electrolyte containing or to be measured iodine ions; S3. Perform electrochemical measurements and acquire dual signals: Apply a scanning voltage to the working electrode using differential pulse voltammetry, and simultaneously record the oxidation peak current signal and the corresponding oxidation peak potential signal generated by iodide ions in a specific potential range; S4. Quantitative analysis based on dual signals: Establish a first linear relationship between the oxidation peak current signal and the iodide ion concentration, and a second linear relationship between the oxidation peak potential signal and the logarithm of the iodide ion concentration, and quantify the iodide ions in the sample through the first linear relationship and / or the second linear relationship.

[0007] Preferably, in step S1, the pH of the alkaline aqueous solution is ≥8, which is adjusted by sodium hydroxide, potassium hydroxide, and ammonia.

[0008] Preferably, in step S1, the alkylpyridine is dodecyl or octadecylpyridine chloride or bromide, with a concentration of 5-200 mM; the silver salt is one or more of silver nitrate, silver chloride, and silver bromide, with a concentration of 5-200 mM; the reaction is carried out at room temperature or under heating conditions (10-100°C). o C) is performed.

[0009] Preferably, in step S1, the ethanol washing is performed 1-10 times until the carbon dots attached to the surface of the silver nanoparticles are removed.

[0010] Preferably, in step S1, the substrate electrode is a glassy carbon electrode, a graphite electrode, or a screen-printed carbon electrode; the loading amount of the ligandless silver nanoparticles on the electrode surface is 0.05-0.30 mg·cm⁻¹. -2 .

[0011] Preferably, in step S2, the electrolyte is a phosphate buffer solution with a pH range of 5.0-9.0.

[0012] Preferably, in step S3, the scanning potential range of the differential pulse voltammetry is -0.4V to -0.5V.

[0013] This invention also provides an application of an electrochemical detection method for trace iodide ions in high-chlorine samples based on a dual-signal strategy for detecting iodide ions in complex matrix samples, including human urine, environmental water, seawater, or their simulated solutions.

[0014] The present invention also provides a portable iodine ion detection device, comprising a screen-printed electrode without ligand silver nanoparticle modification prepared by the electrochemical detection method for trace iodine ions in high chloride samples based on a dual-signal strategy as described in any one of claims 1 to 8, and a portable electrochemical analyzer connected to the electrode, for realizing on-site dual-signal detection of trace samples.

[0015] The present invention achieves the following beneficial technical effects compared to the prior art: This invention provides an electrochemical detection method for trace iodide ions in high-chlorine samples based on a dual-signal strategy. A mild ethanol washing process successfully removes carbon dot ligands from the surface of silver nanoparticles, significantly improving the electrochemical activity and electron transfer efficiency of the material, thus achieving high-sensitivity detection of iodide ions. This method creatively utilizes the dual response law of the oxidation peak current and oxidation peak potential of the ligand-free silver nanoparticle-modified electrode in response to iodide ions, constructing a synchronous calibration relationship between current-concentration and potential-concentration logarithm, forming a unique dual-signal detection mode. This mode not only provides a wider linear range and a lower detection limit, but more importantly, the two independent signals can mutually verify and complement each other, greatly enhancing the reliability and accuracy of the detection results and effectively overcoming the inherent defect of single-signal sensors being susceptible to interference in complex matrices. Particularly noteworthy is the abundant Ag exposed after ligand removal. + The effective catalysis of the iodine oxidation reaction by the active site and the reduction of the reaction potential demonstrate excellent anti-interference ability of this method. It enables specific and highly selective detection of iodide ions in complex environments containing extremely high concentrations of chloride ions, solving the problem of severe performance degradation of existing sensors in high-chlorine matrices. Furthermore, this method can be easily combined with screen-printed electrode technology to construct a portable detection device suitable for rapid on-site analysis of trace amounts of actual samples, exhibiting good practicality, reproducibility, and stability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The diagram shows the synthesis process, morphology, and structural characterization of ligand-free silver nanoparticles in this embodiment of the invention; wherein, (a) is a schematic diagram of the synthesis process, (b) is a UV-Vis absorption spectrum, (c) is a transmission electron microscope image and size distribution statistics, and (d) is a high-resolution transmission electron microscope image.

[0018] Figure 2 The figures show a comparison of the electrochemical performance of silver nanoparticle composite materials under different washing cycles in the embodiments of the present invention; wherein, (a) is an electrochemical impedance spectroscopy, (b) is a bar chart of the corresponding charge transfer resistance value change, (c) is a linear fitting graph of double layer capacitance test, and (d) is a bar chart of the change of electrochemical active area with the number of washing cycles.

[0019] Figure 3The electrochemical behavior of the ligandless silver nanoparticle modified electrode in this embodiment of the invention is shown in the figure. Among them, (a) is a comparison of cyclic voltammetry curves in phosphate buffer containing and without iodide ions, (b) is a comparison of differential pulse voltammetry response of the carbon-dot-loaded silver nanoparticle modified electrode and the ligandless silver nanoparticle modified electrode to iodide ions, (c) is a cyclic voltammetry curve of the ligandless silver nanoparticle modified electrode at different scan rates, and (d) is a linear relationship between the oxidation peak and reduction peak current and the square root of the scan rate.

[0020] Figure 4 The diagram shows the dual-signal detection performance of the ligandless silver nanoparticle modified electrode for iodide ions in the embodiments of the present invention; wherein, (a) is the differential pulse voltammetry curve and the corresponding oxidation peak current-concentration calibration curve (embedded diagram) under different concentrations of iodide ions, (b) is a schematic diagram of the mechanism of the sensitive response of ligandless silver nanoparticles to iodide ions, and (c) is the normalized differential pulse voltammetry curve and the corresponding oxidation peak potential-concentration logarithmic calibration curve (embedded diagram) under different concentrations of iodide ions.

[0021] Figure 5 The following are the anti-interference and stability test results of the sensor in the embodiments of the present invention; wherein, (a) is a selective test bar chart in the presence of multiple coexisting interfering substances, (b) is the detection calibration curve (embedded chart) of iodide ions in simulated seawater in 0.5 M NaCl, (c) is the detection calibration curve (embedded chart) of iodide ions in saturated NaCl solution, and (d) is the long-term stability test result of the sensor.

[0022] Figure 6 The portable detection device constructed according to the embodiments of the present invention and its performance diagram are shown below; (a) is a photograph of the portable electrochemical analyzer and the screen-printed microelectrode, (b) is the differential pulse voltammetric response of the microelectrode to different concentrations of iodine ions and the dual-signal calibration curve (embedded graph), and (c) is the reproducibility test results of seven independently prepared microelectrodes. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The purpose of this invention is to provide an electrochemical detection method for trace iodide ions in high-chlorine samples based on a dual-signal strategy, so as to solve the problems existing in the prior art.

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] This invention provides an electrochemical detection method for trace iodide ions in high-chlorine samples based on a dual-signal strategy. The implementation of this method first relies on the preparation of high-performance ligand-free silver nanoparticle sensing materials. A one-pot method is used, with alkylpyridine acting as both a reducing agent and a stabilizer, to reduce silver salts under alkaline conditions, generating in-situ a composite material of silver nanoparticles loaded with carbon dots. The key innovative step lies in the effective removal of hydrophobic carbon dots coated on the surface of the silver nanoparticles through simple ethanol washing, thereby obtaining ligand-free silver nanoparticles with a clean surface and fully exposed active sites. This process greatly optimizes the electrochemical performance of the material without causing significant nanoparticle aggregation or growth. Subsequently, the obtained ligand-free silver nanoparticle dispersion is drop-coated onto the surface of a pre-treated clean electrode (such as a glassy carbon electrode or a screen-printed carbon electrode), and after drying, a ligand-free silver nanoparticle-modified electrode for iodide ion detection is obtained.

[0027] The modified electrode prepared above is used as the working electrode, forming a three-electrode detection system together with a reference electrode (such as an Ag / AgCl electrode) and a counter electrode (such as a platinum wire electrode), and is immersed in an electrolyte containing the iodide ions to be measured. Detection is preferably performed in a phosphate buffer solution with a pH of 7.0. Differential pulse voltammetry is used for measurement. A scanning potential from -0.4 V to -0.1 V is applied to the working electrode using an electrochemical workstation, and the curve of the response current changing with the potential is recorded simultaneously. A characteristic peak attributable to the electrochemical oxidation of iodide ions can be clearly observed on this curve. The core of this invention lies in recording not only the peak current of this oxidation peak but also its corresponding peak potential. Experiments show that with the increase of iodide ion concentration, the oxidation peak current increases linearly, while the oxidation peak potential shifts regularly in the negative direction and is linearly related to the logarithm of the iodide ion concentration. Therefore, by plotting two independent calibration curves—peak current-concentration and peak potential-logarithm of concentration—dual-signal quantitative detection of iodide ions can be achieved. This dual-signal mode provides internal cross-validation for the detection results, significantly improving the reliability and accuracy of detection in complex matrices.

[0028] To verify the superior performance of the method of the present invention, a detailed description is provided below with reference to specific embodiments and accompanying drawings. Unless otherwise specified, all reagents used in the embodiments are of analytical grade, and the experimental water is ultrapure water.

[0029] Example 1: Preparation of ligand-free silver nanoparticles Weigh out a certain amount of hexadecylpyridine chloride and silver nitrate, and prepare 15 mM hexadecylpyridine chloride solution and 45 mM silver nitrate solution respectively with ultrapure water. Mix 10 mL of hexadecylpyridine chloride solution and 10 mL of silver nitrate solution in a beaker. Under magnetic stirring, slowly add 10 mL of 3 M sodium hydroxide solution to the mixture. The solution color gradually changes from light yellow to dark brown, indicating that the reaction is proceeding. Let the mixture stand at room temperature overnight (approximately 12-24 hours), and a large amount of precipitate will form. Add petroleum ether to the reaction mixture, and extract the silver nanoparticle / carbon dot composite material to the upper organic phase. Separate the upper organic phase and wash it with ethanol 2-4 times, preferably 2 times, centrifuging after each wash. The purpose of washing is to remove the carbon dots attached to the surface of the silver nanoparticles. Dry the washed product under vacuum at 40°C to obtain ligand-free silver nanoparticles. As a control, the sample not washed with ethanol is designated as the silver nanoparticle / carbon dot composite material.

[0030] Figure 1 The synthesis and characterization results of ligand-free silver nanoparticles are presented. Figure 1 a is a schematic diagram of the synthesis process. Figure 1 The UV-Vis absorption spectrum of b shows that the silver nanoparticle / carbon dot composite material has two obvious absorption peaks at 305 nm and 400 nm, which correspond to the surface plasmon resonance absorption peaks of carbon dots and silver nanoparticles, respectively. After washing with ethanol, the absorption of ligand-free silver nanoparticles at 305 nm is significantly reduced, confirming that the carbon dots are effectively removed. Figure 1 Transmission electron microscopy (TEM) images c and 1d show that both the silver nanoparticle / carbon dot composite and the ligandless silver nanoparticles are nearly spherical, with average particle sizes of 4.64 nm and 5.03 nm, respectively. The washing process did not induce significant particle aggregation or growth. High-resolution electron microscopy (HREM) Figure 1 d) shows that both have clear lattice fringes with a spacing of 2.05 Å, corresponding to the crystal planes of face-centered cubic silver.

[0031] Example 2: Preparation of ligand-free silver nanoparticle modified electrode A 3 mm diameter glassy carbon electrode was polished to a mirror finish on chamois leather using 0.3 μm and 0.05 μm alumina polishing powders, followed by ultrasonic cleaning in anhydrous ethanol and ultrapure water for 2 minutes each, and then dried under nitrogen. The ligand-free silver nanoparticles prepared in Example 1 were dissolved in petroleum ether to form a 1 mg / mL dispersion. A 3 μL droplet of the dispersion was injected using a microsyringe and dropped onto the surface of the pretreated glassy carbon electrode. The electrode was then dried under an infrared lamp to obtain a ligand-free silver nanoparticle / glassy carbon electrode. By controlling the droplet volume and concentration, the catalyst loading on the electrode surface was approximately 0.11 mg·cm³. -2Using the same method, a silver nanoparticle / carbon dot / glassy carbon electrode can be prepared as a control electrode using an unwashed silver nanoparticle / carbon dot dispersion.

[0032] Example 3: Electrochemical detection performance and dual-signal calibration All electrochemical tests were performed on a CHI760E electrochemical workstation using a three-electrode system: a ligandless silver nanoparticle / glassy carbon electrode as the working electrode, a saturated Ag / AgCl electrode as the reference electrode, and a platinum wire as the counter electrode. The electrolyte was 0.1 M phosphate buffer, pH 7.0. First, the electrode performance was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. Figure 2 As shown in ab, the charge transfer resistance of the electrode decreases significantly with the increase of the number of ethanol washings, reaching a minimum value after two washings, indicating that electron transfer is smoother after removing carbon dots. Figure 2 The CD data showed that the electrochemical active area reached its maximum after two washes, indicating that the active sites were fully exposed.

[0033] Then, differential pulse voltammetry (DPV) was used for iodide ion detection. The parameters were set as follows: potential range -0.4V to -0.1V, potential increment 4 mV. Different volumes of potassium iodide standard solution were added sequentially to the phosphate buffer solution, varying the concentration from 0.9 μM to 2.5 mM. The DPV curves were recorded after each addition, and the results are shown below. Figure 5 As shown in Figure a, a distinct oxidation peak appears at approximately -0.15 V as the iodide ion concentration increases, and the peak current gradually increases. A plot of peak current against iodide ion concentration shows a good linear relationship in the range of 0.9 μM to 1.4 mM, with the linear equation I = 0.0584 C + 0.123 and a correlation coefficient R0. 2 >0.99. Based on a signal-to-noise ratio of 3, the detection limit is 50 nM. Compared to unwashed silver nanoparticle / carbon dot / glassy carbon electrodes (sensitivity is only 0.0059 μA·μM), this is significantly lower. -1 The sensitivity of the ligandless silver nanoparticle / glassy carbon electrode was improved by approximately 8.9 times.

[0034] More noteworthy is that, such as Figure 4 As shown in Figure c, the oxidation peak potential exhibits a regular negative shift with increasing iodide ion concentration. Plotting the peak potential against the logarithm of iodide ion concentration also reveals a good linear relationship in the range of 2.4 μM to 1.4 mM, with the linear equation Ep = -0.0595logC + 0.0247, R0 2=0.9984, with a slope of 0.0595V, which is in high agreement with the theoretical Nernst slope of a single-electron transfer process, indicating that the reaction is a reversible single-electron process. This potential signal provides a second independent quantitative basis, and the two signals can corroborate each other, together forming a reliable dual-signal detection strategy.

[0035] Example 4: Anti-interference performance and detection of high-chlorine matrix To evaluate the selectivity of the sensor, the effect of common coexisting substances was investigated. In a phosphate buffer solution containing 1 mM potassium iodide, 10 mM Na+ was added... + K + Mg 2+ Ca 2+ Cl - , Br - NO3 - IO3 - SO4 2- SO3 2- CO3 2- And substances such as serine, glucose, and alanine. Figure 5 As shown in a, the presence of these interfering substances has little effect on the current response signal of iodide ions, indicating that the ligandless silver nanoparticle / glassy carbon electrode has excellent selectivity for iodide ions.

[0036] To meet the application requirements of high-chlorine environments, the sensor's performance was tested in 0.5M sodium chloride (simulated seawater) and saturated sodium chloride solutions. Figure 5 As shown in b and 5c, the sensor can still effectively detect iodide ions even in the presence of high concentrations of chloride ions. In 0.5M sodium chloride, the linear range is 8 μM to 2000 μM; in saturated sodium chloride, the linear range is 32 μM to 2000 μM. This demonstrates that the method of this invention has excellent tolerance and practicality in high-chlorine and even saturated chloride ion environments, solving the problem of iodide ion detection in such environments.

[0037] Example 5: Stability, Reproducibility and Real Sample Testing The ligandless silver nanoparticle / glassy carbon electrode was stored at 4°C, and its DPV response to 1 mM potassium iodide was tested periodically. Figure 5 As shown in Figure d, after 14 and 28 days of storage, the current response retained 93.87% and 90.31% of the initial value, respectively, indicating that the sensor has good long-term stability. The relative standard deviation (RSD) of the response current to 1 mM potassium iodide was 0.87% when tested with seven independently prepared ligand-free silver nanoparticle / glassy carbon electrodes; the RSD was 1.73% when tested seven times consecutively with the same electrode, demonstrating excellent inter-electrode reproducibility and measurement repeatability.

[0038] Example 6: Construction of Portable Microelectrodes and Analysis of Actual Samples To facilitate on-site detection, ligand-free silver nanoparticles were modified onto a commercially available screen-printed carbon electrode to prepare a ligand-free silver nanoparticle / screen-printed carbon electrode. This microelectrode was then connected to a portable QTEC500N electrochemical analyzer (e.g.,...). Figure 6 As shown in a), this constitutes a portable detection device. This device requires only 100 μL of sample to complete the test. Iodide ions are detected in 0.1 M phosphate buffer, with a DPV scan range of -0.4 V to -0.2 V. Figure 6 As shown in b, within the concentration range of 8 μM to 240 μM, both peak current and peak potential showed a linear relationship with iodide ion concentration (or its logarithm), with detection limits based on current and potential of 0.8 μM and 1.38 μM, respectively. The RSD of the response of seven independently prepared ligand-free silver nanoparticles / SPE to 100 μM potassium iodide was 2.50% (…). Figure 6 c), which shows good reproducibility.

[0039] The portable device was applied to test the recovery rate of iodide ions in real samples using the standard addition method. Samples included urine from healthy individuals, river water, and simulated seawater. All samples were filtered through a 0.22 μm filter and diluted 10-fold with 0.1 M phosphate buffer before use. As shown in Table 1, regardless of whether the current-based or potentiometric method was used, the recovery rates of iodide ions added to the three real samples at different concentrations ranged from 93.14% to 105.00%, with RSDs all below 10%, indicating that the method of this invention has high accuracy and reliability in the detection of complex real-world samples.

[0040] Table 1 shows the recovery rate of iodine ions in actual samples based on the lf-AgNPs / SPE electrode (n = 3).

[0041] sample Added amount (µM) Current method Potentiometric method Measured value ± standard deviation (µM) Recovery rate (%) RSD (%) Measured value ± standard deviation (µM) Recovery rate (%) RSD (%) Urine 2524.14 ± 0.8796.563.6023.88 ± 2.3295.529.7110099.28 ±1.7499.281.7593.14 ± 9.0793.149.68 River water 2524.99 ± 0.9899.963.9224.61 ±1.8098.407.3110096.61 ± 2.7396.612.8396.01 ± 7.0296.017.29 Simulated seawater 2525.50 ± 0.78102.003.0626.25 ± 2.26105.008.61100104.51 ± 2.94104.512.81102.47 ±8.81102.478.60 In summary, this invention achieves high-performance ligand-free silver nanoparticle sensing materials through a simplified ligand removal process. Furthermore, it innovatively utilizes the dual signal change patterns of current and potential in response to iodide ions to construct a novel electrochemical detection method with high sensitivity, high selectivity, strong anti-interference ability, and particular suitability for high-chlorine environments. This method is easily integrated with miniaturized electrode technology, providing an effective technical solution for the on-site, rapid, and reliable detection of trace amounts of iodide ions in environmental water bodies and clinical samples.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] It should be noted that the components mentioned in the above embodiments are all general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0044] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. A method for electrochemical detection of trace iodide ions in high-chlorine samples based on a two-signal strategy, characterized in that, The method comprises: S1. Preparing a ligand-free silver nanoparticle modified electrode: reacting an alkylpyridine salt with a silver salt in an alkaline aqueous solution to generate a silver nanoparticle composite material loaded with carbon dots; after the composite material is separated by extraction with an organic solvent, the carbon dots are removed by washing with ethanol to obtain ligand-free silver nanoparticles; and loading the ligand-free silver nanoparticles on the surface of an electrode to prepare a ligand-free silver nanoparticle modified electrode; S2. Constructing a dual-signal detection platform: using the ligand-free silver nanoparticle modified electrode as a working electrode, which is placed together with a reference electrode and a counter electrode in an electrolyte containing or to-be-detected iodine ions; S3. Performing electrochemical measurement and obtaining dual signals: applying a scanning voltage to the working electrode by differential pulse voltammetry, and synchronously recording the oxidation peak current signal and the corresponding oxidation peak potential signal of iodine ions in a specific potential interval; S4. Quantitative analysis based on dual signals: establishing a first linear relationship between the oxidation peak current signal and the concentration of iodine ions, and a second linear relationship between the oxidation peak potential signal and the logarithm of the concentration of iodine ions, and quantifying the iodine ions in the sample through the first linear relationship and / or the second linear relationship.

2. The method according to claim 1, wherein the method is characterized by, In step S1, the pH of the alkaline aqueous solution is ≥8, which is controlled by sodium hydroxide, potassium hydroxide, or ammonia water.

3. The method according to claim 1, wherein the method is characterized by, In step S1, the alkylpyridine is chlorinated or brominated dodecyl to octadecyl pyridine, the concentration is 5-200 mM; the silver salt is one or several of silver nitrate, silver chloride, silver bromide, the concentration is 5-200 mM; the reaction is carried out at room temperature or under heating conditions (10-100 o C).

4. The method according to claim 1, wherein the method is characterized by, In step S1, the number of ethanol washes is 1-10 times until the carbon dots attached to the surface of the silver nanoparticles are removed.

5. The method according to claim 1, wherein the method is characterized by, In step S1, the base electrode is a glassy carbon electrode, a graphite electrode or a screen-printed carbon electrode; the loading amount of the ligand-free silver nanoparticles on the electrode surface is 0.05-0.30 mg·cm -2 .

6. The method according to claim 1, wherein the method is characterized by, In step S2, the electrolyte is a phosphate buffer with a pH range of 5.0-9.

0.

7. The method according to claim 1, wherein the method is characterized by, In step S3, the scanning potential interval of the differential pulse voltammetry is -0.4V to -0.5V.

8. Use of the method for electrochemical detection of trace iodide ions in a high-chloride sample based on a dual-signal strategy according to any one of claims 1 to 7 for detecting iodide ions in a complex matrix sample, characterized in that, The complex matrix sample includes human urine, environmental water, seawater, or a simulated liquid thereof.

9. A portable iodide ion detection device characterized by, The device comprises a ligand-free silver nanoparticle modified screen-printed electrode prepared by the dual-signal strategy based electrochemical detection method of trace iodine ions in high-chlorine samples according to any one of claims 1 to 7, and a portable electrochemical analyzer connected to the electrode, which is used to realize on-site dual-signal detection of trace samples.

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